Effect of Allopurinol Use on Kidney Function Among Patients with Gout and Chronic Kidney Disease

The evidence regarding allopurinol's effects on renal function among people with hyperuricemia and gout has been conflicting, though clinicians are often cautious about using allopurinol in chronic kidney disease (CKD). We sought to examine the relation between allopurinol use in those with gout and CKD and the risk of worsening renal function. We conducted a time-stratified propensity score (PS)-matched cohort study on the IQVIA Medical Research Data representative of the UK general population. Among participants 18-89 years old with gout and CKD 3-4 not on urate-lowering therapy within one year prior, we identified new users of allopurinol and matched them 1:1 with a non-user. We analyzed the relation between incident allopurinol use and the changes in the eGFR at one year of follow-up using linear regression adjusted for the potential confounders included in the PS model. We PS-matched 10,716 allopurinol initiators to 10,716 non-users, among whom 42% were female, the mean age was 74 years and 7% had CKD4. The progression to dialysis or kidney transplant was similar in both groups. The mean eGFR prior to the study entry was 48.4 mL/min among allopurinol initiators and 49.5 mL/min among non-users, while the last eGFR within one year was 49.4 and 49.7 mL/min, respectively. The allopurinol initiators had an adjusted mean increase in the eGFR of 0.81 mL/min (95% CI 0.57-1.05) greater than that of non-users. Among those with gout and CKD 3-4, allopurinol did not worsen renal function and may have slightly improved it, suggesting that allopurinol is not detrimental to patients with gout who have CKD.