Article type
Year
Abstract
Background: Systematic reviews can inform the correct design of randomised controlled trials.
Objectives: We report the example of an open cluster randomised controlled trial (C-RCT). The trial assesses the effect on 252 general practitioners (GPs) of different strategies for the implementation of a guideline of non-complicated type 2 diabetes mellitus in the region of Lazio (Italy). Eighty four GPs have been randomised to either undergo a training module and administration of the guideline (arm 1), or administration of the guideline without training (arm 2), or to continue current practice (arm 3).
Methods: Through standard searches and personal contacts we identified three Cochrane EPOC and one systematic review of the evidence of the effects of various interventions to implement clinical guidelines.
Results: Three recurring errors in C-RCTs were identified by the reviews: Unit of analysis errors - when the unit of randomisation was the practitioner but the unit of analysis was the patient analysed independently of the cluster Baseline imbalance - when small arm denominators may cause imbalance between arms in important prognostic factors (e.g. baseline performance) Within group comparisons - when investigators undertake within groups analysis, rather than between groups. The reviews also reported possible non-specific effects on the control arms of C-RCTs which could hinder generalisability of results.
Conclusions: We included an analysis plan addressing the three common errors and decided to use routine data for outcome assessment, enabling measurement of any non-specific effects on arm 3 participants. Use of Cochrane and other systematic reviews and the Cochrane network for expertise-sharing is vital for correct protocol design.
Acknowledgments: Professor Jeremy Grimshaw
References: 1. Grimshaw JM, Thomas RE, Maclennan G et al. Effectiveness and Efficiency of Guideline Dissemination and Implementation Strategies. Health Technol Assess. 2004; Vol 8 No 6. 2. Thomson OBrien MA, Freemantle N, Oxman AD, Wolf F, Davis DA, Herrin J. Continuing education meetings and workshops: effects on professional practice and health care outcomes (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons Ltd. 3. Thomson OBrien MA, Oxman AD, Davis DA et al. Educational outreach visits: effects on professional practice and health care outcomes (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons Ltd. 4. Thomas L, Cullum N, McColl E et al. Guidelines in professions allied to medicine (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons Ltd.
Objectives: We report the example of an open cluster randomised controlled trial (C-RCT). The trial assesses the effect on 252 general practitioners (GPs) of different strategies for the implementation of a guideline of non-complicated type 2 diabetes mellitus in the region of Lazio (Italy). Eighty four GPs have been randomised to either undergo a training module and administration of the guideline (arm 1), or administration of the guideline without training (arm 2), or to continue current practice (arm 3).
Methods: Through standard searches and personal contacts we identified three Cochrane EPOC and one systematic review of the evidence of the effects of various interventions to implement clinical guidelines.
Results: Three recurring errors in C-RCTs were identified by the reviews: Unit of analysis errors - when the unit of randomisation was the practitioner but the unit of analysis was the patient analysed independently of the cluster Baseline imbalance - when small arm denominators may cause imbalance between arms in important prognostic factors (e.g. baseline performance) Within group comparisons - when investigators undertake within groups analysis, rather than between groups. The reviews also reported possible non-specific effects on the control arms of C-RCTs which could hinder generalisability of results.
Conclusions: We included an analysis plan addressing the three common errors and decided to use routine data for outcome assessment, enabling measurement of any non-specific effects on arm 3 participants. Use of Cochrane and other systematic reviews and the Cochrane network for expertise-sharing is vital for correct protocol design.
Acknowledgments: Professor Jeremy Grimshaw
References: 1. Grimshaw JM, Thomas RE, Maclennan G et al. Effectiveness and Efficiency of Guideline Dissemination and Implementation Strategies. Health Technol Assess. 2004; Vol 8 No 6. 2. Thomson OBrien MA, Freemantle N, Oxman AD, Wolf F, Davis DA, Herrin J. Continuing education meetings and workshops: effects on professional practice and health care outcomes (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons Ltd. 3. Thomson OBrien MA, Oxman AD, Davis DA et al. Educational outreach visits: effects on professional practice and health care outcomes (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons Ltd. 4. Thomas L, Cullum N, McColl E et al. Guidelines in professions allied to medicine (Cochrane Review). In: The Cochrane Library, Issue 1, 2004. Chichester, UK: John Wiley & Sons Ltd.