Table 2 The methodological quality of the included studies

1) Is the hypothesis/aim/objective of the study clearly described?

Y

Y

Y

Y

Y

Y

Y

Y

Y

2) Are the main outcomes to be measured clearly described in the Introduction or Method’s section?

Y

Y

Y

Y

Y

Y

Y

Y

Y

3) Are the characteristics of the patients included in the study clearly described?

Y

Y

Y

Y

N

Y

N

Y

N

4) Are the interventions of interest clearly described?

N

Y

Y

N

N

Y

N

N

N

5) Are the distributions of principal confounders in each group of subjects to be compared clearly described?

N

N

N

N

N

N

N

N

N

6) Are the main findings of the study clearly described?

Y

Y

Y

Y

Y

Y

Y

Y

Y

7) Does the study provide estimates of the random variability in the data for the main outcomes?

N

Y

Y

Y

Y

Y

Y

Y

Y

8) Have all important adverse events that may be a consequence of the intervention been reported?

N

N

N

N

N

N

N

N

N

9) Have the characteristics of patients lost to follow-up been described?

Y

Y

Y

Y

Y

Y

Y

Y

Y

10) Have actual probability values been reported (e.g., 0.035 rather than <0.05) for the main outcomes except where the probability value is less than 0.001?

Y

Y

Y

Y

Y

Y

Y

Y

Y

11) Were the subjects asked to participate in the study representative of the entire population from which they were recruited?

U

U

U

U

U

U

U

U

U

12) Were those subjects who were prepared to participate representative of the entire population from which they were recruited?

U

U

U

U

U

U

U

U

U

13) Were the staff, places, and facilities where the patients were treated representative of the treatment the majority of patients receive?

U

U

U

U

U

U

U

U

U

14) Was an attempt made to blind study subjects to the intervention they have received?

N

N

U

N

N

U

N

N

N

15) Was an attempt made to blind those measuring the main outcomes of the intervention?

N

N

Y

N

N

Y

N

N

N

16) If any of the results of the study were based on “data dredging”, was this made clear?

Y

Y

Y

Y

Y

Y

Y

Y

Y

17) In trials and cohort studies, do the analyses adjust for different lengths of follow-up of patients, or in case–control studies, is the time period between the intervention and outcome the same for cases and controls?

N

Y

N

N

N

N

Y

N

N

18) Were the statistical tests used to assess the main outcomes appropriate?

Y

Y

Y

Y

Y

Y

Y

Y

Y

19) Was compliance with the intervention/s reliable?

Y

Y

Y

Y

Y

Y

Y

Y

Y

20) Were the main outcome measures used accurate (valid and reliable)?

Y

Y

Y

Y

Y

Y

Y

Y

Y

21) Were the patients in different intervention groups (trials and cohort studies) or were the cases and controls (case–control studies) recruited from the same population?

N

Y

Y

N

N

Y

N

N

N

22) Were study subjects in different intervention groups (trials and cohort studies) or were the cases and controls (case–control studies) recruited over the same period of time?

N

Y

Y

N

N

Y

N

N

N

23) Were study subjects randomized to intervention groups?

N

N

Y

N

N

Y

N

N

N

24) Was the randomized intervention assignment concealed from both patients and health care staff until recruitment was complete and irrevocable?

N

N

U

N

N

U

N

N

N

25) Was there adequate adjustment for confounding in the analyses from which the main findings were drawn?

N

N

N

N

N

N

N

N

N

26) Were losses of patients to follow-up taken into account?

N

N

N

N

N

Y

Y

Y

N

27) Did the study have sufficient power to detect a clinically important effect where the probability value for a different being due to chance is less than 5 %?

0

0

0

0

0

0

0

0

0

Score

10

15

16

11

10

17

12

12

10