Background/Purpose: Obesity has been shown to exacerbate systemic inflammation in the general population and contributes to worse disease-related outcomes in rheumatoid arthritis. The impact of excess adiposity in systemic lupus erythematosus (SLE) has not been established despite obesity being a common comorbidity in SLE. We aimed to determine whether excess adiposity in women with SLE independently associates with worse patient reported outcomes (PROs).

Methods: Participants in this sample, drawn from the Arthritis Body Composition and Disability (ABCD) study, were at least 18 years old, female, and carried a diagnosis of SLE verified by medical record review. Body mass index (BMI) was calculated as weight (kg) divided by height (m²), and fat mass index (FMI), a measure of total fat mass adjusted for height, was assessed using whole dual x-ray absorptiometry (DXA). Two established definitions for obesity were used: FMI >=13 kg/m² and BMI >=30 kg/m². Dependent variables included 4 validated PROs: disease activity via Systemic Lupus Activity Questionnaire (SLAQ), depressive symptoms via Center for Epidemiologic Studies Depression Scale (CES-D), pain via Short Form 36 Health Survey (SF-36) Pain Subscale, and fatigue via SF-36 Vitality Subscale. We used multivariable linear regression to evaluate the associations of obesity with PROs while controlling for potential confounders (age, race, education, income, smoking, disease duration, disease damage, and prednisone use). We then calculated adjusted means for each outcome based on the multivariable regression.

Results: The sample (n=148) was 65% white, 14% Asian, and 13% African American; mean age 48 (± 12.3) years; 17% with poverty-level income; 86% with education beyond high school; mean disease duration 16 (± 9) years; and 45% taking glucocorticoids. 32% and 30% of participants met criteria for obesity by the FMI and BMI definitions, respectively. In the multivariate regression model, obesity defined by FMI associated with worse scores on each PRO: greater disease activity, higher levels of depressive symptoms, more pain, and more fatigue (Table). The same relationship between obesity and each of the reported PROs was observed after repeating the analyses using the traditional BMI >=30 kg/m² cut-off.

Conclusion: In a representative sample of women with SLE, obesity (by FMI and BMI) independently associated with worse patient reported outcomes, including disease activity, depressive symptoms, and symptoms of pain and fatigue. Obesity may represent a modifiable target for improving outcomes in this patient population.