Published online Nov 21, 2021. doi: 10.3748/wjg.v27.i43.7572
Peer-review started: March 4, 2021
First decision: June 3, 2021
Revised: June 30, 2021
Accepted: October 31, 2021
Article in press: October 31, 2021
Published online: November 21, 2021
Processing time: 259 Days and 22 Hours
A third of randomised controlled trials (RCTs) on interventions for inflammatory bowel disease (IBD) have no adequate power calculation (PC).
A key element of PCs is an estimation of a minimally important clinical difference. The basis of these is capricious within the literature, with many not based on any existing or prior studies and as such can lead to massive shifts in PCs for similar studies, with concerns as to the underlying power.
We systematically reviewed RCTs reporting interventions for the management of IBD and to producted a resource for minimum clinically important difference using clinical data for the future researchers to use as a starting point.
We included RCTs retrieved from Cochrane IBD trial register and CENTRAL investigating anti-inflammatory, immunomodulator and biologic therapies for either induction or maintenance of remission against control, placebo, or no intervention of IBD in patients of any age. The data was extracted and synthesized. We recalculated sample size and the achieved difference, as well as minimum sample sizes and presented in a tabular format.
Of 105 trials were included. A large discrepancy between the estimated figure for the minimal clinically important difference used for the calculations (15% differences observed vs 30% used for calculation) was observed explaining substantial actual sample size deficits. The minimum sample sizes indicated for future trials based on the 25 years of trial data were calculated and grouped by the intervention.
There are large variations in the sample size calculatins in the studies of interventions for IBD with a third of all studies being underpowered. The authors present a sample size estimate resource constructed on the published evidence base for future researchers and key stakeholders within the IBD trial field.
The use of this resource will support research staff, ethics committees and journal editors in ensuring adequate sample sizing and powering of studies across the field.