Association Between Nutritional Status, Body Composition, and Disease Activity in Systemic Lupus Erythematosus: An...

Background: Nutritional abnormalities, alterations in body composition, and impaired muscle function are increasingly recognized as clinically relevant features in patients with Systemic Lupus Erythematosus (SLE). However, the relationship between multidimensional nutritional assessment and disease activity remains incompletely characterized. This study aimed to evaluate the associations between nutritional status, body composition, muscle strength, nutritional risk indices, and disease activity in patients with SLE. Materials and Methods: This exploratory retrospective study included hospitalized patients with SLE. Clinical data, anthropometric measurements, and nutritional status were assessed using the body mass index (BMI), prognostic nutritional index (PNI), controlling nutritional status (CONUT), and nutritional risk index (NRI). Muscle function was evaluated using the SARC-F scale. Disease activity was measured using the SLE Disease Activity Index 2000 (SLEDAI-2K). Multivariable linear regression models were constructed to assess the independent association between nutritional indices and disease activity, adjusting for age, sex, glucocorticoid exposure, and immunosuppressive therapy. Correlation analyses were performed between nutritional indices and disease activity-related variables, and supplementary exploratory Spearman correlations were performed between the SARC-F score and SLEDAI-2K, CRP, complement C3, complement C4, and ESR. False discovery rate correction using the Benjamini-Hochberg procedure was applied to exploratory correlation analyses. Results: A total of 67 patients were included. Nutritional indices (BMI, PNI, CONUT, and NRI) were not independently associated with SLEDAI-2K in multivariable regression analyses. In correlation analyses, after FDR adjustment, the PNI remained significantly associated with SLEDAI-2K, lymphocyte counts, and complement C3 levels, while CONUT remained significantly associated with lymphocyte count and C3 levels. The BMI and NRI were not significantly associated with disease activity or inflammatory markers after correction. SARC-F showed a weak positive correlation with SLEDAI-2K (r = 0.328; p = 0.008; qFDR = 0.040), which remained statistically significant after FDR correction. No significant correlations were observed between SARC-F and CRP, complement C3, complement C4, or ESR after FDR adjustment. Conclusions: Nutritional indices showed limited independent association with disease activity in SLE after adjustment for available confounders. Although the PNI and CONUT retained selected correlations with disease activity-related or immunological markers after FDR correction, these associations should be interpreted cautiously, as albumin- and lymphocyte-based indices may reflect inflammatory activity or disease burdens rather than nutritional status alone. SARC-F remains significantly associated with disease activity (SLEDAI-2K) after FDR adjustment. These findings should be validated in future prospective studies with a larger number of patients.