Search for evidence of effective health promotionBMJ 1998; 316 doi: http://dx.doi.org/10.1136/bmj.316.7132.703a (Published 28 February 1998) Cite this as: BMJ 1998;316:703
Quantitative outcome evaluation with qualitative process evaluation is best
- Annie Britton, Research fellow,
- Margaret Thorogood, Reader,
- Yolande Coombes, Lecturer,
- Gillian Lewando-Hundt, Senior lecturer
- Health Promotion Research Unit, London School of Hygiene and Tropical Medicine, London WC1E 7HT
- NHS Centre for Reviews and Dissemination, University of York, York YO1 5DD
EDITOR—Non-randomised studies are currently regarded as inferior, if not worthless, and Speller et al are right to question whether randomised controlled trials are always the best or most appropriate method of evaluating health promotion.1 Evaluation entails quantifying worth: wellbeing is an important asset but is difficult to quantify and hence to evaluate. It is important to distinguish between “not effective” and “not evaluable.”
Attribution of the effects of an intervention (and the relative costs involved) is the goal of evaluation. An insistence on randomised controlled trials ignores some of the unique features of health promotion: interventions often take place at a community or national level, the expected proportional benefits to individuals are small, and beneficial outcomes are delayed.2 Potential contamination and confounding mean that attribution can rarely be a certainty, and even when it can be, replication is limited.
The external validity of randomised controlled trials of preventive interventions is questionable. Patients who agree to participate in such trials tend to be affluent and better educated and to …
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