Table 2.

Risk of bias within studies

Type of bias	Arendts et al 25	Braes et al 18	Cotter et al 27	Graf et al 26	Lee et al 28	Meldon et al 23	Moons et al 17	Salvi et al 19	Singler et al 20	Suffoletto et al 21	McCusker et al 22	Low et al 24
Design			NA
Setting
Data collection					NA
Withdrawals and dropouts
Statistical analysis
Global rating

NA, not available; , low risk of bias; , moderate risk of bias; , high risk of bias. Global rating: LOW=no high risk of bias, MODERATE=1 high risk of bias, HIGH=2 or more high risk of bias.