Table 3.

Summary assessment of the overall risk of bias—Cochrane Collaboration’s tool

	Study	Different types of bias						Summary within study	Overall risk
		1	2	3	4	5	6
1	Benjaminse et al, 201529	U	U	H	U	L	L	H=1 L=2 U=3	Enrolment, allocation and testing done by the same person. Lack of information in terms of selection and attrition
2	Gokeler et al, 201528	L	L	U	L	L	L	H=0 L=5 U=1	Lack of information in terms of blinding
3	Laufer et al, 200723	U	U	U	L	L	L	H=0 L=3 U=3	Lack of information in terms of selection bias and blinding
4	Prapavessis and McNair, 199924	L	U	U	L	L	L	H=0 L=4 U=2	Allocation concealment not reported. Lack of information in terms of blinding
5	Rotem-Lehrer and Laufer, 200725	U	U	U	L	L		H=0 L=3 U=3	Lack of information in terms of selection bias and blinding
6	Weilbrenner, 201426	L	U	U	L	L	L	H=0 L=4 U=2	Allocation concealment and blinding not reported

Risk of bias criteria: 1, selection bias=random sequence generation; 2, selection bias=allocation concealment; 3, performance bias/detection bias=blinding of personnel and blinding of participants/blinding of outcome assessors; 4, attrition bias=incomplete outcome data; 5, reporting bias=short-term selective outcome reporting; 6, other bias=potential threats to validity, for example, consideration of a protocol. Levels of risk of bias: H, high risk of bias; L, low risk of bias and U, unclear risk of bias.