Objectives: Functional Somatic Syndrome (FSS) is characterized by persistent bothersome symptoms not fully explained by known medical abnormalities. FSS includes Fibromyalgia (FM), Chronic Fatigue Syndrome (CFS), and Irritable Bowel Syndrome (IBS). Many individuals qualifying for an FSS diagnostic label do not receive one. This study investigates factors associated with receiving an FSS diagnostic label among those meeting the diagnostic criteria.
Methods: A cross sectional study was conducted in the Lifelines population cohort. FSS diagnostic criteria were assessed via validated self-reported questionnaires. Logistic regression was used to examine associations between receiving a diagnostic label and demographic, lifestyle, stress-related, health literacy, healthcare use, and comorbidity variables. Linear regression was performed to assess associations between diagnostic status and quality of life, health anxiety, and work capacity variables, adjusted for demographic variables.
Results: Of 152,807 participants, 10,017 met diagnostic criteria for at least one FSS. Among them, 25.2% (FM), 14.2% (CFS), and 47.6% (IBS) reported having received a diagnosis. Female sex, lower education, psychiatric diagnoses other than anxiety and depression, somatic comorbidities, higher healthcare use, and employment were positively associated with receiving a diagnostic label. Older age, smoking, and depressive or anxiety disorders were negatively associated with receiving a diagnostic label. Receiving a diagnostic label was associated with lower quality of life, higher health anxiety, and reduced physical but not mental work capacity.
Conclusion: Only a minority of participants fulfilling the FSS diagnostic criteria received a diagnostic label. FSS labelling is associated with multiple factors that need further evaluation.
Keywords: Diagnosis; Diagnostic label; Functional somatic syndrome; Quality of life.