LITHUANIAN UNIVERISTY OF HEALTH SCIENCES
FACULTY OF NURSING
Department of Geriatrics
Title of master thesis
The risk factors of delirium in older patients hospitalized in geriatric
units
Submitted in partial fulfillment of the requirements for the degree of Master
of Medicine
Author:
Firas Jaly
Supervisor:
Prof. dr. Jurate Macijauskiene
SUMMARY 3 ACKNOWLEDGEMENTS 4 CONFLICT OF INTEREST 4 ABBREVIATIONS 5 INTRODUCTION 6 AIM 8 OBJECTIVES 8 LITERATURE REVIEW 9
NON-MODIFIABLE RISK FACTORS 10
DEMENTIA AND COGNITIVE IMPAIRMENT 10
ADVANCING AGE 11
FRAILTY 12
MALE SEX 12
CHRONIC RENAL OR HEPATIC DISEASE 13
POTENTIALLY MODIFIABLE RISK FACTORS 14
SENSORY IMPAIRMENT 14 URINARY CATHETERIZATION 15 POLYPHARMACY 15 PHYSICAL RESTRAINT 19 ENVIRONMENT 19 INFECTION 20 SURGERY 21
OTHER ASSOCIATED RISK FACTORS 24
SOCIODEMOGRAPHIC AND EDUCATION 24
METHODOLOGY 26
DISCUSSION 28
FINDINGS AND THEIR SIGNIFICANCE: 28
STRENGTHS AND LIMITATIONS OF THIS REVIEW: 30
IMPLICATION FOR FUTURE RESEARCH: 31
IMPLICATION FOR CLINICAL PRACTICE: 31
CONCLUSIONS 33
SUMMARY
Author – Firas Jaly
Scientific Supervisor – prof. Jurate Macijauskiene
Research title – The risk factors of delirium in older patients hospitalized in geriatric units
Aim – To determine the most important risk factors for delirium in older patients hospitalized in geriatric units.
Objecives: 1) To assess and evaluate the most common risk factors of delirium among elderly hospitalized patients by systematically analyzing the literature. 2) To find correlations between patient clinical and sociodemographic variables and the importance of these risk factors. 3) To find the rates at which these risk factors precipitate delirium, and therefore determine their significance. 4) To demonstrate that improved clinical practices can help to decrease the incidence of delirium in older hospitalized patients.
Methodology. This was a Systematic Literature review where research was conducted using different databases (PubMed, UpToDate, BMJ, ResearchGate etc.). Articles from the year 1995 onwards (with well over 70 % of cited papers published in the last 10 years) were chosen with keywords such as “delirium”, “acute confusional state”, “dementia”, “transitory neurological deficit” were first used. These were then cross searched with terms such as “risk factors”, “common causes”, “in elderly”, “old age”, “geriatric patients”, “geriatric department”, “prevalence “and finally “incidence”. Articles which filled these criteria were chosen for this review.
Results. Delirium is a common and serious condition which affects a high proportion of the hospitalized elderly population. Studies estimate that 11% to 25% of older patients will have delirium upon admission, with a further 29% to 31% of those initially admitted without delirium developing it during hospitalization. The most significant risk factor for delirium ion older patients was dementia, followed by surgery. Other significant risk factors identified were polypharmacy, IUC, male sex, sensory impairment, environment, along with education and socioeconomic factors, physical restraint and infection.
ACKNOWLEDGEMENTS
I would like to express my deepest appreciation to Dr Jurate Macijauskiene for her guidance who enabled me through my final year project
ABBREVIATIONS
ADL’s- Activities of daily livingADR’s- Adverse drug reactions
ASA- American society of anesthesiologists BBB- Blood brain barrier
DAP’s- Drugs with anticholinergic properties ICU- Intensive care unit
IUC- Indwelling urinary catheter OR- Operation room
RF’s- Risk factors
SES- Socioeconomic status
INTRODUCTION
Delirium sometimes referred to as acute confusional state is a disorder characterized by acute changes in mental status and alterations of consciousness with one of its defining features being its fluctuating course [1]. Delirium is a common, serious and often-unrecognized complication of age related chronic and acute conditions. The diagnosis of delirium is considered a medical emergency and is often complicated by the lack of early recognition of its risk factors and presenting symptoms by clinicians.
As many as one third of older medical patients experience delirium at as some stage during hospitalization. Studies have shown that among geriatric surgical patients, the risk for delirium varies from 15% to 53%, whilst delirium was recorded in 50% to 80% of those requiring intensive care [2]. Most cases of delirium are diagnosed or develop during hospitalization, with higher incidences found with increasing age. Prevalence of delirium in therapeutic wards is high. According to the literature, 11% to 25% of older patients will have delirium upon admission (prevalent delirium). A further 29% to 31% of those initially admitted without delirium will develop it during their hospital stay (incident delirium) [2]. Past studies have recorded the prevalence of delirium in the Intensive care unit (ICU) at a rate of 11% and 87%, also demonstrating that the risk is particularly higher in elderly patients with pre-existing cognitive impairments [3].
Patients who develop delirium are at an increased risk for adverse medical outcomes. Studies have associated delirium with a 3 to 5 times increased risk of nosocomial infections and a tenfold increased risk of in hospital mortality [4]. Delirium is a major cause of prolonged hospital stay and poor physical recovery and patients who develop it are posed to a significantly increased risk of developing other neurological diseases, such as dementia, further down the line [4]. After hip fracture surgery in patients >60 years of age delirium was the most commonly seen complication (19%), this study further concluded that delirium was one of only two independent risk factors for mortality [5]. The strong association between delirium and morbidity, mortality and increased health care costs have of late led to the its more formal classification as a target organ injury in critical care contexts [6].
As with most diseases seen in the geriatric department delirium is a multifactorial disorder. Risk factors for delirium are numerous and varied and include underlying neurological diseases such as dementia, stroke or Parkinson’ disease [7]. Other precipitating factors include infection, overmedication (or polypharmacy), dehydration and the use of urinary catheters. Multivariate analysis of variables affirmed that old age (>75), diabetes, and ASA classification (> 2 level) were independent risk factors of post-operative delirium [8]. Despite its high incidence the heterogeneity in its
AIM
To determine the most important risk factors for delirium in elderly patients hospitalized in geriatric units.
OBJECTIVES
1. To assess and evaluate the most common risk factors of delirium among elderly hospitalized patients by systematically analyzing the literature.
2. To find correlations between patient clinical and sociodemographic variables and the importance of these risk factors.
3. To find the rates at which these risk factors precipitate delirium, and therefore determine their significance
LITERATURE REVIEW
Development of delirium in geriatric patients is attributed to a series of complex interactions of numerous risk factors [7]. These risk factors are broadly grouped into modifiable (sometimes referred to as potentially modifiable) and non-modifiable risk factors [7]. Modifiable risk factors are behaviors or exposures that can increase a person’s probability of developing a disease, they are modifiable as in principle they can be changed. In contrast non modifiable risk factors are those which are non-adjustable and cannot be varied regardless of actions undertaken.
Table 1
[7] Modifiable and nonmodifiable risk factors of delirium
(Fong TG, Tulebaev SR, Inouye SK)
with underlying dementia and multimorbidity, a relatively benign insult--such as a single dose of sleeping medication--may be enough to precipitate delirium” [12]. The opposite is equally true.
Table 2
[12] Effect of predisposing and precipitating factors on vulnerability of the patients
(Inouye SK, Westendorp RGJ, Saczynski JS)
Table 3
[14] Precipitating and predisposing risk factors
(Davis D)
Non-Modifiable risk factors
Dementia and cognitive impairment
[16] Previous studies had determined dementia as the number one leading risk factor of delirium, with delirium also being cited as an independent risk factor for subsequent dementia [17]. Dementia cause for progressive neuronal loss. Late stage dementia even causes for a decrease in the size of the brain (atrophy) and a progressive worsening in many cognitive functions. This means that the brain “reserve” is diminished, leading to an increase in vulnerability for the development of delirium. In Alzheimer’s disease there is a decrease in cholinergic activity, which contributes to cognitive decline and may result in delirium down the line. However, the exact mechanisms of how dementia predisposes for delirium have not been completely elucidated. There is a lack of studies here. More researched has been the way in which delirium, through direct toxic effects on the brain, cerebral ischemia, and chronic stress leads to neuronal dysfunction and damage. This of course can cause dementia. Many of the same mechanisms may be implicated when it comes to dementia and cognitive impair predisposing to delirium. This has yet to be fully determined. What is unquestionable however, is the link between the presence of cognitive impairment/ dementia and the development of delirium. The prevalence of both delirium and dementia in clinical settings and how they are intrinsically linked has led to them often going unrecognised or being mistaken for each other [17]. One Dutch study which assessed the risk factors of patients acutely admitted to their medical wards found that cognitive impairment was the strongest indicator for the development of delirium, identifying a nine fold increase in risk [18]. This is further supported by previous studies which found cognitive impairment to be a strong predictive marker for delirium (relative risk 2.8; CI, 1.2 to 6.7) [19]. Another study undertaken at the Royal Orthopaedic hospital in Birmingham corroborated this when they found that older patients undergoing femoral fracture surgeries were much more likely to become delirious post-operatively if they had a prior diagnosis of dementia on admission (51% vs 37%, p=0.02) [20].
Advancing Age
delirium is oxidative metabolism. An inadequate supply of oxygen to the brain results in an inadequate oxidative metabolism. This in turn leads to cerebral dysfunction. The normal aging process causes a decrease in organ function which may interfere with oxygen supply. This places older patients at a higher risk of delirium than their younger counterparts, particularly in settings of increased stress, such as postoperatively. Physiologic changes in aging many increase the development of drug induced delirium. This is particularly significant as polypharmacy and anticholinergic toxicity are common place among older patients. Certain geriatric diseases such as Alzheimer’s disease and other forms of dementia are also linked to delirium. Age related decreases in cognitive reserve and brain size also predispose to the onset of an acute confusional state. This may explain increasing rates of delirium in older populations and why advancing age is such an important risk factor of delirium.
Frailty
Frailty, a geriatric syndrome defined “as a clinically recognizable state of increased vulnerability resulting from aging-associated decline in reserve and function across multiple physiologic systems such that the ability to cope with every day or acute stressors is comprised” [24], was found to be intrinsically linked to the development of delirium. Of the 114 patients analyzed 20% developed delirium. Of those 20% almost 90% presented with frailty. On the other hand, the mean frailty score for non-delirious patients was significantly lower than for delirious participants [25]. It has long been established that frailty steadily increases with age, with rates quoted as: 65-69 years: 4%; 70-74 years: 7%; 75-79 years: 9% 80-84 years: 16%; >85 years [26]. With an increase of age leading to an increase in the prevalence of frailty, and a subsequent increase in frailty associated with a greater incidence of delirium, it becomes very clear than age is one of the major risk factor for the development of delirium being both a non-modifiable and predisposing factor. The reasoning behind this is that frailty leads to an increased state of vulnerability in elderly patients for the development of delirium as subjects suffer from a multitude of diseases. They are also usually less mobile, more dependent, and less socially active. These factors when combined lead to a decrease in cognitive reserve and a subsequent increase in the likelihood of the development of delirium when certain precipitating factors are present.
Male Sex
Although there were differences between male and female participants with regards to preoperative risk factors associated with delirium, the relationship between male sex and postoperative delirium remained robust even after adjusting for other risk factors [28]. One clinical study, which analyzed both surgical and medical patients who developed delirium found that more males were recorded in the delirious participants when compared to the control group. There were also more males patients in the medical subgroup (70.4%) and the surgical subgroup (69.5%) than in the control group (46%) [29]. One study carried out in a Lithuanian cardiac intensive care unit demonstrated that on average male patients were 7 years younger than their female counterparts. Furthermore, it showed that patients younger than 65 years of age who experienced delirium were more likely to be male (also had a more severe form of the disease), whilst the majority of patients older than 85 years were female [30]. One study, which evaluated people with dementia who later on suffered from delirium, reported that delirium severity scores were higher for males than for females [15]. Males also had a higher risk of developing delirium in the ICU (63% vs 36%) compared to females [31]. Although much of the evidence points to a general risk increase in men, this is not always the case. In a pooled analysis male sex was not significantly linked with delirium risk [22]. However, it is clear than when taking a wider view and considering factors such as environment (ICU, surgery), age, and various other factors, the male sex was consistently cited as a risk factor in vulnerable patients.
Chronic renal or hepatic disease
Delirium can also be in part attributed to liver disease. One study found that 55% of cirrhotic patients suffer from various psychiatric diseases such as hepatic encephalopathy, anxiety, and also delirium. A vitamin B12 deficiency (caused by liver disease) has also been showed to cause delirium [38] [39]. Hepatic encephalopathy occurs in 60-80% of patients suffering from cirrhotic liver disease. Hepatic encephalopathy is cause by the toxic effects of nitrogenous wastes on the brain. This toxic waste disturbs brain function by altering neurotransmission, which control consciousness and behavior. Most patients with hepatic encephalopathy and liver failure also have a certain degree of cerebral edema, which also adversely effects cognitive function. An increase in ammonia (main nitrogenous waste) leads to more glutamate being present in the brain. This causes astrocytes to swell and precipitates an upregulation in GABA (a neurotransmitter involved in the development of delirium). This complex of reactions means that older patients with hepatic failure, and more specifically hepatic encephalopathy develop a variety of neuropsychiatric disorders, including delirium. Another explanation to why hepatic disease leads to an increase in the incidence of delirium is that patients are usually taking multiple drugs for treatment (polypharmacy) and also present with many comorbidities such as renal disease, infections, and malnutrition (all predisposing and precipitating factors of delirium).
Potentially Modifiable risk factors
Sensory Impairment
implemented, in their renal unit. 42.5% of the sample of patients studied suffered from visual impairment (in large part due to diabetic retinopathy). Providing aids for visual perception was found to improve orientation to the environment and ability to perform ADL’s. Marking a pitcher with red tape enabled patients to have easier access to fluids and prevented dehydration. All of these were found to positively influence patient recovery and hindered the development of delirium [43]. Another study, which implemented similar intervention, found that delirium developed in 9% of the intervention group as compared with 15% in the control group, a 34% decrease in incidence [44]. This shows that although hearing and vision loss are major risk factors for delirium, they can be minimized by improved medical and nursing practices.
Urinary catheterization
The presence of an indwelling urinary catheter poses a considerable risk of delirium in geriatric patients. In 1996, the insertion of a urinary catheter was found to be one of 5 major hospital related insults that could help precipitate new onset delirium [13]. In 1999, minimizing the use of indwelling urinary catheters was shown to reduce the risk of delirium in hospitalized geriatric patients [45]. A study of older patients undergoing surgery for osteoporotic hip fractures confirmed that patients with an indwelling urinary catheter preoperatively had 4.9 times higher risk for delirium perioperatively [46].
Urinary catheters have also been associated with an increased occurrence of delirium in elderly patients hospitalized with cardiac disease [47]. Another Italian study which aimed to evaluate the association of urinary catheterization and delirium in patients >65 yrs. either hospitalized or in nursing homes further strengthened these claims when they found that IUC’s had a significant increase in the incidence of cognitive impairment and delirium (with the latter being significant also in the subset of patients without underlying dementia) [48]. Many mechanisms for why catherization has an affect delirium have been proposed. Indwelling urinary catheters cause a sensation of urination, which can be stressful to patients. This stress may contribute to the development of delirium [49]. It must also be noted that patients who require urinary catherization may have a poorer physical state and suffer from many more comorbidities, which can also conduce to delirium. More importantly, deconditioning-related disability and IUC-deconditioning-related UTIs are what are most attributed to delirium in elderly patients [50]. Therefore, responsible and appropriate use of urinary catheters can go a long way in the prevention of UTI’s, stress, disability, and ultimately delirium particularly in older hospitalized patients.
Polypharmacy
pharmacodynamics along with frequent comorbidities (such as cardiovascular and cognitive disorders) attributed to old age. This means that geriatric patients are more susceptible to ADR’s [51].
Table 4
Pharmacokinetic changes in elderly [52]
(Lee H-C, Tl Huang K, Shen W-K)
that polypharmacy alone may account 12-39% of all cases of delirium [56]. A wide variety of pharmaceuticals have been affiliated with the appearance of delirium, but certain classes of drugs are move commonly identified as causative agents of delirium.
Table 5
[55] Common drugs associated with delirium [
(Alagiakrishnan K, Wiens CA)
whilst only 17% of those not using multiple DAP’s were recorded as having delirium (however in a logistic regression analysis with age, gender and Charlson comorbidity index as covariates, DAP’S did not predict delirium) [60]. Nevertheless, there is a clear association between anticholinergic use and delirium and these drugs, whilst at times difficult to avoid in elderly patients, must be avoided in those at high risk of delirium. Concurrent medical issues also greatly contribute to the appearance of drug induced delirium. For example in those with heart failure, hepatic congestion means a reduction in metabolism, and renal insufficiency means a decline in drug elimination [55]. Another example is the reduced blood brain barrier in those suffering from dementia or stroke, which may allow for potentially harmful drugs to gain access to the brain, therefore making dis-integrity of BBB strongly associated with delirium susceptibility [61]. Pharmacokinetic age related changes, which generally lead to an increased half-life (due to increase in fat mass), decreased renal and hepatic function, along with a minimization in volume of distribution also play a vital role in the event of drug-related delirium. Pharmacodynamic changes such as an increase in cholinergic receptor sensitivity in the older population has also been previously proven [62]. In general, age related receptor changes occur in all organs, with the final outcome being “a heightened sensitivity of the brain to adverse drug reactions (ADR’s) [55]. In short, multiple medications, co-morbidities, and of course physiological changes in the elderly all mean that polypharmacy is one of the major players in the development of delirium in geriatric patients, being at the same time one of the most avoidable.
Physical restraint
Physical restrain has longed been established as a precipitating factor for delirium. Restraint causes an increase in stress in older patients, which may help in precipitating delirium. These patients are also immobilized and often need urinary catheters making infections a more common occurrence. Both these factors are modifiable and precipitating risk factors of delirium in older patients. Patients who require physical restraint often have cognitive impairments, which necessitate forced immobilization. And according to the literature cognitive impairment is one of the most significant risk factors of delirium. This goes a long way in explaining why physical restraint is linked to delirium. The high incidence of delirium in those previously restrained demonstrates a strong association between the two [63]. A common practice in the ICU, almost 40% of one cohort study who were restrained in the intensive care unit developed delirium. Also very importantly, duration and number of restraints were positively related to delirium. Patients who were restrained for more than 6 days had more than a 26x higher risk of delirium than those who were retrained for less than 6 days [64]. There is also an even higher relative risk of delirium for restrained patients outside the ICU according to Inouye [13]. Unnecessary restraints must be banned to mitigate this complication, and necessary restraining must be minimized, or altogether abandoned if alternatives can be found.
On a similar note, environment also plays a key role in the onset of delirium. The abrupt transfer of a patient from one ward to another was found to seemingly increase incidence [63]. Likewise, a reduction in daylight and visitors also left patients at a greater risk for delirium [63]. Recent research indicates apparent beneficial effects that visitors may have on patients admitted to the ICU (as is the case for many geriatric patients) in this sense [65]. These data points to the fact that, simple practice such as increasing visible daylight, and allowing for more visitation times for ill elderly patients may a go a long way in curtailing the prevalence of delirium in this population. The effect which environment has on the onset of delirium stems from either a sensory overload or sensory deprivation. An increase in stressful events such as frequent room transfers, visits to the emergency department (particularly night-time visits) and hectic hospital environments can all contribute to an increased incidence of delirium. Likewise, a low amount of mental stimulation such as in isolation of patients, a lack of visitors, and a reduction of general activity also precipitate delirium. In both cases patients are unable to orientate themselves in their environment and become more detached from reality, predisposing them to cognitive impair. The association between environmental factors and delirium are evidenced by studies demonstrating that non-pharmacological interventions, principally environmental intervention programs are useful in countering the appearance of delirium.
Infection
Surgery
Table 6
[75] Incidence of delirium according to the surgery performed
(Rudolph JL, Marcantonio ER)
Table 7
[78] Rates of delirium after different surgeries
(Pol R, van leeuwen B, Visser L, J Izaks G, Dungen J, Tielliu I, et al)
Other associated risk factors
Sociodemographic and education
Although the link between socioeconomic background and education has not been comprehensively resolved, some studies claim that both poorer levels of education and social class may have a negative impact on the development of delirium. One study, which attempted to assess the association of education with the occurrence of delirium found that, on average, those who developed delirium had a lower mean number of educational years (4.92 years in delirium patients vs 6.96 in non-delirium patients) [83]. The level of educational attainment has been cited frequently as a marker for cognitive reserve. In fact, higher levels of formal education are associated with an increase in cognitive reserve, with lower levels coinciding with a reduction [84]. Another paper, which analyzed 2 separate studies (on patients aged 65+), found that, in both cases, the risk of delirium was augmented among persons with fewer years of education [85]. Furthermore, each year of completed education was associated with a 0.91 lower odds of delirium (95% confidence interval: 0.87, 0.95). When compared to those who had undergone 12 years of formal schooling, those who only completed 7 years had a 1.6 fold increased risk of developing delirium [85]. Another aspect, which must be accounted for, is the influence which education plays on the development of dementia. The relationship between dementia and delirium has already been clarified in this review, with dementia leading to an increased vulnerability of patients for the development of delirium. Studies show, that low education (<6 years) is associated with an increased risk for Alzheimer’s disease [86]. Conversely, higher levels of education convey certain protective factors against dementia [87]. In fact, the strong inverse association of educational attainment with risk for dementia has led some researchers to claim that education may be the most important protective factor for dementia [88]. This fact lends further evidence to the claim that low education increases the incidence of delirium in the elderly, as higher levels of dementia would invariably lead to more cases of delirium.
Peer reviewed papers identified through
electronic search PubMed, NCBI= (432 )
Papers screened on basis of title and abstract=
(123)
Full text assessed for eligibility=(67)
METHODOLOGY
Peer reviewed papers Peer reviewed papers identified through identified through
electronic search electronic search UpToDate, medical ResearchGate, web
Journals= (60 ) search= (40)
Papers screened on basisPapers screened on basis of title and abstract= (25) of title and abstract= (22)
Full text assessed for Full text assessed for
eligibility=(15)eligibility=(12)
To carry out the objectives outlined in this Systematic Literature review databases such as PubMed, UpToDate, and the American Heart Journal (AHJ), ResearchGate were searched. Relevant papers were selected in a rigorous and organized manner. Search terms such as “delirium”, “acute confusional state”, “dementia”, “transitory neurological deficit” were first used. These were then cross-searched with terms such as “risk factors”, “common causes”, “in elderly”, “old age”, “geriatric patients”, “geriatric department”, “prevalence “and finally “incidence”.
Irrelevant papers were then excluded on the basis of title and abstract. The next step involved assessing paper for eligibility based on their full text. Inclusion criteria were employed to further eliminate non-relevant papers from our search. These consisted on the date of publication (papers could be no older than 25 years (although well over 70% of cited papers were published in the last 10 years) and had to be published in English), relevance to the topic, paper had to be peer reviewed and all types of studies were included (both qualitative and quantitative).
DISCUSSION
Findings and their significance:
This review identified 94 studies, which, in varying degrees, studied the risk factors, which both precipitate and predispose to the development of delirium in elderly hospitalized patients. The studies included, by and large, consisted of systematic reviews, meta-analysis, cohort studies, case control studies, and some case-report studies. All of the papers researched which focused primarily on delirium and its risk factors, included the risk factors discussed in the literature review section, alone or in combination (with all of them being referenced to in most cases).
The studies demonstrated that dementia was by far the most significant predisposing, non-modifiable risk factor which elderly patients could possess for the development of delirium. In fact, some studies even claimed that dementia was the number one leading risk factor for delirium. The findings of this study seem to suggest that also, with the strong relationship between prior cognitive impairment and delirium being constantly affirmed in paper after paper. The presence of dementia therefore, should be a red flag for geriatricians, and clinicians alike dealing with older person admitted to their wards.
IUC is, according to the literature, one of the major in-hospital determinants of delirium in both surgical and non-surgical geriatric patients. The longer a urinary catheter is present the more serious the risk. IUC’s should be employed with care. The presence of a urinary catheter preoperatively was associated with an almost fivefold increase in the risk of delirium post-operatively. Even in institutionalized patients (e.g. those in nursing homes) and those on clinical wards, long-term catheterization represented an important risk, regardless of surgery. Indeed, urinary catheterization was among the most frequently mentioned risk factors of delirium during the course of this research.
As in previous studies, male sex and advancing age were found to be statistically significantly risks for delirium. Perhaps not surprisingly increased age was associated with an increased vulnerability (e.g. frailty syndrome) for acute and transient cognitive impairment. The evidence for the male sex predisposing delirium was more varied. Some studies found no significant association between delirium in male and female groups. Other studies claimed that males were more likely to develop delirium in some age groups, and females more likely in others. Nonetheless, the majority of the data encountered during this study pointed to an increase occurrence of delirium in males admitted to the hospital.
Similarly, this study demonstrated clear and unequivocal confirmation that underlying renal and hepatic disease along with the presence of infection predisposed to and precipitated delirium, respectively. CKD necessitating hemodialysis and the presence of liver cirrhosis were the major players. AKI, especially in the context of ICU, was also consistently linked to those who developed delirium. Infection, regardless of its origin, was identified as a trigger of delirium. The presence or absence of any of these conditions should be clarified in all elderly patients admitted to the hospital. This will help to stratify patients according to their risk, and perhaps encourage medical practitioners to take appropriate steps to avert the occurrence of delirium.
Whilst performing this review the importance of environment and its contribution to delirium was very evident. The findings suggest that patients are more likely to develop delirium when they are suddenly transferred from one ward to another. Moreover, physical restraint and sensory impairment (which also form part of the environment of the patient) were consistently found to precipitate delirium to some degree. Geriatricians should always be highly aware of this fact. When these conditions were improved a significant reduction in the number of cases was seen, and this was demonstrated by many of the papers studied.
especially in patients who are hospitalized, is manageable. Physicians must attempt to cut down on the number of drugs that older persons are taking or find alternatives to these drugs, which increase patient vulnerability (e.g. diazepam’s, anticholinergics etc.).
Strengths and limitations of this review:
One of the main strengths of this review is that it is composed of a wide variety of published papers, stemming from various different countries, consisting of multiple different populations and therefore distinctly different sample groups. The difference in location also offered a wide range of different risk factors studied, with studies performed in a number of different departments, including the ICU, orthopedics, cardiac surgery, medical department and many others. Some of the studies included offered a wide range of perspectives, with some studies focusing primarily on nursing practices, and others on patient conditions and medical interventions. This helped to give a broader scope of the subject. The risk factor which most often appeared (and that were studied in greater detail in this review) were present consistently and repeatedly across a wide spectrum of hospital settings. My review was, regrettably, limited to those papers, which were published in English. This may have meant the exclusion of a range of relevant and applicable investigations produced in non-English speaking countries. Although, some of the studies examined in this review were published bilingually (in their native language and also in English).
As in all systematic literature reviews, the possibility of bias is increased when compared to other methods of studies. There is no set method to ensure that all of the relevant literature is considered, and this may increase the likelihood of a somewhat biased result. This review is no different. Although I attempted, as much as possible to study as wide a range of papers as possible, keyword searches mean that, in general, the papers, which were found and analyzed, supported the initial aim of the study. However, a wide range of studies considered, and an inclusion of contrasting papers and results has assisted in lessening this potential bias.
management of this condition. This is a plus, as the importance of interdisciplinary work in the management of geriatric patients is a well-acknowledged fact.
Implication for future research:
The risk factors for delirium are varied and often times intricate. The way in which they interact with one another and provoke delirium in those older persons admitted to the hospital needs to be further investigated. Although some risk factors have been definitively associated with the occurrence delirium, the mechanism in which they bring about this disorder have not been fully elucidated e.g. dementia.
The relationship between frailty syndrome and dementia for instance, has been extensively studied. The same cannot be said however for delirium. There is unfortunately a relative scarcity of research on the topic.
The occurrence of delirium is particularly challenging to document. It is by definition “an acute and transitory condition”. This makes the recording of its appearance very difficult, as it requires periodical monitoring by medical professionals who are able to recognize the condition. This means that the true extent of its prevalence may be overlooked, and therefore its risk factors inadequately analyzed.
Another significant gap in the literature is the study of the pervasiveness of already established risk factors in wards, which harbor aging patients. There is a need for research in this area. Geriatric wards must assess the prevalence of previously identified risk factors among their patient populations. The same can be said for surgical and medical units. Nursing homes also house many elderly patients who at some point develop delirium, both prior and post hospitalization. The rates of delirium risk factors in these institutions must be determined.
Finally, studies, which examined the effects of substituting general anesthesia with local anesthesia in elderly patients at risk of acute cognitive impairment, were few and far between. This is a very promising area, which could produce great benefits in the management of geriatric pts. who visit the OR.
Implication for clinical practice:
tackling deteriorated hearing and vision in older patients improves orientation in their environment, thus hindering the potential appearance of delirium in these patients.
Urinary catheters must be used with care, particularly long-standing catheters. The same can be said for physical restraints. Avoiding this practice, especially in those at high risk, will prevent may cases of in-hospital delirium.
CONCLUSIONS
Delirium is a common and serious condition, which affects a high proportion of the hospitalized elderly population. Studies estimate that 11% to 25% of older patients will have delirium upon admission, with a further 29% to 31% of those initially admitted without delirium developing it during hospitalization.
1. Significant risk factors in this systematic literature review were age, male sex, dementia, underlying renal and hepatic dysfunction, polypharmacy, urinary catheterization, infection, sensory impairment, physical restraint, and surgery.
2. Education and socioeconomic background were also found to contribute to the development of delirium.
3. Dementia and surgery were by far the risk factors, which precipitated delirium at the highest rate. Infection and urinary catheters also caused delirium in a high proportion of patients
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