Background Juvenile idiopathic arthritis (JIA) is a chronic disease, that often requires regular monitoring. Patient-reported outcome measures (PROs) can be a useful tool to observe disease activity between clinic visits, increase the patient involvement and also to aid epidemiological surveys. One of these PROs is the self-reported joint count. The self-reported joint count in a mannequin format, in which the patient indicates which joints are inflamed on a figure, appeared more reliable in rheumatoid arthritis than the text format. It has not been tested before in JIA.

Objectives The objective of this study was to evaluate the reliability of a patient-reported joint count in JIA in a mannequin format.

Methods JIA patients aged 12-21 were asked to mark on a mannequin (see figure 1) the joints they felt to have active arthritis on a mannequin before their regular clinical visit. The physician then performed a formal joint count on the same day without having seen the patient's assessment. Agreement between total scores of physician and patient-reported joint counts was assessed using Intraclass Correlation Coefficient (ICC). Kappa statistics were used to assess reliability of scoring of individual joints.

Results 53 JIA patients (3 systemic, 12 persistent oligoarthritis, 4 extended oligoarthritis, 10 polyarthritis Rheumatoid Factor (RF) positive, 12 polyarthritis RF negative, 7 psoriatic arthritis, 4 enthesitis-related arthritis and 1 undifferentiated arthritis) participated in this study. In general patients had a low number of active joints (median 1 and 2 joints, as indicated by the physician and patient joint counts respectively). ICC was moderate (0.51) and kappas mostly ranged from 0.4-0.7. Taking the physician's joint count as a reference, the predictive value of a patient scoring 0 active joints was 100%. When a patient did score a number of active joints, only in 76% the physician could also find signs and symptoms to confirm this.

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Conclusions The mannequin-format patient-reported joint count gives a reasonable estimate of the number of active joints according to the physician. Patients tend to overestimate the presence of arthritis. Therefore this self-reported joint count cannot fully replace the physicians' joint count in JIA. It can however be used in epidemiological studies with caution. Further research needs to be performed to examine whether agreement can be improved by training and whether the mannequin joint count can be used to detect changes in disease activity over time.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.3138