| References | Risk of bias (RoB) domains a | Tier b | |||||
|---|---|---|---|---|---|---|---|
| Exposure KEY | Outcome KEY | Confounding KEY | Inappropriate selection | Attrition | Other sources of bias/statistics | ||
| Colorectal cancer | |||||||
| Roswall et al. (2010) | + | ++ | – | + | + | + | 2 |
| Wang, Wu, et al. (2021) | + | + | ++ | + | – | + | 1 |
| Otani et al. (2008) | + | + | + | + | + | + | 1 |
| Stevens et al. (2011) | + | + | – | + | + | + | 2 |
| Zhang et al. (2006) | – (c) | + | – | + | + | + | 2 |
| Rossi et al. (2006) | + | NR | – | + | – | + | 2 |
| Zschäbitz et al. ( 2013) | NR | + | ++ | ++ | NR | + | 2 |
| Glynn et al. ( 1996 ) | + | ++ | – | + | + | + | 2 |
| Lee et al. ( 2012 ) | + | + | – | + | + | + | 2 |
| Flood et al. ( 2002 ) | + | – | – | – | + | + | 2 |
| Lee et al. ( 2011 ) | + | + | – | + | – | + | 2 |
| Razzak et al. ( 2012 ) | – (c) | + | – | + | + | + | 2 |
| Neuhouser et al. ( 2015 ) | + | + | – | – | + | + | 2 |
| Shrubsole et al. ( 2009 ) | + | + | + | + | + | NR | 1 |
| Gibson et al. ( 2011 ) | + | + | ++ | + | + | – | 1 |
| Le Marchand et al. ( 2005 ) | – (c) | + | + | + | + | + | 1 |
| Eussen et al. ( 2010 ) | + | + | ++ | + | ++ | + | 1 |
| Van Guelpen et al. ( 2006 ) | + | ++ | – | + | + | + | 2 |
| Kato et al. ( 1999 ) | + | + | – | + | + | + | 2 |
| Kim et al. ( 2010 ) | – | + | + | + | NR | + | 2 |
| Gylling et al. ( 2014 ) | + | ++ | – | + | + | + | 2 |
| Takata et al. ( 2014 ) | + | + | + | + | + | + | 1 |
| Le Marchand et al. ( 2009 ) | + | + | – | + | + | + | 2 |
| Weinstein et al. ( 2008 ) | + | ++ | – | + | + | + | 2 |
| Cho et al. ( 2015 ) | – c | + | – | + | + | NR | 2 |
| Geijsen et al. ( 2020 ) | + | + | – | + | NR | + | 2 |
| Colorectal Adenomas | |||||||
| Baron et al. ( 1998 ) | + | ++ | – | + | + | + | 2 |
| He et al. ( 2018 ) | + | + | – | + | + | NR | 2 |
| Martínez et al. ( 2004 ) | + | + | – | + | + | NR | 2 |
| Murphy et al. ( 2008 ) | + | + | – | + | NR | NR | 2 |
| Lee et al. ( 2011 ) | + | + | – | + | – | + | 2 |
| Martínez et al. ( 2006 ) | + | + | – | + | + | – | 2 |
Expert judgement was translated into a rating scale for each question to be answered as follows: (++): definitely low RoB; (+): probably low RoB; (NR): not reported; (−): probably high RoB; (− −): definitively high RoB.
The individual rating for each question was combined by an algorithm and translated to an overall tier of reliability for each individual study (RoB tier 1: low RoB; RoB tier 2: moderate RoB; RoB tier 3: high RoB).
The rating differs from the initial appraisal (Åkesson et al., 2023); the Panel noted that, in these studies, exposure was assessed before the introduction of mandatory fortification in the US and a large proportion of the follow‐up period occurred after the introduction of mandatory fortification but change in exposure due to the fortification policy was not addressed in the analysis.