Are incident gallstones associated to sex-dependent changes with age? A cohort study.

Age and female sex have repeatedly been identified as gallstone determinants but the underlying mechanisms are not clarified. The objectives of this study were to determine if changes with age in physiology, lifestyle, or reproductive hormones were associated with incident gallstones. A cohort study of a general population random sample (N = 2366) aged 30-60 years was performed. Participants were ultrasound screened for gallstones in 1982-84 and again in 1993-94. Lifestyle data and blood samples were obtained and re-analyzed in 2004. Changes with age in physiology (body mass index, blood pressure, blood lipids, self-rated health), lifestyle (smoking, alcohol and coffee consumption, dietary habits, physical activity level), and indices of reproductive function (number of births, oral contraceptive use, hormone replacement therapy, male reproductive hormones) were explored in females and males separately. Adjusted logistic regression analyses were performed. Incident gallstones (gallstones and cholecystectomy) at ultrasound examination in participants initially free of gallstones at baseline occurred in 9.9% of the study population. In females, increasing alcohol consumption (odds ratio (OR) 0.94, 95% confidence interval (CI) [0.90; 0.98]) and the cessation of hormone replacement therapy (OR 0.29, 95% CI [0.10; 0.83]) inversely determined incident gallstones. In males, increasing levels of SHBG (OR 0.97, 95% CI [0.94; 0.998]) inversely determined incident gallstones. Other changes with age in physiology, lifestyle, or reproductive hormones were not associated. High baseline free testosterone determined incident gallstones in males (OR 1.15, 95% CI [1.02; 1.30]). To conclude, changes with age in alcohol consumption in females and in reproductive hormones determined incident gallstones. Male reproductive hormones seem to have an impact on incident gallstones. Sex differences should be explored further in future studies.