Table 2.

Quality assessment of the included studies.

Study ID		Study design	Data analysis	Allocation generation	Allocation concealment	Blinding	Lost to follow-up
Tambour	2018	RCT	ITT	Adequate	Adequate	Assessor blinded	5.2% at 7 mo
Devoogdt	2018	RCT	ITT	Adequate	Adequate	Assessor blinded	1.2% at 6 mo
Zhang	2016	RCT	PP	Inadequate	Unclear	None reported	None
Cho	2016	RCT	ITT	Inadequate	Unclear	Assessor blinded	14.6% at 1 mo
Bergmann	2014	RCT	ITT	Inadequate	Unclear	None reported	13.6% at 24 d
Ridner	2013	RCT	PP	Computer-generated	Unclear	None reported	None
Zimmermann	2012	RCT	PP	Inadequate	Unclear	None reported	None
Belmonte	2012	RCT	ITT	Computer-generated	Adequate	Assessor blinded	11.1% at 2 mo
Devoogdt	2011	RCT	ITT	Adequate	Adequate	Assessor blinded	4% at 12 mo
Szolnoky	2009	RCT	ITT	Unclear	Unclear	None reported	None
Didem	2005	RCT	PP	Unmarked envelopes	Adequate	Patient blinded	5.4% at 1 mo
McNeely	2004	RCT	PP	Computer-generated code	Adequate	Assessor blinded	11.1% at 1 mo
Williams	2002	RCT	PP	Unclear	Unclear	None reported	6.5% at 3 wk
Sitzia	2002	RCT	PP	Computer-generated	Adequate	None reported	3.6% at 2 wk
Andersen	2000	RCT	ITT	Unclear	Unclear	None reported	2.4 at 3 mo, 9.5% at 12 mo
Johansson	1999	RCT	PP	Inadequate	Unclear	None reported	None
Johansson	1998	RCT	PP	Unclear	Unclear	None reported	None

ITT = intention-to-treat, PP = per-protocol, RCT = randomized controlled trial.