The relationship between obesity and disease relapse in systemic lupus erythematosus: a retrospective cohort study using the LUNA registry

OBJECTIVES: Recent reports have suggested an association between the pathogenesis of systemic lupus erythematosus (SLE) and various adipokines secreted by adipocytes. However, the impact of obesity on the susceptibility to SLE relapses remains unclear. This study investigated the association between obesity and relapse in patients with SLE using a large, multicenter cohort. METHODS: Patients enrolled in LUNA, a nationwide, multicenter SLE registry in Japan, with a body mass index (BMI) ≥ 18.5 kg/m² were included in the study. Participants were divided into two groups: the obese group (BMI ≥ 25 kg/m²) and the normal weight group (18.5 kg/m² ≤ BMI < 25 kg/m²). The one-year relapse rate after LUNA registration was compared between the two groups. Relapses were defined as an increase in glucocorticoid dosage during follow-up. A multivariate analysis was performed using generalized linear models adjusted for age, sex, disease duration, education level, glycated hemoglobin level, disease activity (Systemic Lupus Erythematosus Disease Activity Index), organ damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), current prednisolone (PSL) dose, past maximum PSL dose, calcineurin inhibitor use, and incretin-related drug use as covariates. Furthermore, a sensitivity analysis was performed using the same statistical model and covariate adjustments to reclassify participants into the overweight (BMI ≥ 25 kg/m² and < 30 kg/m²) and non-overweight (BMI ≥ 18.5 kg/m² and < 25 kg/m² or BMI ≥ 30 kg/m²) groups. RESULTS: Among the 1, 134 patients, 909 were classified as normal weight and 225 as obese. The multivariate analysis showed that obesity significantly reduced relapse rates (odds ratio [OR] 0.52, 95% confidence interval [CI] 0.30-0.90, p = 0.02). The sensitivity analysis revealed that overweight was an independent factor associated with a reduced risk of SLE relapses, with an OR lower than that for obesity in the primary analysis (OR 0.43, 95% CI 0.22-0.82, p = 0.01). CONCLUSION: Patients with mild obesity had lower relapse rates than those with normal BMI. The findings suggest that metabolic status may influence the disease course of SLE. Appropriate weight management guidance, including avoiding excessive dietary restriction, may help prevent SLE relapses.