Bias and loss to follow-up in cardiovascular randomized trials: a systematic review

Fong, L. C. W., Ford, T. J. , da Costa, B. R., Jüni, P. and Berry, C. (2020) Bias and loss to follow-up in cardiovascular randomized trials: a systematic review. Journal of the American Heart Association, 9(14), e015361. (doi: 10.1161/JAHA.119.015361) (PMID:32646264) (PMCID:PMC7660731)

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Abstract

Background: Loss to follow‐up (LTFU) is common in randomized controlled trials. However, its potential impact on primary outcomes from cardiovascular randomized controlled trials is not known. Methods and Results: We conducted a prospective systematic review (PROSPERO: CRD42019121959) for randomized controlled trials published in 8 leading journals over 5 years from January 2014 to December 2018. Extent, reporting, and handling of LTFU data were recorded, and the proportion of a trial's primary outcome results that lose statistical significance was calculated after making plausible assumptions for the intervention and control arms. These assumptions could drive differential treatment effects between the groups considering relative event incidence between LTFU participants and those included in the primary outcome. We identified 117 randomized controlled trials of which 91 (78%) trials reported LTFU, 23 (20%) reported no LTFU, and 3 (3%) trials did not report on whether LTFU occurred. The median percentage of study participants lost to follow‐up was 2% (interquartile range, 0.33%–5.3%). Only 10 trials (9%) had a low cluster of risk factors for impairment in trial quality. The percentage of trials losing statistical significance varied from 2% when the relative event incidence for LTFU between the randomized groups was 1 for the intervention arm and 1.5 for the control arm to 16% when the relative event incidence was 3 for the intervention arm and 1 for the control arm. Conclusions: Almost 1 in 6 (16%) cardiovascular randomized trials published in leading journals may have a change in the primary outcome if plausible assumptions are made about differential event rates of participants lost to follow up. There is scope for improvement arising from LTFU in randomized trials in cardiovascular medicine.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Berry, Professor Colin and Ford, Thomas
Authors: Fong, L. C. W., Ford, T. J., da Costa, B. R., Jüni, P., and Berry, C.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
Journal Name:Journal of the American Heart Association
Publisher:American Heart Association, by Wiley
ISSN:2047-9980
ISSN (Online):2047-9980
Published Online:09 July 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First publishe in Journal of the American Heart Association 9:e015361
Publisher Policy:Reproduced under a Creative Commons licence

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
301454CORonary MICrovascular Angina (CorMicA): a pilot trial with a nested MRI sub-studyColin BerryBritish Heart Foundation (BHF)PG/17/25/32884CAMS - Cardiovascular Science
190814BHF centre of excellenceRhian TouyzBritish Heart Foundation (BHF)RE/13/5/30177Institute of Cardiovascular & Medical Sciences
303944BHF Centre of ExcellenceRhian TouyzBritish Heart Foundation (BHF)RE/18/6/34217CAMS - Cardiovascular Science