Table 2. The quality assessment of included studies by the Newcastle-Ottawa Quality Assessment Form for cohort studies.
| Study (Years) | Selection | Comparability | Outcome | Total quality | |||||
| Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposures | Demonstration that outcome of interest was not present at start of study | Comparability of cohorts on the basis of the design or analysis controlled for confounders | Assessment of outcome | Was follow up long enough for outcomes to occur? | Adequacy of follow up of cohort | ||
| Acceptable | From community of general population | From the same community as exposed cohort | From structured interview | Yes | Yes, at least age and sex | Contained objective indicators | At least 4 years | Follow up rate more than 80%, or subjects lost to follow up unlikely to introduce bias | |
| Gopinath (2018) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Daskalopoulou (2018) | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
| LaCroix (2016) | 0 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 8 |
| Almeida (2014) | 0 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 7 |
| Bell (2014) | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
| Gureje (2014) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Hodge (2014) | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
| Hamer (2013) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Sabia (2012) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Sun (2010) | 0 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 8 |
| Kaplan (2008) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Britton (2008) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Haveman-Nies (2003) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Ford (2000) | 1 | 1 | 0 | 1 | 2 | 1 | 0 | 1 | 7 |
| Strawbridge (1996) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |