The assessment of disease activity in obese rheumatoid arthritis (RA) patients provides unique complications, notably in the clinical examination of swollen joints. For this study researchers wanted to investigate the influence of obesity on the American College of Rheumatology (ACR) core set measurements used in measuring RA disease activity, with a particular emphasis on the swollen joint count (SJC). A cross-sectional cohort of 323 early seropositive RA patients (symptom duration ≤15 months) was studied. Patients were biologic-naive, with an SJC of at least 6/44 and a painful joint count of at least 9/44. The ACR core set measurements were gathered, as well as components of the Disease Activity Score (DAS) 44/erythrocyte sedimentation rate (ESR), DAS28/ESR4 item, Clinical Disease Activity Index (CDAI), and body mass index (BMI). Measures of disease activity were examined across BMI groups. Multivariable linear regression models were used to investigate the connection between high BMI (≥30 kg/m2) and lower-extremity (LE) SJC and SJC44 while controlling for other ACR markers.
The Disease Activity Score 44/ESR4 item, the Health Assessment Questionnaire Disability Index, the physician global, and the SJC44 varied between BMI categories (p < 0.05). Metacarpophalangeal and LE joints (knees, ankles, metatarsophalangeal joints) of the SJC44 were linked with greater edema in all BMI categories (p < 0.05). After controlling for ACR core set measurements, obesity was shown to be substantially linked with LE SJC.
In RA patients, there was a clear relationship between higher BMI and increased edema of LE joints. Obese RA patients had larger increases in DAS44–measured disease activity because of more enlarged LE joints. Obesity has no effect on the Disease Activity Score 28 or the Clinical Disease Activity Index, which focussed on upper-extremity joint evaluation.
