Table 1 List of quality criteria

1

Was the rationale of the research described?

2

Were the objectives of the research clearly stated?

3

Was the study a prospective cohort study?

4

Was the follow-up of the cohort study 5 years or longer?

5

Were the key-elements of the study design described?

6

Were the setting, relevant dates and timeframe of the research described?

7

Were the eligibility criteria for participants described?

8

Were the participants free of disability at baseline?

9

Were the predictors and dependent variables described?

10

Were the measurement methods for the predictors and dependent variables described?

11

Were standardized or valid measurements used for the predictors?

12

Were standardized or valid measurements used for the outcome?

13

Were potential types of bias addressed?

14

Was it clear how the quantitative data were handled in the analyses?

15

Were appropriate multivariate analysis techniques used?

16

Did the statistical methods control for confounding and examine subgroups or interactions?

17

Was there a description on how the final number of participants was established?

18

Was the (loss to) follow-up of the participants described?

19

Was the attrition less than 20%?

20

Was information provided regarding the baseline characteristics of participants?

21

Was the number of outcome events or summary measures over time reported?

22

Were the results expressed in an Odds Ratio (OR), Risk Ratio (RR) or Hazard Ratio (HR) with the corresponding 95% confidence interval?

23

If sub-group analyses were performed, were these clearly described?

24

Were the key-results described in the discussion?

25

Were the limitations of the study reported?

26

Were previous research and the limitations of the study taken into account when an overall interpretation of the study results was provided?

27

Was the generalisability of the study results described?