Recruitment and retention of participants in randomised controlled trials: a review of trials funded and published by the United Kingdom Health Technology Assessment Programme

Abstract

BackgroundSubstantial amounts of public funds are invested in health research worldwide. Publicly funded randomised controlled trials (RCTs) often recruit participants at a slower than anticipated rate. Many trials fail to reach their planned sample size within the envisaged trial timescale and trial funding envelope.ObjectivesTo review the consent, recruitment and retention rates for single and multicentre randomised control trials funded and published by the UK's National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme.Data sources and study selectionHTA reports of individually randomised single or multicentre RCTs published from the start of 2004 to the end of April 2016 were reviewed.Data extractionInformation was extracted, relating to the trial characteristics, sample size, recruitment and retention by two independent reviewers.Main outcome measuresTarget sample size and whether it was achieved; recruitment rates (number of participants recruited per centre per month) and retention rates (randomised participants retained and assessed with valid primary outcome data).ResultsThis review identified 151 individually RCTs from 787 NIHR HTA reports. The final recruitment target sample size was achieved in 56% (85/151) of the RCTs and more than 80% of the final target sample size was achieved for 79% of the RCTs (119/151). The median recruitment rate (participants per centre per month) was found to be 0.92 (IQR 0.43–2.79) and the median retention rate (proportion of participants with valid primary outcome data at follow-up) was estimated at 89% (IQR 79–97%).ConclusionsThere is considerable variation in the consent, recruitment and retention rates in publicly funded RCTs. Investigators should bear this in mind at the planning stage of their study and not be overly optimistic about their recruitment projections.

Barriers and facilitators to participant recruitment to randomised controlled trials: A qualitative perspective

“…Data collection took place from August 2017 to November 2017 and comprised 22 interviews (10 face‐to‐face and 12 telephone interviews). Most face‐to‐face interviews with health professionals took place in a clinical setting either during the lunch break or another time outside of work hours. One interview with a wound clinic consultant and interviews with the research project officers took place in the (Name withdrawn for a review purpose) University offices.…”

“…Secondary outcomes are ulcer recurrence, wound pain, quality of life and well-being, adherence to study medication, adherence to compression therapy, serum inflammatory markers, hospitalisations, and adverse events at 24 weeks. Participants are eligible if (1) they are aged 18 years and older, (2) have 1 or more leg ulcers in the presence of chronic venous insufficiency (CVI) as confirmed by clinical assessment and/or duplex ultrasound; (3) the target ulcer (largest ulcer if more than 1) is separated from the other ulcers by at least 1 cm; (4) the target ulcer has been present for at least 6 weeks or the patient has a prior history of venous ulceration; (5) the target ulcer area is ≥1 to ≤20 cm 2 as measured by digital planimetry techniques; (6) ankle brachial pressure index (ABPI) measure of ≥ 0.7 mm Hg or systolic toe pressure ≥ 50 mm Hg to exclude arterial insufficiency; and (7) if the potential participant is capable to provide informed consent (as per clinicians' judgement). 20 Participants are excluded if they are currently using aspirin, have aspirin intolerance, have a contraindication to taking aspirin or to participating in the trial (as per clinicians' judgement), are concurrently using any other antiplatelet or anticoagulation therapy, or are pregnant or breastfeeding.…”

“…Well‐designed randomised controlled trials (RCTs) are considered the “gold standard” in clinical research because they provide high‐quality evidence related to the management of specific conditions, including VLUs . Unfortunately, recruitment issues for participation in the RCTs experienced by health professionals are not uncommon . These issues are related to researchers’ inability to recruit the required number of participants or to retain the recruited participants in the study .…”

“…4 Unfortunately, recruitment issues for participation in the RCTs experienced by health professionals are not uncommon. [5][6][7] These issues are related to researchers' inability to recruit the required number of participants or to retain the recruited participants in the study. 8,9 Findings from a systematic review 10 of discontinued RCTs indicate that 76% of the discontinued RCTs were related to poor recruitment.…”

A Generalizable, Data-Driven Approach to Predict Daily Risk ofClostridium difficileInfection at Two Large Academic Health Centers

“…In clinical trials, costs for new therapeutics are driven in large part by the ability to enroll appropriate subjects. 30,31 Good predictive models could enable investigators to focus recruitment on patient populations at highest risk for disease. This application could, in turn, result in more efficient, and less costly, clinical studies.…”