Table 1C.

The randomized controlled trial checklist consisted of 4 main items: selection bias, performance bias, attrition bias and detection bias. Based on the score of their respective subitems, the main items were scored as low, unclear and high risk of bias. For each main item, a low response indicated that the study was designed and conducted in a manner that minimized the risk of bias for that item. An unclear response was given when the information required to score an item was not reported or was not reported clearly. A priori, was decided that studies were excluded if more than 2 out of 4 main items would be scored as high risk of bias on the basis of low methodological quality.

Study	Selection bias	Performance bias	Attrition bias	Detection bias	Inclusion?
Milano et al27	low	low	low	low	Yes
Van der Zwaal et al34	low	unclear	low	unclear	Yes
Gumina, 201251	unclear	unclear	low	unclear	No
Gumina, 201252	high	unclear	low	unclear	No
Milano, 201328	low	low	low	low	Yes
Berth et al44	high	high	high	high	No
Grasso et al21	low	unclear	low	low	Yes
Milano et al28	low	unclear	low	low	Yes
Nicholas, 201658	unclear	low	unclear	unclear	No
Bryant et al42	low	low	low	low	Yes
Kukkonen et al41	low	unclear	low	low	Yes