Fibromyalgia Prevalence, Somatic Symptom Reporting, and the Dimensionality of Polysymptomatic Distress: Results From a Survey of the General Population

Abstract

OBJECTIVE: To evaluate fibromyalgia in the general population with emphasis on prevalence, dimensionality, and somatic symptom severity. METHODS: We studied 2,445 subjects randomly selected from the German general population in 2012 using the American College of Rheumatology 2010 preliminary diagnostic criteria for fibromyalgia, as modified for survey research, and the polysymptomatic distress scale (PSD). Anxiety, depression, and somatic symptom severity were assessed with the Patient Health Questionnaire (PHQ) series, and measures of symptoms and quality of life were assessed with the European Organization for Research and Treatment of Cancer questionnaire. RESULTS: The prevalence of fibromyalgia was 2.1% (95% confidence interval [95% CI] 1.6, 2.7), with 2.4% (95% CI 1.5, 3.2) in women and 1.8% (95% CI 1.1, 2.6) in men, but the difference was not statistically significant. Prevalence rose with age. Fibromyalgia subjects had markedly abnormal scores for all covariates. We found smooth, nondisordered relationships between PSD and all predictors, providing additional evidence against the hypothesis that fibromyalgia is a discrete disorder and in support of a dimensional or spectrum disorder. There was a strong correlation (r = 0.790) between the PSD and the PHQ somatic symptom severity scale; 38.5% of persons with fibromyalgia satisfied the proposed Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria for a physical symptom disorder. CONCLUSION: The modified 2010 diagnostic criteria do not result in high levels of fibromyalgia. PSD and fibromyalgia are strongly related to somatic symptom severity. There is evidence in support of fibromyalgia as a dimensional or continuum disorder. This has important ramifications for neurobiologic and epidemiology research, and for clinical diagnosis, treatment, and ascertainment of disability.