PsA Disease Activity Measurement — SCE Rheumatology MCQ

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ModerateSpondyloarthropathyPsA Disease Activity MeasurementSCE Rheumatology

A 42-year-old woman with psoriatic arthritis is undergoing formal disease-activity assessment. Which validated composite index separately scores peripheral arthritis, skin disease, enthesitis, dactylitis and axial disease?

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Correct answer: E — CPDAI (Composite Psoriatic Disease Activity Index)

The correct answer is **CPDAI**. It assesses five PsA domains separately: peripheral arthritis, skin disease, enthesitis, dactylitis and axial disease. Each domain is graded from 0 to 3 using disease activity and functional or quality-of-life measures, giving a total score of 0–15. The original keyed option, DAPSA, was unsuitable because DAPSA principally measures peripheral articular activity using tender and swollen joint counts, pain, patient global assessment and CRP; it does not directly score skin, enthesitis or dactylitis. HAQ-DI measures disability rather than inflammatory activity. DAS28 is an RA-derived restricted joint score and omits key PsA domains. BASDAI and ASDAS assess axial spondyloarthritis activity and are not comprehensive multidomain PsA indices.

Reference: Coates LC et al. Advances in the management of psoriatic arthritis in adults, section on composite disease-activity measures. BMJ, 2024. https://www.bmj.com/content/387/bmj-2024-081860