Subacute cutaneous lupus erythematosus and its association with drugs: a population-based matched case-control study of 234 patients in Sweden.

BACKGROUND: Numerous case reports about drug-induced (DI) subacute cutaneous lupus erythematosus (SCLE) have been published. Various drug types with different latencies has been proposed as triggers for this autoimmune skin disease.

OBJECTIVES: To evaluate the association between exposure to certain suspected drugs (previously implicated to induce SCLE) and a subsequent diagnosis of SCLE.

METHODS: We performed a population-based matched case-control study in which all incident cases of SCLE (n=34) from 2006 to 2009 were derived from the National Patient Register. The control group was selected from the general population, matched (1:10) for gender, age and county of residence. The data were linked to the Prescribed Drug Register. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the association between exposures to certain suspected drugs and the development of SCLE.

RESULTS: During the 6 months preceding SCLE diagnosis, 166 (71%) of the patients with SCLE had at least one filled prescription of the suspected drugs. The most increased ORs were found for terbinafine (OR 52.9, 95% CI 6.6-∞), tumour necrosis factor-α inhibitors (OR 8.0, 95% CI 1.6-37.2), antiepileptics (OR 3.4, 95% CI 1.9-5.8) and proton pump inhibitors (OR 2.9, 95% CI 2.0-4.0).

CONCLUSIONS: We found an association between drug exposure and SCLE. More than one third of the SCLE cases could be attributed to drug exposure. No significant OR was found for thiazides, which might be due to longer latency and therefore missed with this study design. DI-SCLE is reversible once the drug is discontinued, indicating the importance of screening patients with SCLE for potentially triggering drugs. A causal relationship cannot be established from this study and the underlying pathogenesis remains unclear.