Clinical disease activity index versus disease activity score (28 joints) for assessment of disease activity in obese patients of rheumatoid arthritis

Abstract

Background: Measurement of disease activity by Disease Activity Score 28 joints -Erythrocyte Sedimentation Rate (DAS28-ESR), Disease Activity Score (28 joints)-C-Reactive Protein (DAS28-CRP), and Clinical Disease Activity Index (CDAI) has become an integral part of management of Rheumatoid Arthritis (RA), by ‘Treatment to Target’ approach. With the exception of CDAI, the other two use inflammatory markers ESR and CRP to measure disease activity. Obesity is also known to increase inflammatory markers like CRP. We undertake this study to examine if obesity confounds the disease activity measurement in RA leading to overestimation of disease activity. Methods: A cross-sectional observation study was conducted on one hundred patients of RA (40 obese and 60 non obese) in remission or low disease activity as defined by CDAI. They were divided into obese and non-obese groups based on Indian standards (BMI>25kg/m2). ESR and CRP were measured in both the groups. DAS28-ESR and DAS28-CRP were calculated and compared using relevant statistical tests. Results: DAS28-ESR and DAS-28-CRP scores were significantly higher in the obese subjects, despite both groups having comparable CDAI scores. Similar findings were also observed with inflammatory markers ESR and CRP, both being higher in obese patients. Conclusions: We conclude that indices incorporating inflammatory markers, like DAS28 overestimate disease activity in obese RA patients. Treatment decisions regarding escalation or addition of DMARDs should be taken after considering the same. CDAI appears to be better suited for disease activity measurements in obese RA patients as compared to DAS 28.