Table 4

Risk of bias/quality assessment

Criteria (yes, no, cannot determine (CD), not applicable (NA) Perry23 Ortiz-Pinto24 Palmer25 Lane26
1.1. Was the research question or objective in this paper clearly stated?YesYesYesYes
2.2. Was the study population clearly specified and defined?NoYesYesYes
3.3. Was the participation rate of eligible persons at least 50%?YesYesCDYes
4.4. Were all the subjects 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?YesYesYesYes
5.5. Was a sample size justification, power description, or variance and effect estimates provided?NoNoNoNo
6.6. For the analyses in this paper, were the exposure(s) of interest measured prior to the outcome(s) being measured?YesYesYesYes
7.7. Was the timeframe sufficient so that one could reasonably expect to see an association between exposure and outcome if it existed?YesNoYesYes
8.8. 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)?YesYesYesYes
9.9. Were the exposure measures (independent variables) clearly defined, valid, reliable and implemented consistently across all study participants?NoYesYesYes
10.10. Was the exposure(s) assessed more than once over time?NoNoNoNo
11.11. Were the outcome measures (dependent variables) clearly defined, valid, reliable and implemented consistently across all study participants?YesNoYesYes
12.12. Were the outcome assessors blinded to the exposure status of participants?NANANANA
13.13. Was loss to follow-up after baseline 20% or less?YesCDYesCD
14.14. Were key potential confounding variables measured and adjusted statistically for their impact on the relationship between exposure(s) and outcome(s)?YesYesYesYes
NF rating (good, fair or poor)GoodFairGoodGood
MW rating (good, fair or poor)FairGoodGoodGood
Overall rating (good, fair or poor)FairFairGoodGood
Additional comments (if poor, state why)BMI measurement protocol lacked detailShort follow-up
No codes specified for identification of primary care events
Unable to determine loss to follow-up
Unable to determine participation rateUnable to determine loss to follow-up
  • BMI, body mass index; CD, cannot determine; NA, not applicable.