Risk of bias assessment of the cohort studies
Author, year | Was selection of exposed and non-exposed cohorts drawn from the same population?* | Can we be confident in the assessment of exposure?† | Can we be confident that the outcome of interest was not present at start of study?‡ | Did the study match exposed and unexposed for all variables that are associated with the outcome of interest or did the statistical analysis adjust for these prognostic variables?§ | Can we be confident in the assessment of the presence or absence of prognostic factors?¶ | Can we be confident in the assessment of outcome?** | Was the follow-up of cohorts adequate?†† | Were cointerventions similar between groups?‡‡ |
|---|---|---|---|---|---|---|---|---|
| Al-Delaimy 201540 | Definitely yes | Probably yes | Definitely yes | Definitely no | Definitely no | Definitely no | Definitely no | Probably no |
| Biener 201529 | Definitely yes | Probably yes | Definitely yes | Definitely no | Definitely no | Definitely no | Definitely no | Probably no |
| Brose 201526–28 | Definitely yes | Probably yes | Probably no | Definitely no | Definitely no | Definitely no | Definitely no | Probably no |
| Hajek 201546 | Probably yes | Probably yes | Probably yes | Definitely no | Probably yes | Probably yes | Probably yes | Probably no |
| Harrington 201545 | Definitely yes | Definitely no | Definitely no | Definitely no | Definitely no | Definitely no | Definitely no | Definitely no |
| Manzoli 201542 | Definitely yes | Probably yes | Definitely no | Definitely no | Definitely no | Probably no | Definitely no | Probably no |
| Borderud 201441 | Definitely yes | Probably yes | Definitely yes | Definitely no | Definitely no | Definitely no | Definitely no | Definitely yes |
| Prochaska 201443 | Definitely yes | Probably yes | Definitely yes | Definitely yes | Probably yes | Definitely no | Definitely yes | Probably No |
| Vickerman 201344 | Probably yes | Definitely no | Definitely no | Definitely no | Definitely no | Definitely no | Definitely no | Definitely no |
All answers as: definitely yes (low risk of bias), probably yes, probably no, definitely no (high risk of bias).
*Examples of low risk of bias: Exposed and unexposed drawn from same administrative data base of patients presenting at same points of care over the same time frame.
†This means that investigators accurately assess the use of ENDS at baseline.
‡This means that smoking cessation was not present at the start of the study.
§Examples of low risk of bias: comprehensive matching or adjustment for all plausible prognostic variables.
¶Examples of low risk of bias: Interview of all participants; self-completed survey from all participants; review of charts with reproducibility demonstrated; from data base with documentation of accuracy of abstraction of prognostic data.
**Outcome self-reported was considered as definitely no for adequate assessment. Smoking abstinence, biochemically verified was considered as definitely yes for adequate assessment.
††Defined as less than 10% loss to outcome data or subjects lost to follow-up unlikely to introduce bias.
‡‡Examples of low risk of bias: Most or all relevant cointerventions that might influence the outcome of interest are documented to be similar in the exposed and unexposed.