Monitoring Disease Activity: DAS28, SDAI, CDAI and the ACR Response Criteria

Rather than running every available disease activity index, Dr. Ajmani was candid that in real practice, monitoring usually comes down to counting swollen joints, tender joints, checking the ESR, and making a general 0-100 assessment of how the patient is doing, examining the shoulders, elbows, wrists, metacarpophalangeal joints, proximal interphalangeal joints and knees.

DAS28, SDAI and CDAI

DAS28 (Disease Activity Score, 28 joints) combines these findings into a score: above 5.1 indicates high disease activity, and below 2.6 corresponds to remission. The Simplified Disease Activity Index (SDAI) adds the patient's own global assessment (rated 0-10), the physician's global assessment, the tender and swollen joint counts, and the CRP value; a score under 3.3 indicates remission, under 11 is low disease activity, under 26 is moderate, and 26 to 86 is high activity. The Clinical Disease Activity Index (CDAI) is the same calculation without the CRP component.

ACR response criteria and defining remission

The ACR response criteria measure improvement rather than absolute state: ACR20 means 20% improvement, ACR50 means 50% improvement, and so on. For a formal definition of remission, the ACR criteria require a tender joint count of one or fewer, a swollen joint count of one or fewer, a CRP under one, and the patient's own assessment of their disease at one or zero. The overarching treatment goal is to achieve either low disease activity or full remission.

This article is based on a Jivo Masterclass session conducted by Dr. Sajal Ajmani, HOD, Rheumatology, Manipal Hospital, Dwarka, New Delhi. The article has been summarised with the assistance of an AI tool from the original masterclass recording. Watch the full Masterclass recording

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