Articles | Health Evidence Bulletins - Wales: Questions to assist with the critical appraisal of an observational study eg cohort, case-control, cross-sectional. (Type IV evidence) | Ballestas [27] | Bandaranaike [30] | Blatchford [28] | Connors [29] | Radowski [31] | Townsend [32] | |
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A. What is this paper about? | 1. Is the study relevant to the needs of the project? | Y | Y | Y | Y | Y | Y | |
2. Does the paper address a clearly focussed issue in terms of: | The population studied? | Y | Y | Y | Y | Y | Y | |
(Case-control only) Is the case definition explicit and confirmed? | na | na | na | na | na | na | ||
The outcomes considered? | Y | Y | Y | Y | Y | Y | ||
Are the aims of the investigation clearly stated? | Y | Y | Y | Y | Y | Y | ||
B. Do I trust it? | 3. Is the choice of study method appropriate? | Y | Y | Y | Y | Y | Y | |
4. Is the population studied appropriate? | (Cohort study) Was an appropriate control group used – i.e. were the groups comparable (Case-control study) Were the controls randomly selected from the same population as the cases? | N | N | N | N | N | N | |
5. Is confounding and bias considered? | Have all possible explanations of the effects been considered? | N | N | Y | Y | Y | Y | |
(Cohort study) Were the assessors blind to the different groups? | na | na | na | na | na | na | ||
(Cohort study) Could selective drop-out explain the effect? | Y | Y | N | N | N | N | ||
(Case-control study) How comparable are the cases and controls with respect to confounding factors? | na | na | na | na | na | na | ||
(Case-control study) Were interventions and other exposures assessed in the same way for cases and controls? | na | na | na | na | na | na | ||
(Case-control study) Is it possible that overmatching has occurred in that cases and controls were matched on factors related to exposure? | na | na | na | na | na | na | ||
6. (Cohort study)Was follow up for long enough | Could all likely effects have appeared in the time frame? | Y | N | Y | N | N | Y | |
Could the effects be transitory? | N | Y | N | Y | Y | Y | ||
Was follow up sufficiently complete? | N | N | Y | N | N | N | ||
Was dose response shown? | na | na | na | na | na | na | ||
C. What did they find? | 7. Are tables/graphs labelled and understandable? | na | Y | Y | na | na | Y | |
8. Are you confident with the author’s choice and use of statistical methods, if employed? | na | na | Y | na | na | Y | ||
9. What are the results of this piece of research? Are the author’s conclusions adequately supported by information cited? | Y | N | Y | N | N | Y | ||
D. Are the results relevant locally? | 10. Can the results be applied to the local situation? Consider differences between the local and study populations which could affect the relevance of the study | Y | N | Y | N | Y | Y | |
11. Were all important outcomes/results considered? | N | N | Y | N | N | Y | ||
12. Is any cost information provided? | N | N | N | N | N | N | ||
13. Accept for use as further Type IV evidence? | Y | Y | Y | Y | Y | Y |