Table 2. Assessment of risk of bias of included articles.
| Author, year | Study Participants | Predictors | Outcome | Sample size and missing data | Overall |
|---|---|---|---|---|---|
| Genetic risk factors alone | |||||
| Dunlop 2013a | + | + | + | + | + |
| Frampton 2016 | ? | + | + | ? | ? |
| Hosono 2016a | ? | ? | + | ? | ? |
| Huyghe 2019 | + | + | + | ? | + |
| Ibanez-Sanz 2017a | + | + | + | ? | + |
| Jenkins 2016, 2019 | + | + | + | ? | + |
| Smith 2018a | + | + | + | + | + |
| Wang 2013 | ? | − | + | ? | − |
| Xin 2018a | ? | + | + | ? | ? |
| Genetic plus phenotypic risk factors excluding age | |||||
| Ibanez-Sanz 2017b | + | + | + | ? | + |
| Jeon 2018a and b | + | + | + | ? | + |
| Procopciuc 2017 | − | ? | + | − | − |
| Xin 2018b | ? | ? | + | ? | ? |
| Yarnell 2013 | ? | + | + | ? | ? |
| Genetic plus phenotypic risk factors plus age | |||||
| Abe 2017 | ? | + | + | ? | ? |
| Dunlop 2013b | + | ? | + | + | + |
| Hosono 2016b | ? | ? | + | ? | ? |
| Hsu 2015b | + | ? | + | ? | ? |
| Iwasaki 2017b | + | + | + | ? | + |
| Jo 2012 a and b | ? | − | + | − | − |
| Jung 2015 | + | ? | + | ? | ? |
| Jung 2019 | + | − | + | ? | − |
| Li 2015 | ? | ? | + | ? | ? |
| Shiao 2018 | − | ? | + | − | − |
| Smith 2018b | + | + | + | + | + |
| Smith 2018c | + | + | + | + | + |
| Weigl 2018 | + | + | + | ? | + |
+ = low risk;? = unclear risk; - = high risk