scholarly journals DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial

BMJ ◽  
2018 ◽  
pp. k3750 ◽  
Author(s):  
Jonathan A Cook ◽  
Steven A Julious ◽  
William Sones ◽  
Lisa V Hampson ◽  
Catherine Hewitt ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Controlled Trial ◽  
Sample Size Calculation ◽  
Target Difference ◽  
Randomised Controlled

scholarly journals DELTA2 guidance on choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial

Trials ◽  
2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Jonathan A. Cook ◽  
Steven A. Julious ◽  
William Sones ◽  
Lisa V. Hampson ◽  
Catherine Hewitt ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Controlled Trial ◽  
Sample Size Calculation ◽  
Target Difference ◽  
Randomised Controlled

scholarly journals Correction to: Choosing the target difference and undertaking and reporting the sample size calculation for a randomised controlled trial – the development of the DELTA2 guidance

Trials ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
William Sones ◽  
Steven A. Julious ◽  
Joanne C. Rothwell ◽  
Craig Robert Ramsay ◽  
Lisa V. Hampson ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Controlled Trial ◽  
Sample Size Calculation ◽  
Target Difference ◽  
Randomised Controlled

Following publication of the original article [1], we have been notified of a few mistakes:

scholarly journals Choosing the Target Difference (“effect size”) for a Randomised Controlled Trial - DELTA2 Guidance

2018 ◽  
Author(s):  
Jonathan A. Cook ◽  
Steven A. Julious ◽  
William Sones ◽  
Lisa V. Hampson ◽  
Catherine Hewitt ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Controlled Trial ◽  
Sample Size Calculation ◽  
Main Body ◽  
Target Difference ◽  
Superiority Trial ◽  
The Difference ◽  
The One ◽  
Randomised Controlled

The aim of this document is to provide practical guidance on the choice of target difference used in the sample size calculation of a randomised controlled trial (RCT). Guidance is provided with a definitive trial, one that seeks to provide a useful answer, in mind and not those of a more exploratory nature. The term “target difference” is taken throughout to refer to the difference that is used in the sample size calculation (the one that the study formally “targets”). Please see the glossary for definitions and clarification with regards other relevant concepts. In order to address the specification of the target difference, it is appropriate, and to some degree necessary, to touch on related statistical aspects of conducting a sample size calculation. Generally the discussion of other aspects and more technical details is kept to a minimum, with more technical aspects covered in the appendices and referencing of relevant sources provided for further reading.The main body of this guidance assumes a standard RCT design is used; formally, this can be described as a two-arm parallel-group superiority trial. Most RCTs test for superiority of the interventions, that is, whether or not one of the interventions is superior to the other (See Box 1 for a formal definition of superiority, and of the two most common alternative approaches). Some common alternative trial designs are considered in Appendix 3. Additionally, it is assumed in the main body of the text that the conventional (Neyman-Pearson) approach to the sample size calculation of an RCT is being used. Other approaches (Bayesian, precision and value of information) are briefly considered in Appendix 2 with reference to the specification of the target difference.

scholarly journals Practical help for specifying the target difference in sample size calculations for RCTs: the DELTA2 five-stage study, including a workshop

2019 ◽  
Vol 23 (60) ◽  
pp. 1-88 ◽  
Author(s):  
Jonathan A Cook ◽  
Steven A Julious ◽  
William Sones ◽  
Lisa V Hampson ◽  
Catherine Hewitt ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Health Research ◽  
Controlled Trial ◽  
Sample Size Calculation ◽  
Conventional Approach ◽  
Target Difference ◽  
Sample Size Calculations ◽  
The Difference ◽  
Randomised Controlled

Background The randomised controlled trial is widely considered to be the gold standard study for comparing the effectiveness of health interventions. Central to its design is a calculation of the number of participants needed (the sample size) for the trial. The sample size is typically calculated by specifying the magnitude of the difference in the primary outcome between the intervention effects for the population of interest. This difference is called the ‘target difference’ and should be appropriate for the principal estimand of interest and determined by the primary aim of the study. The target difference between treatments should be considered realistic and/or important by one or more key stakeholder groups. Objective The objective of the report is to provide practical help on the choice of target difference used in the sample size calculation for a randomised controlled trial for researchers and funder representatives. Methods The Difference ELicitation in TriAls2 (DELTA2) recommendations and advice were developed through a five-stage process, which included two literature reviews of existing funder guidance and recent methodological literature; a Delphi process to engage with a wider group of stakeholders; a 2-day workshop; and finalising the core document. Results Advice is provided for definitive trials (Phase III/IV studies). Methods for choosing the target difference are reviewed. To aid those new to the topic, and to encourage better practice, 10 recommendations are made regarding choosing the target difference and undertaking a sample size calculation. Recommended reporting items for trial proposal, protocols and results papers under the conventional approach are also provided. Case studies reflecting different trial designs and covering different conditions are provided. Alternative trial designs and methods for choosing the sample size are also briefly considered. Conclusions Choosing an appropriate sample size is crucial if a study is to inform clinical practice. The number of patients recruited into the trial needs to be sufficient to answer the objectives; however, the number should not be higher than necessary to avoid unnecessary burden on patients and wasting precious resources. The choice of the target difference is a key part of this process under the conventional approach to sample size calculations. This document provides advice and recommendations to improve practice and reporting regarding this aspect of trial design. Future work could extend the work to address other less common approaches to the sample size calculations, particularly in terms of appropriate reporting items. Funding Funded by the Medical Research Council (MRC) UK and the National Institute for Health Research as part of the MRC–National Institute for Health Research Methodology Research programme.

scholarly journals Use of methods for specifying the target difference in randomised controlled trial sample size calculations: Two surveys of trialists’ practice

2014 ◽  
Vol 11 (3) ◽  
pp. 300-308 ◽  
Author(s):  
Jonathan A Cook ◽  
Jennifer M Hislop ◽  
Doug G Altman ◽  
Andrew H Briggs ◽  
Peter M Fayers ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Controlled Trial ◽  
Target Difference ◽  
Sample Size Calculations ◽  
Randomised Controlled

scholarly journals The effect of alcohol strength on alcohol consumption: findings from a randomised controlled cross-over pilot trial.

2021 ◽  
Author(s):  
Parvati Rose Perman-Howe ◽  
Emma L Davies ◽  
David R Foxcroft
Keyword(s):  
Randomised Controlled Trial ◽  
Alcohol Consumption ◽  
Sample Size ◽  
Study Protocol ◽  
Controlled Trial ◽  
Pilot Trial ◽  
Recruitment Rate ◽  
Participant Recruitment ◽  
Licensed Premises ◽  
Randomised Controlled

Abstract Background Reducing the alcohol content of drinks has the potential to reduce alcohol consumption. Aims: (1) test the feasibility of a randomised controlled trial (RCT) to assess the effect of alcohol strength on alcohol consumption within licensed premises in the United Kingdom (UK), (2) provide data to estimate key parameters for a RCT. Methods Double-blind randomised controlled cross-over pilot trial based within four licensed premises in the UK. Participants (n=36) purchased and consumed ad libitum a 3.5% lager and a 4.8% lager during two separate study sessions. Descriptive statistics reported the efficacy and efficiency of the study processes, and the rates of licensed premises recruitment, and participant recruitment and attrition. Mean and the 95% confidence interval (CI) compared alcohol consumption between conditions. The mean, standard deviation (SD) and CI of UK units of alcohol consumed were used to calculate a sample size for a RCT. Responses to participant questionnaires and duration of participation in study sessions between conditions were analysed.Results Components of the study protocol were effective and efficient. The venue recruitment rate was less than anticipated. The participant recruitment rate was greater than anticipated. The rate of attrition was 23% and varied by less than 1% according to the arm of the trial. There was a reduction of alcohol consumed under the intervention conditions. Estimated mean difference, and 95% CI (UK units): -3.76 (-5.01 to -2.52).The sample size required for a RCT is 53. Participants did not find one lager more pleasant in taste: (on a scale of one to 10) -0.95 (-2.11 to 0.21). Participants found the reduced-strength lager less enjoyable: (on a scale of one to 10) -1.44 (-2.64 to -0.24) and they perceived themselves to be less intoxicated after consuming it: (on a scale of one to 10) -1.00 (-1.61 to -0.40).Conclusion A RCT is feasible with minor alterations to the study protocol and scoping work to establish different brands of alcohol that are more alike and more enjoyable than the products used in the pilot trial. Trial registration Registered in the American Economic Association (AEA) Randomised Controlled Trial (RCT) Registry as of 16 June 2017: https://www.socialscienceregistry.org/trials/2266. Unique identifying number: AEARCTR-0002266.

scholarly journals Effects of priming intermittent theta burst stimulation on upper limb motor recovery after stroke: study protocol for a proof-of-concept randomised controlled trial

BMJ Open ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. e035348
Author(s):  
Jack Jiaqi Zhang ◽  
Kenneth N K Fong
Keyword(s):  
Randomised Controlled Trial ◽  
Upper Limb ◽  
Primary Motor Cortex ◽  
Controlled Trial ◽  
Sample Size Calculation ◽  
Facilitatory Effect ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
Randomised Controlled ◽  
Theta Burst

IntroductionIntermittent theta burst stimulation (iTBS), a form of repetitive transcranial magnetic stimulation (rTMS), delivered to the ipsilesional primary motor cortex (M1), appears to enhance the brain’s response to rehabilitative training in patients with stroke. However, its clinical utility is highly subject to variability in different protocols. New evidence has reported that preceding iTBS, with continuous theta burst stimulation (cTBS) may stabilise and even boost the facilitatory effect of iTBS on the stimulated M1, via metaplasticity. The aim of this study is to investigate the effects of iTBS primed with cTBS (ie, priming iTBS), in addition to robot-assisted training (RAT), on the improvement of the hemiparetic upper limb functions of stroke patients and to explore potential sensorimotor neuroplasticity using electroencephalography (EEG).Methods and analysisA three-arm, subjects and assessors-blinded, randomised controlled trial will be performed with patients with chronic stroke. An estimated sample of 36 patients will be needed based on the prior sample size calculation. All participants will be randomly allocated to receive 10 sessions of rTMS with different TBS protocols (cTBS+iTBS, sham cTBS+iTBS and sham cTBS+sham iTBS), three to five sessions per week, for 2–3 weeks. All participants will receive 60 min of RAT after each stimulation session. Primary outcomes will be assessed using Fugl-Meyer Assessment-Upper Extremity scores and Action Research Arm Test. Secondary outcomes will be assessed using kinematic outcomes generated during RAT and EEG.Ethics and disseminationEthical approval has been obtained from The Human Subjects Ethics Sub-committee, University Research Committee of The Hong Kong Polytechnic University (reference number: HSEARS20190718003). The results yielded from this study will be presented at international conferences and sent to a peer-review journal to be considered for publication.Trial registration numberNCT04034069.

scholarly journals A Randomised Controlled Trial Comparing the Effect of E-learning, with a Taught Workshop, on the Knowledge and Search Skills of Health Professionals

2006 ◽  
Vol 1 (3) ◽  
pp. 44 ◽  
Author(s):  
Nicola Pearce-Smith
Keyword(s):  
Randomised Controlled Trial ◽  
Sample Size ◽  
Health Professionals ◽  
Search Strategy ◽  
Small Sample Size ◽  
Controlled Trial ◽  
Small Sample ◽  
Post Intervention ◽  
E Learning ◽  
Randomised Controlled

Objective - The aim of the trial was to establish whether there is a significant difference in terms of knowledge and skills, between self-directed learning using a web-based resource, compared with a classroom based interactive workshop, for teaching health professionals how to search. The outcomes measured were knowledge of databases and study designs, and search skills. Methods - The study design was a randomised controlled trial (RCT). 17 health professionals were randomised into one of two groups – one group (EG) received access to a search-skills web resource, and the other group received a search workshop (WG) taught by a librarian. Participants completed pre- and post-intervention tests involving multiple choice questions and practical searching using clinical scenarios.. Results - 9 WG and 6 EG participants completed both pre-and post-intervention tests. The test results were blindly marked using a score chart developed with two other librarians. For question formulation and devising a search strategy, all participants obtained a score that was the same or better after receiving the intervention (both WG and EG), but statistical analysis showed that the only significant outcomes were for the WG devising a search strategy (p=0.01) and preferring to search using MeSH after receiving the taught workshop (p=0.02). The Mann-Whitney test showed there were no significant differences in any of the outcomes (p>0.05), between the WG and the EG. The statistical analyses must be viewed with caution due to the small sample size. Conclusions - There were no significant differences in knowledge of databases and study design, or search skills, when the WG and the EG were compared. Although many participants obtained a score that was higher post-intervention, only devising a search strategy and preferring to search using MeSH were significant for the WG. The question of whether a taught workshop and an e-learning module are of equal effectiveness in teaching search skills, is an important one for health librarians involved in user education, and was a justifiable topic to propose and conduct research. The fact that the results are mainly inconclusive due to the small sample size is disappointing, but does not diminish the importance of conducting the study.

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

Trials ◽  
2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Jonathan A Cook ◽  
◽  
Jenni Hislop ◽  
Douglas G Altman ◽  
Peter Fayers ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Primary Outcome ◽  
Controlled Trial ◽  
Target Difference ◽  
Randomised Controlled
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