Specifying the target difference in the primary outcome for a randomised controlled trial: guidance for researchers.

Autor: Cook JA; Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK. jonathan.cook@ndorms.ox.ac.uk.; Health Services Research Unit, University of Aberdeen, Health Sciences Building, Foresthill, Aberdeen, AB25 2ZD, UK. jonathan.cook@ndorms.ox.ac.uk., Hislop J; Institute of Health and Society, Newcastle University, The Baddiley-Clark Building, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK. jenni.hislop@newcastle.ac.uk., Altman DG; Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Nuffield Orthopaedic Centre, Windmill Road, Oxford, OX3 7LD, UK. doug.altman@csm.ox.ac.uk., Fayers P; Population Health, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen, AB25 2ZD, UK. p.fayers@abdn.ac.uk.; Department of Cancer Research and Molecular, Norwegian University of Science and Technology, Mailbox 8905, Trondheim, N-7491, Norway. p.fayers@abdn.ac.uk., Briggs AH; Health Economics and Health Technology Assessment, University of Glasgow, 1 Lilybank Gardens, Glasgow, G12 8RZ, UK. Andrew.briggs@glasgow.ac.uk., Ramsay CR; Health Services Research Unit, University of Aberdeen, Health Sciences Building, Foresthill, Aberdeen, AB25 2ZD, UK. c.r.ramsay@abdn.ac.uk., Norrie JD; Centre for Healthcare Randomised Trials (CHaRT), University of Aberdeen, Health Sciences Building, Aberdeen, AB25 2ZD, UK. j.norrie@abdn.ac.uk., Harvey IM; Faculty of Medicine and Health Sciences, University of East Anglia, Elizabeth Fry Building, Norwich Research Park, Norwich, NR4 7TJ, UK. Ian.harvey@uea.ac.uk., Buckley B; National University of Ireland, University Road, Galway, Ireland. briansbuckley@gmail.com., Fergusson D; Clinical Epidemiology Program, Ottawa Hospital Research Institute, 725 Parkdale Avenue, Ottawa, ON, K1Y 4E9, Canada. dafergusson@ohri.ca., Ford I; Robertson Centre for Biostatistics, University of Glasgow, Boyd Orr Building, University Avenue, Glasgow, G12 8QQ, UK. ian.ford@glasgow.ac.uk., Vale LD; Institute of Health and Society, Newcastle University, The Baddiley-Clark Building, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK. luke.vale@newcastle.ac.uk.
Jazyk: angličtina
Zdroj: Trials [Trials] 2015 Jan 15; Vol. 16, pp. 12. Date of Electronic Publication: 2015 Jan 15.
DOI: 10.1186/s13063-014-0526-8
Abstrakt: Background: Central to the design of a randomised controlled trial is the calculation of the number of participants needed. This is typically achieved by specifying a target difference and calculating the corresponding sample size, which provides reassurance that the trial will have the required statistical power (at the planned statistical significance level) to identify whether a difference of a particular magnitude exists. Beyond pure statistical or scientific concerns, it is ethically imperative that an appropriate number of participants should be recruited. Despite the critical role of the target difference for the primary outcome in the design of randomised controlled trials, its determination has received surprisingly little attention. This article provides guidance on the specification of the target difference for the primary outcome in a sample size calculation for a two parallel group randomised controlled trial with a superiority question.
Methods: This work was part of the DELTA (Difference ELicitation in TriAls) project. Draft guidance was developed by the project steering and advisory groups utilising the results of the systematic review and surveys. Findings were circulated and presented to members of the combined group at a face-to-face meeting, along with a proposed outline of the guidance document structure, containing recommendations and reporting items for a trial protocol and report. The guidance and was subsequently drafted and circulated for further comment before finalisation.
Results: Guidance on specification of a target difference in the primary outcome for a two group parallel randomised controlled trial was produced. Additionally, a list of reporting items for protocols and trial reports was generated.
Conclusions: Specification of the target difference for the primary outcome is a key component of a randomized controlled trial sample size calculation. There is a need for better justification of the target difference and reporting of its specification.
Databáze: MEDLINE
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