ASSOCIATION BETWEEN WEATHER AND WELL-BEING OF PATIENTS WITH CORONARY ARTERY DISEASE

LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY

Dalia Stroputė

ASSOCIATION BETWEEN

WEATHER AND WELL-BEING

OF PATIENTS WITH CORONARY

ARTERY DISEASE

Doctoral Dissertation Biomedical Sciences,

Public Health (09B)

Dissertation was prepared at the Behavioral Medicine Institute, Lithuanian University of Health Sciences, Medical Academy, during 2009-2014.

Scientific Supervisor

Prof. Dr. Ričardas Radišauskas

(Lithuanian University of Health Sciences, Medical Academy, Biomedi-cal Sciences, Public Health – 09B)

Consultant:

Habil. Dr. Robertas Bunevičius

(Lithuanian University of Health Sciences, Medical Academy, Biomedi-cal Sciences, Medicine – 06B)

CONTENT

LIST OF ABBREVIATIONS ... 5

INTRODUCTION ... 6

1. REVIEW OF LITERATURE ... 10

1.1. The weather-health relationship ... 10

1.1.1. Cardiovascular diseases and weather conditions ... 11

1.1.2. The relationship between weather conditions and behavioral and mental disorders ... 16

1.1.3. Influence of weather variables on pain ... 20

1.1.4. Increased health risk and seasonality ... 24

1.2. Subjective weather-related well-being ... 25

1.3. Psychological distress, personality traits and coronary artery disease ... 28

1.4. Recent biometeorology researches in Lithuania ... 30

1.5. Summary of review of literature ... 32

2. MATERIAL AND METHODS ... 34

2.1. Subjects and procedure ... 34

2.2. Methods ... 38

2.2.1. Well-being ... 38

2.2.2. Personality and emotional distress ... 39

2.2.3. Weather data ... 39

2.3. Statistical analysis ... 40

3. RESULTS ... 44

3.1. Type D (distressed) personality and its assessment with the DS14 in patients with coronary artery disease (Stage I) ... 44

3.1.1. Baseline characteristics of patients ... 44

3.1.2. Internal validity and temporal stability ... 44

3.1.3. Construct validity ... 46

3.1.4. Increased vulnerability for poor mental health ... 47

3.2. Psychometric properties of the Palanga self-assessment diary for weather sensitivity in patients with coronary artery disease (Stage II) .... 48

3.3. Associations between the subjective well-being of patients with coronary artery disease and the weather parameters (Stage II) ... 55

3.3.1. The descriptive statistic of PSAD-WS ... 55

3.3.2. Weather parameters across study period ... 56

3.3.3. Patient’s characteristics stratified by self-report weather sensitivity ... 58

3.3.4. Associations between subjective well-being and weather parameters: univariate analysis ... 59

3.3.5. Associations between subjective well-being and weather

parameters: multivariate approach ... 61

3.3.6. Associations between subjective weather-related well-being in patients with CAD and anxiety, depression and personality... 70

3.3.7. Factors associated with subjective well-being of patients with CAD evaluated by PSAD-WS ... 77

4. DISCUSSION ... 85

4.1. Type D (distressed) personality and its assessment with the DS14 in patients with coronary artery disease ... 85

4.2 Psychometric properties of the Palanga self-assessment diary for weather sensitivity ... 86

4.3. Associations between subjective well-being of patients with coronary artery disease and weather parameters ... 87

CONCLUSIONS ... 95

STRENGTHS AND LIMITATIONS OF THE STUDY AND NEED FOR FURTHER RESEARCH ... 96

PRACTICAL RECOMMENDATIONS ... 97

REFERENCE LIST ... 98

PUBLICATIONS ON THE DISSERTATION THEME ... 120

OTHER PUBLICATIONS AND THE PRESENTATIONS ON THE DISSERTATIONS THEME ... 120

ANNEXES ... 122

LIST OF ABBREVIATIONS

°C – The degree Celsius

BMI – Body mass index

CAD – Coronary artery disease

DS14 – 14 item Type D personality scale EFA – Exploratory factor analysis

HADS – Hospital Anxiety and Depression Scale HADS-A – HADS Anxiety subscale

HADS-D – HADS Depression subscale

hPa – Hectopascal

KMO – Kaiser-Meyer-Olkin test

m/s – Meters per second

MI – Myocardial infarction

NA – Negative affectivity NE – Northeast (wind direction) NW – Northwest (wind direction) NYHA – New York Heart Association

OR – Odds ratio

PCA – Principal component analysis PCI – Percutaneous coronary intervention

PSAD-WS – Palanga self-assessment diary for weather sensitivity SE – Southeast (wind direction)

SI – Social inhibition

SW – Southwest (wind direction) TIPI – Ten Item Personality Inventory W/m2 _{– Watts per square metre}

INTRODUCTION

Interest of studies on interactions between weather conditions and human well-being and health is growing, especially following general concern on climate change [5, 157, 185,]. Many works on this subject refer to the inter-action in the variation of weather conditions and human health and this in-teraction has a very wide range, from subjective well-being to death [215, 269]. The instability of weather factors, such as atmospheric pressure, tem-perature, humidity, wind speed and direction, precipitation, sunny hours and etc., some of them acting together or separately, may cause multiform disor-ders in the normal life of sensitive persons: aggravation of chronic diseases, growing incidence of depression, seasonal affective disorders, headache, migraine, pain and many other symptoms [156, 245, 257, 260, 269]. The research shows that 40% of cases of death happened in an abnormal mete-orological condition. Therefore research on the relationship between the weather conditions and human health is very important [36]. An understand-ing of the nature of the effects of weather conditions on health is essential for optimal health protection and this weather-health association has become a public health concern [271].

With respect to reactions to weather variations, people can be divided into two main groups: weather-resistant and weather-sensitive or mete-orosensitive [67, 269]. Weather-resistant persons have a stable adjustment to weather changes, because they are protected by a variety of internal mecha-nisms. While the term “weather sensitivity” is used to define the impairment of well-being and/or incidence of symptoms or exacerbations of diseases in response to weather changes [260]. Weather-sensitive people constitute about 30%-60% of the general population [67, 249, 260] while the percent-age of this subpopulation in higher risk groups (e.g., elderly percent-age, persons with chronic diseases) can reach 50–85% [269]. The individuals appear to be differentially sensitive to different weather conditions and individuals with specific diseases may suffer from similar weather-related problems [26, 100, 189, 221]. Some reporting patterns suggested that patients could relia-bly identify which meteorological variables influenced their health but could not reliably determine which physical symptoms were consistently affected [221]. It appears that the subjective experience of weather sensitivity is of-ten greater than it has been possible to demonstrate objectively [66]. How-ever, there is the lack of standardised tools to evaluate weather sensitivity and to help to discriminate weather sensitive people. Also there is the lack of standardised tools to evaluate more objectively which symptoms of well-being are mostly related with weather conditions in different groups. The

studies use various methodologies and various populations making compari-son of results complicated.

One of particularly vulnerable groups for environmental triggers such as adverse weather conditions are people with heart disease [75, 118, 215]. Various studies link meteorological variables with cardiovascular morbidity and mortality [87, 109, 149, 159, 199, 206, 251, 267]and according to

stud-ies developed in different world areas heart diseases are known to have sea-sonality [5, 63, 75, 121, 174, 187]. The studies have suggested that changes in meteorological conditions may affect hemodynamic and other factors ad-versely, thereby catalysing the acute coronary syndromes event [12]. Also it

is known that psychological factors affect biological processes involved in the progression of coronary artery disease (CAD) [123]. About 17% to 27% of patients with heart disease have major depression, while even greater numbers of individuals suffer from subsyndromal symptoms [205]. There are evidences that depression, anger and anxiety may promote CAD, sug-gesting that emotional distress in general may be related to increased car-diovascular risk [37, 43, 124, 192, 200]. Furthermore, in recent years, Type D (distressed) personality has been introduced as a vulnerability factor for general psychological distress in patients with CAD [53]. Psychologically troubled people or people with sensitive nervous system are other well-known weather sensitive group [189, 230, 254, 269]. Also, in recent years, it is hypothesized that individual differences such as personality traits may have an effect on sensitivity to weather changes [50, 230].

Normally, weather and its variabilities are not the primary causes of dis-ease; however, they may induce responses in pre-disposed, vulnerable parts of the body and thus exacerbate negative health outcomes [261]. However, relation between daily weather conditions and daily weather-related well-being has not been widely investigated, especially in patients with CAD. Most of studies have been carried out to determine association between cer-tain weather conditions or extreme climate events and increased mortality, morbidity, hospital admissions, calls or visits to emergency aid services with different diseases and have been used as statistical data. There is the lack of new researches in Lithuania in the field of biometeorology, espe-cially in the relations between daily weather conditions and daily weather-related well-being.

Since psychological distress and Type-D are both associated with devel-opment and progression of CAD and according to evidences in literature that people with emotional distress are considered to be more sensitive to weather change than others, it was hypothesized that both of these factors can influence occurrence of weather-related symptoms.

To the best of our knowledge, the current study is the first attempt to de-velop and test the psychometric properties of self-assessment diary for weather sensitivity and to evaluate associations between personality and emotional distress and subjective weather-related well-being in patients with CAD. The hypotheses, which are aimed to verify performing this study, are: (1) self-assessment diary is valid and reliable tool collecting information regarding the weather sensitivity in patients with CAD; (2) higher symp-toms of anxiety and depression contribute to the greater weather sensitivity in patients with CAD; (3) Type-D and different personality traits moderate the effect of weather on well-being.

AIM AND OBJECTIVES

The aim of this study was to examine and to evaluate associations

be-tween weather parameters and subjective well-being of patients with coro-nary artery disease and it associations with personality, anxiety and depres-sion symptoms.

The objectives of the study:

1. To examine the validity of Type D personality assessment instrument used in this study.

2. To develop and test the psychometric properties of self-assessment diary for weather sensitivity in patients with coronary artery disease. 3. To evaluate associations between the subjective well-being of

pa-tients with coronary artery disease and the weather parameters.

4. To evaluate associations between anxiety, depression and personality and the subjective weather-related well-being in patients with coro-nary artery disease.

Scientific novelty of the study

In this study for the first time in Lithuania was developed and tested the psychometric properties of self-assessment diary for weather sensitivity in patients with coronary artery disease. This study is the attempt to create more objective instrument to evaluate weather sensitivity which will be based not only on subjective opinion of respondents, but also on more ob-jective evaluation whether self-reported subob-jective symptoms is associated with weather conditions. Furthermore, this is the first study in Lithuania where was evaluated not only associations between daily weather conditions and subjective daily weather-related well-being, but also evaluated associa-tions between anxiety, depression and personality and subjective weather-related well-being in patients with coronary artery disease. The analysis of the cumulative data during more than 4 years allowed us to assess not only the daily weather associations with subjective well-being, but also the sea-sonality.

There is the lack of new studies in Lithuania in the field of biometeorol-ogy, especially in the relations between daily weather conditions and daily weather-related well-being. It is the hope that the methodology of this study and the results obtained will contribute to better understanding of problem analysed and may be useful for future researches in the field of biometeo-rology in Lithuania.

1. REVIEW OF LITERATURE

The awareness of the impacts of weather/climate on health has a long history since Hippocrates, who related meteorological changes to health [223]. An understanding of the nature of the effects of weather conditions on health is essential for optimal health protection. Weather variables are believed to have influence on human health and this climate/weather-mortality/morbidity relationship has been a public health concern for centu-ries.

Many diseases are influenced by weather conditions or display strong seasonality, suggestive of a possible climatic contribution [185]. Because the climate and its effects on many natural processes are fundamental com-ponents that allow life to exist on Earth, interest of studies on interactions between weather conditions and human well-being and health is growing, especially following general concern on climate change [5, 191]. The poten-tial effects of climate changes on population health have been classified by whether these effects occur via the direct impact of a climate variable, such as increasing temperature or weather variability, or are mediated by change in indirect mechanisms, such as infection agents or via ecological disruption [185]. Climate change directly affects five components of the environment: water, air, weather, oceans, and ecosystems [191].

The interdisciplinary science that considers the interactions between at-mospheric processes and living organisms with the central question within the field being ‘how does weather and climate impact the well-being of all living creatures?’ is called biometeorology [157]. In the studies of biome-teorology the terms “weather“ and “climate“ often used as synonyms [86] but there are some distinctions. Weather refers to short-term fluctuations in the atmosphere (hours to day), as opposed to long-term, or climatic changes. Weather is ofen identified and studied in terms of atmospheric pressure, brightness, cloudiness, humidity, precipitation, temperature and wind. Cli-mate is usually defined as average weather over period of time (years) and in a particular geographic region. Climate descriptions and quantitative measures include statistical information on various climate variables. Owing to the longer time scale involved, these may include information on climate variability and extreme events. Climate involves variations in interactions between different components of the climate system, the atmosphere, the oceans, sea ice, and the land and its features. Change in any of the climate system components, whether from internal or external forcing, can cause

climate to vary and also can cause weather variability [185]. Thereby bio-meteorology is very extensive field.

Various studies concerning the effects of weather variability on human being refer to the interaction in the variation of weather conditions and hu-man health and this interaction has a very wide range, from subjective well-being to the death [215, 269].

There are a number of studies concerning the effects of the weather on diverse kinds of diseases: cardiac [12, 61, 159], respiratory [110, 261], chronic pain [101, 221, 224], rheumatoid arthritis [59, 76, 257], psychologi-cal impairments [28, 67, 230, 269]. Some of these studies were related to mortality [35, 41, 149, 272], while others referred to emergency aid services or hospitalization [61, 206, 228]. Weather has been considered to influence not only people’s health but also a wide variety of human behaviour: fre-quency of police calls or calls to crisis intervention services, job accidents, birth and death rates, and psychological states such as violent suicide and some criminal behaviors [10, 14, 142, 147].

Certain groups of people have been described as more weather sensitive than others [2]. Women and elderly have been claimed to be more sensitive than men [154, 260], people with chronic diseases [101, 260] or suffering from depression and neuroses [189] more than healthy persons. With respect to reactions to weather variations, people can be divided into two main groups: weather-resistant and weather-sensitive or meteorosensitive [67, 269]. The term “weather sensitivity” is used to define the impairment of well-being and/or incidence of symptoms or exacerbations of diseases in response to weather changes [260]. The instability of weather factors, such as atmospheric pressure, temperature, humidity, wind speed and direction, precipitation, sunny hours and etc., some of them acting together or sepa-rately, may cause multiform disorders in the normal life of sensitive persons [269]. Some studies suggest that when weather changes slowly, the human body adapts to the weather condition. However, when the activity of cold and warm air is sudden or frequent, there is a greater incidence of disease [36, 230]. On the other hand, it is unclear, whether the impairment of well-being and/or incidence of symptoms or exacerbations of diseases are more likely to be altered by a sudden change in weather conditions or the ‘accu-mulation’ of certain uninterrupted conditions [55].

1.1.1. Cardiovascular diseases and weather conditions

Heart disease is a leading cause of death, so that it is not surprising that fluctuations in the physical functions of the heart are the subject of intensive study by physicians, environmental physiologists and biometeorologists

[171]. The numerous studies have demonstrated a variety of relationships between changes in weather variables and cardiac admissions and even mor-tality. Most of the studies analyse mortality data based on national death sta-tistics or hospital admission rates, other studies examine the relationship be-tween weather variables and the incidence of cardiovascular events, con-sider seasonal or monthly variations or investigate the influence of meteor-ology on cardiovascular events rates on a daily basis [267]. Changing weather variables may not directly cause these health outcomes but may create conditions that influence physiological functioning [61, 215]. The results of studies suggested that changes in weather conditions may affect hemodynamic and other factors adversely, thereby catalyzing the acute coronary syndromes event [7, 42, 65, 168, 199, 251, 267]. Further, there is often a lag between mortality/morbidity and weather conditions in addition to the immediate impact of weather on health, because the effects of weather parameters can occur after some delay. Weather conditions can affect mor-tality not only on the current day but also on several preceding days [27]. In exploring the delayed effects of weather on mortality, multiple-day lags ranging from 0 to 14 days before death were examined. In addition, the risk of death increases substantially when thermal stress persists for several con-secutive days coupled with high overnight temperatures [196].

The associations with high and low temperature. The most extensively

studied weather-health relationship is the association between temperature and mortality. This association is a public health threat of considerable magnitude. Every year, a large number of hospitalizations and deaths occur in association with exposure to elevated ambient temperatures [17, 64, 145]. The majority of deaths resulting from hot weather are associated with pre-existing cardiovascular disorders [131, 132]. Basu R. (2009) performed the review of recent evidence on mortality from elevated ambient temperature for studies published from January 2001 to December 2008. The most part of studies have been conducted in the US and Europe, also in Latin Amer-ica, Australia, Canada. The results showed that elevated temperature was associated with increased risk for those dying from cardiovascular, respira-tory, cerebrovascular, and some specific cardiovascular diseases, such as ischemic heart disease, congestive heart failure, and myocardial infarction. Other vulnerable subgroups were Black racial/ethnic group, women, those with lower socioeconomic status, and all age groups, particularly the elderly over 65 years of age as well as infants and young children. Similar results were obtained in studies performed in China [35, 272]. The greater effects were observed for cardiovascular and respiratory mortality. Women, the elderly and people with lower socioeconomic status were at significantly higher risk of heat wave-associated mortality.

Despite the results of studies which have demonstrated variation in the temperature-mortality relationship by race, gender, age, socioeconomic status, and adaptation measures such as weather conditioning [8, 19, 179], the influences of some effect modifiers still remain unclear. For example, some studies identified a higher temperature effect among women for mor-tality, while others observed men to be a greater risk [19, 229, 274]. On the other hand, some studies reported no effect modification by gender or age [16, 140]. Moreover, the effects of ambient temperature and which subpopu-lation is most vulnerable to temperature depend on the cause and type of health outcome considered as well as several factors such as population characteristics (e.g., sex, age, baseline health status, health care system, and adaptation such as air conditioning) that will vary by place [228].

The influences of temperature on mortality have usually been described by U-, V-, or J-shaped functions [27] and extent of temperature-related mor-tality seems to vary with geography [4, 27, 41, 127, 146, 184, 185]. Martens (1998) described this relationship as a “V-shaped” function based on a meta-analysis of several studies of urban population selected for the estima-tion of the effect of temperature changes on mortality. The comfortable temperature range varied between 16.5°C in the Netherlands and 29°C in Taiwan. McMichael et al [185] suggested that the relationship is “J-shaped”, indicating asymmetry with a steeper slope at higher temperatures. To ascer-tain weather/mortality relationship is used a “threshold temperature”, which represents the temperature at each location, above which mortality increases more steeply [106]. The threshold temperature is calculated objectively by measuring the dissimilarity of mortality above and below a given tempera-ture. The thereshold temperature in London for summer is 20.5°C, Budapest – 19.6°_{C, Milan – 23.4}°_{C, Hong Kong – 28.2}°_{C, Delhi – 29}°_{C and mortality}

increases at temperatures above this level [35, 106]. For example, an aver-age 1°C increase in daily mean temperature above 28.2°C in Hong Kong was associated with an estimated 1.8% increase in mortality [35]. It is important both for summer and winter. In winter, the threshold temperature represents the temperature below which mortality increases. Other studies suggest that the response to increasing temperature does not occur just at the upper range, but also that there is a steep gradient in daily mortality and hospitali-zations that begins at mean temperatures of about 20–25°_{C [17, 41, 84, 85,}

87, 179, 120, 127].

The available evidence of the impact of climatic conditions on acute car-diovascular morbidity is more limited and controversial than the findings regarding cardiovascular mortality [218]. On the other hand, the rise in hos-pital admissions due to circulatory causes attributed to inclement weather is smaller than the rise in respective mortality [141].

Increased morbidity and mortality for cardiovascular diseases is associ-ated with both extreme hot and cold weather compared with an intermediate, comfortable temperature range [117]. The cold stress has a considerable im-pact on mortality in central Europe, representing a public health threat of an importance similar to heat waves [128]. The V-shaped curve of temperature and mortality implies that, in addition to increased mortality in unusually hot weather, death rates increase with decreasing temperatures. Epidemiol-ogical evidence showing that in temperate and subtropical countries, coun-tries having milder winter climates, seasonal death rates are highest in win-ter [117, 217] and mostly from cardiovascular diseases [127, 129, 161]. The association between cardiovascular mortality and winter cold spells was evaluated in the population of the Czech Republic over 21-year period 1986–2006 [128]. Cold spells were associated with positive mean excess cardiovascular mortality in all age groups (25–59, 60–69, 70–79 and 80+ years) and in both men and women. The elevated mortality risks in men aged 25–59 years may be related to occupational exposure of large numbers of men working outdoors in winter. The registry-based study was carried out over 10 years in a region of tempered climate in Germany [267]. Spe-cific aims were to test whether effects on fatal and nonfatal or incident and recurrent myocardial infarction (MI) are similar, to assess the exposure-response function, to compare different temperature metrics, to study the influence of warm and cold years, and to inspect potential effect modifica-tion by personal characteristics. The daily rates of total MI, nonfatal and fa-tal events and recurrent events were analyzed. The results showed an in-creased risk for the occurrence of MI in association with a decrease in air temperature. For the total MI cases, a 10°C decrease in 5-day average tem-perature was associated with a relative risk of 1.10 (95% confidence inter-val, 1.04 to 1.15). The effect of temperature on the occurrence of nonfatal events showed a delayed pattern, whereas the association with fatal MI was more immediate. The association was similar for winters and summers and was more pronounced in years with higher average temperatures. Authors suggest that the influence of unexpected temperature decreases is more rele-vant than the absolute temperature level itself.

Panagiotakos et al. (2004) examined the relationship between average, maximum and minimum daily temperature, relative humidity, wind speed, and barometric pressure and admissions due to non-fatal acute coronary syndromes in cardiology emergency units in the greater Athens area. The findings suggest a significant association between cold weather and in-creased coronary heart disease incidence, especially in the elderly and fe-males. Ebi at al. (2004) evaluated associations between temperature, precipi-tation, days of extreme heat, and other weather changes (lagged 7 days),

with hospitalizations for acute MI, angina pectoris, congestive heart failure, and stroke in three California regions. Associations varied by region, age, and gender. In Los Angeles, temperature changes resulted in small changes in hospitalizations. Among San Francisco residents 70+ years of age, tem-perature changes increased hospitalizations for nearly all outcomes from 6% to 13%. Associations among Sacramento residents were similar to those in San Francisco: among men 70+ years of age, temperature changes increased hospitalizations by 6%–11% for acute myocardial infarction and congestive heart failure, and 10%–18% for stroke. The results of study in Korea showed that cardiovascular hospitalizations were significantly associated with high temperature whereas hospitalizations for allergic disease, asthma, and selected respiratory disease were significantly associated with low tem-perature and that more susceptible were women and younger persons [228].

Several studies have shown that arterial blood pressure tends to increase with decreasing outdoor temperature. This inverse correlation has been de-scribed in both normotensive [99] and hypertensive [126] populations. Stud-ies suggested that temperature associated variations of systolic blood pres-sure and diastolic blood prespres-sure increase with age in adult populations [99, 268]. A change in blood pressure, blood viscosity, cholesterol, and/or heart rate associated with psychological adjustment to temperature change may explain the increased mortality/morbidity from cardiovascular diseases [111]. There are some potential mechanisms to explain the increased risk for incident coronary events in association with changes in weather. Tempera-ture is believed to affect blood pressure and blood viscosity [127, 162]. Blood pressure increases with lower temperature although higher tempera-ture may increase nocturnal levels [103]. Low temperatempera-ture also increases blood viscosity and heart rate [127] and may trigger circulatory diseases. In addition, blood viscosity and cholesterol level also escalate with high tem-peratures [112] and these increases will interact with atrial fibrillation pro-voking blood clot. The body’s thermoregulatory mechanisms can cope with a certain amount of increase in temperature through perspiration and vasodi-lation of cutaneous vessels [117]. The ability to respond to heat stress is thus limited by the capacity to increase maximum cardiac output required for cu-taneous blood flow. The elderly, the very young, persons with impaired mo-bility, and persons suffering from cardiovascular diseases are disproportion-ately affected because of their limited physiological capacity to adapt.

The associations with other weather parameters. Apart from

tempera-ture, other weather variables, such as humidity, barometric pressure, wind speed and rainfall, are also found to be related to mortality and morbidity [4, 33, 65, 104, 107, 127, 218]. Temperature, dew point temperature, wind and pressure were correlated with ischaemic heart disease mortality in

Birming-ham UK [158]. Cardiovascular death was detected to escalate as humidity and pressure increased and a U shaped temperature relationship were dis-covered in Taiwan [250]. Some studies revealed that pressure was the major weather variable causing circulatory deaths [33, 104, 135]. Decreased at-mospheric pressure from the previous day was found to be associated with oxygen saturation - a screening test for early detection of heart obstructive disease - and congestive heart failure [73], the occurrence of acute MI [94], ischemic stroke [167] and hemorrhagic stroke [46]. Danet et al. (1999) stud-ied the impacts of atmospheric temperature and pressure on daily rates of MI and coronary deaths. During the 10-year longitudinal survey, 3616 events occurred. It was found a V-shaped relationship between and mini-mum of daily event rates at 1016 mbar. A 10°C decrease was associated with a 13% increase in event rates (p<0.0001); a 10-mbar decrease <1016 mbar and a 10-mbar increase >1016 mbar were associated with a 12% in-crease (p=0.001) and an 11% inin-crease (p=0.01) in event rates, respectively. These effects were independent and influenced both coronary morbidity and mortality rates, with stronger effects in older age groups and for recurrent events. Temperature and humidity were associated with significant changes in heart rate and in ECG parameters in patients of a heart rehabilitation clinic [215].

Another wide research field is the impact of geomagnetic activity on car-diovascular diseases. The results of studies reported statistical associations between geomagnetic activity and several cardiovascular health endpoints, including variations in capillary blood flow [82], paroxysmal atrial fibrilla-tion [241], heart rate variability [178, 180], blood pressure [704, 24, 262, 263] and myocardial infarction related deaths [39, 236].

1.1.2. The relationship between weather conditions and behavioral and mental disorders

The most well-known group effects associated with weather changes in-volve people with emotional distress. This population are considered to be more sensitive to periods of atmospheric lability than others [267]. The nervous system usually responds first to the changes in its environment and greatly influences the endocrine system; therefore, the most common weather-triggered biological reactions have for the most part a psychologi-cal, emotional or behavioral character. Most of studies sought to clarify the links between weather-related behaviours focusing on the relationship be-tween the weather and mood [50, 97, 114, 264], psychiatric admission rates or emergency services [28, 149, 160], number of telephone calls [60], sea-sonal affective disorder [113, 173, 202] or suicide rates [56, 207]. Despite

some significant evidence that weather effect on behavioural and mental disorders exist, the relationship between weather conditions and human be-haviour is a continuous subject of speculation due to contradictory findings [28]. In general, for every study that has correlated some parameters of the weather with some response indicative of emotional state, another has found opposite or contradictory results.

The weak but significant relationship between weather and mood is one of the oldest and most frequent topics in popular biometeorology [230]. In fact, it is a common and well-spread belief that people feel happier on days with a lot of sunshine as compared to dark and rainy days [50, 264] and some studies supported this. Schwarz and Clore (1983) found that people reported significantly higher general happiness, life satisfaction, and content with current life on sunny vs. rainy days. Results of study among 126 pa-tients with seasonal affective disorder showed that increases in (hours of) sun time, day length and temperature were associated with lower depression scores, while (hours of) rainfall was not significantly associated [164]. Mo-mirovic et al. (2005) found that apathy and sleepiness were the most com-mon mood changes associated with weather changes, whereas humid weather was indicated as a weather type that caused most discomforts in study subjects.

In some studies high barometric pressure [74], low levels of humidity [210], and high temperature [40, 96] have been associated with high mood. Howarth and Hoffman (1984) investigated the relationship between eight weather variables (hours of sunshine, precipitation, temperature, wind direc-tion, wind velocity, humidity, change in barometric pressure and absolute barometric pressure) and 10 mood variables (concentration, cooperation, anxiety, potency, aggression, depression, sleepiness, scepticism, control, and optimism). Data was collected from 24 male subjects over 11 consecu-tive days. Humidity, temperature and hours of sunshine have the greatest effect on mood. High levels of humidity lowered scores on concentration, while increasing reports of sleepiness. Rising temperatures lowered anxiety and scepticism mood scores.

However, other studies found small or no relationships between mood and any weather variable [50, 97, 114, 264]. Watson (2000) reviewed data collected in 478 students, and found that mood was unrelated to (hours of) sunshine and rain. Huibers et al. (2010) assessed the influence of weather conditions on the seasonal variation of depression observed in the general population in the south of the Netherlands. Seasonal prevalence of DSM-IV classified major depression and sad mood in a sample of 14,478 participants from the general population was calculated, and linked to mean daily tem-perature, duration of sunshine and duration of rainfall in logistic regression

analyses. The results showed that weather conditions were not associated with mood, and did not explain the seasonal variation they found.

Keller et al. (2005) investigated the effect of temperature and barometric pressure on mood and cognition (memory and cognitive style) of 97 North American participants. They found no consistent main effects of weather on mood, though they observed that higher temperature or barometric pressure was related to higher mood, better memory, and ‘‘broadened’’ cognitive style during the spring as time spent outside increased. The same relation-ships between mood and weather were not observed during other times of year, and indeed on summer days, however, spending more time outside on warm days was associated with decreased mood. According to Keller et al. (2005), these results are consistent with findings on seasonal affective dis-order, and suggest that pleasant weather improves mood and broadens cog-nition in spring because people have been deprived of such weather during the winter.

Denissen et al. (2008) extended Watson (2000) and Keller et al (2005) findings. They investigated the effects of six weather parameters (tempera-ture, wind power, sunlight, precipitation, air pressure, and photoperiod) on mood (positive affect, negative affect and tiredness). They analysed the re-sults from an online diary study of 1233 people. The rere-sults revealed main effects of temperature, wind power, and sunlight on negative affect. Sunlight had a main effect on tiredness and mediated the effects of precipi-tation and air pressure on tiredness. According to Denissen et al. (2008) the average effect of weather on mood was only small, though significant ran-dom variation was found across individuals, especially regarding the effect of photoperiod. The weakly relations were found in recent study performed in Estonia [122]. An increase in temperature was related to a small rise in both negative and positive affect. Positive affect was also related to sunlight. And fatigue showed a distinct tendency for greater incidence of sleepiness in cold and dark weather.

Looking at specific weather parameters over a period of time prior to hospital admissions or number of daily emergencies may also provide evi-dence of a link between weather and some psychiatric conditions. Salib (2002) examined the association between relative humidity, sunshine hours, diurnal variations in temperature and rainfall and psychiatric admissions in North Cheshire, UK. A significant inverse relationship (with time lag) was found between admissions for affective disorders and relative humidity in the week preceding admission. Changes in diurnal variations in temperature, sunshine hours and rainfall a few days before admission were also noted, but the findings did not achieve statistical significance for any diagnostic category. The effect of weather parameters on mental health is likely to be

influenced by other seasonal factors, as well as non-climatic factors, pre-dominantly social, that may have contributed to the study findings. Bulbena et al. (2005) investigated panic attacks and non-panic anxiety in relation to specific meteorological variables such as wind speed and direction, daily rainfall, temperature, humidity and solar radiation. Seasons and weekend days were also included. Panic attacks, unlike other anxiety episodes, in a psychiatric emergency department in Barcelona seem to show significant meteorotropism. Episodes of panic were three times more common with the poniente wind (hot wind), twice less often with rainfall, and one and a half times more common in autumn than in other seasons. This is not observed in non-panic anxiety, where meteorological effects were not found to be significant.

Other study examined the daily symptoms fluctuations in a patient suffer-ing from recurrent anxiety disorder and found that energy levels were low-ered by wind from the southeast [25]. This effect could not be explained by other weather parameters. Further, a positive feedback loop between energy and anxiety was found. Decreases in energy in turn predicted increases in anxiety. Santiago et al. (2005) evaluated the influence which the factors such as temperature, precipitation, speed and direction of the wind and light could have on the number of evaluations made in emergency department and on admissions. They found a significant correlation between tempera-ture and number of visits to psychiatric emergencies in a series of 1909 pa-tients evaluated during one year in the hospital centre in California. The au-thors concluded that the admissions were more frequent on hot and dry days. A direct relationship between increase environmental temperature and the number of patients attended in the hospital emergency department was found in the study in Spain too [67]. The daily visits also were statistically significant related with humidity (p=0.033), but in a non-linear way (p=0.02).

In any case, the results do not always agree. McWilliams et al. (2012) examined whether daily meteorological variables, such as wind speed and direction, barometric pressure, rainfall, hours of sunshine, sunlight radiation and temperature, influenced admission rates for mania and depression across 12 regions in Ireland over a 31-year period. Although they found some very weak but interesting trends for barometric pressure in relation to mania missions, daily meteorological patterns did not appear to affect hospital ad-missions overall for mania or depression.

There are three obvious mechanisms by which environment could exert a causal effect on suicides: sociological, biological and psychological. Socio-logical explanations suggest that the pattern and intensity of social behav-iours are influenced by weather variables and that it is these social

interac-tions that precipitate suicide [73, 253]. For example, high temperatures have been found to lead individuals to behave in a more disinhibited, aggressive and violent manner, which might in turn result in an increased propensity for suicidal acts [9]. But this weather-suicide relation also is still unclear.

In one of the most comprehensive reviews of climate–suicide research, Deisenhammer (2003) explains that despite much research on the topic, the pathophysiological mechanisms of climate effects on humans are widely unknown. Most of the papers reported a statistical association of suicidal acts with at least one weather factor. However, the results are not conclusive and in part contradictory. For example, temperature which was the most fre-quently assessed variable in the studies reviewed was positively associated with suicidal acts in a number of studies [68, 147, 193, 194, 271] but nega-tively in others [137, 138, 150]. Similar findings were reported for humidity, precipitation and sunshine duration.

1.1.3. Influence of weather variables on pain

Since ancient times there has been a widespread belief that pain is some-how affected by external environmental exposures. The first published re-port of a linkage between weather and pain appeared in 1887, “approaching storms, dropping barometric pressure and rain were associated with in-creased pain complaint” [221]. Folklore suggests that myriad medical prob-lems are exacerbated by changes in weather including migraine, fibromyal-gia, and chronic pain [2, 76, 101].

The meteorologic factors that have been suspected of contributing to changes in pain include temperature, barometric pressure, precipitation, hu-midity, thunderstorms, sunshine, and increased ionization of the air [46, 163]. Certain pain diagnoses have been reported to be especially sensitive to weather changes, including rheumatoid arthritis [1, 81, 222, 245], os-teoarthritis [155, 265], fibromyalgia [275], phantom limb pain [88], head-aches [38, 92], low back pain [130], and pain influenced by mood disorder [188, 201].

Persons with different pain diagnosis tend to describe themselves as be-ing more weather sensitive than other persons. Hill (1972) estimated that between 80% and 90% of patients diagnosed with arthritis report weather sensitivity. Yunus et al. (1981) reported that 92% (N = 50) of fibromyalgia patients believed that "cold and humid" weather negatively influenced their pain symptoms. The results of Internet survey of people with fibromyalgia where participated 2,569 people, revealed that 80% of the respondents en-dorsed that perceived adverse effect of weather changes is one of frequently cited exacerbating factors [20]. More recently, the relation of pain

percep-tion and weather changes was assessed using a self-applied quespercep-tionnaire through the Visual Analogue Scale (VAS), in which the authors observed that 70% of the interviewees believed that their disease was infl uenced by the weather, and 40% said that it had great influence [46, 163]. Regarding meteorological variables, relative humidity (67%) and low temperature (59%) were the most mentioned. The authors concluded that the perception of atmospheric changes influencing on pain and consequently on disease occurred to a high number of patients. In a study with 1,750 migraine pa-tients, Kelman (2007) found that each patient reported on average about seven different triggers. After stress, hormones (in women) and not eating, weather was the fourth common individual trigger. Patients with rheuma-tism often report that they can sense changes in the air hours or days before a front approaches [226]. The pain typically increases when the front is ap-proaching, and reaches a maximum when the patient is situated at or near the center of the front.

In one month prospective study of 62 rheumatic patients - 16 with rheu-matoid arthritis, 24 with osteoarthritis, 11 with inflammatory arthritis, 11 with fibromyalgia joint pain - swelling and everyday activity was compared with changes in daily weather conditions [81]. Weather changes increased arthritic symptoms for most patients. Women were more sensitive to weather than men (62% v 37%). Pain was affected positively by barometric pressure and temperature in rheumatoid arthritis, by temperature, rain, and barometric pressure in osteoarthritis, and by barometric pressure in fi-bromyalgia. Low temperature, high atmospheric pressure, and high humid-ity were significantly correlated with pain in rheumatoid arthritis, low tem-perature and high humidity correlated with pain in osteoarthritis and low temperature and high atmospheric pressure correlated with fibromyalgia in study performed in Cordoba City, Argentina [245]. No correlation was found in healthy subjects control group. Patients described themselves as being weather sensitive correlated only with high humidity. These results support the belief of most rheumatic patients that weather conditions sig-nificantly influence their day to day symptoms.

The study, conducted in the Australian inland city of Bendigo, sought to establish a possible relationship between the pain and rigidity of arthritis and the weather variables of temperature, relative humidity, barometric pressure, wind speed and precipitation [3]. Stepwise multiple regression analysis indicated that meteorological variables and time of day accounted for 38% of the variance in mean pain and 20% of the variance in mean ri-gidity when data of all months were considered. The results suggest that de-creased temperature is associated with both inde-creased pain and inde-creased

rigidity and that increased relative humidity is associated with increased pain and rigidity in arthritis sufferers.

Cold and damp conditions were considered to influence pain the most [101]. Pienimäki (2002) investigated how cold exposure may be associated with musculoskeletal problems either on symptomatic or disease level and performed a review of scientific literature. The results indicated that muscu-loskeletal symptoms are more frequent in cold store work and in related conditions than in normal temperature work and symptoms seem to be in-creased when the working time in cold environment increases. In cold store work low back pain and knee pain are more frequent problems than in nor-mal temperature working environment.

A great proportion of people report low back pain associated with low temperature conditions. In a study by Lapossy et al. (1994) cold-induced vasospasm has been reported to be more frequent (38%) in patients with fi-bromyalgia and in low back pain patients (20%) than in healthy control (8%), which shows that the effect of cold may be different in different con-ditions.

Various explanations have been given to account for the effects of weather changes on pain [101, 133]. Because tendons, muscles, bones, and scar tissue are of various densities, cold and damp may expand or contract them in different ways. Sites of microtrauma may also be sensitive to ex-pansions and contractions due to atmospheric changes. Changes in baromet-ric pressure and temperature may increase stiffness in the joints and trigger subtle movements that heighten a nociceptive response. Such alteration of structure may be particularly problematic in inflammatory joints whose sen-sitized nociceptors are affected by movement [22, 197]. Change in baromet-ric pressure may also cause a transient "disequilibrium" in body pressure that may sensitize nerve endings and account for increased pain preceding changes in temperature or humidity. Finally, seasonal weather patterns in-fluence mood in some persons [201, 248] and thereby indirectly affect pain perception. Pain is subjective health complaint and most weather variables are clearly perceptible, e.g. temperature wind, precipitation, relative humid-ity, therefore it is hard to disentangle biophysiological effects from the psy-chological ones. And there might be a mediating effect of mood. If wet and cold days lead to a lowered mood state and influence the pain threshold, persons could conclude that they have more pain on wet and cold days [224]. Although weather sensitivity seems to be a multifactorial phenome-non, the results of most studies suggest that exploring a physiological basis for weather-oriented changes in pain perception in persons with chronic pain may be fruitful [101].

Another common issue in researches of biometeorology is weather vari-ables like migraine triggers. Migraineurs also claim weather as a potential trigger for migraine [115], though many studies either failed to show a link between particular weather components and incidence of headache or pro-duced conflicting results in investigating major atmospheric variables such as atmospheric pressure, temperature, humidity, wind or thunderstorm activ-ity [23,170, 195]. Hoffman et al. (2011) analyzed headache data of 20 ran-domly selected patients over a period of 12 consecutive months and corre-lated these to specific weather components and their relative changes in or-der to determine whether any of these factors is linked to the occurrence or severity of a migraine attack. Migraine attacks started most frequently at 4 a.m. and reached the highest intensity between 4 and 8 a.m. A highly sig-nificant association between meteorological variables and the occurrence of migraine attacks was found in six patients. The onset of an attack as well as high headache intensity was associated with lower temperature and higher humidity. Data indicate that a subgroup of migraineurs is highly sensitive to changes of certain weather components. Scheidt et al. (2013) used smart-phone apps and a web form to collect around 4,700 migraine messages in Germany between June 2011 and February 2012. Analyses were focused on the relationship between temperature changes and the frequency of occur-rence of migraine attacks. Both increases and decreases in temperature lead to a significant increase in the number of migraine messages. A temperature increase (decrease) of 5 °C resulted in an increase of 19±7 % (24±8 %) in the number of migraine messages.

Despite numerous works showing relationship between pain and weather variables, data is still controversial. Some other studies have found small or non significant associations and some have found no associations between weather and pain [66, 76, 115, 198, 276]. It appears that the subjective ex-perience of weather sensitivity is often greater than it has been possible to demonstrate objectively [66]. However, several recently published reviews did not deny the hypothesis that pain is influenced by weather. Smedslund G. et al. (2011) performed systematic review of longitudinal observational studies to examine the association between weather and pain in rheumatoid arthritis. No consistent group effect of weather conditions on pain in people with rheumatoid arthritis was found, but the review concluded that pain in some individuals is more affected by the weather than in others with differ-ent reactions to the weather. Despite the methodological diversity and biases of the analyzed studies [46], results of review articles related to the influ-ence of meteorological elements in the osteoarthritis pain also showed that there is a trend to confirm the influence of weather in osteoarthritis pain in-tensity.

1.1.4. Increased health risk and seasonality

Despite the conflicting results discussed in the previous sections one of the most consistent themes that has emerged from weather–health research is that this relation tend to display seasonal distributions. Many studies per-formed in different cities around the world have statistically shown that a relevant part of the seasonal behavior of pathologies is related to weather conditions [11, 75, 97, 214]. These data may also help to understand the mechanisms that trigger weather-related well-being/health disturbances.

Seasonal peaks in cardiovascular disease incidence have been widely re-ported, especially in cardiovascular mortality, suggesting weather has a role [42, 119, 159, 187]. The studies, conducted in Canada, New Zealand, Europe, the USA, and other countries, have shown seasonal variability in CVD rates and mortality, which were found to be higher during winter as well as in summer [44, 75, 187]. Except for 1 study [69] which did not see any seasonal changes in incident of myocardial infarctions, the seasonality pattern for coronary heart disease with winter peak and summer trough could be confirmed [187, 267]. For example, observational study suggests that there is a seasonal occurrence of acute myocardial infarction that is characterized by a marked peak of cases in the winter month and a nadir in the summer months [231]. This pattern was observed in all subgroups ana-lysed as well as in different geographical areas [220].

Seasonal variations in death are greater than those in admissions [57], suggesting that survival also varies through the year [187]. Seasonal varia-tions are not consistent across age and gender groups. Winter peaks in car-diovascular mortality increase with age. This is likely to reflect a combina-tion of factors including poorer autonomic control, lower level of physical activity, less use of protective clothing, greater time spent at home, and poorer household heating and insulation. Younger age-groups exhibit a spring peak in addition to the winter peaks seen in other sub-groups [58, 63]. This is particularly prominent in younger men.

The seasonal variation in emotional and psychiatric disorders also is the wide field of interest in many weather-health related studies. However, the results are inconsistent. A specific form of seasonality, seasonal affective disorder (SAD) [202], also known as winter depression, appears to be rela-tively common [148]. Some studies a peak prevalence of depression re-ported during the winter months [89, 148, 169, 181], other population stud-ies demonstrate symptom peaks during spring [175, 235], summer [182] and fall [235]. For example, the prevalence of major depression and sad mood showed seasonal variation, with peaks in the summer and fall in the in the general population in the south of the Netherlands [97]. A peak in hospital

admissions for mania was identified in spring/summer [34, 136] and in win-ter/spring [259], and a peak in admissions for mixed episodes in early spring [136] and late summer [34]. Seasonality also is associated with suicide counts with the most common peak in late spring or early summer [55].

Although not all studies have supported the influence of seasonality in mood disorders, admissions for mania or/and depression [47, 71, 252]. Bauer et al. (2009) investigated if a seasonal pattern was present in daily self-reported daily mood ratings from patients living in five climate zones in the northern and southern hemispheres. Additionally, they investigated the influence of latitude and seasonal climate variables on mood. The observa-tions were provided by patients from different geographic locaobserva-tions in North and South America, Europe and Australia. In spite of vastly different weather, daily self-reported mood ratings of most patients with bipolar dis-order did not show a seasonal pattern and neither latitude nor climate vari-ables were associated with mood by season or month.

Seasonal variation has been shown in a number of rheumatic diseases [214] too. However studies also reported conflicting results: some authors found a seasonal effect [98, 204] but others did not [90, 134]. Iikun et al. (2007) examined whether a seasonal fluctuation exists with rheumatoid ar-thritis activity found definite seasonal differences in rheumatoid arar-thritis patients, both subjectively and objectively. Rheumatoid arthritis disease ac-tivity was higher in spring and lower during fall. In the other study, rheuma-toid arthritis patients considered fall and winter the seasons associated to higher intensity of pain [163].

Thus, scientific evidence of the seasonal behavior of pathologies is non-conclusive. Discrepancies could be related to the diverse climatic conditions from each geographic area studied and also due to the different methodolo-gies used.

1.2. Subjective weather-related well-being

Two representative weather sensitivity surveys were conducted inde-pendently in Germany and Canada [260]. The aim of this study was to iden-tify the prevalence, to describe weather-related symptoms and the corre-sponding weather conditions, and to compare the findings in two countries. The results showed that 19.2% of the German population thought that weather affected their health “to a strong degree,” 35.3% that weather had “some influence on their health” (sum of both=54.5% weather sensitive). In Canada 61% of the respondents considered themselves to be sensitive to the weather. The highest prevalence of weather senstitivity (WS) (high + some influence) in Germans was found in the age group older than 60 years

(68%), which was almost identical in the Canadian population (69%). In Germany the highest frequencies of weather-related symptoms were re-ported for stormy weather (30%) and increasingly cold weather (29%). In Canada, mainly cold weather (46%), dampness (21%), and rain (20%) were considered to affect health more than other weather types. The most fre-quent symptoms reported in Germany were headache/migraine (61%), leth-argy (47%), sleep disturbances (46%), fatigue (42%), joint pain (40%), irri-tation (31%), depression (27%), vertigo (26%), concentration problems (26%) and scar pain (23%).

Table 1.1.1. Percentage of co-morbidity of the whole German sample,

weather-sensitive and non-weather-sensitive people (odds ratios and confi-dence intervals) [260]

Co-morbidity, % _(n=1,064)Total Weather sensitive (n=581) Non-weather sensitive (n=483) Odds ratio (95% CI) Circulatory disturbances 24.4 38.8 6.9 7.12 (4.81–10.53)* Allergies 20.5 26.2 13.6 2.70 (1.94–3.77)* Hay fever 11.5 12.7 10.0 1.67 (1.12–2.48)* Rheumatism 10.9 16.3 4.4 2.87 (1.73–4.77)*

Diseases of the respiratory

tract 10.5 13.1 7.3 1.79 (1.17–2.74)* Heart disease 9.3 12.9 4.9 1.87 (1.13–3.10)* Chronic pain 9.3 13.4 4.3 2.68 (1.62–4.43)* Skin disease 9.2 10.8 7.3 1.67 (1.07–2.59)* Vascular disease 8.5 11.5 4.9 1.87 (1.13–3.11)* Gastrointestinal disease 7.2 8.7 5.4 1.48 (0.90–2.44) Diabetes 6.6 8.3 4.5 1.30 (0.76–2.23)

Renal or bladder inflammation 6.1 7.2 4.8 1.26 (0.74–2.16)

Ear, nose and throat

inflamma-tion 4.7 3.6 6.0 0.54 (0.30–0.98)*

Liver or gall bladder diseases 4.1 6.0 1.8 2.71 (1.27–5.80)*

Asthma 3.4 4.0 2.7 1.20 (0.59–2.42)

Other diseases 12.7 16.1 8.6 1.93* (1.30–2.85)

*Statistically significant

Canadian weather-sensitive persons reported colds (29%), psychological effects (28%) and painful joints, muscles or arthritis (10%).

Koppe et al. (2013) conducted the study to identify the prevalence of weather sensitivity in Germany in 2013 and compared their findings with data surveyed in 2001 [93]. The scientists used the same questionnaire and conducted the survey in the same month (January) as Höppe et al. (2002).

The results showed that weather sensitivity still affects about 50% of the population in Germany. Compared to the survey of 2001 the amount of the weather sensitive individuals was slightly lower (2001: 54%) but the differ-ence was not significant. As in 2001 headaches and migraines are still the most frequent symptoms (2001: 61%; 2013: 59%) followed by fatigue (2001: 42%; 2013: 55%; p~0.07).

Table 1.1.2. Percentages of comorbidity in the whole Canadian sample,

weather-sensitive and non-weather-sensitive people [260]

Co-morbidity, % _(n=1,506)Total Weather sensitive (n=915)

Non-weather sensitive (n=591)

Odds ratio (95% CI)

No health problems 28.2 18.5 43.3 0.30 (0.23–0.37)*

Stress, emotional instability,

changes in energy level 32.1 41.8 17.0 3.48 (2.70–4.47)*

Muscles, joints, impairment of

movement 31.75 38.3 21.7 2.24 (1.77–2.84)*

Asthma, hay fever, respiratory 21.4 26.6 13.4 2.34 (1.77–3.10)*

Eyes, ear, nose, throat 20.5 25.2 13.2 2.22 (1.68–2.94)*

Severe headaches or migraines 19.7 22.9 14.7 1.73 (1.31–2.27)*

Allergies 18.3 22.8 11.3 2.32 (1.72–3.12)*

Skin conditions 12.1 15.7 6.4 2.72 (1.87–3.95)*

Heart, blood, circulatory 11.7 12.9 9.8 1.36 (0.98–1.90)

Diabetes or digestive conditions 9.4 10.2 8.3 1.25 (0.87–1.80)

Cancer 2.5 2.9 1.9 1.60 (0.79–3.26)

Other conditions 1.3 1.6 0.9 1.95 (0.71–5.40)

*Statistically significant

Mackensen et al. (2005) also compared weather sensitive and non-weather-sensitive people examining the prevalence of chronic diseases (co-morbidity) in two different countries (Table 1.1.1 and Table 1.1.2). Despite some differences which can be explained by different medical and cultural aspects, the prevalence of many chronic diseases was higher in the weather-sensitive group, especially in Germany. These results stress that persons with chronic disease have a higher risk of suffering from weather-related symptoms. These results back the hypothesis, that weather associated symp-toms especially concern people with pre-morbidity. This also seems to be the reason why the group of elderly show the highest WS prevalence rates.

Similar survey was performed in Lithunian population [143]. Five hun-dred respondents were surveyed in all the regions of Lithuania. The results

showed that nearly three-quarters of the population considered weather to be influencing the state of human health: about 55 % were of the opinion that weather had some influence on their health, while some 19 % considered weather to be influencing their health strongly. The most weather-sensitive were respondents over 60 years of age. The highest frequencies of weather-related symptoms were reported for moist weather (35%), when weather cooling down (27%) and for the stormy weather (12%). The most weather-related symptoms were joint pain, limited activity, fatigue and lethargy, also headache, muscular pain, nervousness, depression and irritability. People were more sensitive to changeable rather than persistent weather, the most influential being vast variations of temperature. The results also revealed that even 84% of the weather-sensitive people had some health problems: they suffered at least one of the diseases listed in the questionnaire.

The results of questionnaire-based survey of patients among rheumatol-ogy outpatients showed, that 74% patients thought that change in weather affect their pain [176]. Similar percentage was found in other studies [163]. Seventy percent of weather sensitive subjects described pain exacerbation prior and/or during weather changes and humidity and low temperature were reported how most frequently being associated with worsening of symptoms (66% and 72%, respectively).

1.3. Psychological distress, personality traits and coronary artery disease

Psychological distress is associated with development and progression of coronary artery disease (CAD) and is closely related to the clinical out-comes of patients with CAD [32, 116, 203]. In recent years, Type D (dis-tressed) personality has been introduced as a vulnerability factor for general psychological distress in patients with CAD [53].

Type D personality refers to a combination of high levels of negative af-fectivity (NA; tendency to experience negative emotions) and social inhibi-tion (SI; tendency to inhibit self-expression in social interacinhibi-tions) [51]. Both NA and SI are normal and stable personality traits, whereas mood disorders refer to pathologic conditions that tend to be episodic and are affected by environmental factors [48]. In patients with CAD, Type D personality has been associated with an increased risk of cardiovascular events [53], poor quality of life [6], high levels of fatigue [227], and behavioral risk factors such as poor medication adherence [266]. In addition, Type D personality carries an increased risk for future mental disorders, such as depression and anxiety [233], thereby increasing the emotional burden of CAD. These

ad-verse psychological effects of Type D personality are independent from CAD severity [48, 151] or co-morbid mood and anxiety symptoms [52].

The 14-item Type D personality Scale (DS14) was specifically developed to assess NA and SI, and currently is the most widely used instrument to identify patients with a Type D profile [51]. There is some evidence for the validity of the DS14 assessment of the Type D construct in western [21, 79, 95, 232], and non-western [139, 186, 273] countries, but more research is needed to assess its cross-cultural validity as a vulnerability marker for psy-chological distress.

Since psychological distress and type-D are both associated with devel-opment and progression of coronary artery disease (CAD) and according to evidences in literature that people with emotional distress are considered to be more sensitive to weather changes than others, it was hypothesized that both of these factors can influence the occurrance of weather-related symp-toms.

The individual differences in sensitivity to daily weather have not been widely studied, but the results of some studies suggest a link between sea-sonality and persea-sonality, especially concerning the trait of neuroticism [102, 172]. Kane and Lowis (1999) sought to investigate the relationship between seasonal mood variations and the personality aspects of neuroticism, psy-choticism, and extraversion, as assessed by Eysenck's Personality Question-naire. A significant and positive relationship was found between high scores on both the SAD and neuroticism scales, but there was an inverse correla-tion between SAD and psychoticism scores. Spasova (2011) analyzed the effect of weather and its changes on emotional state including major basic personality traits using the same Eysenck's Personality Questionnaire. The findings revealed that neurotic people have higher sensitivity to the weather while the emotionally stable individuals are more “protected” against the weather influence on their emotions. The women had higher scores of neu-roticism than men. The norms of the dimension neuneu-roticism are 9.69 points for men and 13.25 for women (statistically significant difference). Author concluded that this difference allow to state that women are more vulner-able. Kööts et al. (2011) found that people who generally felt more negative feelings tended to be more influenced by warmer temperature and that with increasing openness, feelings of fatigue were slightly less susceptible to the influence of temperature.

Other studies presented contrary results. Denissen et al. (2008) investi-gated the effects of daily weather on people’s mood taking individual differ-ences into account. Authors expected that the effects of weather on mood differ across individuals and the link between sensitivity to daily weather and personality exists. The Five Factor Model personality traits were

as-sessed using the Big Five Inventory. The test is measuring extraversion, neuroticism, openness to experiences, conscientiousness, and agreeableness. However, no significant effect was found. Fors and Sexton (2002)examined the association between fibromyalgic pain and weather and sought which factors might contribute to greater weather sensitivity. They also included the analysis of the personality characteristics such as anxiousness and dyst-hymia, as well as the initial levels of negative thoughts, anxiety, and depres-sion. However, they did not find any influence of all these factors on the re-lationship between fibromyalgic pain and the weather. Like the most results of the research in the field of biometeorology the role of personality as a factor in weather sensitivity is uncertain and this issue requires an additional consideration.

1.4. Recent biometeorology researches in Lithuania

Biometeorology is still a young science in Lithuania. The impact of weather on human health has not been widely investigated. Many aspects of the problem are not completely analyzed yet especially the relation between daily weather conditions and daily weather-related well-being. There is a lack of new studies in Lithuania in the field of biometeorology. In recent years separate studies are carried out in Lithuanian University of Health Sciences and in Vilnius University. The majority of them are concentrated on cardiovascular morbidity and mortality and heliogeophysical factors such as solar-cosmic-geomagnetic activity [237-239, 242, 243, 246, 247, 255, 256]

A group of scientists from Lithuanian University of Health Sciences found that active-stormy geomagnetic activity (GMA) on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR=1.58, 95%CI 1.07–2.32) and that the ef-fects of heliophysical conditions were stronger for women and older patients [255]. It was found that two days after geomagnetic storms the risk of myo-cardial infarction with ST elevation (STEMI) increased over 1.5 times in patients who had a medical history of myocardial infarction, stable angina, renal or pulmonary diseases and two days after solar proton in patients with stable angina [256]. The solar proton events also were associated with an increase of risk for patients with renal diseases in history.

A group of scientists from Vilnius University analysed cosmic ray flux variations and changes in cardiovascular disease [246, 247]. It was found that hard cosmic ray flux variations contribute only insignificantly to leaps in the number of cases of cardiovascular diseases, which are evoked by the sum effects of other factors [246]. Other studies sought correlations between