Table 3.
Results of risk of bias assessment using the Newcastle-Ottawa scale for assessing risk of bias of non-randomized studies
| First author and year | Representative exposed cohort?1 | Selection of non-exposed cohort2 | Ascertainment of exposure3 | Outcome not present at start of study4 | Comparability of cohorts5 | Assessment of outcome6 | Long enough follow-up?7 | Adequacy of follow-up8 | Overall risk of bias rating9 |
|---|---|---|---|---|---|---|---|---|---|
| Barrett 2024 | A | A | A | A | A, B | B | A | A | Low |
| Braun 2004 | A | C | A | A | N/A | B | A | D | Low |
| Chang 2015 | A | A | A | A | A, B | B | A | A | Low |
| Farrah 2021 | A | A | A | A | A, B | B | A | B | Low |
| Fleischmann-Struzek 2021 | A | C | A | A | N/A | B | A | D | Low |
| Gadre 2019 | A | C | A | A | A, B | B | A | D | Low |
| Goodwin 2015 | A | C | A | A | A, B | B | A | A | Low |
| Lee 2004 | A | C | D | A | N/A | B | A | D | Not low |
| Letarte 2002 | A | C | A | A | N/A | B | A | B | Low |
| Mageau 2019 | A | A | A | A | A, B | B | A | D | Low |
| Nissenson 2005 | A | A | A | A | B | B | A | C | Low |
| Pandolfi 2023 | A | C | A | A | N/A | B | A | A | Low |
| Paoli 2018 | A | C | A | A | N/A | B | A | B | Low |
| Prescott 2014 | A | A | C | A | A | B | A | B | Low |
| Puceta 2024 | A | A | A | A | A, B | B | A | A | Low |
| Rose 2023 | A | C | A | A | N/A | B | A | A | Low |
| Sankaran 2024 | A | C | A | A | N/A | B | A | A | Low |
| Schmidt 2022 | A | C | A | A | N/A | B, C | A | D | Low |
| Stinehart 2024 | A | C | A | A | N/A | B | A | A | Low |
| Tew 2021 | A | A | A | B | A, B | B | A | B | Low |
| Thompson 2018 | C | A | A | A | A, B | B | A | D | Low |
| Weycker 2003 | A | C | A | A | N/A | B | A | B | Low |
| Winkler 2023 | A | A | A | A | A, B | B | A | D | Low |
1 Representativeness of the exposed cohort: A* = truly representative of the average ___ in the community. B* = somewhat representative of the average ____ in the community. C = selected group of users. D = no description of the derivation of the cohort
2 Selection of the non-exposed cohort: A* = drawn from the same community as the exposed cohort. B = drawn from a different source. C = no description of the derivation of the non-exposed cohort
3 Ascertainment of exposure: A* = secure record (e.g. surgical records). B* = structured interview. C = written self-report. D = no description
4 Demonstration that outcome of interest was not present at the start of study: A* = yes. B = no
5 Comparability of cohorts on the basis of design or analysis: A* = study controls for ___ (most important factor). B* = study controls for any additional factor
6 Assessment of outcome: A* = independent blind assessment. B* = record linkage. C = self-report. D = no description
7 Was follow-up long enough for outcomes to occur: A* = yes. B = no
8 Adequacy of follow-up of cohorts: A* = complete follow-up – all subjects accounted for. B* = subjects lost to follow up unlikely to introduce bias – small number lost, or description provided of those lost. C = follow up rate low and no description of those lost. D = no statement
9 Overall risk of bias rating: Low risk of bias = 3 or 4 stars in selection domain AND 1 or 2 stars in comparability domain AND 2 or 3 stars in outcome domain. Not low risk of bias = 2 stars in selection domain AND 1 or 2 stars in comparability domain AND 2 or 3 stars in outcome domain, or fewer stars across domains