Table 3 Quality appraisal checklist and total quality score for included quantitative studies

Question / objective sufficiently described?

2

2

2

2

2

Study design evident and appropriate?

2

2

1

2

2

Method of subject/comparison group selection or input variables described and appropriate?

2

2

2

2

2

Subject characteristics sufficiently described?

2

2

2

2

2

If interventional and random allocation was possible, was it described?

N/A

N/A

2

2

N/A

If interventional and blinding of investigators was possible, was it reported?

N/A

N/A

0

0

N/A

If interventional and blinding of subjects was possible, was it reported?

N/A

N/A

1

0

N/A

Outcome and (if applicable) exposure measure(s) well defined and robust to measurement / misclassification bias?

2

2

2

2

2

Sample size appropriate?

0

0

1

2

2

Analytic methods described/justified and appropriate?

2

2

2

2

2

Some estimate of variance is reported for the main results?

1

2

2

1

2

Controlled for confounding?

1

0

1

2

N/A

Results reported in sufficient detail?

2

2

2

2

2

Conclusions supported by the results?

2

2

2

2

2

Total score (%)

82%

82%

79%

82%

100%