Biomarkers for Bile Acid Malabsorption in Diarrhea-predominant Irritable Bowel Syndrome : A Systematic Review and Meta-analysis

Abstract

Background and Aim:

A clear relationship of biological indexes between bile acid malabsorption (BAM) and diarrhea-predominant irritable bowel syndrome (IBS-D) has not been well analyzed. This meta-analysis aimed to establish a more convenient method to diagnose BAM in IBS-D patients by comparing the differences in biomarkers between IBS-D patients and healthy people.

Methods:

Multiple databases were searched for relevant case-control studies. Indicators used to diagnose BAM included ⁷⁵Se-homocholic acid taurine (SeHCAT), 7α-hydroxy-4-cholesten-3-one(C4), fibroblast growth factor-19 and 48-hour fecal bile acid (48FBA). The rate of BAM (SeHCAT) was calculated by using a random-effect model. The levels of C4, FGF19, and 48FBA were compared, and the overall effect size was combined by a fixed effect model.

Results:

The search strategy identified 10 relevant studies comprising 1034 IBS-D patients and 232 healthy volunteers. The pooled rate of BAM in IBS-D patients was 32% (according to SeHCAT; 95% CI: 24%–40%). The level of C4 in IBS-D patients was significantly higher than that in the control group (2.86 ng/mL; 95% CI: 1.09, 4.63); The level of FGF19 was significantly lower than that in the control group (−33.97 pg/mL; 95% CI: −51.13, −16.82); The level of 48FBA was significantly higher than that in the control group (0.059; 95% CI: 0.41, 0.77).

Conclusions:

The results mainly concluded serum C4 and FGF19 levels in IBS-D patients. Most of the studies have different normal cutoff points of serum C4 and FGF19 levels; the performance of each test should be further estimated. By comparing the levels of these biomarkers, BAM in patients with IBS-D could be identified more accurately, which would lead to more effective treatment.