Risk estimates for drugs suspected of being associated with Stevens‐Johnson syndrome and toxic epidermal necrolysis: a case‐control study

The purpose of this case-control study is to estimate the risks of Stevens-Johnson syndrome or toxic epidermal necrolysis associated with the use of specific drugs. The suspected cases were identified from the computerized hospital discharge file. We calculated crude relative risks and adjusted them for confounding by multivariate anal- ysis. The analysis was based on 35 cases and 105 con- trols. This study showed that the use of carbamazepine, phenytoin and allopurinol is most associated with the risks in the oriental population. (Intern Med J 2005; 35: 188-190) Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare, but life-threatening cuta- neous reactions. Both disorders are characterized by high fever, malaise, blistering macules, erosions of the mucous membranes, extensive detachment of epidermis and severe constitutional symptoms. SJS represents cases of less than 10% body surface area involvement, TEN indicates more than 30% and those in between are labelled SJS-TEN 'overlap'. The incidence rates are 1-6 cases/10 6 person-years (SJS), and 0.4-1.2 cases/10 6 person-years (TEN), respectively. 1 Death occurs in up to 18% of patients with SJS, and up to 50% of patients with TEN. 2,3 The aetiology of SJS and TEN is usually drug-related (80-95% of patients with TEN, >50% with SJS). 3-7 Many drugs, including sulphonamides, anti- convulsant agents, chlormezanone, piroxicam, allo- purinol and aminopenicillins are consistently reported with these severe conditions. 8 A case-series study conducted in Taiwan 7 found that each of three drugs, carbamazepine, phenytoin and allopurinol, had more than three cases of SJS/TEN reported and were highly suspected to be associated with SJS/TEN occurrence. Thus, it is important for drug safety to estimate the risk for SJS/TEN. We conducted a case-control study to estimate the relative risks of SJS/TEN associated with certain selected