Table 2.

Risk of bias assessment for included studies

Risk of bias criterion	Banerjee et al. [3]	Goldberg et al. [8]	Hawkins et al. [10]	Hawkins et al. [11]	Imhoff et al. [17]	Neviaser et al. [27]	Pevny et al. [29]	Porcellini et al. [32]	Simank et al. [37]	Sonnabend [38]	Voos et al. [42]
(1) Is the outcome absent at the start of the study?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
(2) Did analyses account for clustering at the group level?	No	No	No	No	No	No	No	No	No	No	No
(3a) Were the outcome assessors (for the primary outcome) blind to the intervention?	No	No	No	No	No	No	No	No	No	No	No
(3b) Was the outcome measurement performed in the same manner with similar intensity in the groups being compared?	Yes	Yes	Not known	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
(4) Did similarly trained individuals administer the intervention across groups?	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
(5) Were the groups similar at baseline?	Yes	Yes	No	No	Yes	No	No	Yes	No	No	Yes
(6) Did the authors perform analyses adjusting for known confounders?	No	No	No	No	Yes	No	No	No	Yes	No	No