Patients who survived Stevens-Johnson syndrome or toxic epidermal necrolysis had a 7% incidence of recurrence, based on data from a 10-year population study of more than 500 Canadian patients.
The findings were published June 4 in a research letter in JAMA.
Overall, 42 of 581 patients (7%) were hospitalized for a recurrent episode of either Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN), with a median time to first recurrence of 315 days. Eight patients (1%) had multiple recurrences (JAMA 2014;311:2231-2).
Given the rare incidence of SJS and TEN in the general population (fewer than 8 cases per million people per year), "the observed recurrence risk in our population (greater than 7%) is several thousand–fold higher than would be expected if subsequent episodes were probabilistically independent of the first SJS or TEN episode," wrote Dr. Yaron Finkelstein of the Hospital for Sick Children, Toronto, and colleagues.
"We speculate that this increased risk reflects individual susceptibility," they added. "Genetic predisposition has been identified for several medications in association with specific genotypes," and recurrence also has been reported after exposure to medications, including carbamazepine and zonisamide, they said.
The study included 708 patients hospitalized for an initial episode of SJS or TEN; 127 died following the initial episode. The researchers followed the remaining patients for approximately 10 years, which yielded data for 2,621 person-years.
Approximately 18% of the patients with an initial episode were younger than 18 years, but 21% of the patients who had a recurrence were younger than 18 years (9 of 42 patients). Adult patients who developed recurrence were significantly younger at the time of the first episode than those who didn’t have recurrences, the researchers noted. Other factors significantly associated with recurrence of SJS or TEN included male gender, rural residence, and treatment of the first episode at an academic hospital.
The results were limited by the lack of access to patient data about medication exposures, the researchers noted. But the findings confirm the need to review the pros and cons of drug therapy in patients with a history of SJS or TEN, keeping in mind the risk of drug-induced recurrence, they added.
The study was funded by a grant from the Canadian Institutes of Health Research, the Canadian Drug Safety and Effectiveness Research Network, and the Institute for Clinical Evaluative Sciences. The researchers had no financial conflicts to disclose.