Abstract
BackgroundA key aspect of the design of randomised controlled trials (RCTs) is determining the sample size. It is important that the trial sample size is appropriately calculated. The required sample size will differ by clinical area, for instance, due to the prevalence of the condition and the choice of primary outcome. Additionally, it will depend upon the choice of target difference assumed in the calculation. Focussing upon the hip and knee osteoarthritis population, this study aims to systematically review how the trial size was determined for trials of osteoarthritis, on what basis, and how well these aspects are reported.MethodsSeveral electronic databases (Medline, Cochrane library, CINAHL, EMBASE, PsycINFO, PEDro and AMED) will be searched to identify articles on RCTs of hip and knee osteoarthritis published in 2016. Articles will be screened for eligibility and data extracted independently by two reviewers. Data will be extracted on study characteristics (design, population, intervention and control treatments), primary outcome, chosen sample size and justification, parameters used to calculate the sample size (including treatment effect in control arm, level of variability in primary outcome, loss to follow-up rates). Data will be summarised across the studies using appropriate summary statistics (e.g. n and %, median and interquartile range). The proportion of studies which report each key component of the sample size calculation will be presented. The reproducibility of the sample size calculation will be tested.DiscussionThe findings of this systematic review will summarise the current practice for sample size calculation in trials of hip and knee osteoarthritis. It will also provide evidence on the completeness of the reporting of the sample size calculation, reproducibility of the chosen sample size and the basis for the values used in the calculation.Trial registrationAs this review was not eligible to be registered on PROSPERO, the summary information was uploaded to Figshare to make it publicly accessible in order to avoid unnecessary duplication amongst other benefits (https://doi.org/10.6084/m9.figshare.5009027.v1); Registered January 17, 2017.
Highlights
A key aspect of the design of randomised controlled trials (RCTs) is determining the sample size
This review will examine the current practice for sample size calculation in randomised trials of hip and knee osteoarthritis, which will include the target difference that studies are designed to detect, the chosen sample size and justification of key inputs
This systematic review will provide insight into the number of randomised trials being conducted on hip and knee osteoarthritis and the variety of interventions being evaluated
Summary
A key aspect of the design of randomised controlled trials (RCTs) is determining the sample size. The required sample size will differ by clinical area, for instance, due to the prevalence of the condition and the choice of primary outcome. It will depend upon the choice of target difference assumed in the calculation. The sample size and target difference of a clinical trial is a key feature that impacts on how the trial is designed and conducted [1]. There are multiple factors which contribute to the determination of the required sample size with choice of target difference arguably the most important [2, 3]. Tavernier and Giraudeau hypothesised that this mis-specification may be due to the imprecision and more homogeneous populations of pilot studies often used to estimate the parameter [9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
