Economic Evaluation of HLA-B*15:02 Genotyping for Asian Australian Patients With Epilepsy.

Importance: The HLA-B*15:02 allele has been associated with an increased risk of carbamazepine-induced Stevens-Johnson syndrome and toxic epidermal necrolysis in specific Asian populations (including Han Chinese, Malaysian, Thai, and Vietnamese individuals). While HLA-B*15:02 genotype testing in Asian populations is recommended by several international prescribing guidelines, it is not subsidized by the Medicare Benefits Schedule in Australia.

Objective: To evaluate the cost-effectiveness of HLA-B*15:02 genotyping in Asian Australian patients with epilepsy.

Design, setting, and participants: A model with components of decision analysis and Markov simulation was developed to simulate clinical trajectories of adult Asian Australian patients with newly diagnosed epilepsy being considered for carbamazepine treatment. Cost-effectiveness and cost-utility analyses over a lifetime time horizon were conducted from the perspective of the Australian health care sector. The study was conducted in May 2023 and data analysis was performed from August 2023 to November 2023.

Intervention: No HLA-B*15:02 genotyping and the empirical initiation of treatment with carbamazepine vs HLA-B*15:02 genotyping and the initiation of treatment with valproate in allele carriers.

Main outcomes and measures: Life-years (LYs), quality-adjusted life-years (QALYs), and costs in 2023 Australian dollars (A$); incremental cost-effectiveness ratios.

Results: HLA-B*15:02 screening was associated with an additional mean cost of A$114 (95% CI, -A$83 to A$374; US$76; 95% CI, -US$55 to US$248) and a reduction in 0.0152 LYs (95% CI, 0.0045 to 0.0287 LYs) but improvement by 0.00722 QALYs (95% CI, -0.0247 to -0.01210) compared with no screening, resulting in an incremental cost-effectiveness ratio of A$15 839 per QALY gained (US$10 523 per QALY). Therefore, universal genotyping for Asian Australian individuals was cost-effective compared with current standards of practice at the A$50 000 per QALY willingness-to-pay threshold. Sensitivity analyses demonstrated that the intervention remained cost-effective across a range of costs, utilities, transition probabilities, and willingness-to-pay thresholds. At the A$50 000 per QALY willingness-to-pay threshold, universal screening was the preferred strategy in 88.60% of simulations.

Conclusions and relevance: The results of this economic evaluation suggest that HLA-B*15:02 screening represents a cost-effective choice for Asian Australian patients with epilepsy who are being considered for treatment with carbamazepine.