Recruitment patterns in multicentre randomised trials fit more closely to Price's Law than the Pareto Principle: A review of trials funded and published by the United Kingdom Health Technology Assessment Programme

TY - JOUR

T1 - Recruitment patterns in multicentre randomised trials fit more closely to Price's Law than the Pareto Principle

T2 - A review of trials funded and published by the United Kingdom Health Technology Assessment Programme

AU - Knowlson, Catherine Nicolle

AU - Dean, Alex

AU - Doherty, Laura

AU - Fairhurst, Caroline Marie

AU - Brealey, Stephen Derek

AU - Torgerson, David John

PY - 2022/2/1

Y1 - 2022/2/1

N2 - ObjectiveThis review investigates whether the distribution of recruitment to multicentre randomised controlled trials (RCTs) fits the “Pareto Principle”, i.e. 80% of participants are recruited by 20% of sites, or Price's Law, i.e. 50% of participants are recruited by the square root of the total number of sites.MethodsA review of HTA reports published between 2017 and 2019.Results40 RCTs conducted face-to-face recruitment, five recruited via mail-outs and one used both methods. For face-to-face recruitment (n = 41 studies), 80% of participants were recruited by the top recruiting 42.6% of sites; for mail-out methods (n = 6 studies) this was 52.0%. From the square root of sites, 51.3% and 31.8% of participants were recruited for the two recruitment approaches, respectively. Specifically, 3 (7.3%, 95% CI 2.5% to 19.4%) and 20 (48.8%, 95% CI 34.3% to 63.5%) RCTs that recruited face-to-face followed Pareto Principle and Price's Law, respectively. One mail-out recruitment study followed one of these principles, Price's Law. Chief Investigator (CI) sites (n = 24) in face-to-face recruitment studies recruited 18.1% of participants.ConclusionFace-to-face recruitment to HTA-funded RCTs fits more closely to Price's Law than the Pareto Principle, with the CI's site recruiting nearly a fifth of participants. Since we focussed on HTA-funded RCTs with ≥9 recruiting sites and for which the recruitment method and number recruited by site were known, our findings are limited in their generalisability. However, this trend could be used as a guide to aid in estimating how many sites RCTs need. More accurate estimation may prevent the need for recruitment extensions.

AB - ObjectiveThis review investigates whether the distribution of recruitment to multicentre randomised controlled trials (RCTs) fits the “Pareto Principle”, i.e. 80% of participants are recruited by 20% of sites, or Price's Law, i.e. 50% of participants are recruited by the square root of the total number of sites.MethodsA review of HTA reports published between 2017 and 2019.Results40 RCTs conducted face-to-face recruitment, five recruited via mail-outs and one used both methods. For face-to-face recruitment (n = 41 studies), 80% of participants were recruited by the top recruiting 42.6% of sites; for mail-out methods (n = 6 studies) this was 52.0%. From the square root of sites, 51.3% and 31.8% of participants were recruited for the two recruitment approaches, respectively. Specifically, 3 (7.3%, 95% CI 2.5% to 19.4%) and 20 (48.8%, 95% CI 34.3% to 63.5%) RCTs that recruited face-to-face followed Pareto Principle and Price's Law, respectively. One mail-out recruitment study followed one of these principles, Price's Law. Chief Investigator (CI) sites (n = 24) in face-to-face recruitment studies recruited 18.1% of participants.ConclusionFace-to-face recruitment to HTA-funded RCTs fits more closely to Price's Law than the Pareto Principle, with the CI's site recruiting nearly a fifth of participants. Since we focussed on HTA-funded RCTs with ≥9 recruiting sites and for which the recruitment method and number recruited by site were known, our findings are limited in their generalisability. However, this trend could be used as a guide to aid in estimating how many sites RCTs need. More accurate estimation may prevent the need for recruitment extensions.

U2 - 10.1016/j.cct.2021.106665

DO - 10.1016/j.cct.2021.106665

M3 - Article

SN - 1551-7144

VL - 113

JO - Contemporary Clinical Trials

JF - Contemporary Clinical Trials

M1 - 106665

ER -