Abstract
BACKGROUND: Juvenile fibromyalgia (JFM) is a chronic pain condition affecting children and adolescents, often accompanied by emotional distress. Evidence suggests that autonomic dysregulation, as measured by reduced heart rate variability (HRV), may play a key role in symptom expression. This study aimed to explore clinical, emotional, and physiological differences between children with and without JFM. METHODS: This observational cross-sectional study enrolled 30 participants aged 8 to 17, divided into two equal groups based on JFM diagnosis according to ACR 2010 criteria. Clinical evaluation included Widespread Pain Index (WPI), Symptom Severity Scale (SSS), Numerical Rating Scale (NRS), and the Multidimensional Anxiety Scale for Children - Second Edition (MASC-2). HRV coherence was measured using the emWave Pro system. Group comparisons were analyzed using non-parametric Wilcoxon tests. Correlations were assessed with Spearman's rank-order test, and logistic regression was used to examine HRV as a predictor of JFM. RESULTS: Children with JFM showed significantly higher levels of pain and anxiety compared to controls (p < 0.001), and significantly lower HRV coherence (mean 0.91 vs. 1.27; p < 0.01). Inverse correlations were found between HRV and symptom severity (WPI, SSS) as well as anxiety levels. CONCLUSIONS: Reduced HRV coherence is associated with greater symptom burden and psychological distress in children with JFM. These preliminary findings suggest that HRV may represent a potential biomarker in pediatric fibromyalgia, but larger and more robust studies are required before drawing firm conclusions. HRV biofeedback may offer a supportive, non-pharmacological approach for improving autonomic regulation and managing chronic pain in youth. TRIAL REGISTRATION: Not applicable. This observational study was not registered as it did not involve a healthcare intervention.