Alterations in fecal microbiota composition by probiotic supplementation in healthy adults: a systematic review of randomized controlled trials

Table 2 Assessment of risk of bias in the studies reviewed

Study	Concealment of randomization	RCT stopped early	Patients blinded	Healthcare providers blinded	Data collectors blinded	Outcome assessors blinded	Reporting drop-out or withdrawal	Other potential bias	Selective outcome reporting	Jadad score
Lahti et al. 2013 [22]	Yes	No	Yes	Yes	Yes	No	Yes	No	No	4
Rampelli et al. 2013 [23]	Yes	No	Yes	Unclear^a	Unclear^a	Unclear^a	Unclear	Yes^c	Yes^c	3
Ferrario et al. 2014 [27]	Yes	No	Yes	Unclear^a	Unclear^a	Unclear^a	Yes	No	No	3
Bjerg et al. 2015 [19]	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes^b	No	5
Brahe et al. 2015 [20]	Yes	No	Yes	No	No	No	Yes	No	No	4
Hanifi et al. 2015 [21]	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes^b	No	5
Simon et al. 2015 [24]	Yes	No	Yes	Unclear^a	Unclear^a	Unclear^a	Yes	No	No	4

Based on PRISMA (and Cochrane)’s tools for assessing risk of bias. The Jadad score is a three-item instrument that evaluates likelihood of bias in terms of quality of randomization, quality of blinding, and reasons for withdrawal/drop-out. It is compiled of the following quality items from the table: Concealment of randomization, Patients blinded, Healthcare providers blinded, Data collectors blinded, Outcome assessors blinded, and Reporting drop-out or withdrawal
^aDouble-blinded study but unclear whether healthcare providers, data collectors, and outcome assessors were all blinded
^bPerformed next-generation sequencing on fecal samples from a subgroup of the included individuals. Bjerg et al. selected 10 (of 32) placebo-treated and 10 (of 32) probiotic-treated participants with the highest triacylglycerol concentration in the blood at week 0. Hanifi et al. selected 20 (all) placebo-treated and 17 (of 20) probiotic-treated participants from the group with the highest dose (10 × 10⁹ colony-forming units) of the probiotic treatment
^cNo direct comparison between treatment groups was made for the age-related dysbiosis

ISSN: 1756-994X