Table 2.
Assessment of the quality of the eligible studies based on NOS1.
| Case-control study | Selection | Comparability6 | Exposure | Total | |||||
| Definition2 | Representativeness3 | Selection4 | Definition5 | Ascertainment7 | Method8 | Rate9 | |||
| Andersson et al(1996) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Mayer et al(1997) | 1 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 6 |
| Vlajinac et al(1997) | 1 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 6 |
| Key et al(1997) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Demeo-Pellegrini et al(1999) | 1 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 6 |
| Jain et al(1999) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 7 |
| Kristal et al(1999) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Ramon et al(2000) | 1 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 6 |
| Cohen et al(2000) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| McCann et al(2005) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Bidoli et al(2009) | 1 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 6 |
| Lewis et al(2009) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Cohort study | Selection | Comparability6 | Outcome | Total | |||||
| Representativeness10 | Selection11 | Ascertainment7 | Demonstration12 | Assessment13 | Duration14 | Adequacy15 | |||
| Shibaba et al(1992) | 1 | 1 | 1 | 1 | 2 | 1 | 0 | 1 | 8 |
| Daviglus et al(1996) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Kirsh et al(2006) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Rohrmann et al(2007) | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
| Kristal et al(2008) | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
| Roswall et al(2013) | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
1Assessed with the 9-star Newcastle-Ottawa Scale (NOS); 2Adequate definition of cases (0, 1); 3Consecutive or obviously representative series of cases (0, 1); 4Selection of controls: Community controls (0, 1); 5Definition of controls: No history of disease (0, 1); 6Study controls for the most important factor or any additional factor (0, 1, 2); 7Secure record (0, 1); 8Same method of ascertainment for cases and controls (0, 1); 9Same non-response rate for both groups (0, 1); 10Truly or somewhat representative of the exposed cohort (0, 1); 11Selection of the non exposed cohort (0, 1); 12Demonstration that outcome of interest was not present at start of study (0, 1); 13Assessment of outcome (0, 1); 14Follow-up long enough for outcomes to occur (0, 1); 15Adequacy of follow up of cohorts (0, 1).