Adding Chinese herbal medicine to probiotics for irritable bowel syndrome-diarrhea: a systematic review and meta-analysis of randomized controlled trials

Abstract Objective This study assessed whether Chinese herbal medicine (CHM) combined with probiotics/synbiotics for irritable bowel syndrome - diarrhea (IBS-D) was more effective and safer than probiotics/synbiotics alone. Methods Ten databases were searched for randomized control trials (RCTs) of IBS-D as diagnosed by Manning or Rome criteria. Trials comparing probiotics and probiotics with CHM were included. The Cochrane risk of bias (ROB) was evaluated for each trial. RevMan 5.3 was used to conduct a meta-analysis. Results Twenty-six RCTs were included (25 Chinese, 1 English), involving 2045 participants. Meta-analysis was conducted on two outcomes: overall symptom improvement and relapse. CHM combined with live Bifidobacterium and Lactobacillus preparations reduced relapse rate (RR 0.28, 95%CI 0.15-0.52, 3 trials, n = 205) compared with probiotics alone. The subgroup analysis showed the benefit of CHM prescriptions based on soothing liver and invigorating spleen (1.28, 1.14-1.44, 3, 244), invigorating spleen and resolving dampness (1.20, 1.03-1.41, 2, 128), or warming and invigorating spleen and kidney formulae (1.27, 1.09-1.46, 2, 210) combined with triple Bifidobacterium preparations than the same probiotics alone which improved overall symptoms for IBS-D. There was unclear bias in almost domains of ROB. Most studies had a high risk of bias due to lack of blinding of investigator and participants, and selective reporting. Conclusions This study showed that CHM combined with probiotics may reduce relapse rate by 72%, and improve overall symptoms of IBS-D (as diagnosed by Rome II and III) compared to probiotics alone. From the limited subgroup analysis, only soothing liver and invigorating spleen formulae, represented by Tongxie Yaofang, added to triple Bifidobacterium preparations may be superior to the single preparations in terms of overall symptoms. However, due to the poor methodological quality and small sample size of the trials, these findings must be interpreted with caution.