Prevalence of Fibromyalgia and Chronic Fatigue Syndrome among Individuals with Irritable Bowel Syndrome: An Analysis of United States National Inpatient Sample Database.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with other somatic disorders. We studied the prevalence and predictors of fibromyalgia and chronic fatigue syndrome (CFS) in IBS patients. We used the National Inpatient Sample and included hospitalization of individuals with IBS, using ICD-10 codes, from 2016-2019. The prevalence and predictors of fibromyalgia and CFS in IBS patients were studied. Univariate and multivariate patient- and hospital-level regression models were used to calculate the adjusted odds of fibromyalgia and CFS in the IBS patient population. Of 1,256,325 patients with an ICD-10 code of IBS included in the study, 10.73% (134,890) also had ICD-10 codes for fibromyalgia and 0.42% (5220) for CFS. The prevalence of fibromyalgia and CFS was significantly higher in IBS patients (adjusted odds ratio (AOR) 5.33, 95% confidence interval (CI) 5.24-5.41, < 0.001, and AOR 5.40, 95% CI 5.04-5.78, < 0.001, respectively) compared to the general adult population without IBS. IBS-diarrhea, IBS-constipation, and IBS-mixed types were independently associated with increased odds of fibromyalgia and CFS. Increasing age (AOR 1.02, 95% CI 1.01-1.04, 0.003; AOR 1.02, 95% CI 1.01-1.03, 0.001), female gender (AOR 11.2, 95% CI 11.1-11.4, < 0.001; AOR 1.86, 95% CI 1.78-1.93, < 0.001) and white race (AOR 2.04, 95% CI 1.95-2.12, < 0.001; AOR 1.69, 95% CI 1.34-2.13, < 0.001) were independent predictors of increased odds of fibromyalgia and CFS, respectively. It appears that IBS is associated with an increased prevalence of somatic disorders such as fibromyalgia and CFS.