Methodological quality criteria
| Item | Judgement |
|---|---|
| External validity | |
| Were the subjects asked to participate in the study representative of the entire population from which they were recruited? | Yes/No/Unable to determine |
| Internal validity | |
| Were the determinants measured used accurate? | Yes/No/Unable to determine |
| Were the statistical tests used to assess the main outcomes appropriate? | Yes/No/Unable to determine |
| Were losses of patients to follow-up taken into account? | Yes/No/Unable to determine |
| Was there adequate adjustment for confounding in the analysis from which the main findings were drawn? | Yes/No/Unable to determine |