New indicator for discordance between patient-reported and traditional disease activity outcomes in patients with early rheumatoid arthritis

Abstract

Objective: To unravel disease impact in early RA by separately quantifying patient-reported (PRF), clinical (CF) and laboratory (LF) factors. We propose a new indicator, the discordance score (DS), for early identification and prediction of patient's unmet needs and of future achievement of sustained remission (SR) and RA-related quality of life (QoL).

Methods: Factor-scores obtained by factor analysis in the CareRA trial, allowed to compute DS, reflecting the difference between PRF and the mean of CF and LF. Improvement from baseline to week 104 (%) and area-under-the-curve (AUC) across time points per factor-score were calculated and compared between patients achieving/not achieving sustained (week 16-104) remission (DAS28CRP < 2.6) with ANOVA. Logistic and linear regressions were used to predict SR based on previous factor and discordance scores, and QoL at year 1 and 2 based on DS at week 16.

Results: PRF, CF and LF scores improved rapidly within 8 weeks. PRF improved 57%, CF 90% and LF 27%, in those achieving SR, compared with 32% (PRF: P = 0.13), 77% (CF: P < 0.001) and 9% (LF: P = 0.36) in patients not achieving SR. Patients achieving SR had an AUC of 15.7, 3.4 and 4.8 for PRF, CF and LF, respectively, compared with 33.2, 10.1 and 7.2 in participants not achieving SR (P < 0.001 for all). Early discordance was associated with later factor scores, QoL and self-efficacy.

Conclusions: All factor scores improved rapidly, especially in patients achieving sustained remission. Patient-reported burden improved less. Discordance scores could help predicting the need for additional non-pharmacological interventions to achieve sustained remission and decrease disease impact.

Keywords: discordance; early RA; factor scores; measurement instrument; patient-reported outcomes; unmet needs.