Table 3.

Quality of Evidence of the included studies according to the Cambridge Quality Checklists.

Authors	Checklist for Correlates	Checklist for Risk Factor	Checklist for Causal Risk Factors	Total
Ankolkar et al., 2012 [26]	2	1	2	5
Boissonnas et al., 2010 [34]	2	1	2	5
Camprubí et al., 2012 [27]	2	1	2	5
Dong et al., 2017 [21]	2	1	2	5
El-Hajj et al., 2011 [28]	2	1	2	5
Laurentino et al., 2015 [29]	1	1	2	4
Li et al., 2013 [22]	2	1	2	5
Li et al., 2016 [23]	2	1	2	5
Montjean et al., 2015 [30]	2	1	1	4
Peng et al., 2018 [24]	2	1	2	5
Xu et al., 2016 [25]	2	1	2	5