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DI-045 Should patients of thai, han chinese and hong kong chinese origin be tested for the HLA-B*1502 allele prior to phenytoin treatment?
  1. R El-Sharkawi
  1. Abertawe Bro Morgannwg University Health Board, Pharmacy Department, Swansea, UK


Background The potentially fatal adverse drug reactions Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN) are ten times higher in Thai, Han Chinese and Hong Kong Chinese (T/HC/HKC) than the Caucasian population. This is associated with the presence of the human leukocyte antigen HLA-B*1502 which is present in 6.1%/9%/7.2% of the T/HC/HKC populations respectively. It is already established that carbamazepine (CBZ)-induced SJS/TEN is greater in patients with HLA-B*1502. The Medicines and Healthcare products Regulatory Agency and the Food and Drug Administration advise testing for HLA-B*1502 prior to initiation of CBZ in T/HC/HKC patients. They recommend that phenytoin (PHT) should be avoided if the patient is known to have HLA-B*1502 but do not advise routine testing for the allele. However, there is increasing evidence regarding the link between HLA-B*1502 and PHT-induced SJS/TEN that may alter the management of patients of T/HC/HKC origin.

Purpose To assess the association of HLA-B*1502 and PHT-induced SJS/TEN in patients of T/HC/HKC origin.

Material and methods A literature search was performed on PubMed and ScienceDirect databases until October 2014, using search words “phenytoin”, “HLA-B*1502”, “SJS” and “TEN”. Other articles used were those cited in papers identified via the literature search, and analysis was restricted to systematic reviews and meta-analyses to establish the odds ratio (OR).

Results In total, 45 cases and 217 controls were assessed. There was an increased risk of PHT-induced SJS/TEN in patients with the HLA-B*1502 allele compared to those who did not possess the allele. This was statistically significant with OR = 5.87, 95% confidence intervals, 2.87 to 12.04, p value < 0.0001.

Conclusion There is strong evidence associating PHT-induced SJS/TEN and individuals with HLA-B*1502 of T/HC/HKC origin. The occurrence of SJS/TEN could be prevented by routine testing for the HLA-B*1502 allele in patients of T/HC/HKC origin and avoiding use of phenytoin treatment in this subset of patients.

References and/or acknowledgements No conflict of interest.

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