Table 2.

JBI critical appraisal of the included cohort studies.

	Study	Tsui et al., 2014 [13]	Lin et al., 2017 [15]
Q1	Were the two groups similar and recruited from the same population?	Yes	Yes
Q2	Were the exposures measured similarly to assign people to both exposed and unexposed groups?	Yes	Yes
Q3	Was the exposure measured in a valid and reliable way?	Yes	Yes
Q4	Were confounding factors identified?	No	Yes
Q5	Were strategies to deal with confounding factors stated?	No	Yes
Q6	Were the groups/participants free of the outcome at the start of the study?	Not applicable	Not applicable
Q7	Were the outcomes measured in a valid and reliable way?	Yes	Yes
Q8	Was the follow up time reported and sufficient to be long enough for outcomes to occur?	Yes	Yes
Q9	Was follow up complete, and if not, were the reasons to loss to follow up described and explored?	Yes	Yes
Q10	Were strategies to address incomplete follow up utilized?	Not applicable	Not applicable
Q11	Was appropriate statistical analysis used?	Yes	Yes
	Total Score	64%	82%