Study Identifies Predictors of Fibromyalgia, Chronic Fatigue in IBS Patients

Zahid Tarar, MD

Credit: University of Missouri School of Medicine

Findings from a recent study are calling attention to an increased prevalence of somatic comorbidities among patients with irritable bowel syndrome (IBS), highlighting increased odds of having fibromyalgia and chronic fatigue syndrome among this group.

Results from the retrospective cohort study identified several factors including increasing age, female sex, white race, obesity, smoking, and hyperlipidemia as predictors for having a co-diagnosis of both fibromyalgia and chronic fatigue syndrome in patients with IBS.¹

“To the best of our knowledge, this is the first published study utilizing a large U.S. national general population database to evaluate the burden of fibromyalgia and [chronic fatigue syndrome] among individuals diagnosed with IBS,” wrote investigators.¹

A gastrointestinal disorder impacting the digestive system, IBS affects about 10-15% of the adult population in the US. It is the most common disease diagnosed by gastroenterologists and is frequently accompanied by other comorbid diseases or conditions. The International Foundation for Gastrointestinal Disorders estimates 50% of patients seen in primary care or by gastroenterologists have at least 1 comorbid condition, but the exact incidence and pathology of these overlaps are unknown.^2,3

To assess the prevalence and predictors of fibromyalgia and chronic fatigue syndrome in patients with IBS, Zahid Ijaz Tarar, MD, clinical instructor at the University of Missouri School of Medicine, and colleagues collected hospitalization data for patients with a primary or secondary admission diagnosis of IBS with a co-diagnosis of fibromyalgia and chronic fatigue syndrome from the US National Inpatient Sample. The study population was selected using ICD-10-CM codes for IBS with diarrhea (K58.0), IBS with constipation (K58.1), IBS-mixed type (K58.2), IBS other (K58.3), IBS without diarrhea (K58.9), fibromyalgia (M79.7), and chronic fatigue syndrome (R53.82). Patients younger than 18 years of age were excluded from the study.¹

In total, investigators identified 1,256,325 hospital admissions with a primary or secondary diagnosis of IBS, including 134,890 (10.73%) with fibromyalgia and 5220 (0.42%) with chronic fatigue syndrome. The prevalence and predictors of fibromyalgia and chronic fatigue syndrome in the IBS population were assessed and compared to the population without IBS.¹

Investigators performed univariate and multivariate regression analyses to determine the unadjusted and adjusted odds of a co-diagnosis of fibromyalgia or chronic fatigue syndrome in patients with IBS. The results were adjusted for patient demographics, hospital characteristics, and comorbidities including hypertension, diabetes mellitus, dyslipidemia, coronary artery disease, congestive heart failure, chronic kidney disease, cerebrovascular accident, smoking, malnutrition, alcohol abuse, and malignancy.¹

Upon analysis, the prevalence of fibromyalgia and chronic fatigue syndrome was significantly greater in patients with IBS (adjusted odds ratio [aOR], 5.33; 95% confidence interval [CI], 5.24-5.41; P < .001 and aOR, 5.40; 95% CI, 5.04-5.78; P < .001, respectively) compared to the general adult population without IBS. IBS-D, IBS-C, and IBS-mixed types were independently associated with increased odds of fibromyalgia and chronic fatigue syndrome.¹

Investigators pointed out patients with IBS with fibromyalgia and/or chronic fatigue syndrome were younger when compared to those without fibromyalgia (58.7 years of age vs 62 years of age) and chronic fatigue syndrome (59.9 years of age vs 61.6 years of age). Hypertension was documented in 45.6% of patients with fibromyalgia and 42.6% with chronic fatigue syndrome while obesity was seen in 25.7% of those with fibromyalgia and 21.1% of those with chronic fatigue syndrome. Other comorbidities in fibromyalgia and chronic fatigue syndrome patients were dyslipidemia (36.2% and 36.1%), diabetes (25.1% and 19.9%), and coronary artery disease (13.8% and 13%).¹

Investigators performed a multivariate regression analysis and identified the following factors as independent predictors of increased odds of fibromyalgia and chronic fatigue syndrome:

• Increasing age (aOR, 1.02; 95% CI, 1.01-1.04; P < .003 for fibromyalgia and aOR, 1.02; 95% CI, 1.01-1.03; P < .001 for chronic fatigue syndrome)
• Female gender (aOR, 11.2; 95% CI, 11.1-11.4; P < .001 for fibromyalgia and aOR, 1.86; 95% CI, 1.78-1.93; P < .001 for chronic fatigue syndrome)
• White race (aOR, 2.04; 95% CI, 1.95-2.12; P < .001 for fibromyalgia and aOR, 1.69; 95% CI, 1.34-2.13; P < .001 for chronic fatigue syndrome)

“Earlier identification of comorbidities in IBS patients will be valuable, since they can be managed with better treatment strategies. In current clinical practice, there is a high risk of neglecting multi-syndromic patients,” concluded investigators.¹ “We as clinicians should integrate in our practice with regular screening for other somatic disorders in the IBS population and determine the need to consult other specialties like rheumatology and psychiatry to improve the overall health outcome in IBS patients.”

References:

1. Tarar ZI, Farooq U, Nawaz A, et al. Prevalence of Fibromyalgia and Chronic Fatigue Syndrome among Individuals with Irritable Bowel Syndrome: An Analysis of United States National Inpatient Sample Database. Biomedicines. 2023;11(10):2594. Published 2023 Sep 22. doi:10.3390/biomedicines11102594
2. Cleveland Clinic. Irritable Bowel Syndrome (IBS). Diseases & Conditions. September 24, 2020. Accessed October 31, 2023. https://my.clevelandclinic.org/health/diseases/4342-irritable-bowel-syndrome-ibs
3. IFFGD. Overlapping Conditions with IBS. IBS and Other Disorders. Accessed October 31, 2023. https://aboutibs.org/what-is-ibs/ibs-and-other-disorders/overlapping-condition-with-irritable-bowel-syndrome/