To analyze the Routine Assessment of Patient Index Data 3 (RAPID3), a patient-reported, composite index, designed initially for feasibility in clinical care. RAPID3 was developed in rheumatoid arthritis, but has been found useful in many rheumatic diseases. We analyzed RAPID3 in patients with psoriatic arthritis (PsA).
Post hoc analyses were performed on 2 independent data sets, the Tight Control of Psoriatic Arthritis (TICOPA) clinical trial, and the Long-Term Outcome in Psoriatic Arthritis Study (LOPAS II), an observational cohort. RAPID3 (range 0-30) is the total of three 0-10 scores for the Health Assessment Questionnaire disability index (recalculated from 0-3), pain visual analog scale (VAS), and global VAS. RAPID3 scores were compared to the Psoriatic Arthritis Disease Activity Score (PASDAS), the Disease Activity in Psoriatic Arthritis (DAPSA), and other available clinical measures, according to Spearman's correlation coefficients, standardized response mean, SEM, smallest detectible difference, minimally important difference (in patients who improved), and receiver operating characteristic curves. RAPID3 remission was compared to criteria for both standard minimal disease activity (MDA) and very low disease activity (VLDA).
RAPID3 was correlated significantly with PASDAS in TICOPA (r = 0.79, P < 0.01) and with DAPSA in LOPAS II (ρ = 0.59, P < 0.01), and with most other measures in both data sets. RAPID3 discriminated between tight control and standard care in TICOPA at 48 weeks at levels comparable to DAPSA and the PASDAS (P < 0.01). RAPID3 remission discriminated treatment groups in TICOPA intermediate between MDA and VLDA criteria.
RAPID3 appears comparably informative to PASDAS and DAPSA in PsA, with greater feasibility for routine clinical care.