Table 3.

Critical appraisal of included studies using CASP (n = 4).

	Validity						Results			Local application
	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Study	Address a clearly focussed issue	Acceptable cohort recruitment	Accurate exposure measurement	Accurate outcome measure	Confounding factors identified	Confounding factors accounted for	Subjects follow-up completeness	Subjects follow-up time frame	Results	Precision of results	Believability of results	Local application	Other evidence available	Study implications	Total score X/14
Daya, 2011	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	U	13
Karwacińska et al., 2012	✓	✓	×	✓	✓	✓	✓	✓	✓	×	✓	✓	✓	U	11
Sawada et al., 1998	✓	✓	U	×	×	×	✓	✓	U	×	×	×	✓	×	5
Toscano et al. 2016	✓	✓	U	U	✓	×	✓	✓	✓	U	U	U	✓	×	7

✓, yes; ×, no; U, unable to determine.