Table 1 Newcastle-Ottawa Scale Scores (Scores between 1 and 8)

Representative-ness of the intervention cohort

Selection of non-intervention cohort

Ascertainment of intervention

Outcome of interest not present at start of study

Cohort comparable on the basis of the design

Assessment of outcome

Follow-up long enough

Adequacy of follow-up

Waldron et al., 1990 [15]

No

No

Yes

Yes

No

Yes

Yes

Yes

Ben-Nun et al., 2004 [16]

Yes

No

Yes

Yes

No

Yes

Yes

Yes

Davidson et al., 2012 [17]

Yes

No

Yes

Yes

No

Yes

No

No

Muhammad et al., 2012 [18]

Yes

No

Yes

Yes

No

Yes

No

Yes

Fang et al., 2015 [19]

Yes

No

Yes

Yes

No

Yes

No

No

Miklus et al., 1989 [20]

Yes

No

Yes

Yes

No

Yes

No

No

Cook et al., 1991 [21]

Yes

No

Yes

Yes

No

Yes

Yes

Yes

Nugent et al., 1991 [22]

Yes

No

Yes

Yes

No

Yes

No

No

Boyle et al., 1993 [23]

Yes

No

Yes

Yes

No

Yes

No

Yes

Hawkins et al., 1995 [24]

Yes

No

Yes

Yes

No

Yes

Yes

No

Jacobson et al., 1996 [25]

Yes

No

Yes

Yes

No

Yes

Yes

No

Isaacs et al., 1997 [26]

Yes

No

Yes

Yes

No

Yes

Yes

No

Leibovici et al., 1997 [27]

Yes

No

Yes

Yes

No

Yes

No

No

Wright et al., 2003 [28]

Yes

No

Yes

Yes

No

Yes

Yes

No

Bair et al., 2003 [29]

Yes

No

Yes

Yes

No

Yes

No

Yes

McIntosh et al., 2008 [30]

Yes

No

Yes

Yes

No

Yes

No

Yes

Warner et al., 2009 [31]

Yes

No

Yes

Yes

No

Yes

No

Yes

King et al., 2012 [32]

Yes

No

Yes

Yes

No

Yes

No

No

Darby et al., 2016 [33]

Yes

No

Yes

Yes

No

Yes

No

No

Gillespie et al., 1999 [34]

Yes

Yes

Yes

Yes

No

Yes

Yes

No

Beshey et al., 2014 [35]

Yes

Yes

Yes

Yes

Yes

Yes

No

No