Association of discoid lupus erythematosus with other clinical manifestations among patients with systemic lupus erythematosus

Background Cutaneous discoid lupus erythematosus (DLE) among patients with systemic lupus erythematosus (SLE) may be associated with less severe disease and with low frequency of nephritis and end-stage renal disease (ESRD). Objective We sought to investigate associations between confirmed DLE and other SLE manifestations, adjusting for confounders. Methods We identified patients with rheumatologist confirmation, according to 1997 American College of Rheumatology (ACR) SLE classification criteria, more than 2 visits, longer than 3 months of follow-up, and documented year of SLE diagnosis. DLE was confirmed by a dermatologist, supported by histopathology and images. SLE manifestations, medications, and serologies were collected. Multivariable-adjusted logistic regression analyses tested for associations between DLE and each of the ACR SLE criteria, and ESRD. Results A total of 1043 patients with SLE (117 with DLE and 926 without DLE) were included in the study. After multivariable adjustment, DLE in SLE was significantly associated with photosensitivity (odds ratio [OR] 1.63), leukopenia (OR 1.55), and anti-Smith antibodies (OR 2.41). DLE was significantly associated with reduced risks of arthritis (OR 0.49) and pleuritis (OR 0.56). We found no significant associations between DLE and nephritis or ESRD. Limitations Cross-sectional data collection with risk of data not captured from visits outside system was a limitation. Conclusions In our SLE cohort, DLE was confirmed by a dermatologist and we adjusted for possible confounding by medication use, in particular hydroxychloroquine. We found increased risks of photosensitivity, leukopenia, and anti-Smith antibodies and decreased risks of pleuritis and arthritis in patients with SLE and DLE. DLE was not related to anti-double-stranded DNA antibodies, lupus nephritis, or ESRD. These findings have implications for prognosis among patients with SLE.