Adult urolithiasis in a population-based study in Iran: prevalence, incidence, and associated risk factors.

The aim of this study was to determine the prevalence, incidence, and risk factors of adult urolithiasis in Iran. A total of 8,413 persons aged over 14 years enrolled in this cross-sectional study. They were questioned on the occurrence of urinary stones during their lifetime (prevalence) and on acute urolithiasis in 2005 (incidence) by 62 general practitioners. The subjects were randomly identified from 30 counties of Iran. Data on risk factors for urolithiasis including age, race, education, body mass index, hypertension, and current use of medication were also obtained by self-administered questionnaire. Of the 7,649 participants who provided information, 5.7% (436) [95% confidence interval (CI) 4.2-5.4], reported urinary stones. The prevalence increased from 0.9% in adults aged 15-29 years to 8.2% in those aged 60-69 years (test for trend, P = 0.001). Urolithiasis was slightly more frequent and persisted in males (6.1%) than females (5.3%) giving a male-to-female ratio of 1.15:1 [odds ratio (OR) 1.03; 95% CI 0.64-1.36; P = 0.814]. The annual incidence of urolithiasis in 2005 was 145.1. The average cumulative recurrence rate was 16% after 1 year, 32% after 5 years, and 53% after 10 years. Urinary stones were more in number among men and women who lived in south central and southwest counties, with odds increasing from west to east and from north to south. A positive association was found between urolithiasis and obesity (OR 1.74; 95% CI 1.21-2.31; P = 0.04), diuretic use (OR 1.62; 95% CI 1.18-2.70; P = 0.03), hypertension (OR 1.88; 95% CI 1.26-2.18; P = 0.04), unemployment (OR 2.10; 95% CI 1.43-2.14; P = 0.04), consumption of tea (OR 1.64; 95% CI 1.32-2.62; P = 0.03), consumption of cola (OR 1.49; 95% CI 1.23-2.19; P = 0.02), and meat consumption (OR 1.38; 95% CI 1.29-2.21; P = 0.02). This study provides a quantitative estimate of the prevalence, incidence, and main risk factors for adult urolithiasis in the Iranian population. Further studies are warranted in order to determine the incidence and prevalence of urolithiasis in different ethnic groups.