Inter-observer agreement of the physician's global assessment of disease activity in children with juvenile idiopathic arthritis.

OBJECTIVE: To assess the inter-observer agreement in the physician's global assessment of overall disease activity (MD global) in a cohort of patients with juvenile idiopathic arthritis (JIA).
METHODS: Forty consecutive patients with JIA, who were representative of a wide spectrum of disease activity and severity, were examined simultaneously by 4 observers. Observer 1 (who was the most experienced rheumatologist) carried out a routine rheumatologic examination of each patient including a complete articular assessment, and subsequently calculated in secrecy the MD global score on an anchored horizontal 10-cm VAS. Observers 2, 3 and 4 were present during the examination; afterwards they also scored in secrecy the MD global score for the patient. Agreement was measured by the intra-class correlation coefficient (ICC), using the score of Observer 1 as the gold standard. An ICC below 0.75 was considered unsatisfactory.
RESULTS: The mean (SD) MD global scores for Observers 1, 2, 3, and 4 were 5.2 (3.4), 6.7 (3.9), 5.9 (3.5), and 5.6 (3.7), respectively. The level of agreement with Observer 1 in scoring was 0.83 for Observer 2, 0.88 for Observer 3, and 0.90 for Observer 4, indicating good agreement for all observers.
CONCLUSIONS: Our study shows a good inter-observer agreement in the physician's global assessment of overall disease activity in patients with JIA. Analyses involving investigators from different countries are needed to determine whether these results can be generalized.