Table 3.

Overview of risk of bias

	AARTUN	Burton	Coenen	Grimmer	Kjaer	Mikkelsson	Sjolie	Szpalski
Overall rating	Poor	Poor	Good	Fair	Fair	Fair	Poor	Poor
Risk of bias	Reporting bias Misclassification bias Differential drop outs Analytical bias Selective outcome reporting	Selection bias Reporting bias Misclassification bias Loss to follow-up	Selection bias	Misclassification bias Loss to follow-up Analytical bias	Selection bias Reporting bias Misclassification bias	Reporting bias Misclassification bias	Reporting bias Misclassification bias Analytical bias	Selection bias Reporting bias Misclassification bias Analytical bias Selective outcome reporting