Abstract Background: Irritable bowel syndrome (IBS) is one of the most acommon functional gastrointestinal disorders characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. Leading to significant negative effect on patients’ quality of life and huge financial burden to health system, the management of IBS is a great challenge. Probiotics are considered as an effective therapy, however, in a lack of high-quality evidence of efficacy, no specific strain- and dose-probiotics were recommended in clinical guidelines. This study aims to evaluate the efficacy of the bifidobacterium quadruple viable tablet in the treatment of IBS-D.Methods/design: A multicenter randomized controlled trial will be performed in fourteen hospitals. A total of three hundred patients fulfill the eligible criteria will be stratified divided into an experimental group and a control group randomly in a ratio of 1:1. The experimental group is treated with the bifidobacterium quadruple viable tablet while the control group is treated with placebo. All the patients will receive a 4-week treatment and a 2-week follow-up. The primary outcome is the effectiveness in improving abdominal pain and stool consistency, the secondary outcome include evaluation of overall symptom relief, frequency of defecation, bloating, urgency of defecation, remedial medication, score of IBS-QOL and changes of microbiota and metabonomics. Physical examination, vital signs, laboratory tests, adverse events and concomitant medication will be taken into account for intervention safety assessment during the trial.Discussion: This multicenter randomized controlled trial may provide high-quality evidence on the efficacy of the bifidobacterium quadruple viable tablet for IBS-D on both physical and mental dimensions in China. To fill the gap of previous probiotics intervention studies, in addition, this study will also present safety assessment which will be a significant emphasis.Trial registration: Chinese Clinical Trial Registry, ID: ChiCTR1800017721 ( http://www.chictr.org.cn/showproj.aspx?proj=29440 ). Registered on 10 August 2018.

Background: Irritable bowel syndrome (IBS) is one of the most acommon functional gastrointestinal disorders characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. Leading to significant negative effect on patients’ quality of life and huge financial burden to health system, the management of IBS is a great challenge. Probiotics are considered as an effective therapy, however, in a lack of high-quality evidence of efficacy, no specific strain- and dose-probiotics were recommended in clinical guidelines. This study aims to evaluate the efficacy of the bifidobacterium quadruple viable tablet in the treatment of IBS-D. Methods/design: A multicenter randomized controlled trial will be performed in fourteen hospitals. A total of three hundred patients fulfill the eligible criteria will be stratified divided into an experimental group and a control group randomly in a ratio of 1:1. The experimental group is treated with the bifidobacterium quadruple viable tablet while the control group is treated with placebo. All the patients will receive a 4-week treatment and a 2-week follow-up. The primary outcome is the effectiveness in improving abdominal pain and stool consistency, the secondary outcome include evaluation of overall symptom relief, frequency of defecation, bloating, urgency of defecation, remedial medication, score of IBS-QOL and changes of microbiota and metabonomics. Physical examination, vital signs, laboratory tests, adverse events and concomitant medication will be taken into account for intervention safety assessment during the trial. Discussion: This multicenter randomized controlled trial may provide high-quality evidence on the efficacy of the bifidobacterium quadruple viable tablet for IBS-D on both physical and mental dimensions in China. To fill the gap of previous probiotics intervention studies, in addition, this study will also present safety assessment which will be a significant emphasis.

Background Irritable bowel syndrome (IBS) is one of the most acommon functional gastrointestinal disorders characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. Leading to significant negative effect on patients’ quality of life and huge financial burden to health system, the management of IBS is a great challenge. Probiotics are considered as an effective therapy, however, in a lack of high-quality evidence of efficacy, no specific strain- and dose-probiotics were recommended in clinical guidelines. This study aims to evaluate the efficacy of the bifidobacterium quadruple viable tablet in the treatment of IBS-D. Methods/design A multicenter randomized controlled trial will be performed in fourteen hospitals. A total of three hundred patients fulfill the eligible criteria will be stratified divided into an experimental group and a control group randomly in a ratio of 1:1. The experimental group is treated with the bifidobacterium quadruple viable tablet while the control group is treated with placebo. All the patients will receive a 4-week treatment and a 2-week follow-up. The primary outcome is the effectiveness in improving abdominal pain and stool consistency, the secondary outcome include evaluation of overall symptom relief, frequency of defecation, bloating, urgency of defecation, remedial medication, score of IBS-QOL and changes of microbiota and metabonomics. Physical examination, vital signs, laboratory tests, adverse events and concomitant medication will be taken into account for intervention safety assessment during the trial. Discussion This multicenter randomized controlled trial may provide high-quality evidence on the efficacy of the bifidobacterium quadruple viable tablet for IBS-D on both physical and mental dimensions in China. To fill the gap of previous probiotics intervention studies, in addition, this study will also present safety assessment which will be a significant emphasis.