Association of Body Mass Index with SARS ‐ CoV ‐2 Infection in Inflammatory Arthritis Patients Receiving Biologic Therapy: Singapore National Biologics Register Findings

ABSTRACT Purpose To determine the association of body mass index (BMI) with incident COVID‐19 infection in patients with inflammatory arthritis (IA) using biologic disease‐modifying anti‐rheumatic drugs (bDMARDs) and targeted synthetic DMARDs (tsDMARDs) and to describe characteristics of patients with severe COVID‐19 infection. Methods This prospective inception cohort study included IA patients ≥ 21 years old initiating a bDMARD after July 2016 across five public hospitals in Singapore. Data were collected via questionnaires and electronic medical records. Baseline characteristics were compared between patients who developed COVID‐19 and those who did not. The association between BMI and time to incident COVID‐19 infection was assessed using Cox proportional hazards regression, adjusting for demographic and clinical factors. Results Five hundred sixty‐one patients (60.1% female, 69.0% Chinese; median age 49.0 years) were included. Diagnoses included rheumatoid arthritis (39.6%), psoriatic arthritis (26.6%), and spondyloarthritides (33.9%). Most (63.8%) were on tumor necrosis factor (TNF) inhibitors. SARS‐CoV‐2 infection occurred in 140 (25.0%) patients. Those infected had higher BMI (27.0 vs. 25.0 kg/m 2 , p = 0.005). BMI ≥ 23 kg/m 2 was independently associated with increased risk of infection (HR 1.63 [95% CI 1.05, 2.53]; p = 0.029). Severe COVID‐19 infection occurred in five patients. All were male, and four had underlying comorbidities. The underlying rheumatic diagnoses included rheumatoid arthritis, axial spondyloarthritis, and psoriatic arthritis. These patients were receiving b/tsDMARDs including golimumab, tofacitinib, adalimumab biosimilar (Amgevita), and infliximab biosimilar (Remsima). Importantly, no deaths were reported. Conclusion Being overweight or obese (BMI ≥ 23 kg/m 2 ) was independently associated with higher COVID‐19 infection risk. Severe infections were rare.