Effect of allopurinol on all-cause mortality in adults with incident gout: propensity score-matched landmark analysis

Abstract

Objective: To examine the association between allopurinol use and all-cause mortality for patients with incident gout.

Methods: We compared all-cause mortality in incident gout patients who received allopurinol for at least 6 months within the exposure window (1 year or 3 years) with those who did not, using the UK Clinical Practice Research Data-link. Landmark analysis was used to account for immortal time bias and propensity score matching was used to control for potential effects of known confounders.

Results: Of 23 332 incident gout patients identified, the propensity score-matched cohorts contained 1016 patients exposed to allopurinol on the date 1 year from diagnosis (landmark date) and 1016 allopurinol non-users. Over a median follow-up period of 10 years after the landmark date, there were 437 allopurinol users and 443 allopurinol non-users who died during follow-up. Allopurinol users and non-users had similar risk for all-cause mortality (hazard ratio 0.99; 95% CI 0.87, 1.12). In the 3-year landmark analysis, 3519 allopurinol users (1280 died) were compared with 3519 non-users (1265 died). The hazard ratio for all-cause mortality was 1.01 (95% CI 0.92, 1.09).

Conclusion: This propensity score-matched landmark analysis in a population of incident gout patients in the UK primary care setting found a neutral effect on the risk of all-cause mortality. Our study provides reassurance about the prescription of allopurinol for gout patients early in their disease course to prevent untoward consequences of chronic uncontrolled hyperuricaemia. However, whether higher than the commonly used dose of allopurinol could influence mortality remains to be determined.

Keywords: allopurinol; gout; landmark analysis; mortality; propensity score.