Patients With NAFLD at an Increased Risk of Irritable Bowel Syndrome

Both non-alcoholic fatty liver disease (NAFLD) and non-alcoholic fatty liver degree are linked to an increased incident risk of developing irritable bowel syndrome (IBS).

A team, led by Shanshan Wu, Department of Gastroenterology, National Clinical Research Center for Digestive Disease, Beijing Digestive Disease Center, Beijing Key Laboratory for Precancerous Lesion of Digestive Disease, Beijing Friendship Hospital, Capital Medical University, investigated the prospective association between non-alcoholic fatty liver degree, NAFLD and incident IBS.

NAFLD and IBS

There is not much known about the relationship between non-alcoholic fatty liver degree, NAFLD and IBS.

In the study, the investigators examined 396,838 patients free of IBS, coeliac disease, inflammatory bowel disease, alcoholic liver disease, and any cancer at baseline using the UK Biobank. They measured non-alcoholic fatty liver degree using a well-validated fatty liver index (FLI), with a FLI of at least 60 deemed an indicator of NAFLD. The UK Biobank is a large-scale, prospective cohort involving more than 500,000 participants in the UK.

Patients included in the final analysis were aged 37-73 years from 22 assessment centers in England, Wales, and Scotland between 2006-2010.

Each patient completed baseline questionnaires with anthropometric assessments and self-reported medical conditions. Each patient enrolled in the study was free of IBS at baseline.

The data from the cohort did not include imaging, ultrasonography, or histological data regarding fatty liver, forcing the investigators to use FLI to measure the degree of NAFLD.

Primary Outcomes

The investigators sought a primary outcome of incident IBS, determined using ICD-10 codes. IBS diagnosis was based on self-report or linkage to primary care and/or hospital admission data up until June 2021.

They also investigated the associated risk of incident IBS using a Cox proportional hazard model.

In the patient population, the mean FLI was 48.29 ± 30.07, while 38.6% (n = 153-203) of patients with diagnosed with NAFLD at baseline. During the median follow-up of 12.4 years, the investigators identified 7129 cases of incident IBS.

The Risk

NAFLD patients also had a 13% higher risk of developing IBS (HR, 1.13; 95% CI, 1.05–1.17) after multivariable adjustment compared to patients without NAFLD.

The highest FLI quartile was associated with a significant increase in the risk of IBS (HRQ4 VS Q1, 1.21; 95% CI, 1.13–1.30, P <0.001) compared to the lowest quartile.

The positive association between non-alcoholic fatty liver degree and IBS was observed by per standard deviation change of FLI (aHR, 1.08; 95% CI, 1.05-1.10).

Finally, sensitivity and subgroup analysis showed similar results, with the positive association particularly observed in females and not males.

“High degree of non-alcoholic fatty liver as well as non-alcoholic fatty liver disease is associated with increased risk of incident IBS. Further studies are warranted to confirm the findings and elucidate the underlying biological mechanisms,” the authors wrote.

The study, “Non-alcoholic fatty liver is associated with increased risk of irritable bowel syndrome: a prospective cohort study,” was published online in BMC Medicine.