The aim of this study was to explore the clinical utility of the clinical disease activity index (CDAI). We compared the disease control with protocolized treatment adjustment following a tight control strategy utilizing either the simplified disease activity index (SDAI) or the CDAI.
In a prospective 12 month study, DMARD-naive RA patients were randomized to either a CDAI or SDAI arm and were treated with traditional DMARDs, increased on a monthly basis according to a predefined protocol to achieve low disease activity.
Of 102 patients (84 females, 96 Black Africans), the mean symptom duration was 3.0 years (s.d. 3.8) and the mean 28-joint DAS (DAS28) at baseline was 6.2 (s.d. 1.2). By 12 months, the proportion of patients in the CDAI and SDAI groups achieving low disease activity (30% and 32%) and remission (33 and 34%) were similar. There were no significant differences in the mean DAS28 or its components or in HAQ Disability Index or health-related quality of life scores. Baseline predictors of low disease activity at 12 months were shorter symptom duration (P = 0.03) and lower HAQ-DI score (P = 0.04).
Given that the CDAI performed as well as the SDAI, and considering the cost savings and convenience because no acute phase reactant test is necessary, we suggest the CDAI may be an appropriate tool for monthly disease activity monitoring as part of a tight control strategy in developing countries.