Cost–effectiveness analysis of genotyping for HLA-B*5801 and an enhanced safety program in gout patients starting allopurinol in Singapore

Abstract

Aims: Allopurinol is an efficacious urate-lowering therapy (ULT), but is associated with rare serious adverse drug reactions of Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), with higher risk among HLA-B*5801 carriers. We assessed the cost–effectiveness of HLA-B*5801 testing, an enhanced safety program or strategies with both components. Methods: The analysis adopted a health systems perspective and considered Singaporean patients with chronic gout, over a lifetime horizon, using allopurinol or probenecid. The model incorporated SJS/TEN and gout treatment outcomes, allele frequencies, drug prices and other medical costs. Results: Based on cost–effectiveness threshold of US$50,000 per quality-adjusted life year, HLA-B*5801-guided ULT selection or enhanced safety program was not cost effective. Avoidance of ULTs was the least preferred strategy as uncontrolled gout leads to lower quality-adjusted life years and higher costs. Conclusion: The analysis underscores the need for biomarkers with higher positive predictive value for SJS/TEN, less expensive genetic tests or safety programs, or more effective gout drugs. .