Are allopurinol dose and duration of use nephroprotective in the elderly? A Medicare claims study of allopurinol use and incident renal failure.
OBJECTIVE
To assess the effect of allopurinol dose/duration on the risk of renal failure in the elderly with allopurinol use.


METHODS
We used the 5% random Medicare claims data from 2006 to 2012. Multivariable-adjusted Cox regression analyses assessed the association of allopurinol dose/duration with subsequent risk of developing incident renal failure or end-stage renal disease (ESRD) (no prior diagnosis in last 183 days) in allopurinol users, controlling for age, sex, race and Charlson-Romano comorbidity index. HRs with 95% CIs were calculated. Sensitivity analyses considered a longer baseline period (365 days), controlled for gout or used more specific codes.


RESULTS
Among the 30 022 allopurinol treatment episodes, 8314 incident renal failure episodes occurred. Compared with 1-199 mg/day, allopurinol dose of 200-299 mg/day (HR 0.81; 95% CI 0.75 to 0.87) and ≥300 mg/day, 0.71 (0.67 to 0.76), had significantly lower hazard of renal failure in multivariable-adjustment model, confirmed in multiple sensitivity analyses. Longer allopurinol use duration was significantly associated with lower hazards in sensitivity analyses (365-day look-back; reference, <0.5 year): 0.5-1 year, 1.00 (0.88, 1.15); >1-2 years, 0.85 (0.73 to 0.99); and >2 years, 0.81 (0.67 to 0.98). Allopurinol ≥300 mg/day was also associated with significantly lower risk of acute renal failure and ESRD with HR of 0.89 (0.83 to 0.94) and 0.57 (0.46 to 0.71), respectively.


CONCLUSIONS
Higher allopurinol dose is independently protective against incident renal failure in the elderly allopurinol users. A longer duration of allopurinol use may be associated with lower risk of incident renal failure. Potential mechanisms of these effects need to be examined.
Medicine Service, Birmingham VA Medical Center, Birmingham, Alabama, USA.|Division of Epidemiology, Department of Medicine School of Medicine, School of Public Health, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.|Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
Jasvinder A
JA
Singh
Division of Epidemiology, Department of Medicine School of Medicine, School of Public Health, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.
Shaohua
S
Yu
D058186:Acute Kidney Injury / Q000453:epidemiology*; D000067575:Administrative Claims, Healthcare / Q000706:statistics & numerical data; D000368:Aged; D000369:Aged, 80 and over; D000493:Allopurinol / Q000008:administration & dosage*; D005260:Female; D006073:Gout / Q000188:drug therapy*; D006074:Gout Suppressants / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000453:epidemiology*; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D065840:Protective Factors; D012189:Retrospective Studies; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D006074:Gout Suppressants; D000493:Allopurinol
Epidemiology; Gout; Outcomes research