Gallstones are common with prevalences as high as 60% to 70% in American Indians and 10% to 15% in white adults of developed countries. Ethnic differences abound with a reduced frequency in black Americans and those from East Asia, while being rare in sub-Saharan Africa. Certain risk factors for gallstones are immutable: female gender, increasing age, and ethnicity/family (genetic traits). Others are modifiable: obesity, the metabolic syndrome, rapid weight loss, certain diseases (cirrhosis and Crohn disease), gallbladder stasis (from spinal cord injury or drugs, such as somatostatin), and lifestyle.
Gallstone disease is a major health problem that is escalating. To identify risk factors in a given population, epidemiologic studies must first define the frequency of disease. Such information should not only direct public health initiatives but also reveal causal relationships; biologic plausibility reaffirms correlations and this then drives research to advance health care.
The prevalence of gallstones (ie, the number of individuals harboring gallstones at a certain point in time) is best determined by studies in well-defined patient populations that use ultrasonography, a noninvasive and safe method. Ultrasonography eliminates the bias of autopsy, which implies death, and of clinical diagnosis, which requires biliary symptoms, yet only 20% ever experience symptoms. The frequency of cholecystectomy, another potential measure of disease burden, has only a limited relationship to the prevalence of gallstone disease in a population, limited by the perceived threshold for surgery (largely doctor driven) and patient access to care. Less well studied is its incidence, the risk of developing gallstones within a certain period of time or per person-years.
Burden of gallstone disease
Gallstones are an ancient entity, having occurred more than 3500 years ago according to autopsies performed on Egyptian and Chinese mummies. Gallbladder disease today is a common problem: 20 to 25 million Americans harbor gallstones, representing 10% to 15% of the adult population. It constitutes a major health burden, with direct plus indirect costs of approximately $6.2 billion annually in the United States. This burden has increased more than 20% since the 1980s and accounts for an estimated 1.8 million ambulatory care visits. Gallstone disease is now a leading cause of hospital admissions for gastrointestinal problems, yielding 622,000 discharges (according to the most responsible diagnosis) each year in the United States. This hospital burden is actually an underestimate; most admissions occur for laparoscopic cholecystectomy, commonly done without an overnight stay and thus not included in hospitalization statistics. Gallstone disease has a low mortality rate of 0.6%, but considering the burden of the disease, there were still an estimated 1092 gallstone-related deaths in 2004. Case fatality rates have steadily diminished from more than 5000 deaths in 1950, falling more than 50% between 1979 and 2004. This decline represents the greatest decrease for any digestive disease.
Although most gallstones are clinically silent, 20% of people harboring stones experience true biliary symptoms at some time; 1% to 2% of patients each year experience complications and require surgical removal of the gallbladder. Yet the number of operations for cholelithiasis has increased since 1950 in developed countries. During the mid-twentieth century, the frequency of gallbladder surgeries was 6 times higher in the United States than in Western Europe. Gallstone disease in Europe, however, is similar to that in the United States, with a median prevalence in large population surveys ranging from 5.9% to 21.9%. The reason for this discrepancy does not lie in the prevalence of cholelithiasis but most likely represent differences in surgical practice. The introduction of laparoscopic cholecystectomy in 1989 further increased the cholecystectomy rate in the United States and the United Kingdom From 1990 to 1993, there was a 28% escalation in the numbers of cholecystectomies performed. A likely explanation for this increase is that laparoscopy is less invasive, providing a lower surgical risk and better patient acceptance compared with conventional (open) surgery, therefore leading to more surgeries in patients previously thought too high a risk or in those with minimal symptoms. Although there is undoubtedly an element of overuse, cholecystectomy is now the most common elective abdominal surgery performed in the United States, with more than 750,000 operations annually.
Ethnicity and gallstone disease
The highest prevalence of gallstone disease has been described in North American Indians: 64.1% of women and 29.5% of men have gallstones ( Table 1 ). This apparent epidemic reaches a high of 73% in Pima Indian women over age 30. Similar high occurrences have been reported among the aboriginal populations of South America. In the native Mapuche of Chile, gallstone disease afflicts 49.4% of women and 12.6% of men, exceeding 60% in women in their 50s. Mexican Americans are also at an increased risk when compared with white Americans. As elsewhere in the Americas, this risk is directly related to the degree of Amerindian admixture. White Americans have a prevalence of 16.6% in women and 8.6% in men. In Northern Europe, prevalence is somewhat higher at 20%, whereas lower rates are evident in Italy at 11%. Intermediate prevalence rates occur in Asian populations and black Americans (13.9% of women; 5.3% of men). The lowest frequencies occur in sub-Saharan black Africans (<5%) ; the entity is virtually nonexistent in the Masai and the Bantu.
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