• Epidemiology
• Outcomes Research
• Treatment

Few recent studies1–3 reported that hyperuricemia may be protective against dementia, a common disease in the elderly associated with significant morbidity and mortality.4 5 We hypothesised that allopurinol or febuxostat use (the two most common urate-lowering therapies (ULTs)) in the elderly will be associated with a higher risk of dementia.

Study methods for this new user design study (a more robust design than a prevalent user design) were similar to those previously reported.6 Patients were eligible for this retrospective cohort study if they were (1) US residents enrolled in Medicare fee-for-service (covers all Americans ≥65 years) with pharmacy coverage, ie, enrolled in Medicare parts A (inpatient care), B (outpatient doctor and laboratory service) and D (prescription drugs) and not enrolled in a Medicare Advantage Plan (a standard approach for analysis)7 during 2006–2012 and (2) filled a new allopurinol (or febuxostat) prescription with a clean baseline period of 365 days with no exposure to either drug. Incident dementia was identified by new occurrence (no diagnosis in the 183-day baseline period) of an International Classification of Diseases, 9th Revision code, 290.xx, 294.1x or 331.2, a valid approach for dementia studies.8 9 We followed each eligible patient until the loss of Medicare coverage, dementia, death or the end of the study period, whichever came first. We used multivariable-adjusted Cox proportional …