(RxWiki News) Patients who have had a certain type of life-threatening medication reaction may be at increased risk for another episode.
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are skin reactions that most often occur in response to treatment with medications.
In these reactions, the upper layer of skin and the lower layer may separate in a process that can be very severe.
About one in a million people get SJS or TEN each year, but researchers have found that once a patient has had one of these reactions, the chance of having another is much greater.
"Tell your doctor if you've had any previous reactions to medications."
The lead author of this study was Yaron Finkelstein, MD, ADCP, from the Department of Pediatrics, Hospital for Sick Children in Toronto, Canada.
The research team conducted a study of over 13 million people who were hospitalized to identify patients who had a first episode of SJS or TEN.
The patients were followed by the researchers for 10 years or until they died. The research team collected data on how many people had another occurrence of SJS or TEN, as well as how many were still alive 10 years later.
The researchers found 708 people who had had an episode of SJS or TEN. Of those, 80 percent had SJS and 20 percent had TEN.
About 26 percent of the patients were admitted to a hospital critical care or burn unit and 18 percent died within 60 days after leaving the hospital (short-term death). The short-term death rate was 23 percent for TEN patients and 9 percent for SJS patients.
Of the surviving patients, 7 percent had another episode of SJS or TEN. This frequency of recurrence meant that about 16 out of 1,000 people had another episode. Most additional reactions happened about 315 days after the first reaction.
About 1.5 percent of the surviving patients had more than one additional recurrence.
Factors that increased the chance of recurrence were being male, living in a rural area and getting care at an academic hospital (affiliated with a teaching institution) for the first SJS or TEN reaction.
Most patients who had their first episode of SJS were 53 years old. The most common age of patients when they had their first episode of TEN was 44.
More than 17 percent of the recurrences of SJS and 20 percent of the recurrences of TEN occurred in patients younger than 17 years old.
The authors concluded that the number of repeat SJS or TEN reactions they observed in their study was “several thousand-fold higher than expected."
Reasons for this observation, the authors wrote, might stem from a patient’s individual genetic susceptibility. Some associations of SJS or TEN with specific genes have been identified.
“Because most such episodes are drug-induced, the high risk of recurrence should be recognized, and the benefits of drug therapy weighted carefully against the potential risks,” the authors wrote.
“This is particularly true for drugs commonly associated with the development of these frequently fatal conditions,” they wrote.
One limitation of this study was that the researchers did not have direct access to patient medical records and had to rely on a health care database for their information. The database also did not consistently identify patients who had SJS or TEN.
This study was published in the June issue of JAMA.
Funding for the research was provided by the Canadian Institutes of Health Research, Canadian Drug Safety and Effectiveness Research Network and the Institute for Clinical Evaluative Sciences.
The authors declared no conflicts of interest.