Use of the Sharp and Larsen scoring methods in the assessment of radiographic progression in juvenile idiopathic arthritis

Objective. To investigate the applicability of the Sharp and Larsen scoring methods for radiographic damage in juvenile idiopathic arthritis (JIA). Methods. Wrist/hand radiographs of 25 patients with polyarthritis obtained at first observation and then yearly for 4-5 years were assessed independently by 2 pediatric rheumatologists according to the Sharp and Larsen methods. To facilitate score assignment, each patient radiograph was compared with a bone age-related standard. A third pediatric rheumatologist measured the Poznanski score, and a pediatric radiologist provided a semiquantitative assessment of radiographic damage severity. Results. Interobserver and intraobserver agreement on longitudinal scores were good for both Sharp and Larsen methods, with intraclass correlation coefficient >0.9. Agreement on change assessment was good for the Sharp method and moderate for the Larsen method. Both methods yielded a steady increase in scores during the study, with score change being more marked in the first year. Sharp and Larsen scores were highly correlated (r s = 0.96). Correlations of both scores with the Poznanski score were moderate to high (r s from -0.62 to -0.72). Radiologist score was correlated at borderline-high level with both Sharp (r s = 0.70) and Larsen (r s = 0.71) scores. Sharp and Larsen score change from baseline to final visit was moderately to highly correlated with the number of joints with active arthritis and restricted motion and the Childhood Health Assessment Questionnaire score at final visit. Conclusion. Our results demonstrate that the Sharp and Larsen scoring systems are potentially reliable and valid for assessment of radiographic progression in patients with polyarticular JIA.