Incidence, causative factors and mortality rates of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) in northern Italy: data from the REACT registry

PURPOSE Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but severe cutaneous adverse drug reactions. We assessed incidence, drug exposure and mortality, analysing data obtained from the Lombardy Registry of Severe Cutaneous Reactions (REACT). METHODS Data were collected from hospitals in the Italian Lombardy region (9,502,272 people). A trained monitor was sent to the reporting hospital to collect data on drug exposure and clinical features. The algorithm for drug causality for epidermal necrolysis algorithm was applied to assess drug causality. Defined Daily Dose (DDD) was used to express drug consumption. RESULTS From April 2009 to November 2014, 17 cases of TEN and 59 cases of SJS were collected. The overall incidence rate was 1.40 cases (95%CI, 1.12-1.76) per million people per year. A total of 15 cases died during hospitalization with a mortality rate of 16.9% for SJS and 29.4% for TEN. Overall, 55.4% of cases had a probable or very probable relation with drug exposure. In a total of five patients (6.6%), no causative drug for the reaction was identifiable. Allopurinol contributed to the highest number of cases (23 cases), while the highest incidence based on more than one case reported was observed for cotrimoxazole and lamotrigine, with 5.37 cases (95%CI, 2.09-13.80) and 3.54 (95%CI, 1.21-10.42) per 10 million DDD/year, respectively. CONCLUSIONS We confirmed that SJS and TEN are rare adverse cutaneous reactions. As expected, mortality was influenced by the degree of skin detachment. The profile of drugs associated with the reactions was in agreement with data from other surveillance systems.