J. Mark Elwood
This book presents a logical system of critical appraisal, to allow readers to evaluate studies and to carry out their own studies more effectively. This system emphasizes the central importance of cause and effect relationships. Its great strength is that it is applicable to a wide range of
issues, and both to intervention trials and observational studies.
This system unifies the often different approaches used in epidemiology, health services research, clinical trials, and evidence-based medicine, starting from a logical consideration of cause and effect. The author's
approach to the issues of study design, selection of subjects, bias, confounding, and the place of statistical methods has been praised for its clarity and interest. Systematic reviews, meta-analysis, and the applications of this logic to evidence-based medicine, knowledge-based health care, and
health practice and policy are discussed. Current and often controversial examples are used, including screening for prostate cancer, publication bias in psychiatry, public health issues in developing countries, and conflicts between observational studies and randomized trials. Statistical issues
are explained clearly without complex mathematics, and the most useful methods are summarized in the appendix.
The final chapters give six applications of the critical appraisal of major studies: randomized trials of medical treatment and prevention, a prospective and a retrospective cohort
study, a small matched case-control study, and a large case-control study. In these chapters, sections of the original papers are reproduced and the original studies placed in context by a summary of current developments.
1. The importance of causal relationships in medicine and health care
2. Study designs which can demonstrate and test causation
3. The results obtained from studies of causation
4. Selection of subjects for study
5. Error and bias in observations
8. Combining results from several studies: systematic review and meta-analysis
9. The diagnosis of causation
Critical appraisal in action - introduction to Chapters 10 to 15
10. Critical appraisal of a randomized clinical trial
11. Critical appraisal of a randomized
trial of a preventive agent
12. Critical appraisal of a prospective cohort study
13. Critical appraisal of a retrospective cohort study
14. Critical appraisal of a matched case-control study
15. Critical appraisal of a large, population based, case-control study
Answers to self
Appendix: Methods of statistical analysis: formulae and worked examples
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Mark Elwood is an epidemiologist with particular interests in cancer prevention, screening, and evidence-based medicine. He has worked in three continents and trained in Belfast, in Ottawa and at Harvard. He has recently returned to the British Columbia Cancer Agency, Vancouver, where he was
the first Head of Epidemiology. He has been Professor of Epidemiology and Community Medicine at the University of Nottingham, UK and Director of the National Cancer Control Initiative in Australia. His research has focused on the prevention and early diagnosis of cancers and birth defects, the
evaluation of clinical and public health interventions, and the evaluation of environmental hazards. Professor Elwood is the author of several books and over 250 scientific papers.