To use statistical methods to establish a threshold for individual response in patient-reported outcomes (PROs) in patients with rheumatoid arthritis.
We used an analysis of variance model in patients on stable therapy (discovery cohort) to establish critical differences (d
In the discovery cohort (n = 700), PROs showed excellent long-term retest reliability. The minimum change that exceeded random fluctuation was conservatively determined to be 3 points for pain, 4 points for fatigue, and 16 points for function. In the treatment cohort (n = 2,788), 1,483 patients (53.2%) achieved a significant individual therapeutic response as assessed by Disease Activity Score in 28 joints (DAS28)-d
The establishment of critical differences in PROs distinguishes true responses from random variation and provides insights into appropriate patient management.