Table 2. Methodological quality using the Newcastle Ottawa Scale for cohort studies.

Author ID	Selection (Maximum 4)	Compatibility (Maximum 1)	Outcome (Maximum 3)	Total Score	Quality
Kwon et al., 2008 [8]	3	1	2	6	Moderate
El-Shintenawy et al., 2019 [14]	2	1	3	6	Moderate
Swen et al., 2001 [15]	3	1	3	7	High
El Miedany et al., 2004 [10]	3	1	2	6	Moderate
Pimentel et al., 2018 [16]	3	1	3	7	High
Visser et al., 2007 [17]	2	1	2	5	Moderate
Filho et al., 2014 [6]	3	1	2	6	Moderate
El Badry et al., 2016 [18]	4	1	2	7	High
Kele et al., 2003 [19]	3	1	2	6	Moderate
Azami et al., 2014 [20]	2	1	3	6	Moderate
Fowler et al. 2014 [21]	2	1	2	5	Moderate
Moran et al., 2009 [22]	3	1	2	6	High