Table 3 CASP methodological quality appraisal of quantitative studies

1

Did the study address a clearly focused issue?

Yes

Yes

Yes

Yes

2

Were the participants recruited in an acceptable way?

Yes

Yes

Yes^a

Yes

3

Was the exposure accurately measured to minimise bias?

N/A

N/A

N/A

N/A

4

Was the outcome accurately measured to minimise bias?

Unclear^

Yes

Unclear^b

Clear

5a

Have the authors identified all important confounding factors?

N/A

N/A

N/A

N/A

5b

Have they taken account of the confounding factors in the design and/or analysis?

N/A

N/A

N/A

N/A

6

A) Was the follow up of subjects complete enough? B) Was the follow up of subjects long enough?

N/A

N/A

N/A

N/A

7

What are the results of this study?

Clear

Clear

Clear

Clear

8

How precise are the results?

Unclear

Clear

Unclear

Clear

9

Do you believe the results?

Yes

Yes

Unclear

Yes

10

Can the results be applied to the local population?

Yes

Yes

Yes

Yes

11

Do the results of the study fit with other available evidence?

Yes

Yes

Yes

Yes

12

What are the implications of this study for practice?

Clear

Clear

Clear

Clear