Table 3

Risk of bias assessment.

Study	Clear Definition of Study Population	Clear Definition of Outcomes and Outcome Assessment	Independent Assessment of Outcome Parameters	Random Sequence Generation (Selection Bias)	Allocation Concealment (Selection Bias)	Blinding of participants and Personnel (Performance Bias)	Sufficient Duration of Follow-Up	No Selective Loss During Follow-Up	Important Cofounders and Prognostic Factors Identified
Slotman 199812	+	+	+	×	×	×	+	+	+
Van den Akker 201113	+	+	+	+	+	+	×	+	+
Rampersaud 201125	+	+	+	×	×	×	+	×	+
Wang 201216	+	+	+	×	×	×	+	+	+
Pelton 201217	+	+	+	×	×	×	×	+	+
Parker 201215	+	+	+	×	×	×	+	+	+
Lucio 201214	+	+	+	×	×	×	+	+	+
Udeh 201318	+	+	+	×	×	×	+	+	+
Cahill 201319	+	+	+	×	×	×	+	+	+
Parker 201320	+	+	+	×	×	×	+	+	+
Parker 201422	+	+	+	×	×	×	+	+	+
Singh 201421	+	+	+	×	×	×	+	+	+
Sulaiman 201423	+	+	+	×	×	×	+	×	+
Maillard 201524	+	+	+	×	×	×	×	+	+
Vertuani 201526	+	+	+	×	×	×	+	+	+
Gandhoke 201627	+	+	+	×	×	×	+	+	+
Djurasovic201928	+	+	+	×	×	×	+	+	+