Table 2.

Summary of quality assessment

Author (year)	1	2	3	4	5	6	7	8	9
Ackermann et al. (1998) [22]	Yes	Yes	Yes	Yes	Not applicable	Yes	Yes	No	Yes
Hsiao and Hing (2014) [15]	Yes	Yes	Yes	Yes	Not clear	Yes	Yes	Yes	Yes
Kihlgren (2014) [14]	Yes	Yes	Yes	Yes	Not clear	Yes	Yes	Yes	Yes
LaMantia et al. (2016) [23]	Yes	Yes	Yes	Yes	Not applicable	Yes	Yes	Yes	Yes
McGregor et al. (2014) [18]	Yes	Yes	Yes	Yes	Not applicable	Yes	Yes	Yes	Yes
Stephens et al. (2012) [24]	Yes	Yes	Yes	Yes	Not applicable	Yes	Yes	Yes	Yes
Stephens et al. (2014) [25]	Yes	Yes	Yes	Yes	Not applicable	Yes	Yes	Yes	Yes

Quality appraisal criteria [21]:

1. Was the sample frame appropriate to address the target population?

2. Were study participants sampled in an appropriate way?

3. Was the sample size adequate?

4. Were the study subjects and setting described in detail?

5. Was the data analysis conducted with sufficient coverage of the identified sample?

6. Were valid methods used for the identification of the condition?

7. Was the condition measured in a standard, reliable way for all participants?

8. Was there appropriate statistical analysis?

9. Was the response rate adequate, and if not, was the low response rate managed appropriately?