Are some feasibility studies more feasible than others? A review of the outcomes of feasibility studies on the ISRCTN registry

Abstract

Background Feasibility studies are often conducted before committing to a randomised controlled trial (RCT), yet there is little published evidence to inform how useful feasibility studies are, especially in terms of adding or reducing waste in research. This study attempted to examine how many feasibility studies demonstrated that the full trial was feasible and whether some feasibility studies were inherently likely to be feasible or not feasible, based on the topic area and/or research setting. Methods Keyword searches were conducted on the International Standard Randomised Controlled Trials Number (ISRCTN) registry to identify all completed feasibility studies which had been conducted in the UK. Results A total of 625 records from the 1933 identified were reviewed before it became evident that it would be futile to continue. Of 329 feasibility studies identified, 160 had a known outcome (49%), 133 (83%) trials were deemed to be feasible and only 27 (17%) were reported to be non-feasible. There were therefore too few studies to allow the intended comparison of differences in non-feasible studies by topic and/or setting. Conclusions There were too few studies reported as non-feasible to draw any useful conclusions on whether topic and/or setting had an effect. However, the high feasibility rate (83%) may suggest that non-feasible studies are subject to publication bias or that many feasible studies are redundant and may be adding waste to the research pathway.

Internet‐administered, low‐intensity cognitive behavioral therapy for parents of children treated for cancer: A feasibility trial (ENGAGE)

“…The intervention protocol is published in accordance with TIDieR guidelines 34 and reporting of methods and results are transparent and complete in accordance with calls for better reporting of feasibility studies. 58 A novel recruitment strategy was adopted with participants identified via the CCR, meaning invited participants are a nationally representative sample of parents of children treated for cancer. We also successfully adopted an opt-out recruitment strategy and explored reasons for non-participation, 41 which will inform recruitment strategies used in the future pilot RCT.…”

Determining external randomised pilot trial feasibility in preparation for a definitive trial: a web-based survey of corresponding authors of external pilot trial publications

“…Interestingly, our response rate amongst authors of external pilot trial protocols was lower than authors of external pilot trial results publications. This finding might be explained by publication bias, with non-feasible pilot trial result publications perhaps less likely to be published [ 8 ], and authors more willing to complete the survey where external pilot trials were feasible, had completed and been published. The COVID-19 pandemic likely also impacted and delayed many of the pilot trials included in this study and many might not have proceeded to completion in the timeframe between protocol publication and survey administration.…”

“…It has been suggested that authors of external pilot trials that do not report progression criteria or report unclear progression criteria, may be optimistic in reporting that a definitive RCT is feasible [ 8 ]. However, our findings indicated only slightly more respondents who did not report clear progression criteria in their external pilot trial publication considered their pilot trial to be feasible or feasible with changes compared to those who did include progression criteria (94%, 32/34 versus 87%, 48/55 respectively).…”

“…It has been suggested that authors of external pilot trials that do not report progression criteria or report unclear progression criteria, may be more optimistic in reporting that a definitive RCT is feasible [ 8 ], and previous research has highlighted lack of progression criteria reporting in external pilot trial protocols [ 9 ]. We previously conducted a methodological review to investigate the application and reporting of progression criteria in a more recent sample of the external randomised pilot trial protocol and results publications published in four major journals ( Pilot and Feasibility Studies , BMJ Open , Trials and PLoS One ) between January 2018 and December 2019 [ 10 ].…”

Inclusion of progression criteria in external randomised pilot trials: a cross-sectional study of funding applications submitted to the NIHR Research for Patient Benefit Programme

“…This was updated in 2021 (v2.0, February 2021) to cover all types of preparatory studies and included the expectation that the application would include progression criteria and set out the pathway to RCT [2]. Pre-specifying clear progression criteria facilitate the transparent assessment of pilot trial feasibility and limit the potential for research waste where unfeasible pilot trials progress to unfeasible RCTs [3], and feasible pilot trials do not progress to further research [4].…”