8. Methodological quality of nonexperimental cohort studies.
| Study | Selection | Comparability | Outcome | Total (out of 9) | ||||||
| S1 | S2 | S3 | S4 | C1 | C2 | O1 | O2 | O3 | ||
| Allen 2004 | c(0) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | a(1) | a(1) | 7 |
| Chyou 1993 | b(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Dai 2010 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | b(0) | b(1) | 8 |
| Fujino 2002 in: Inoue 2009a | a(1) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | a(1) | a(1) | 8 |
| Galanis 1998 | b(1) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | b(0) | b(1) | 7 |
| Hoshiyama 2002 in: Inoue 2009a | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | c(0) | 8 |
| Hoshiyama 2004a in: Inoue 2009a | a(1) | a(1) | a(1) | a(1) | 1 | 1 | b(1) | a(1) | c(0) | 8 |
| Ide 2007 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Inoue 2009a | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Inoue 2009b | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Ishikawa 2006 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | c(0) | 8 |
| Iwai 2002 | a(1) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | a(1) | b(1) | 8 |
| Iwasaki 2010a | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Iwasaki 2010b in: Iwasaki 2010a | a(1) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | a(1) | b(1) | 8 |
| Key 1999 | c(0) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | a(1) | a(1) | 7 |
| Khan 2004 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Kikuchi 2006 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Kurahashi 2007 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Kurahashi 2009 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Kuriyama 2006 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Lee 2007 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Li 2008 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Li 2018 | c(0) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 8 |
| Lin 2008 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Liu 2016 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Luo 2007 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Makiuchi 2016 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Michikawa 2011 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Montague 2012 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Nagano 2001 | c(0) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 8 |
| Naganuma 2009 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Nakachi 2000 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Nakamura 2011 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Nechuta 2012 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 9 |
| Oba 2006 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Odegaard 2015 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Ogawa 2016 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Saito 2015 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Sasazuki 2004 in: Inoue 2009a | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Sauvaget 2005 in: Nagano 2001 | c(0) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | a(1) | 8 |
| Severson 1989 | a(1) | a(1) | b(1) | a(1) | 1 | 0 | b(1) | a(1) | b(1) | 8 |
| Shimazu 2008 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Sun 2007 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Suzuki 2004 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Suzuki 2005 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Suzuki 2009 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Tamura 2018 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Tsubono 2001 in: Inoue 2009a | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Ugai 2017 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Ugai 2018 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Ui 2009 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Yang 2007 in: Nechuta 2012 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Yang 2011a | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
| Zhao 2017 | a(1) | a(1) | b(1) | a(1) | 1 | 1 | b(1) | a(1) | b(1) | 9 |
aCase‐cohort study