Smoking exposure in pack-years predicts cutaneous manifestations and damage in systemic lupus erythematosus

To examine the impact of cumulative smoking in pack-years on systemic lupus erythematosus (SLE) cutaneous manifestations and damage.

Our cohort study included 632 adult SLE patients at an academic center, meeting 1997 ACR or 2012 SLICC classification criteria. Outcomes were: (1) cutaneous SLICC Damage Index (SDI), (2) ACR and SLICC criteria. Smoking exposure was defined as low (<5 pack-years), medium (5-10), and high (>10), compared to non-smokers. Analysis used multivariable logistic regression to calculate odds ratios and confidence intervals (OR, (95% CI)).

Among 632 SLE patients, mean age 42 ± 14, 91% were female, 82% White, and 40% were ever smokers. Black patients were more likely to have smoked (51% vs. 41% White, 11% Other). Chronic SLICC and SDI cutaneous criteria showed linear pack-year trends, meeting significance with high smoking exposure (OR 2.2, (1.2, 4.2); OR 4.2, (1.9, 9.2)). Those with medium exposure were more likely to meet acute SLICC cutaneous criteria (OR 2.3, (1.1, 5.1)). Low exposure predicted any cutaneous SLICC and ACR criteria (OR 3.7, (1.3, 10.6); OR 2.0 (1.03, 3.8)). Patients of color had more chronic SLICC cutaneous criteria (Other Race OR 3.6 (1.6, 8.1)) and SDI skin damage (Black OR 2.6 (1.1, 5.9)) even controlling for smoking exposure.

Smoking was an independent risk factor for cutaneous SLE. High pack-year exposure and non-White race increased chronic skin manifestations and SDI damage. Findings suggested a dose relationship between smoking and cutaneous SLE damage, making cessation messaging important to potentially improve outcomes and reduce some disparities.