SDAI Definition — SCE Rheumatology MCQ
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Correct answer: C — TJC28 + SJC28 + patient global assessment (0–10) + physician global assessment (0–10) + CRP (mg/dL), using simple addition
Explanation lettering: C = shown as A · D = shown as C · A = shown as D
The SDAI is the unweighted arithmetic sum of five components: tender joint count in 28 joints, swollen joint count in 28 joints, patient global assessment, physician/evaluator global assessment, and CRP expressed in mg/dL. Therefore, D is correct. Option A describes the CDAI, which uses the same four clinical measures but omits CRP. Options B and E each omit one of the required global assessments. Option C more closely resembles the structure of a DAS28 calculation: DAS28 uses a weighted formula and may incorporate ESR, whereas SDAI is calculated by straightforward addition. Standard SDAI categories are remission ≤3.3, low disease activity >3.3 to ≤11, moderate disease activity >11 to ≤26, and high disease activity >26.
Reference: European Alliance of Associations for Rheumatology (EULAR), Outcome Measures Library: Simplified Disease Activity Index, scoring recommendations. https://oml.eular.org/oml_search_results_details.cfm?action=All+information&id=304&lightbox%5Bheight%5D=90p&lightbox%5Biframe%5D=true&lightbox%5Bwidth%5D=90p