Table 5.

Quality ratings of selected studies using modified Downs and Black criteria for randomized and cohort studies

Item	Author (Year)
	Patient factors								Facility factors
	Vincent et al. (2010)	Chu et al. (2016)	Folden & Tappen (2007)	Tian et al. (2010)	Siebens et al. (2012)	Siebens et al. (2016)	Cogan et al. (2021)	Kim et al. (2021)	Chimenti et al. (2007)	DeJong et al. (2009a)	DeJong et al. (2009b)	Munin et al. (2010)	Herbold et al. (2011)	Mallinson et al. (2011)	Tian et al. (2012)	Padgett et al. (2018)	Fleischman et al. (2019)
Quality of Reporting
Is the hypothesis/aim/objective of the study clearly described?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Are the main outcomes to be measured clearly described in the Introduction or Methods section?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Are the characteristics of the patients included in the study clearly described?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Are the exposure variables clearly described?	+	0	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Are the distributions of principal confounders in each group of subjects to be compared clearly described?	+	0	0	+	0	+	+	+	+	+	+	+	+	+	+	0	+
Are the main findings of the study clearly described?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Does the study provide estimates of the random variability in the data for the main outcomes?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	0	+
Have all important adverse events that may be a consequence of the exposure variables been reported?	+	+	+	+	0	0	0	+	0	0	0	0	0	0	0	+	+
Have the characteristics of patients lost to follow-up been described?	0	0	0	0	+	0	0	0	0	0	+	0	0	0	0	0	0
Have actual probability values been reported for the main outcomes?	0	0	+	+	+	+	+	+	+	+	+	+	+	0	+	+	+
Internal validity - bias
In trials and cohort studies, do the analyses adjust for different lengths of follow-up of patients?	+	*	*	+	+	+	+	+	0	+	+	+	0	+	+	+	-
Were the statistical tests used to assess the main outcomes appropriate?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Was compliance with the intervention/s reliable?	*	*	*	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Were the main outcome measures used accurate (valid and reliable)?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Internal validity - confounding (selection bias)
Were the patients in different exposure groups recruited from the same population?	+	+	0	0	+	0	+	+	+	+	+	+	+	+	+	+	+
Were study subjects in different exposure groups (trials and cohort studies) recruited over the same period of time?	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+	+
Were study subjects randomized to exposure groups?	*	*	*	*	*	*	*	+	*	*	*	*	*	*	*	*	+
Was there adequate adjustment for confounding in the analyses from which the main findings were drawn?	+	0	+	+	+	+	+	+	0	+	+	+	+	+	+	+	+
Power *
Did the study have sufficient power to detect a clinically important effect where the probability value for a difference being due to chance is less than 5%? Sample sizes have been calculated to detect a difference of x% and y%.	0	0	0	0	0	0	0	+	0	0	0	0	0	0	0	0	+
External validity
Were the subjects asked to participate in the study representative of the entire population from which they were recruited?	+	-	-	0	0	0	-	-	0	-	-	0	-	-	-	+	-

+/− Reported and how performed was a strength (+) or weakness (−)

0 Not reported

^*= Not applicable (N/A)