Intercenter variability in patient-reported outcomes (PROs) is lower than objective measures of rheumatoid arthritis (RA) activity demonstrating that PROs may be more comparable across centers, a recent study found, and that there is a need for standardization of objective measures. 7,023 patients were recruited (84 centers; 30 countries) using a standard protocol in the Quantitative Standard Monitoring of Patients with RA study. Analysis of variance (ANOVA) and mixed-effect analysis of covariance models were used to model the relationship between study center and different patient-reported and physician-reported RA activity measures. Researchers found:

• The proportion of variances attributable to recruiting center was lower for PROs, compared with objective measures in all models.
• In the full model, variance in PROs attributable to recruiting center ranged from 1.53% for patient global to 3.71% for Health Assessment Questionnaire compared with objective measures that ranged from 5.92% for physician global to 9.25% for erythrocyte sedimentation rate (ESR); and was lower for Routine Assessment of Patient Index Data 3 (2.6%) compared with Disease Activity Score (DAS28v3) (11.75%).