HLA‐B*1502 Strongly Predicts Carbamazepine‐Induced Stevens–Johnson Syndrome and Toxic Epidermal Necrolysis in Thai Patients with Neuropathic Pain

Abstract

Carbamazepine (CBZ) is one of the standard pharmacological treatments for neuropathic pain. However, its serious adverse drug reactions include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Recently, HLA-B*1502 allele was implicated as a genetic marker of CBZ-induced SJS/TEN in some Asian epilepsy populations. This is a case control study to describe the clinical characteristics of SJS/TEN in Thai patients with neuropathic pain who were treated with CBZ, and to determine the association of HLA-B*1502 in these patients, comparing with those who exposed to CBZ for at least 6 months without any cutaneous reactions. Thirty-four SJS/TEN patients and 40 control patients were included in this study. Mean age of SJS/TEN patients was 47 years. SJS/TEN was developed in 10.8 ± 1.4 days after initiation of CBZ. HLA-B*1502 allele was found in 32 of 34 SJS/TEN patients (94.1%) but it was found only in 7 of 40 control patients (17.5%). The association was very strong with an odds ratio of 75.4. Sensitivity and specificity of this HLA-B*1502 genotype test were 94.1% and 82.5%, respectively, while the positive predictive value and negative predictive value were 1.43% and 99.98%, respectively. Positive and negative likelihood ratios were 5.37 and 0.07, respectively. HLA-B*1502 is a strong genetic marker for CBZ-induced SJS/TEN in Thai patients with neuropathic pain. The screening for this marker should be performed prior to initiation of CBZ treatment to assess the risk of this serious side effect.