An Updated Economic Evaluation of HLA-B*58:01 Genotype Testing in Gouty Patients for Preventing Severe Allopurinol Hypersensitivity in Thailand.

Objective: Human Leukocyte Antigen (HLA), specifically HLA-B*58:01, testing before allopurinol initiation in patients with gout in Thailand was previously shown to be cost-effective. However, several drugs are available in the treatment of gout in Thailand, so the updated cost-effectiveness analysis is warranted. This study aimed to update the cost-effectiveness of HLA-B*58:01 testing before allopurinol initiation in patients with gout in Thailand.

Methods: A hybrid model consisting of a decision tree and a Markov model with a lifetime horizon from a societal perspective was undertaken. The HLA-B*58:01 testing was compared to the standard of care as no testing. Total health care costs and quality-adjusted life years (QALYs) were assessed. A comprehensive literature review along with retrospective data analysis and prospective data collection were conducted to determine inputs to inform the model. The incremental cost-effectiveness ratio analysis was calculated.

Results: HLA-B*58:01 testing could avoid 1.554 Stevens-Johnson syndrome and toxic epidermal necrosis cases, resulting in a saving of 0.140 patients' lives per 1,000 patients. It could gain 0.002 life-years and 0.004 QALYs compared to no testing. However, it required a higher lifetime cost of 4,690 Thai baht (THB), resulting in an incremental cost-effectiveness ratio of 1,093,068 THB/QALY (31,404 US dollars per QALY).

Conclusion: HLA-B*58:01 testing was not cost-effective before allopurinol initiation in Thai patients with gout at the current price of 1,000 THB per test. However, HLA-B*58:01 testing would be cost-effective if only probenecid was the alternative treatment for patients with positive HLA-B*58:01 results. This result would be useful for health authorities, policy decision-makers, and physicians' organizations in providing the recommendation for HLA-B*58:01 testing before initiation of allopurinol.