Nocturia and obesity: a population-based study in Finland.

The authors' aim in this study was to analyze the association of nocturia with overweight and obesity. In 2003-2004, a questionnaire was mailed to 6,000 randomly selected Finns aged 18-79 years who were identified from the Finnish Population Register Centre. Information on nocturia was collected through questionnaires using the Danish Prostatic Symptom Score and the American Urological Association Symptom Index. Self-reported body weight and height were used to calculate body mass index (BMI; weight (kg)/height (m)2). Subjects were classified on the basis of BMI as nonoverweight (BMI<25), overweight (BMI 25-29.9 kgm2), or obese (BMI>or=30). Of the 6,000 subjects, 62.4% participated. Among men, the age-standardized prevalence of nocturia, defined as at least one void per night, was 33.4% (95% confidence interval (CI): 28.5, 38.3) in the nonoverweight, 35.8% (95% CI: 31.4, 40.1) in the overweight, and 48.2% (95% CI: 38.8, 57.6) in the obese. Among women, the corresponding figures were 37.2% (95% CI: 33.0, 41.5) in the nonoverweight, 48.3% (95% CI: 42.5, 54.2) in the overweight, and 53.6% (95% CI: 43.9, 63.2) in the obese. The associations remained similar when nocturia was defined as two or more voids per night. The age-standardized attributable fraction (population) of increased BMI for nocturia was 17.7% for men and 18.5% for women, corresponding to an 8.5% increase in the crude prevalence of nocturia in men and a 13.9% increase in women. The authors conclude that obesity is associated with increased nocturia, more strongly among women than among men.