Objective: To determine allopurinol treatment patterns and adherence to published standards of care for patients with gout.
Patients and methods: This retrospective claims analysis in a managed care database included patients 18 years or older, with continuous eligibility for 1 year before and after the start date and 2 or more visits during which the gout disease code (274.xx) was assigned or 1 or more pharmacy prescriptions for a gout-specific medication between January 1, 2000, and December 31, 2002 (intake period). Factors associated with compliance with allopurinol therapy were measured based on the medication possession ratio, and adherence to 2 quality-of-care indicators for gout management was assessed using multivariable logistic regression analysis.
Results: A total of 64.9% of allopurinol users had a modal daily dose or the most commonly observed daily dose of 300 mg/d, median length of therapy was 3 months, and a high proportion of patients had a medication possession ratio of 10% or less. Suggested quality-of-care Indicators for gout had low performance: 53% of patients with renal impairment received a modal daily dose of 300 mg or greater, and 83% of patients who started taking allopurinol did not have their serum urate levels measured within 180 days. Patients with gout flares were less likely to be compliant with allopurinol (odds ratio, 0.50; 95% confidence interval, 0.40-0.63). Patients with renal impairment at baseline were 3.2 times more likely to undergo serum urate testing than patients without renal impairment (odds ratio, 3.20; 95% confidence Interval, 1.25-8.23).
Conclusion: There was low compliance with allopurinol therapy for treatment of gout. Patients potentially received suboptimal quality of care as measured by serum urate testing and appropriateness of allopurinol dosing in patients with renal impairment.