Sex-Related Differences in Symptoms and Psychosocial Outcomes in Patients With Fibromyalgia: A Prospective Questionnaire Study

OBJECTIVE: To investigate sex-related differences in patients with fibromyalgia (FM) in terms of demographic characteristics and clinical features, including tender point count (TPC), mood disorders, sleep problems, FM symptom severity, fatigue, cognitive dysfunction, and quality of life (QOL). PATIENTS AND METHODS: We studied 668 consecutive patients with FM (606 women) from May 1, 2012, to November 30, 2013. Validated questionnaires assessed outcomes of depression (Patient Health Questionnaire-9), anxiety (Generalized Anxiety Disorder-7), sleep problems (Medical Outcomes Study Sleep Scale), FM symptom severity (Revised Fibromyalgia Impact Questionnaire), fatigue (Multidimensional Fatigue Inventory), cognitive dysfunction (Multiple Ability Self-report Questionnaire), and QOL (36-Item Short Form Health Survey). Nonparametric Mann-Whitney U and Pearson χ(2) tests were used to compare continuous and categorical outcome measures, respectively, between men and women. Linear regression models were performed for all continuous dependent variables, adjusting for age, body mass index, ethnicity, marital status, and highest education level completed. P<.05 was considered statistically significant. The Benjamini-Hochberg procedure was used to adjust for multiple comparisons. RESULTS: Multiple linear regression analysis revealed a significant association of female sex and greater TPC (P<.001), lower overall FM symptom severity (lower overall Revised Fibromyalgia Impact Questionnaire score; P=.03), and higher QOL subscale score for vitality (36-Item Short Form Health Survey vitality subscale score; P=.02). After adjustment for multiple comparisons, only the association between female sex and greater TPC remained significant. There were no sex-related differences in demographic characteristics, depression, anxiety, sleep problems, FM symptom severity, cognitive dysfunction, and QOL. CONCLUSION: A higher TPC may be associated with female sex in patients with FM. The assumption of other sex-based differences in the clinical presentation of FM was not supported in our study.