Study protocol
Looking inside the black box: a theory-based process evaluation alongside a randomised controlled trial of printed educational materials (the Ontario printed educational message, OPEM) to improve referral and prescribing practices in primary care in Ontario, Canada
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* Corresponding author: Jeremy M Grimshaw jgrimshaw@ohri.ca
- † Equal contributors
1 Clinical Epidemiology Program, Ottawa Health Research Institute, Ottawa, Canada
2 Institute of Population Health, University of Ottawa, Ottawa, Canada
3 Institute of Clinical Evaluative Sciences, Toronto, Canada
4 KT Program, University of Toronto, Canada
5 School of Nursing, University of Laval, Quebec City, Canada
6 School of Nursing, University of Ottawa, Ottawa, Canada
7 School of Psychology, University of Ottawa, Ottawa, Canada
8 Centre for Health Services Research, University of Newcastle upon Tyne, Newcastle upon Tyne, UK
9 Department of Psychology, University of Aberdeen, Aberdeen, UK
10 Health Services Research Unit, University of Aberdeen, UK
11 Department of Family Medicine, University of Laval, Quebec City, Canada
12 Canadian Institute of Health Research, Ottawa, Canada
Implementation Science 2007, 2:38 doi:10.1186/1748-5908-2-38
Published: 26 November 2007Abstract
Background
Randomised controlled trials of implementation strategies tell us whether (or not) an intervention results in changes in professional behaviour but little about the causal mechanisms that produce any change. Theory-based process evaluations collect data on theoretical constructs alongside randomised trials to explore possible causal mechanisms and effect modifiers. This is similar to measuring intermediate endpoints in clinical trials to further understand the biological basis of any observed effects (for example, measuring lipid profiles alongside trials of lipid lowering drugs where the primary endpoint could be reduction in vascular related deaths).
This study protocol describes a theory-based process evaluation alongside the Ontario Printed Educational Message (OPEM) trial. We hypothesize that the OPEM interventions are most likely to operate through changes in physicians' behavioural intentions due to improved attitudes or subjective norms with little or no change in perceived behavioural control. We will test this hypothesis using a well-validated social cognition model, the theory of planned behaviour (TPB) that incorporates these constructs.
Methods/design
We will develop theory-based surveys using standard methods based upon the TPB for the second and third replications, and survey a subsample of Ontario family physicians from each arm of the trial two months before and six months after the dissemination of the index edition of informed, the evidence based newsletter used for the interventions. In the third replication, our study will converge with the "TRY-ME" protocol (a second study conducted alongside the OPEM trial), in which the content of educational messages was constructed using both standard methods and methods informed by psychological theory. We will modify Dillman's total design method to maximise response rates. Preliminary analyses will initially assess the internal reliability of the measures and use regression to explore the relationships between predictor and dependent variable (intention to advise diabetic patients to have annual retinopathy screening and to prescribe thiazide diuretics for first line treatment of uncomplicated hypertension). We will then compare groups using methods appropriate for comparing independent samples to determine whether there have been changes in the predicted constructs (attitudes, subjective norms, or intentions) across the study groups as hypothesised, and will assess the convergence between the process evaluation results and the main trial results.
Trial registration number
Current controlled trial ISRCTN72772651