Background/Purpose: Juvenile idiopathic arthritis (JIA) is a common chronic disease, requiring regular monitoring. Patient-reported outcomes can assist monitoring, may promote patient self-management and can be useful in epidemiological surveys. Our objective was to evaluate reliability of a mannequin-format patient-reported joint-count in JIA, and to detect changes in agreement at a follow-up visit.

Methods: JIA patients aged 12-21 marked joints with active arthritis on a mannequin (see Figure 1) before their regular clinic visit. The physician performed a joint-count without having seen the patient’s assessment. For two subsequent clinic visits, agreement between the physician and patient-reported joint-counts was assessed using Intraclass Correlation Coefficient (ICC) and kappa statistics. The ability of the patient-reported joint-count to discriminate between active and inactive disease was evaluated using positive and negative predictive values. Sensitivity to change was estimated using Pearsons’s rho and standardized response mean (SRM).

Results: 75 JIA patients were included. In general, patients had a low number of active joints (median 1 joint, indicated by the physician). ICC was moderate (0.61) and kappas ranged from 0.3-0.7. At the follow-up (n= 53), kappas were similar; the ICC was 0.19. When a patient scored 0 joints, the physician confirmed this in 93-100%. When the patient marked ≥ 1 joints, the physician confirmed arthritis in 59-76%. Sensitivity to change was moderate (Pearson’s rho: 0.44, p=0.001, SRM in worsening patients: 0.67).

Conclusion: Agreement between physician and patient on joint-counts was reasonable. Untrained patients tended to overestimate presence of arthritis when they marked active joints on a mannequin-format joint-count. When the patient indicated absence of arthritis, the physician usually confirmed this. The sensitivity to change was moderate for patients who worsened over time.The agreement did not improve at follow-up; future research should focus on the possibility of achieving this through training. For now, the patient-reported joint-count cannot fully replace the physicians’ joint-count in clinical practice; it may be used in epidemiological studies with caution.

Figure 1 Mannequin (translated from Dutch)