Summary of quality assessment
| Study: first author (year), location | Quality assessment stars allocation | Total score (max 12) | Quality | |||
|---|---|---|---|---|---|---|
| Selection (max 3) | Comparability (max 2) | Exposure (max 3) | Outcome (max 4) | |||
| Von Kries (1999), Germany | 3 | 2 | 1 | 4 | 10 | High |
| Power (2002), UK | 2 | 1 | 1 | 3 | 7 | Medium |
| Von Kries (2002), Germany | 3 | 2 | 1 | 4 | 10 | High |
| Wideroe (2003), Norway and Sweden | 2 | 2 | 1 | 4 | 9 | Medium |
| Salsberry (2005), USA | 1 | 2 | 2 | 2 | 7 | Medium |
| Al Mamum (2006), Australia | 2 | 2 | 2 | 3 | 9 | Medium |
| Chen (2006), USA | 2 | 2 | 2 | 4 | 10 | High |
| Dubois (2007), Canada | 3 | 0 | 2 | 4 | 9 | Medium |
| Salsberry (2007), USA | 1 | 2 | 1 | 2 | 6 | Medium |
| Toschke (2007), Germany | 3 | 1 | 1 | 3 | 8 | Medium |
| Mendez (2008), Spain | 3 | 2 | 2 | 4 | 11 | High |
| Moschonis (2008), Greece | 2 | 1 | 1 | 3 | 7 | Medium |
| Fasting (2009), Norway | 2 | 1 | 1 | 3 | 7 | Medium |
| Hawkins (2009), UK | 3 | 2 | 2 | 3 | 10 | High |
| Kleiser (2009), Germany | 2 | 2 | 1 | 3 | 8 | Medium |
| Suzuki (2009), Japan | 3 | 1 | 1 | 4 | 9 | Medium |
| Ajslev (2010), Denmark | 2 | 0 | 2 | 2 | 6 | Medium |
| Braun (2010), USA | 2 | 2 | 2 | 3 | 9 | Medium |
| Ferreira (2010), Brazil | 2 | 0 | 1 | 2 | 5 | Low |
| Kuhle (2010), Novo Scotia | 1 | 1 | 1 | 2 | 5 | Low |
| Mangio (2010), Sweden | 2 | 2 | 1 | 3 | 8 | Medium |
| Olson (2010), USA | 2 | 2 | 1 | 3 | 8 | Medium |
| Pinot de Moira (2010), UK | 2 | 2 | 1 | 3 | 8 | Medium |
| Seach (2010), Australia | 2 | 2 | 2 | 3 | 9 | Medium |
| Gorog (2011), Central Europe | 2 | 2 | 1 | 3 | 8 | Medium |
| Raum (2011), Germany | 3 | 1 | 1 | 3 | 8 | Medium |
| Laitinen (2012), Finland | 3 | 1 | 2 | 4 | 10 | High |
| Messiah (2012), USA | 3 | 2 | 1 | 3 | 9 | Medium |
| Risvas (2012), Greece | 1 | 1 | 1 | 3 | 6 | Medium |
| Harris (2013), USA | 3 | 1 | 1 | 2 | 7 | Medium |
| Shi (2013), Canada | 3 | 1 | 1 | 3 | 8 | Medium |
| Yang (2013), Belarus | 2 | 2 | 2 | 4 | 10 | High |
| Anderson (2014), Hawaii | 2 | 1 | 2 | 4 | 9 | Medium |
| Bammann (2014), Europe | 2 | 2 | 1 | 3 | 8 | Medium |
| Grazuleviciene (2014), Lithuania | 1 | 2 | 1 | 2 | 6 | Medium |
| Moller (2014), Denmark | 3 | 2 | 2 | 3 | 10 | High |
| Suzuki (2014), Japan | 3 | 1 | 1 | 4 | 9 | Medium |
| Timmermans (2014), the Netherlands | 2 | 2 | 1 | 4 | 9 | Medium |
| Wen (2014), Australia | 2 | 0 | 2 | 4 | 8 | Medium |