Use of Clinical Disease Activity Index Score for Assessment of Disease Activity in Rheumatoid Arthritis Patients: An Indian Experience

Introduction. Serial objective assessment of disease activity in Rheumatoid Arthritis (RA) is imperative to achieve remission. The CDAI score appears more practical than DAS-28 in routine assessment of disease activity in RA patients. Objective. To evaluate correlation and agreement of the DAS-28 with CDAI in RA patients. Methods. A total of 200 patients of RA were evaluated by DAS-28 and CDAI and divided into 4 categories of disease activity i.e. Group-I: Remission (DAS-28 < 2.6; CDAI < 2.8), Group II: Low disease activity (DAS-28 = 2.6–3.2; CDAI = 2.8–10), Group III: Moderate disease activity (DAS-28 = 3.2– 5.1; CDAI = 10–22), Group IV: High disease activity (DAS-28 > 5.1; CDAI > 22). DAS-28 was compared to CDAI in each group using spearman correlation coefficient and kappa statistics. Results. Group I shows mean DAS-28 of 1.99 ± 0.38; mean CDAI of 0.90 ± 0.65, (P = 0.0001). Group II shows mean DAS-28 of 3.04 ± 0.17; mean CDAI of 6.45 ± 02.35, (P = 0.0001). Group III shows mean DAS-28 of 4.25 ± 0.58; mean CDAI of 16.46 ± 3.31 (P < 0.0001). Group IV shows mean DAS-28 of 6.38 ± 0.87; mean CDAI of 38.56 ± 11.88 (P < 0.0001). Kappa statistics (κ) of the above comparison was 0.533. Conclusion. Our findings indicate that CDAI—a composite score that employs only clinical variables and omits assessment of Acute Phase Reactant (APR), has moderate to good correlation (Kappa value = 0.533) to DAS-28 for assessment of disease activity in RA patients.