ROBINS-I tool for assessing quality of non-randomised studies for intervention (NRSIs)
| Author and year of publication | Confounding | Selection of participants | Intervention classification | Deviations from interventions | Missing data | Measurement of outcome | Selective reporting | Overall bias |
| Agha 2004 | Low risk | Some concerns | Low risk | Low risk | Some concerns | Low risk | Low risk | Some concerns |
| Dancy 2014 | Low risk | Some concerns | Some concerns | Low risk | Some concerns | High risk | Some concerns | High risk |
| Eruklar 2004 | Low risk | Some concerns | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Gelfond 2016 | Low risk | Low risk | Low risk | Some concerns | Some concerns | Some concerns | Low risk | Some concerns |
| Mason-Jones 2011 | Some concerns | Some concerns | Low risk | Some concerns | Low risk | Low-risk | Low risk | Some concerns |
| Hegan 2012 | High risk | Low risk | Low risk | Low risk | Some concerns | Low risk | Low risk | High risk |
| Kim 2001 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Kinsler 2004 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Speizer 2001 | Some concerns | Low risk | Low risk | Low risk | Some concerns | Low risk | Low risk | Some concerns |
| Philliber 2002 | Some concerns | Low risk | Low risk | Low risk | Some concerns | Low risk | Low risk | Some concerns |
| Lou 2004 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Cartagena 2006 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |
| Hanna 1994 | Some concerns | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Some concerns |
| Daniel 2008 | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk | Low risk |