Table 3. Preclinical risk of bias assessment.

Study	Baseline characteristics	Incomplete outcome data	Selective reporting	Other bias
Agusti et al. 2017	Unclear	Low	Low	Low
Barrera-Bugueno et al. 2017	Unclear	Low	Low	High
Beilharz et al. 2017	Unclear	Low	Low	Low
Bercik et al. 2010	Unclear	Low	Low	Unclear
Bercik et al. 2011	Unclear	Unclear	Low	Unclear
Bharwani et al. 2017	Unclear	Unclear	High	Unclear
Bravo et al. 2011	Unclear	Unclear	Low	Low
Cowan et al. 2016	Low	Unclear	Low	Low
Divyashri et al. 2015	Unclear	Unclear	Low	Unclear
Emge et al. 2016	Unclear	Unclear	Low	High
Jang et al. 2017	Unclear	Low	Low	Low
Liang et al. 2015	Unclear	Low	Low	Low
Liu, W et al. 2016	Unclear	Low	Low	Low
Liu, Y et al. 2016	Unclear	Unclear	High	Low
Luo et al. 2014	Unclear	Low	Low	Low
Mackos et al. 2013	Unclear	Low	Low	High
Matthews et al. 2013	Unclear	Low	High	Low
McKernan et al. 2010	Unclear	Low	Low	Unclear
Moya-Perez et al. 2017	Unclear	Low	High	Low
Smith et al. 2014	Unclear	Unclear	Low	Unclear
Vanhaecke et al. 2017	Unclear	Unclear	Low	Unclear
Wang et al. 2015	Unclear	Low	Low	Unclear

Risk of bias relating to Sequence generation, Allocation concealment, Random housing, Blinding (intervention), Random outcome assessment, and Blinding (assessment) was Unclear for all included studies, and as such these domains have been omitted from the table