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Chronic Diseases:
Epidemiology and Health Care Disparities
Chronic diseases, with their prolonged span of pain and suf- fering, are a major cause of disability and death. The 25 million Americans, who are victims of chronic diseases, are unable to work, experience a decreased quality of life and find themselves sub- ject to significantly increased direct and indirect medical costs. In the United States, cardiovascular disease (including stroke), cancer, and diabetes make up about 2/3rds of all deaths annually (Eyre, et al., 2004; CDC, National Center for Chronic Disease Prevention and Health Promotion, p. 1, http://www.cdc.gov/needphp/overview.
htm).
These conditions are the result of complex interactions among environmental, social, and genetic factors (Quadrilatero and Hoffman-Goetz, 2003). Health care problems such as: smoking, overweight, obesity, poor nutrition, sedentary lifestyles, and genet- ics are some of the many factors associated with chronic diseases.
Racial, ethnic, gender, age, and socioeconomic disparities in health care may be risk factors for chronic diseases and also exac- erbate the impact of these conditions. Chronic health problems, such as diabetes and cardiovascular disease, pose a particularly severe burden on disadvantaged minority groups, including
African-Americans, Hispanics, and Native-American Indians, women, and disadvantaged socioeconomic groups. For instance, in the United States, African-Americans suffer a disproportionate stroke-burden and African-American stroke survivors have greater functional impairment than white stroke survivors (Ruland and Gorelick, 2005; MMWR Morb Mortal Weekly Report, 2005).
In the United States cardiovascular disease is the overall leading cause of death. Smoking, obesity, poor nutrition, physical inactivity, and genetic factors increase the risk of cardiovascular disease burden. In 2000, among U.S. adults, ages 25 to 44 years, heart disease was the leading cause of death among non-Hispanic Black adults and the 5th leading cause among Hispanics. Among adults in the 45 to 64 year age group, heart disease was the 2nd leading cause among Non-Hispanic Blacks, and the 2nd leading cause among Hispanics.
Gender differences in cardiovascular disease and its treatment have been documented. Several investigations have shown that women with coronary heart disease have a poorer prognosis as compared to men (Horsten, et al., 2000). Women are less likely than men to have invasive treatment of coronary heart disease although the prevalence of angina is increasing in women (Philpott, et al., 2001).
Socioeconomic factors are also related to coronary artery disease risk factors, coronary morbidity, and mortality in various developed countries such as the United States (Horne, et al., 2004;
Sonmez, et al., 2004; Rutledge, et al., 2003). Low socioeconomic status has been linked to coronary artery risk factors, such as higher body mass index and waist-to-hip ratios, cigarette smoking, seden- tary behavior, and higher risk for hypertension (Rutledge, et al., 2003). Patients with coronary artery disease who reside in lower socioeconomic status neighborhoods have been found to have an increased risk of death or myocardial infarction (Horne, et al., 2004).
Cancer is the second leading cause of death in the United States and is expected to become the leading cause of death during the next decade (Stewart, et al., 2004). In addition to genetic factors, lifestyle choices such as smoking, obesity, poor nutrition, alcohol use, a sedentary lifestyle, socioeconomic status, and environmental/
occupational exposures can be related to cancer morbidity and
mortality. Ethnic and racial disparities in cancer have been docu- mented. Cancer was the leading cause of death among Non- Hispanic Blacks and Hispanics in the 45 to 64 year age group (Centers for Disease Control and Prevention, 2001).
Ethnic and racial disparities in diabetes have been a prevalent pattern in the United States. In 2001, diabetes was the 4thleading cause among Non-Hispanic Blacks, and the 5th leading cause among Hispanics (Centers for Disease Control and Prevention, 2001). Obesity, sedentary lifestyles, and poor nutrition contribute significantly to the diabetes disease burden.
Arthritis, osteoporosis, fibromyalgia, and low back pain also have a major adverse impact on society because of the chronic, dis- abling nature of these prevalent disorders. Lifestyle, occupational, and genetic factors increase the risk of certain types of arthritis, other rheumatic conditions, and musculoskeletal disorders. One study estimated that in 1997, there were 2.5 million hospitalizations with any-listed arthritis diagnosis and 744,000 hospitalizations with the principal diagnosis of arthritis (Lethbridge-Cejku, 2003).
Gender disparities in arthritis have been documented, with women having a greater risk of developing the disease and suffer- ing higher levels of disability than men. Inequalities in health and access to arthritis care may be related to age, geography, and socioeconomic deprivation. For example, one study of access to knee joint replacements for people in need in the United Kingdom discovered that older and low socioeconomic status persons were less likely to access knee joint replacement services (Yong, et al., 2004).
The epidemiology of these diseases is detailed below.
Trends in Diabetes
Adult type 2 diabetes mellitus (also known as non-insulin- dependent diabetes mellitus or NIDDM) and other abnormalities involving glucose intolerance emerged as an epidemic in the 20th century and continues unchecked into the 21st century (Engelgau, et al., 2004; Shaw and Chisholm, 2003). In 1995, there were an esti- mated 135 million persons with diabetes worldwide, and the World Health Organization estimates that this number will grow to 300
million by 2025 (Pradeepa and Mohan, 2002). The geographical regions with the largest potential increases in diabetes are Asia and Africa (Amos, et al., 1997).
In the United States, the number of individuals with diabetes is predicted to increase 165%, from 11 million in 2000 to 29 million in 2050 (Boyle, et al., 2001). One investigation reported that between 1988 and 1994, the prevalence of the metabolic syndrome (a constellation of risk factors, including impaired glucose regula- tion, insulin resistance, raised arterial pressure, raised plasma triglyceride, and central obesity) increased among U.S. adults, aged 20 and older, especially among women. Ford, et al. (2004) found that the increase in the prevalence of the metabolic syndrome was due to increases in high blood pressure, waist circumference, and high triglycerides. The increase in the prevalence of the metabolic syndrome is likely to produce future increases in the prevalence of diabetes and cardiovascular disease.
Age disparities in diabetes have been found. The greatest percent increase in diagnosed diabetes is projected to be among those persons 75 years and older (271% increase in women and 437% increase in men) (Boyle, et al., 2001). It is projected that the fastest growing ethnic/racial group with diagnosed diabetes will be African-American males (363% increase between 2000 and 2050), followed by African-American females (217% increase), White males (148% increase), and White females (107% increase).
The rise in the prevalence of type-2 diabetes is associated with an increase in the prevalence of obesity. One report estimates that there are at least 1.1 billion adults who are overweight and 312 million who are obese (James, 2004). Another study estimated that the prevalence of obesity (a body mass index greater or equal to 30 kg/m2) among United States adults in 2000 was 19.8% and the prevalence of diabetes was 7.3% (Mokdad, 2001).
Of particular concern is that children and adolescents have some of the same risk factors as adults, and there is a growing epi- demic of type 2 diabetes among children and adolescents. Duncan, et al. (2004) discovered that among adolescents in the United States, especially overweight adolescents, there was a significant increase in the incidence of the metabolic syndrome. Based on an initial sample of 2,165 adolescents, aged 12 to 19 years, the authors reported an increased prevalence of the metabolic syndrome in
both sexes, although it was more prevalent in adolescent males than females. An increased prevalence of the metabolic syndrome was discovered in all three major racial and ethnic groups.
Trends in Arthritis, Osteoporosis, Fibromyalgia, and Low Back Pain
In the United States, arthritis, other rheumatic conditions, and musculoskeletal disorders are the leading cause of disability and impaired quality of life. In 2001, seventy million U.S. adults were afflicted with arthritis and other rheumatic conditions (MMWR Morb Mortal Wkly Rep, 2003). Age disparities in arthritis have been found, with older persons being at greater risk for developing arthritis and other rheumatic diseases. Given the projected growth of the older population, it is expected that the number of older persons with arthritis will double in the next 25 years (Leveille, 2004).
Rheumatoid arthritis, an inflammatory condition that usually affects multiple joints, is a painful, disabling disorder that can lead to joint destruction with major adverse economic, physical, and social effects (Woolf and Pfleger, 2003; Dai, et al., 2003). Rheuma- toid arthritis affects 0.3 to 1.0% of the general population and is more prevalent among women and in developed nations (Woolf and Pfleger, 2003). Rheumatoid arthritis occurs in 1% of the adult population worldwide (Markenson, 1991).
Another type of arthritis, osteoarthritis, is characterized by the loss of joint cartilage, which can result in pain and disability primarily in the knees, hips, and ankles (Woolf and Pfleger, 2003;
Felson, 2004). Osteoarthritis afflicts 9.6% of men and 18% of women over the age of 60. It is the leading cause of pain and disability among the elderly and is the 3rd leading cause of life-years lost due to disability (March and Bagga, 2004; Carmona, et al., 2001).
Because of increases in life expectancy and the aging of popula- tions, osteoarthritis is expected to become the 4thleading cause of disability by 2020 (Woolf and Pfleger, 2003).
Forty-four million women and men, ages 50 years or older, develop osteoporosis and osteopenia (Hansen and Vondracek, 2004). Osteoporosis, a condition involving low bone mass and
microarchitectural deterioration, significantly increases the risks of fractures of the hip, vertebrae, and distal forearm (Woolf and Pfleger, 2003). The most serious fracture is that of the hip since it is related to a 20% mortality rate and a 50% permanent disability rate. Gender disparities in osteoporosis are well known with women having a higher prevalence of the disease and related impairment, than men.
Fibromyalgia has been described as a disorder of endocrine stress responses. The disease consists of a collection of symptoms that have no identifiable cause, although the set of symptoms are clearly considered a distinct disease (Cymet, 2003). Some research indicates that psychosocial stress is implicated in the etiology of the disease and exacerbates the pain symptoms (Dedert, et al., 2004).
This controversial pain syndrome has increasingly become a major source of disability claims (Wolfe and Potter, 1996). Gender disparities in fibromyalgia have been found, with women having higher rates of the disease and impairment than men.
The most prevalent musculoskeletal disorder is low back pain, a leading cause of disability (Ozguler, et al., 2004; Ehrlich, 2003a;
Ehrlich, 2003b). Almost everyone suffers from low back pain at some point in their life, and at any given time, it is estimated that 4% to 30% of the population suffers from low back pain (Woolf and Pfleger, 2003). Another estimate is that the annual prevalence of low back pain is between 15% and 45% (Ozguler, et al., 2004).
Trends in Cardiovascular Disease
Despite enhanced patient care, greater public awareness, and extensive use of medical innovations, cardiovascular disease remains the leading cause of death in the United States (MMWR, 2001). Lifestyle and socioeconomic factors are major contributors to cardiovascular disease and associated mortality and morbidity.
Cigarette smoking causes over 400,000 deaths annually and is a major cause of coronary heart disease (Burns, 2003). Obesity, a sedentary lifestyle, and socioeconomic status factors are also major risk factors for cardiovascular disease morbidity and mortality.
Trends in Cancer
According to the American Cancer Society, 1,368,000 new cases of cancer and 563,700 deaths are expected in the United States in 2004. Among men, cancer incidence rates stabilized between 1995 and 2000, while cancer incidence rates continued to increase between 1987 and 2000 among women. Among men, cancer death rates have continued to decrease from three sites (lung and bronchus, colon and rectum, and prostate), while among women, cancer death rates have continued to decrease from two sites (female breast and colon and rectum) (Jemal, et al., 2004).
Large ethnic and racial disparities occur in the prevalence of cancer. African-American men and women have the highest rates of cancer mortality: 40% and 20% higher mortality rates from all cancers than White men and women, respectively (Jemal, et al., 2004).
It is estimated that 172,570 new cases of lung cancer (both small cell and non-small cell) and 163,510 lung cancer-related deaths will occur in the United States in 2005 (National Cancer Institute, MedNews, www.meb.uni-bonn.de/cancer.gov). In the United States, breast cancer is the most prevalent cancer in women (Harwood, 2004). It is projected that in 2005, more than 215,000 women in the United States will be diagnosed with invasive breast cancer, and more than 40,000 will die from the disease (Eneman, et al., 2004). In western countries, colorectal adenocarcinoma is the second cause of death due to cancer (Pasetto, et al., 2005). It is projected that more than one million cases of skin cancer will be diagnosed in 2005. Of these cancers, about 80% will be basal cell carcinoma, 16% squamous cell carcinoma, and 4% melanoma (Tung and Vidimos, The Cleveland Clinic, www.clevelandclinicmeded.
com).
