Clinical Characteristics and Prognosis of Patients with Chronic Recurrent Multifocal Osteomyelitis Based on Cluster Analysis: A 6-Year Cohort Study

Objective: This multicenter study aimed to address the heterogeneity of chronic recurrent multifocal osteomyelitis (CRMO) by identifying clinical subtypes through cluster analysis, exploring clinical features, treatment approaches, and short-term prognosis to improve management of pediatric CRMO. Methods: Data from 42 pediatric CRMO patients (47.6% male; mean age 7.87 ± 3.45 years) diagnosed between June 2018 and June 2024 were analyzed. Using cluster analysis with 17 variables, patients were categorized into phenotypic subgroups. Statistical tests assessed differences in clinical features, treatment, and outcomes. Kaplan-Meier survival analysis and log-rank tests evaluated recurrence risk and final PGA scores. Results: Patients were classified into two groups: chronic bone pain and acute systemic inflammation. Significant differences were found in fever occurrence (P = 0.002), CRP, IL-6, TNF-α elevation (P = 0.013, 0.003, 0.029), and HB, ALP reduction (P = 0.007, <0.001). PGA scores also differed significantly (P < 0.001). Although baseline differences existed, post-treatment recurrence risk and final PGA scores showed no significant differences (P = 0.247, P = 0.211). Treatment differed only in glucocorticoid use; NSAIDs, DMARDs, TNF inhibitors, and diphosphonates showed no statistical differences. Both groups reached remission approximately 12 months post-diagnosis. Conclusion: Two distinct clinical phenotypes of pediatric CRMO were identified, each achieving favorable outcomes with tailored treatments. Recognizing these phenotypes may guide clinical strategies and improve prognosis for CRMO patients.