Gout, not induced by diuretics? A case-control study from primary care.

BACKGROUND It is taken for granted that diuretics may induce gout, but there is a general lack of evidence on this topic. OBJECTIVES To determine the incidence of gout in patients who use diuretics, taking into account concurrent hypertension and cardiovascular diseases. METHODS A case-control study was designed. From a primary care population all patients with a first gout registration (59 men, 11 women; mean (SD) age 55.1 (13.5)) were identified as cases. To relate the occurrence of gout to diuretic use a matched reference series of three controls for each case was compiled. Conditional logistic regression analyses were applied to estimate incidence rate ratios (IRRs) of gout, and 95% confidence intervals (CIs), in subjects with and without diuretic treatment, hypertension, and cardiovascular diseases. Additional stratification analyses were made, particularly in the subjects not using diuretics. RESULTS The IRRs of gout in subjects with v those without diuretic treatment, hypertension, heart failure, and myocardial infarction were 2.8 (95% CI 1.2 to 6.6), 2.6 (95% CI 1.2 to 5.6), 20.9 (95% CI 2.5 to 173.8), and 1.9 (95% CI 0.7 to 4.7), respectively. After adjustment, the IRR of gout for diuretic use dropped to 0.6 (95% CI 0.2 to 2.0), while the IRRs of gout for hypertension, heart failure, and myocardial infarction were still >1. This was also the case for subjects with hypertension or myocardial infarction, who had not used diuretics. CONCLUSION The results suggest that diuretics do not actually increase the risk of gout. Cardiovascular indications for treatment may have confounded previous inferences.