Supplemental Material for: Disease-Specific Associations of Physical Activity in Patients with Rheumatoid Arthritis and Systemic Lupus Erythematosus

Associations were examined using multivariable logistic regression models. </p><p dir="ltr">Results</p><p dir="ltr">Patients with RA showed lower physical performance (p < 0.001) but higher PA levels than SLE (p < 0.001). In RA, fibromyalgia remained the only statistically significant variable and was associated with lower PA (OR = 0.001, 95 % CI <0.001–0.289; p = 0.017). In SLE, no independent predictors were identified; fibromyalgia (OR = 0.374, p = 0.209) and depressive symptoms (OR = 0.341, p = 0.063) showed non-significant trends.

Self-reported PA and objective walking performance were moderately associated in both groups (RA: R² = 0.19; SLE: R² = 0.12).</p><p dir="ltr">Conclusion</p><p dir="ltr">Associations with PA differ between RA and SLE. In RA, fibromyalgia is associated with lower PA, whereas in SLE, PA reflects a multifactorial interplay of functional and psychological factors, supporting disease-specific approaches to PA promotion.</p>