@article { , title = {Exploratory study into the relationship between the symptoms of chronic fatigue syndrome (CFS)/myalgic encephalomyelitis (ME) and fibromyalgia (FM) using a quasiexperimental design}, abstract = {Objective To explore the relationship between symptoms of chronic fatigue syndrome (CFS)/myalgic encephalomyelitis (ME) and fibromyalgia (FM). The hypothesis predicated that there would be no significant differences between the group’s symptom experience. Design A quasiexperimental design. Structural equation modelling (SEM) and invariance testing. Participants Males (M) and females (F) >16 with a confirmed diagnosis of CFS/ME or FM by a general practitioner or specialist. CFS/ME (n=101, F: n=86, M: n=15, mean (M) age M=45.5 years). FM (n=107, F: n=95, M: n=12, M=47.2 years). Outcome measures Diagnostic criteria: the American Centers for Disease Control and Prevention (CDC) for CFS/ME and the American College of Rheumatology (ACR) criteria for FM. Additional symptom questionnaires measuring: pain, sleep quality, fatigue, quality of life, anxiety and depression, locus of control and self-esteem. Results Invariance was confirmed with the exception of the American CDC Symptom Inventory, Fibromyalgia Impact Questionnaire and Hospital Anxiety and Depression Scale (p}, doi = {10.1136/bmjopen-2020-041947}, eissn = {2044-6055}, issn = {2044-6055}, issue = {2}, journal = {BMJ Open}, note = {1 Open access}, publicationstatus = {Published}, publisher = {BMJ Publishing Group}, url = {https://hull-repository.worktribe.com/output/3725637}, volume = {11}, keyword = {Health and Health Inequalities, General Medicine}, year = {2021}, author = {Mckay, Pamela G and Walker, Helen and Martin, Colin R. and Fleming, Mick} }