Patient-reported joint count in juvenile idiopathic arthritis: the reliability of a manikin format.

Objective: To evaluate the reliability of a manikin format, patient-reported joint count in juvenile idiopathic arthritis (JIA), and to detect changes in agreement at a second visit.

Methods: Patients with JIA aged 12-21 were asked to mark joints with active arthritis on a manikin before their regular clinic visit. The physician then performed a joint count without having seen the patient's assessment. Agreement between scores of physician-reported and patient-reported joint counts was assessed using ICC. Kappa statistics were used to assess reliability of scoring individual joints.

Results: The study included 75 patients with JIA. In general, patients had a low number of active joints (median 1 joint, indicated by the physician). ICC was moderate (0.61) and κ ranged from 0.3-0.7. At the second visit, κ were similar; the ICC was 0.19. When a patient scored 0 joints, the physician confirmed this 93%-100% of the time. When the patient marked ≥ 1 joints, the physician confirmed arthritis 59%-76% of the time. Sensitivity to change was moderate.

Conclusion: Agreement between physician and patient on the number of joints with active arthritis was reasonable. Untrained patients tended to overestimate the presence of arthritis when they marked active joints on a manikin-format joint count. When the patient indicated absence of arthritis, the physician usually confirmed this. As the agreement did not improve at followup, future research should focus on the possibility of achieving this through training. For now, the patient-reported joint count cannot replace the physicians' joint count in clinical practice; it may be used in epidemiological studies with caution.