Self-Reported Symptom Burden and Clinical Characteristics in Fibromyalgia: Evidence from a Large Online Survey in...

Background and Objectives: Fibromyalgia (FM) is a chronic primary pain syndrome. Its hallmark symptom is widespread pain, often accompanied by fatigue, sleep disturbances, and cognitive symptoms. Online surveys efficiently collect patient-reported data, but individuals recruited through this approach remain poorly characterized. This study aimed to describe a large online cohort of individuals with FM, providing data for comparison with the Italian Fibromyalgia Registry (IFR). Materials and Methods: Participants who self-reported a physician diagnosis of FM completed an online survey assessing socio-demographic and clinical characteristics, treatments and their perceived effectiveness, lifestyle, and impact variables. Disease severity and symptom burden were assessed using the Fibromyalgia Impact Questionnaire-Revised (FIQR), Widespread Pain Index (WPI), and Symptom Severity Scale (SSS). Participants were classified according to the 2016 American College of Rheumatology (ACR) criteria. Descriptive statistics were computed, and exploratory analyses assessed sex differences and differences according to ACR status using independent-samples t-tests with Bonferroni correction. Results: A total of 6022 participants were included (mean age 52.3 ± 10.3 years, 96.7% female). Nearly half (49.6%) reported pain duration > 10 years, and 50.4% had received conflicting diagnoses. Disease burden was high, with >70% classified as moderate-to-severe according to the FIQR. Overall, 79.4% fulfilled the 2016 ACR criteria. Participants not fulfilling the criteria showed lower symptom severity, although considerable clinical overlap was observed between groups. Pharmacological treatments were used by 81.1% of participants and non-pharmacological approaches by 55.1%, both with moderate perceived effectiveness. FM substantially affected daily life, particularly work and social functioning. After correction for multiple comparisons, sex differences were limited to FIQR functioning and symptom domains, with small effect sizes. Conclusions: Compared with published registry-based data, participants recruited through this online survey reported a higher symptom burden and longer pain duration, while showing a broadly similar symptom profile. Although the descriptive nature of the comparison precludes causal inferences, the findings suggest that online surveys and clinical registries may provide complementary perspectives on the FM population.