Table 4 Quality assessment criteria by study design

Total quality assessment score (maximum of 8) was derived for the fulfilment of following criteria:

Total quality assessment score (maximum of 6) was derived for the fulfilment of following criteria:

Total quality assessment score (maximum of 12) was derived for the fulfilment of following criteria:

1) Randomisation

1) More than 50 participants analysed

1) Research questions clearly stated

2) Effect of intervention reported for all outcomes

2) Studies representing general population

2) Approach appropriate for the research question

3) Pre-intervention data on all outcomes

3) Prospective study design

3) Qualitative approach clearly justified

4) Post-intervention data on all outcomes

4) Adjusted/multivariate analysis

4) Study context clearly described

5) Allocation concealment

5) Objective measure of outcome

5) Role of the researcher clearly described

6) Blinding

6) Objective measure of exposure

6) Sampling method clearly described

7) Objective measurement of outcome

7) Sampling strategy appropriate for the research question

8) Retention >70 %

8) Method of data collection clearly described

Studies with small sample size (n < 50) and no control group were considered to provide lower quality evidence and not scored

9) Data collection method appropriate

10) Method of analysis clearly described

11) Analysis appropriate for the research question

12) Conclusions supported by sufficient evidence