Table 1 Customized risk of bias assessment—risk of bias was categorized as high when < 49% requirements met, moderate when 50–75% requirements met, and low when > 75% requirements met
| Â | Question | Blair [46] | Braun [44] | Sidney [48] | Ceaser [47] | Finger [52] | Shmueli [50] | Fogelholm [43] | Lindgren [53] | Thai [49] | Dyrstad [42] | Cleland [51] | Lakka [41] | MacAuley [128] | Ittermann [45] | Shishebor [54] |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the research question clearly stated? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
1a | Were the correlates being investigated clearly stated? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
1b | Was the CRF outcome clearly stated? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
2 | Was the study population clearly defined? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
3 | Study participant selection | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
3a | Was a probability-based sampling strategy used? | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 0 |
3b | Was sampling frame at a national level? | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 |
3c | If participants were selected from clusters, were there ≥50 clusters? | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | NA | NR | 0 | 0 |
3d | Were inclusion and exclusion criteria pre-specified? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
4 | Was the sample size greater than 1200? | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 |
4a | Was sample size justification or power description provided? | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | NR | NR | 0 |
5 | Response rate | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
5a | Was response rate of eligible participants > 50%? | NA | 1 | 1 | 1 | 1 | NA | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | NA |
6 | Loss to follow-up in cohort studies | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
6a | Was loss to follow-up after baseline ≤20%? | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 0 | NA | NA | NA | NA |
7 | Were correlates of CRF and potential confounders objectively measured using validated instruments? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
7a | Were few exposure variables self-reported? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
7b | Was the outcome variable clearly defined, valid, reliable, and reliable? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
8 | Was CRF measured using an objective, reliable, and validated methodology? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
8a | Was CRF measured consistently for all participants? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 |
9 | Were the exposure variables measured prior to measurement of the outcome variables? | 1 | NR | NR | NR | 1 | NR | 1 | NR | 1 | NR | 0 | NR | NR | NR | 1 |
10 | Were key potential confounding variables measured and adjusted for statistically? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
11 | Did the study investigate interaction between exposure variables? | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
12 | Did analysis include sensitivity analysis? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 |
13 | Was funding source and/or conflicts of interest reported? | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 |
| Â | Final Assessment | 63% | 92% | 92% | 92% | 96% | 63% | 73% | 57% | 100% | 61% | 77% | 66% | 71% | 84% | 63% |
| Â | Risk of Bias Evaluation | Medium | Low | Low | Low | Low | Medium | Medium | Medium | Low | Medium | Low | Medium | Medium | Low | Medium |