Table 1.
Author, year | Selection of participants | Classification of exposure | Classification of missing data | Bias in measurement of outcomes | Bias in selection of reported result | Total |
---|---|---|---|---|---|---|
Case–control studies | ||||||
Motzkus-Feagans et al, 201119 | 3 | 2 | 4 | 3 | n/a | 12 |
Naggie et al, 201124 | 3 | 2 | 4 | 3 | n/a | 12 |
Nseir et al, 201325 | 2 | 2 | 3 | 3 | n/a | 10 |
Elashery et al, 201427 | 1 | 2 | 3 | 2 | n/a | 8 |
Kumarappa et al, 201226 | 2 | 1 | 3 | 1 | n/a | 7 |
Ewelukwa et al, 201429 | 1 | 1 | 3 | 2 | n/a | 7 |
Cohort studies | ||||||
McGuire et al, 200918 | 1 | 1 | 3 | 2 | n/a | 7 |
Tartof et al, 201528 | 2 | 2 | 3 | 3 | n/a | 10 |
- • Bias in selection of participants into the study
- • Was selection of participants into the study (or into the analysis) based on participant characteristics observed after the start of intervention?
- • Do start of follow-up and start of intervention coincide for most participants?
- • Were adjustment techniques used that are likely to correct for the presence of selection biases?
- • Bias in classification of intervention/exposure
- • Were intervention/exposure groups clearly defined?
- • Was the information used to define intervention/exposure group recorded at the start of the intervention/exposure?
- • Could classification of intervention/exposure status have been affected by knowledge of the outcome or risk of the outcome?
- • Bias due to missing data
- • Were outcome data available for all, or nearly all, participants?
- • Were no participants excluded due to missing data on intervention status?
- • Were participants excluded due to missing data on any variables that was required for analysis?
- • Are the proportion of participants and reasons for missing data similar across interventions?
- • Is there evidence that results were robust due to the presence of missing data?
- • Bias in measurement of outcomes
- • Could the outcome measure have been influenced by knowledge of the intervention/exposure received?
- • Were outcome assessors aware of the intervention/exposure received by study participants?
- • Were the methods of outcome assessment comparable across intervention/exposure groups?
- • Were any systematic errors in measurement of the outcome related to intervention/exposure received?
- • Bias in measurement of outcomes
- • Is the reported effect estimate likely to be selected, on the basis of the results, from multiple outcome “measurements” within the outcome domain?
- • Is the reported effect estimate likely to be selected, on the basis of the results, from multiple “analyses” of the intervention–outcome relationship?
- • Is the reported effect estimate likely to be selected, on the basis of the results, from different “subgroups”?
Abbreviation: n/a, not available.