Background/Purpose: Smoking is associated with increased disease activity in patients with systemic lupus erythematosus (SLE) and cutaneous lupus erythematosus (CLE) in cross-sectional analyses. We sought to determine the associations between smoking status, presence of cutaneous activity, and SLE dis­­­ease activity among patients enrolled in a US-based SLE Cohort featuring a large African-American population.

Methods: The Hopkins Lupus Cohort was queried for demographic information, clinical information, and laboratory parameters between current smokers and never smokers. SLE patients that developed rash vs. those that did not (according to the validated SLEDAI criteria for rash) were compared with smoking status and the following co-variables: age, ethnicity, sex, ESR, urine protein/creatinine ratio, anti-Ro, anti-La, anti-DNA, Low C3, and Low C4.

Results: Current smokers vs. never smokers Current smokers were significantly more likely than never smokers to have an active rash (49.58% vs. 36.31%, p <0.0001) and ESR > 20 (p < 0.0006). Non-smokers were significantly more likely to have anti-Ro antibodies as compared to current smokers with no significant differences found in additional co-variables. SLE Patients who developed new rash during the course of follow-up vs. patients without rash SLE patients who developed a new rash were significantly more likely than SLE patients without a rash to have a younger age of SLE diagnosis (p < 0.0015), higher SLEDAI continuous score (5.53 vs. 2.26, p < 0.0001) and SLEDAI score ≥ 2 (100% vs. 57.04%, p < 0.0001), Urine protein creatinine ratio > 0.5 (p 0.0256), anti-dsDNA ≥ 10 (36.12% vs. 23.78%, p<0.0001), low C3 < 79 and low C4 < 12 with no significant differences in percentage of patients positive for anti-Ro and anti-La antibodies. Association between Smoking and New Rash Smoking was significantly associated with new rash in SLE patients after adjusting for sex, ethnicity, and hydroxychloroquine use (p < 0.0001). Duration from SLE diagnosis to new rash were compared between current smokers and never smokers. Both non-parametric Kaplan-Meier curve and a parametric Weibull curve demonstrated current smokers developed rash significantly earlier than never smokers. The hazard of developing a rash is 40% higher among current smokers than never smokers, with the effect persisting after adjusting for sex and ethnicity.

Conclusion: Current smokers with SLE are significantly more likely than non-smokers to have an active rash. The hazard of developing a rash is 40% higher among current smokers than never smokers. SLE patients who developed rash as compared to patients that did not develop a rash had significantly increased SLE disease activity and several laboratory abnormalities including increased urine protein creatinine ratio > 0.5, anti-dsDNA ≥ 10, low C3 < 79 and low C4.

Figure 1: Kaplan-Meier Plot & Weibull Curve examining risk of developing rash among never smokers vs. current smokers