Swollen and tender joints, important in assessing rheumatoid arthritis (RA) activity, have traditionally been evaluated by health professionals. Whether patients can accurately evaluate joints is uncertain. This study evaluated 1) the reliability of patient-assessed swollen joint counts (SJCs) and tender joint counts (TJCs) versus those assessed by a physician, nurse, and B-mode ultrasonography (US) and 2) patient-derived Disease Activity Score in 28 joints (DAS28) compared with physician-, nurse-, and US-derived DAS28.
Fifty RA patients self-assessed 28 joints (shoulders, elbows, wrists, metacarpophalangeal, proximal interphalangeal, and knees) for swelling and tenderness. They were then assessed separately by a physician, a nurse, and an ultrasonographer. Nine patients were tested twice (intraobserver reliability), and reliability was assessed at the patient level (28 joints) by intraclass correlation coefficients (ICCs) and at the joint level by prevalence-adjusted bias-adjusted kappa.
TJC reliability was good for patient versus physician (ICC 0.85 [95% confidence interval (95% CI) 0.65, 0.94]) and patient versus nurse (ICC 0.76 [95% CI 0.47, 0.90]). However, SJC reliability was poor for patient versus physician (ICC 0.41 [95% CI -0.05, 0.72]) and patient versus nurse (ICC 0.44 [95% CI -0.005, 0.74]). SJC reliability was poor in all assessors compared with B-mode US, particularly patient-assessed SJC (ICC 0.22 [95% CI -0.25, 0.61]). However, patient-derived DAS28 correlated well with US-derived DAS28 (ICC 0.95 [95% CI 0.87, 0.98]). Intraobserver reliability was good for all assessors for TJC, but was lower for SJC.
Patient-derived DAS28 is at least as reliable as physician-, nurse-, or US-derived DAS28, despite poor reliability in patient-assessed SJC.