Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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.