Rheumatoid arthritis (RA) patients’ severity of morning stiffness and morning pain have stronger correlations with their disease’s activity than does the duration of their morning stiffness, according to an analysis of 350 patients who participated in a randomized, controlled trial.
During the 12-week study of patients with symptomatic RA despite treatment with disease-modifying antirheumatic drugs, 231 of the patients added delayed-release prednisone to their treatment and the remaining 119 patients took a placebo. The patients’ disease activity was measured with the ACR20, 28-joint Disease Activity Score (DAS28), and the Health Assessment Questionnaire-Disability Index, while Pearson correlations were used to determine relationships between patients’ responses to treatment and their disease activity.
The correlations between severity of morning stiffness or intensity of pain on waking and DAS28 or ACR20 ranged from 0.44 to 0.48 for the full study cohort. The weaker correlation between duration of morning stiffness and disease activity ranged from 0.24 to 0.28. The researchers also found a statistically significant 0.91 correlation between the severity of morning stiffness and intensity of morning pain.
“These findings suggest that severity and duration of morning stiffness may provide subtly different measures of RA and its impact on patients. The superior measurement characteristics of the severity of morning stiffness favor this as the preferred outcome measure,” wrote first author Dr. Maarten Boers and his colleagues.
Find the full study in Arthritis Care & Research ( doi:10.1002/acr.22592 ).