OBJECTIVES: Co-trimoxazole is an essential preventive therapy for pneumocystis pneumonia (PCP) and other infections in people living with HIV. Besides its benefits, co-trimoxazole has been found to have a strong association with the occurrence of severe cutaneous adverse reactions (SCARs) among those who carry the HLA-B*13:01 allele. Genetic screening before initiation of co-trimoxazole is a potential strategy to reduce co-trimoxazole-induced SCARs cases. However, it bears additional costs of testing. Therefore, this study aims to evaluate the cost-effectiveness of HLA-B*13:01 allele screening before co-trimoxazole initiation in HIV-infected patients in Thailand.

METHODS: A Markov model was employed to project lifetime costs and outcomes of two treatments treatment strategies: 1) HLA-B*13:01 screening before co-trimoxazole initiation and 2) usual practice from societal perspective. Alternative drugs are not considered because dapsone (the second-line drug) also presents a high risk of SCAR associated with HLA-B*13:01. Input parameters were obtained from literature, government documents, and a part of the TREAR Asia HIV Observational Database. One-way sensitivity analyses and probabilistic analyses were performed to determine robustness of the findings. All costs were adjusted and presented in the 2020-year value.

RESULTS: The HLA-B*13:01 screening strategy contributed to 10 SCARs cases averted per 10,000 patients. After the screening, fewer patients received co-trimoxazole preventive therapy which resulted in higher cases and deaths from PCP infection. Quality-adjusted life years decreased by 0.0061 with an increased cost of 370 THB ($11.84) compared with usual practice. The probability of the genetic screening strategy being cost-effective is 9.54%.

CONCLUSIONS: This analysis demonstrated that HLA-B*13:01 allele screening before initiating co-trimoxazole among people living with HIV is unlikely to be cost-effective in Thailand. However, it is necessary to have an alternative drug provided for those who are contraindicated for co-trimoxazole. Our findings will help policymakers make an evidence-informed decision making.