The childhood arthritis radiographic score of the hip: the proposal cut-off value using cluster analysis

• Published in: Clinical rheumatology 2024, Vol.43 (1), p.465-472
• Main Authors: Ferjani, Hanene Lassoued, Dhia, Siwar Ben, Nessib, Dorra Ben, Dghaies, Abir, Kaffel, Dhia, Maatallah, Kaouther, Hamdi, Wafa
• Format: Article
• Language: English
• Subjects: Acetabulum; Adolescent; Arthritis, Juvenile - diagnosis; Arthritis, Psoriatic; Body weight; C-reactive protein; Child; Childhood; Children; Cluster analysis; Cross-Sectional Studies; Hip; Humans; Male; Medicine; Medicine & Public Health; Original Article; Patients; Pediatrics; Phenotypes; Polyarthritis; Psoriatic arthritis; Quality of Life; Radiography; Reproducibility of Results; Rheumatology; Sclerosis
• ISSN: 0770-3198; 1434-9949
• DOI: 10.1007/s10067-023-06749-8

Background Juvenile idiopathic arthritis (JIA) is a chronic rheumatic disease that affects children. It is crucial to detect and treat hip involvement in JIA early to prevent functional impairment and reduced quality of life. The Childhood Arthritis Radiographic Score of the Hip (CARSH) is a validated radiographic scoring system used to assess hip involvement in JIA. In this study, we aimed to determine cut-off values for CARSH scores using cluster analysis. Methods The study was conducted as a cross-sectional analysis and included JIA patients with hip involvement who underwent a pelvic radiograph. The same pelvic radiograph was interpreted by two experienced pediatric rheumatologists at baseline and after 3 weeks by both readers for reliability. The CARSH scores were calculated for each hip four times (twice by each reader). For the 50 hips, a total of 200 interpretations of the CARSH score were obtained. Model-based clustering was employed to identify distinct groups of CARSH score interpretations and characterize the phenotype of each cluster. Results Twenty-five children with hip involvement were included. The mean age was 13.9 ± 4.6 years. JIA subtypes were as follows: ERA in 64%, oligoarthritis in 16%, psoriatic arthritis in 12%, polyarthritis RF + in 4%, and RF − in 4% of patients. For the 200 hip interpretations, three clusters based on the level of the CARSH were identified by model-based clustering. Cluster 1 consisted of 17 CARSH score interpretations with a median score of 7 ± 3 (ranging from 1 to 15). This group primarily comprised patients with enthesitis-related arthritis (ERA) and psoriatic arthritis. Patients in cluster 1 were generally older, experienced longer diagnostic delays, and had a longer disease duration compared to the other clusters. Cluster 2 exhibited a moderate CARSH score, with an average score of 4 ± 3 (1 to 15). Patients in this group had significantly higher body weight compared to the other clusters. Cluster 3 represented the group with the least severe hip involvement, characterized by CARSH scores of 2 ± 1 (ranging from 0 to 9). This cluster had a higher proportion of male patients and higher C-reactive protein (CRP) levels than the other clusters. Regarding the individual items of the CARSH score, cluster 1 showed higher percentages of hip radiograph abnormalities such as joint space narrowing, erosions, growth abnormalities, and subchondral cysts. Cluster 2 was characterized by a high rate of acetabular sclerosis,