Table 3

Assessment of study quality (selective items reported; derived from an adapted Downs and Black checklist;21 higher score indicates better study quality)

Author	Data source	Study population described	Ethics approval mentioned	Sample size explained	Standard of care described	Intervention described	Waiting time definitions provided	Control group present	Baseline group differences discussed	Statistical tests used	Limitations discussed	Downs and black quality score (/21)
Ramchandani et al (2002)5	Questionnaire Interview	Yes	No	Yes	Yes	Yes	Yes	No	No	No	Yes	17
Leach et al (2004)33	Administrative data	Yes	No	No	No	Yes	Yes	Yes	No	No	Yes	10
Singh et al (2005)31	Administrative data	Yes	Yes	Yes	Yes	Yes	No	Yes	No	Yes	Yes	9
Sri-Ram et al (2005)32	Hospital data	Yes	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	8
Vasilakis et al (2007)30	Administrative data	Yes	No	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	21
Bungard et al (2008)26	Descriptive	Yes	No	NA	Yes	Yes	Yes	NA	NA	NA	NA	17
Cipriano et al (2008)27	Administrative data	Yes	No	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	14
Bichel et al (2009)24	Administrative data	Yes	No	No	No	Yes	Yes	Yes	No	Yes	Yes	13
Bungard et al (2009)25	Administrative data	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	20
Macleod et al (2009)28	Administrative data	Yes	No	No	Yes	Yes	Yes	Yes	No	No	Yes	11
van den Heuvel (2012)29	Questionnaire	Yes	No	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	18

NA, not available.