Background:  Carbamazepine (CBZ) is broadly used for the treatment of epilepsy, neuropathic pain and other neurological diseases, owing to its effectiveness and low price. CBZ can induce Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). There are several studies that found an association between HLA-B*1502 and CBZ-induced SJS/TEN, especially in people of Thai origin. In Thailand the prevalence of HLA-B*1502 was found to be in the range 8.1–14 %. 

Objective: This study aimed to determine if screening for HLA-B*1502 in Thai patients who were to receive CBZ is cost effective.

Setting:  Srinagarind Hospital, Khon Kaen University, Thailand. Method A comparison between treatment cost of CBZ induced SJS/TEN and the HLAB*1502 screening costs in the Thai population. Main outcome measureComparison of the costs of treatment of CBZ induced SJS/TEN and costs of HLA-B*1502 screening test. 

Results: When persons having the HLA-B*1502 allele receive CBZ, the chance of developing SJS/TEN is as high as 88.1 %, while persons without the HLA-B*1502 allele do not develop SJS/TEN. Therefore, a model was calculated to compare the cost of treatment between HLA-B*1502 testing before giving CBZ and if the patients were not tested for HLAB*1502. It was found that screening 100 patients before giving CBZ would save an amount of 98,549.94 baht per 100 cases of CBZ-prescribed patients. 

Conclusion:  The screening for HLA-B*1502 allele before giving carbamazepine is cost effective. The results of the present study may also apply to other populations if the HLA-B*1502 frequency is high enough.