Table 1. Basic information and bias risk assessments of the study.
| Author | Year | Country | Registration Number | Intervening measure(I) | Control measure(C) | Daily intake of colonies (10^9 CFU/day) | Sample size | Treatment duration | Diagnostic criteria | Outcome included | Criteria for abdominal pain score | Literature quality score | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| I | C | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective reporting | Other bias | |||||||||||
| Başturk, A. | 2016 | Turkey | - | Synbiotic (Bifidobacterium lactis B94 with inulin) | Prebiotic (inulin) | 10 | 23 | 24 | 4 week | Rome III | ⑥ | - | Low | Low | Low | Low | Low | Low | Unclear |
| Bauserman, M. | 2005 | US | - | Lactobacillus GG | Placebo | 20 | 25 | 25 | 6 week | Rome II | ①④⑥ | Abdominal pain severity score | Low | Low | Low | Low | Unclear | Low | Unclear |
| Francavilla, R. | 2010 | Italy | NCT00876291 | Lactobacillus GG | Placebo | 6 | 42 | 38 | 8 week | Rome II | ①④⑤ | visual an alog scale and the Faces Pain Scale (FPS) | Low | Low | Low | Low | Low | Low | Unclear |
| Gawrońska, A. | 2007 | Poland | - | Lactobacillus GG | Placebo | 6 | 18 | 19 | 4 week | Rome II | ①③④⑤ | Facial responses were transformed into a score that ranged from 0 (a relaxed face) to 6 (intense pain). | Low | Low | Low | Low | Low | Low | Unclear |
| Giannetti, E. | 2017 | Italy | NCT02566876 | A probiotic mixture of Bifidobacterium infantis M-63, breve M-16V and longum BB536 | Placebo | 5 | 48 | 48 | 6 week | Rome III | ③ | - | Low | Low | Low | Low | Unclear | Low | Unclear |
| Guandalini, S. | 2015 | Italy | - | VSL#3 | Placebo | 225 | 59 | 59 | 6 week | Rome II | ①② | subject’s global relief of symptoms (SGARC) | Unclear | Low | Low | Low | Unclear | Low | Unclear |
| Kianifar, Hamidreza | 2015 | Iran | IRCT201205219825N1 | Lactobacillus GG | Placebo | 20 | 26 | 26 | 4 week | Rome III | ① | A five-point Likert scale | Unclear | Low | Low | Low | Unclear | Low | Unclear |
| Rahmani, P. | 2020 | Iran | - | Probiotic chewable tablets (containing 108 colony forming units L. reuteri) | Placebo | Unclear | 15 | 15 | 4 week | Rome III | ①③⑤ | Wang-Baker FACES Pain Rating Scale (WBFPRS)2 | Low | Low | Low | Low | Low | Low | Unclear |
| Sudha, M. Ratna | 2018 | India | CTRI/2017/02/007810 | Bacillus coagulans Unique IS2 | Placebo | 2 | 72 | 69 | 8 week | Rome III | ①② | 0–10 Likert scale | Low | Low | Low | Low | Low | Unclear | Unclear |
Outcomes: (1)Abdominal pain score, (2)Subject’s Global Assessment of Relief (SGARC) score, (3)Abdominal pain treatment success, (4)Abdominal pain relief, (5)Frequency of abdominal pain, (6)Rate of bloating after treatment.