Journal of the Medical Association of Thailand Vol 104, No 10:OCTOBER 2021 0125-2208 104 10 2021 Oct Prevalence of Abacavir Hypersensitivity Reaction and Cost-Effectiveness of HLA-B*5701 Screening: A Ten-Year Experience in The HRH Princess Maha Chakri Sirindhorn Medical Center 1698-705 EN Pattarin Pitakchotiwan Patcharasarn Linasmita Jirawat Buppanharun Prasit Upapan Niti Wanthong Woraphot Tantisiriwat Original Article To study the prevalence of ABC-HSR, the abacavir use pattern and the cost effectiveness for the routine human leukocyte antigen (HLA)-B*5701 screening before abacavir use by analyses of the MSMC data. All patients at the MSMC who were prescribed abacavir from October 1, 2010 to September 30, 2020 were retrospectively reviewed for ABC-HSR and the abacavir use pattern at the time when abacavir was started. The cost-effectiveness analysis was applied by analyzing the cost between the routine HLA-B*5701 screening before abacavir use and the HLA-B*5701 confirmation for ABC-HSR. The cost for the prevention of a case of ABC-HSR was defined. There were total of 54 patients who were prescribed abacavir and only one ABC-HSR case diagnosed. The prevalence of ABC-HSR was 1.85%. The main reason for the abacavir prescription was a substitution for tenofovir (TDF) because of the TDF adverse effects (81.13%). The HLA-B*5701 screening before abacavir use was done in 26.42% at the MSMC. If all eligible patients were routinely screened for the HLA-B*5701 allele before abacavir use, the cost would be 54,000 Baht. The cost for the diagnosis and the management of the ABC- HSR case was 7,230 Baht. The cost for the prevention of a case of ABC-HSR was 46,770 Baht. The prevalence of ABC-HSR was low. The main reason for abacavir use was a substitution for TDF. The cost for the prevention for a case of ABC-HSR was 46,770 Baht which would be less if the cost for the HLA-B*5701 test was reduced. Abacavir; Hypersensitivity reaction; Prevalence; HLA-B*5701DOI: doi.org/10.35755/jmedassocthai.2021.10.13128Received 25 June 2021 | Revised 10 September 2021 | Accepted 10 September 2021