CDAI (clinical disease activity index) in rheumatoid arthritis: cut-off values for classification into different grades of disease activity

CDAI is a composite index for quantifying disease activity in RA. It utilises 4 clinical parameters namely, swollen and tender joints out of 28 (the set designated for DAS28) and global assessment of the patient and assessor on a visual analogue scale. No laboratory parameter is needed. To determine cut-off values for CDAI (clinical disease activity index) in Indian patients with rheumatoid arthritis (RA) for classification into different grades of disease activity. CDAI and DAS28 (disease activity score on 28 joints) were measured at the first and again at the last clinic visit on 100 adult patients with RA seen over a period of 1½ years. Using recommended DAS28 values as a comparator for classifying patients into the following 4 categories of disease activity namely ‘remission’, ‘low disease activity’, ‘moderate disease activity, and ‘high disease activity’, the corresponding CDAI cut-off values were derived statistically. Among Indian patients CDAI cut-off values for the classification of patients into 4 categories of disease activity were: remission ≤ 2.2, low disease activity > 2.2 to ≤ 5, moderate disease activity > 5 to ≤ 21 and high disease activity > 21. CDAI, a simple tool that is based on clinical parameters alone, was applied to the Indian patients with RA. The cut-off values derived in this study by a standardised assessment methodology could be useful in routine monitoring and therapeutic decisions in RA.