Prevalence and characteristics of fibromyalgia according to three fibromyalgia diagnostic criteria: A secondary analysis study.

Objective: The purpose of this study was to explore the prevalence of fibromyalgia (FM) according to different diagnostic criteria in a clinical sample and to explore the clinical characteristics in cases and non-cases by the diagnostic criteria used.

Methods: A sample of 182 participants, both positive (n = 120) and negative (n = 62) FM individuals according to a clinical, pragmatic classification was used. Their characteristics were explored according to three different FM diagnostic criteria, i.e., the American College of Rheumatology (ACR) 1990, ACR 2016, and APS Pain Taxonomy (AAPT), respectively. Thus, impact of FM (FIQ), symptoms of anxiety and depression (HADS), tender point (TP) counts, and mechanical pressure sensitivity (in kPa) were compared in cases versus non-cases depending on diagnostic criteria of FM used. Descriptive analyses used chi-square statistic for categorical variables and non-parametric Mann-Whitney U tests for continuous variables.

Results: From the clinical positive FM sample (n = 120), n = 99, 108, and 110 persons were diagnosed positive according to the ACR 1990, ACR 2016, and AAPT FM diagnostic criteria, respectively. All these three diagnostic tools discriminated FM positively from diagnostic FM non-cases when measuring TP-counts, mechanical pressures, and most FIQ-items, but they varied for anxiety and depression.

Conclusion: The prevalence of FM differed somewhat with the use of ACR 1990, ACR 2016, and the AAPT as diagnostic tools. The anxiety and depression symptoms differed significantly between cases and non-cases using some but not all the diagnostic criteria. Regarding other FM symptoms, e.g., TPs and most FIQ items, all diagnostic criteria contrasted case from non-case.