There is a direct association between increased body mass index (BMI) and increased swelling of lower-extremity (LE) joints in patients with rheumatoid arthritis (RA), according to a recent study. Furthermore, increases in Disease Activity Score 44 (DAS44)-measures are higher in obese RA patients because of increased LE swollen joints. DAS28 and Clinical Disease Activity Index (CDAI), which emphasize upper-extremity joint assessment, are not significantly influenced by obesity. Researchers examined a cross-sectional cohort of 323 early seropositive RA patients (symptom duration ≤15 months). Patients were biologic-naive with ≥6/44 swollen joint count (SJC) and ≥9/44 tender joint count. The American College of Rheumatology (ACR) core set measures, components of DAS44/erythrocyte sedimentation rate (ESR), DAS28/ESR4 item, CDAI, and BMI were collected. Disease activity measures were compared between BMI categories. They found:

• DAS44/ESR4 item, Health Assessment Questionnaire Disability Index, physician global, and SJC44 differed across BMI categories.
• Of the SJC44, metacarpophalangeal joints and LE joints (knees, ankles, metatarsophalangeal joints) were associated with increased swelling in all BMI groups.
• Obesity was significantly associated with LE SJC after adjusting for ACR core set measures.