Title |
Pragmatic controlled clinical trials in primary care: the struggle between external and internal validity
|
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Published in |
BMC Medical Research Methodology, December 2003
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DOI | 10.1186/1471-2288-3-28 |
Pubmed ID | |
Authors |
Marshall Godwin, Lucia Ruhland, Ian Casson, Susan MacDonald, Dianne Delva, Richard Birtwhistle, Miu Lam, Rachelle Seguin |
Abstract |
Controlled clinical trials of health care interventions are either explanatory or pragmatic. Explanatory trials test whether an intervention is efficacious; that is, whether it can have a beneficial effect in an ideal situation. Pragmatic trials measure effectiveness; they measure the degree of beneficial effect in real clinical practice. In pragmatic trials, a balance between external validity (generalizability of the results) and internal validity (reliability or accuracy of the results) needs to be achieved. The explanatory trial seeks to maximize the internal validity by assuring rigorous control of all variables other than the intervention. The pragmatic trial seeks to maximize external validity to ensure that the results can be generalized. However the danger of pragmatic trials is that internal validity may be overly compromised in the effort to ensure generalizability. We are conducting two pragmatic randomized controlled trials on interventions in the management of hypertension in primary care. We describe the design of the trials and the steps taken to deal with the competing demands of external and internal validity. |
X Demographics
Geographical breakdown
Country | Count | As % |
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United States | 1 | 17% |
Sweden | 1 | 17% |
United Kingdom | 1 | 17% |
Unknown | 3 | 50% |
Demographic breakdown
Type | Count | As % |
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Members of the public | 4 | 67% |
Scientists | 2 | 33% |
Mendeley readers
Geographical breakdown
Country | Count | As % |
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United States | 8 | 2% |
United Kingdom | 5 | 1% |
Brazil | 3 | <1% |
Netherlands | 2 | <1% |
Spain | 2 | <1% |
France | 1 | <1% |
Austria | 1 | <1% |
Tanzania, United Republic of | 1 | <1% |
Colombia | 1 | <1% |
Other | 7 | 2% |
Unknown | 404 | 93% |
Demographic breakdown
Readers by professional status | Count | As % |
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Student > Master | 82 | 19% |
Researcher | 63 | 14% |
Student > Ph. D. Student | 63 | 14% |
Student > Postgraduate | 29 | 7% |
Student > Bachelor | 28 | 6% |
Other | 108 | 25% |
Unknown | 62 | 14% |
Readers by discipline | Count | As % |
---|---|---|
Medicine and Dentistry | 160 | 37% |
Nursing and Health Professions | 46 | 11% |
Social Sciences | 35 | 8% |
Psychology | 27 | 6% |
Agricultural and Biological Sciences | 21 | 5% |
Other | 64 | 15% |
Unknown | 82 | 19% |