The influence of immunosuppressants on the non-melanoma skin cancer among patients with systemic lupus erythematosus and primary Sjögren's syndrome: a nationwide retrospective case-control study in Taiwan.

OBJECTIVES: To investigate the influence of corticosteroids and hydroxychloroquine on the association with non-melanoma skin cancer (NMSC) among patients with systemic lupus erythematosus (SLE) or primary Sjogren's syndrome (pSS). METHODS: This nationwide retrospective case-control study retrieved data from Taiwan National Health Insurance Research Database from 1995-2013. Cases with newly-diagnosed NMSC (n=19,603) and controls without NMSC were matched in a 1:1 ratio according to age, sex, and reference date. SLE, pSS, NMSC, and co-morbidities were determined by ICD-9-CM code. Cumulative drug exposures were defined by cumulative dosages or total defined daily dose (TDDD) of the Anatomical Therapeutic Chemical code of medicines. The analysis used conditional logistic regression and adjusted for age, sex, residential area, occupation, and co-morbidities. Case-control studies cannot infer the causality. RESULTS: Compared to patients without SLE or pSS, the patients with SLE had significantly higher associations with NMSC (cases/controls: n=23/10, adjusted odds ratio (AOR)=2.33, 95% confidence interval (CI) 1.08-5.01), particularly those using corticosteroids with a cumulative dosage >5g (cases/controls: n=17/5, AOR=2.96, 95%CI 1.06-8.23); and those using hydroxychloroquine with a cumulative dosage >100 TDDD (cases/controls: n=18/6, AOR=2.7, 95%CI 1.04-6.98). The patients with pSS had significantly higher associations with NMSC (cases/controls: n=28/11, AOR=2.56, 95%CI 1.25-5.23), particularly those using hydroxychloroquine with a cumulative dosage >100TDDD (cases/controls: n=20/4, AOR=5.41, 95%CI 1.82-16.11), and those using corticosteroids with a cumulative dosage >1g (cases/controls: n=13/3, AOR=4.92, 95%CI 1.37-17.61). CONCLUSIONS: The patients with SLE or pSS had significantly increased associations with NMSC, especially those receiving higher cumulative doses of corticosteroids and hydroxychloroquine.