Cost-effectiveness of allopurinol and febuxostat for the management of gout

Background: Gout is the most common inflammatory arthritis in the United States.

Objective: To evaluate the cost-effectiveness of urate-lowering treatment strategies for the management of gout.

Design: Markov model.

Data Sources: Published literature and expert opinion.

Target Population: Patients for whom allopurinol or febuxostat is a suitable initial urate-lowering treatment.

Time Horizon: Lifetime.

Perspective: Health care payer.

Intervention: 5 urate-lowering treatment strategies were evaluated: no treatment; allopurinol- or febuxostat-only therapy; allopurinol- febuxostat sequential therapy; and febuxostat-allopurinol sequential therapy. Two dosing scenarios were investigated: fixed dose (80 mg of febuxostat daily, 0.80 success rate; 300 mg of allopurinol daily, 0.39 success rate) and dose escalation (-120 mg of febuxostat daily, 0.82 success rate; -800 mg of allopurinol daily, 0.78 success rate).

Outcome Measures: Discounted costs, discounted quality-adjusted life-years, and incremental cost-effectiveness ratios.

Results of Base-Case Analysis: In both dosing scenarios, allopurinol-only therapy was cost-saving. Dose-escalation allopurinol- febuxostat sequential therapy was more costly but more effective than dose-escalation allopurinol therapy, with an incremental cost-effectiveness ratio of $39 400 per quality-adjusted life-year.

Results of Sensitivity Analysis: The relative rankings of treatments did not change. Our results were relatively sensitive to several potential variations of model assumptions; however, the costeffectiveness ratios of dose escalation with allopurinol-febuxostat sequential therapy remained lower than the willingness-to-pay threshold of $109 000 per quality-adjusted life-year.

Limitation: Long-term outcome data for patients with gout, including medication adherence, are limited.

Conclusion: Allopurinol single therapy is cost-saving compared with no treatment. Dose-escalation allopurinol-febuxostat sequential therapy is cost-effective compared with accepted willingnessto- pay thresholds.