Genotyping to Prevent Cases of DRESS and SJS/TEN in East Asians Treated with Allopurinol-A Canadian Missed Opportunity.

BACKGROUND AND OBJECTIVE

East Asians exposed to the urate-lowering drug allopurinol have a predilection for severe cutaneous drug reactions such as drug-induced hypersensitivity syndrome or drug reaction with eosinophilia and systemic symptoms (DRESS) and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Screening is recommended in patients of East Asian descent for the presence of prior to allopurinol initiation to avoid these complications. Utilization rates of the predictive screening test within the Greater Vancouver area, which has a population composed of 40.1% people of East Asian descent, are unknown.

MEASURES

We identified cases of DRESS or SJS/TEN due to allopurinol using the Vancouver General Hospital dermatology consult service database. We next compared the frequency in which the screening test was ordered since 2012 to the estimated frequency of new prescriptions for allopurinol prescribed for the management of gout among the East Asians.

RESULTS

We report 5 cases of East Asian patients exposed to allopurinol for management of gout between 2012 and 2016, who developed DRESS (4 patients) or SJS/TEN (1 patient). All were of genotype, representing preventable cases. The test was ordered 6 times in 2012, whereas the estimated number of new cases of allopurinol-prescribed gout among patients of East Asian descent during that time period was 13. For 2012, testing was ordered for only 46% of at-risk patients.

CONCLUSION

We continue to observe cases of severe cutaneous drug reactions among high-risk individuals due to allopurinol exposure. The screening test for allopurinol hypersensitivity is underutilized in our geographic area.