Table 1.

Evidence quality

Study	Randomiza- tion methods or NRS	NRS: NOS se- lection criterion	NRS: NOS comparability	Follow-up period	Loss or chart re- view	Evidence qual- itya
Ball 1991	−1	NA	NA	−1	−1	Very low
Bonny 2009	−1	-	-	−1	-	Low
Castle 1978	−1	-	−1	−1	−1	Very low (poor)
Dal’Ava 2012	−1	-	-	-	-	Moderate
Dal’Ava 2014	−1	-	-	-	−1	Low
Dos Santos 2014	−1	-	-	-	−1	Low
Espey 2000	−1	-	-	-	−1	Low
Modesto 2015	−1	-	-	-	−1	Low
Moore 1995	−1	-	-	-	−1	Low
Napolitano 2015	−1	-	−1	-	-	Low
Nyirati 2013	−1	-	−1	-	−1	Very low
Pantoja 2010	−1	-	-	-	−1	Low
Salem 1984	−1	-	−1	−1	-	Very low
Salem 1988	-	NA	NA	-	−1	Moderate
Sivin 1998	-	NA	NA	-	−1	Moderate
Sule 2005	−1	-	−1	-	−1	Very low
Taneepanichskul 1998	−1	−1	-	-	−1	Very low
Tankeyoon 1976	−1	-	-	-	−1	Low
Tuchman 2005	−1	-	−1	-	−1	Very low
Vickery 2013	−1	-	-	-	−1	Low
Westhoff 2007	−1	NA	NA	-	−1	Low
WHO 1983	−1	NA	NA	-	−1	Low

^aDowngraded for the following: (1) Risk of bias high for randomization sequence generation or allocation concealment, or no information provided on either, or study not randomized (NRS); (2) NRS: high risk of bias in selection; (3) NRS: no stars for comparability, i.e. not controlling for relevant confounding; (4) follow-up < 12 months for change in weight or BMI; (6) loss to follow-up > 20%, combined loss to follow-up and discontinuation > 50%, major differential losses between groups, or retrospective chart review of selected cases

NA = not applicable

NOS = Newcastle-Ottawa Quality Assessessment Scale