Vasectomy is associated with an increased risk for urolithiasis.

We evaluated vasectomy as a potential risk factor for urolithiasis. Vasectomy is a common method of contraception among otherwise healthy men. This is also the population at highest risk for urolithiasis. We conducted a case-control study of patients in a large prepaid health maintenance organization. Cases were men experiencing initial episodes of urolithiasis, ascertained by reviewing radiology logs and medical records. The age-matched controls were men with no history of urolithiasis. In logistic regression models, the relative risk of urolithiasis for men with vasectomies compared with men without vasectomies was 1.9 for men younger than 46 years of age (95% confidence interval = 1.2 to 3.1, P = 0.005), and the relative risk was 0.9 (95% confidence interval = 0.5 to 1.5, P > 0.8) for men who were at least 46 years old. The relative risk of urinary calculi was 2.0 (95% confidence interval 1.0 to 4.1, P < 0.05) for men with vasectomies 0 to 4 years before evaluation compared with men without vasectomies, and the excess risk persisted as long as 14 years postvasectomy. Vasectomy was associated with a twofold increased risk for urolithiasis in men younger than 46 years of age. This increased risk may persist for up to 14 years postvasectomy. Given the large number of men who undergo vasectomy worldwide each year, the increased risk for urolithiasis among vasectomized men may result in substantial excess morbidity.

Dietary and behavioral risk factors for urolithiasis: potential implications for prevention.

Few studies have examined urolithiasis in primary care populations, and limited data are available on non-drug interventions to reduce the risk for urinary calculi. Therefore, we conducted a case control study of patients enrolled in a large prepaid health maintenance organization. The 240 study cases were men experiencing initial episodes of urolithiasis, ascertained by reviewing radiology procedure logs and medical records. The 392 controls were age-matched men with no history of urolithiasis chosen from a list of randomly selected men. Data were collected using standardized telephone interviews. Odds ratios were calculated for potential risk factors. In logistic regression analyses the risk for urinary tract calculi was related to both consumption variables, such as a low-fat or weight reduction diet (adjusted odds ratio, 0.41; P < 0.0005) and beer drinking (adjusted odds ratio, 0.41; P < 0.0001), and to demographic variables, such as African-American ethnicity (adjusted odds ratio, 0.29; P = 0.03) and a positive family history (adjusted odds ratio, 2.22; P < 0.001). These findings suggest the need to evaluate appropriate behavioral interventions to reduce the morbidity associated with urolithiasis. Prospective studies should evaluate the possibilities that beer drinking, even in modest amounts, and a low-fat or weight reduction diet are associated with substantial reductions in risk.