Dissociation in fibromyalgia: a systematic review with meta-analysis.

BACKGROUND: Fibromyalgia (FM) is a complex chronic condition characterized by widespread pain and sensitivity to sensory stimuli, often associated with psychological comorbidities. Among these, dissociative symptoms (DS) - both psychological and somatoform - may play a role in symptom amplification. The aim of this review was to synthesize the available evidence on dissociative symptoms in FM, focusing on their severity, characteristics, and clinical correlates. METHODS: Following the PRISMA guidelines, a comprehensive search was conducted on PubMed, Scopus, and Web of Science. The protocol was registered in PROSPERO. Thirteen studies met the inclusion criteria and were analyzed with regard to study design, sample characteristics, assessment tools, and key outcomes. A meta-analysis was conducted on a subgroup of nine case-control studies, using a multilevel mixed-effects model to estimate the combined effect size of DS in patients with FM compared to controls. RESULTS: Patients with FM showed higher levels of dissociation than healthy or clinical control groups. The meta-analysis revealed a significant, moderate-to-large combined effect (d = 0.743, 95% CI: 0.612-0.875, p < .001), with low heterogeneity. Somatoform dissociation emerged as particularly prevalent and was often linked to increased pain, psychological distress, and functional impairment. Childhood trauma, alexithymia, and emotional distress were often associated with DS. CONCLUSIONS: Dissociation, particularly somatoform dissociation, may be a clinically relevant but underestimated component in a subgroup of patients with FM.