Results for the quality assessment with Quality Assessment Tool or Observational Cohort and Cross-sectional Studies
| Criteria/included studies | Kulund et al23 | Calhoon and Fry17 | Junge et al10 | Jonasson et al19 | Engebretsen et al18 | Brown and Kimball16 | Keogh et al20 | Siewe et al22 | Raske and Norlin21 |
|---|---|---|---|---|---|---|---|---|---|
| 1. Was the research question or objective in this paper clearly stated? | N | Y | Y | Y | Y | Y | Y | Y | Y |
| 2. Was the study population clearly specified and defined? | N | N | Y | Y | Y | Y | Y | Y | Y |
| 3. Was the participation rate of eligible persons at least 50%? | CD | CD | Y | Y | Y | Y | Y | CD | Y |
| 4. Were all the individuals selected or recruited from the same or similar populations (including the same time period)? Were inclusion and exclusion criteria for being in the study prespecified and applied uniformly to all participants? | CD | Y | N | Y | N | N | N | N | N |
| 5. Was a sample size justification, power description, or variance and effect estimates provided? | N | N | N | N | N | N | N | N | N |
| 6. For the analyses in this paper, were the exposure(s) of interest measured prior to the outcome(s) being measured? | N | N | N | N | N | N | N | N | N |
| 7. Was the timeframe sufficient so that one could reasonably expect to see an association between exposure and outcome if it existed? | N | N | N | N | N | N | N | N | N |
| 8. For exposures that can vary in amount or level, did the study examine different levels of the exposure as related to the outcome (eg, categories of exposure, or exposure measured as continuous variable)? | N | N | N | N | N | N | Y | Y | Y |
| 9. Were the exposure measures (independent variables) clearly defined, valid, reliable and implemented consistently across all study participants? | N | N | N | N | N | N | Y | N | N |
| 10. Was the exposure(s) assessed more than once over time? | N | N | N | N | N | N | N | N | Y |
| 11. Were the outcome measures (dependent variables) clearly defined, valid, reliable and implemented consistently across all study participants? | N | Y | Y | N | Y | N | Y | N | N |
| 12. Were the outcome assessors blinded to the exposure status of participants? | NA | NA | N | NA | N | NA | NA | NA | N |
| 13. Was loss to follow-up after baseline 20% or less? | NA | NA | CD | NA | CD | NA | NA | NA | N |
| 14. Were key potential confounding variables measured and adjusted statistically for their impact on the relationship between exposure(s) and outcome(s)? | N | N | N | N | N | N | N | N | N |
| Quality rating | Poor | Poor | Fair | Fair | Fair | Poor | Good | Poor | Fair |
CD, Cannot determine; N, No; NA, not applicable; Y, Yes.