Network Analysis of Legg-Calve-Perthes Disease and Its Comorbidities

Background/Objectives: Legg-Calvé-Perthes disease (LCPD) is characterized by idiopathic avascular necrosis of the femoral head in children. There are several hypotheses regarding the cause of LCPD; however, the exact cause remains unclear. Studies on comorbidities can provide better insight into the disease. We aimed to perform a network analysis to identify the associations between LCPD and comorbidities. Methods: We analyzed patients aged ≤ 12 years with LCPD as defined by ICD-10 codes M91.1, M91.8, and M91.9 registered in the National Health Insurance Service cohort database from 2002 to 2015. A control group was designed using propensity score matching. Comorbidities were identified and network analysis was performed. The identified comorbidities were reclassified into clinical disease groups considering their clinical relevance, and a network map was created using odds ratios. Results: In total, 23 significant disease clusters were identified. Injury-related disease clusters with ICD-10 codes starting with "S" were the most frequent. They were reclassified into 11 disease groups based on clinical relevance. Among these, congenital deformities of hip (Q65) had the highest odds ratio. Congenital deformities of feet (Q66) and other anemia (D64) had a single association with LCPD in the comorbidity network analysis. Conclusions: We confirmed the association between LCPD and comorbidities using a network analysis. The LCPD comorbidity network identified in this study is expected to serve as the basis for future research on LCPD.