Abstract
BackgroundSystematic reviews have shown uncertainty about the size or direction of any 'trial effect' for patients in trials compared to those treated outside trials. We are not aware of any systematic review of whether there is a 'trial effect' related to being treated by healthcare practitioners or institutions that take part in research.MethodsWe searched the Cochrane Methodology Register and MEDLINE (most recently in January 2009) for studies in which patients were allocated to treatment in one or other setting, and cohort studies reporting the outcomes of patients from different settings. We independently assessed study quality, including the control of bias in the generation of the comparison groups, and extracted data.ResultsWe retrieved and checked more than 15,000 records. Thirteen articles were eligible: five practitioner studies and eight institution studies. Meta-analyses were not possible because of heterogeneity. Two practitioner studies were judged to be 'controlled' or better. A Canadian study among nurses found that use of research evidence was higher for those who took part in research working groups and a Danish study on general practitioners found that trial doctors were more likely to prescribe in accordance with research evidence and guidelines. Five institution studies were 'controlled' but provided mixed results. A study of North American patients at hospitals that had taken part in trials for myocardial infarction found no statistically significant difference in treatment for patients in trial and non-trial hospitals. A Canadian study of myocardial infarction patients found that trial participants had better survival than patients in the same hospitals who were not in trials or those in non-trial hospitals. A study of general practices in Denmark did not detect differences in guideline adherence between trial and non-trial practices but found that trial practices were more likely to prescribe the trial sponsor's drugs. The other two 'controlled' studies of institutions found lower mortality in trial than non-trial hospitals.ConclusionsThe available findings from existing research suggest that there might be a 'trial effect' of better outcomes, greater adherence to guidelines and more use of evidence by practitioners and institutions that take part in trials. However, the consequences for patient health are uncertain and the most robust conclusion may be that there is no apparent evidence that patients treated by practitioners or in institutions that take part in trials do worse than those treated elsewhere.
Highlights
Systematic reviews have shown uncertainty about the size or direction of any ‘trial effect’ for patients in trials compared to those treated outside trials
We report here a systematic review of whether there is a trial effect at the level of healthcare practitioners or institutions
We set out to answer the question: do patients who are treated by practitioners or in institutions that take part in trials have different outcomes to patients treated elsewhere? The answer to this question is important to patients who might wish to use the evidence when making a choice about where they receive their health care and from whom, or who wish to use it as a guide to the quality of care they will receive
Summary
Systematic reviews have shown uncertainty about the size or direction of any ‘trial effect’ for patients in trials compared to those treated outside trials. It is important that policy makers and others involved in decisions about practitioners and institutions have access to evidence on possible relationships between the participation in research of practitioners or institutions and the outcomes of their non-trial patients. We examined this with research that has looked at health outcomes for patients, the uptake of evidence from research, and adherence to practice guidelines. This review was commissioned by the National Institute for Health Research, including an assessment of the effects on patients of their own participation in clinical trials, supplementing the work of Vist et al [1], but that is not reported here as it confirmed their findings
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