Table 3

 Methodological quality of included studies

Study12345Risk of biasCompliance
Quality criteria: 1, allocation; 2, outcome assessment; 3, co-intervention; 4, losses to follow up; 5, intention to treat.
Categories: +, met; ?, unclear; –, not met.
Overall quality: 5 met  =  low risk of bias; 3–4 met  =  moderate risk of bias; <3 met  =  high risk of bias.
Alpert 199016+++++Low98%
Tuckman 198637++++ModerateGood according to the author
Bluechardt 199418??+++Moderate85% in intervention group, 100% in control group
Herman-Tofler 199823+++Moderate100%
MacMahon 198727?+++?ModerateNot reported
Marsh 198828+++ModerateGood according to the author
Salukon 199434+?++ModerateNot reported
Smith 198235+++ModerateGood according to the author
Smith 198436??+++ModerateNot reported
Basile 199517+?+?HighNot reported
Elstein 197721++HighNot reported
MacMahon 198815?++?HighNot reported
Munson 198831++HighNot reported
Platzer 197633?++HighGood according to the author
Boyd 199719?+??HighNot reported
Bruya 197720????HighNot reported
Ford 198922??+??HighNot reported
Hilyer 197925??+??HighNot reported
Hilyer 198224?+?HighNot reported
Luebke 197726?+??HighNot reported
McGowan 197429?????HighNot reported
Munson 198530+?HighNot reported
Percy 198132?????HighNot reported