Cited by 60Heart Failure Treatment and ManagementStatistical Methods in Clinical TrialsEthics in Clinical Research

Relationship Between Clinical Trial Site Enrollment With Participant Characteristics, Protocol Completion, and Outcomes

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Butler, Javed, Subacius, Haris, Vaduganathan, Muthiah, Fonarow, Gregg C., Ambrosy, Andrew P., Konstam, Marvin A., Maggioni, Aldo, Mentz, Robert J. +3 more·2013·Journal of the American College of Cardiology

Abstract

Objectives The study investigated whether the number of participants enrolled per site in an acute heart failure trial is associated with participant characteristics and outcomes.Background Whether and how site enrollment volume affects clinical trials is not known.Methods A total of 4,133 participants enrolled among 359 sites were grouped on the basis of total enrollment into 1 to 10, 11 to 30, and >30 participants per site and were compared for outcomes (cardiovascular mortality or heart failure hospitalization).Results Per-site enrollment ranged from 0 to 75 (median 6; 77 sites had no enrollment). Regional differences in enrollment were noted between North and South America, and Western and Eastern Europe (p < 0.001). Participants from sites with fewer enrollments were more likely to be older and male, have lower ejection fraction and blood pressure as well as worse comorbidity and laboratory profile, and were less likely to be on angiotensin-converting enzyme inhibitors or aldosterone antagonists. During a median follow-up of 9.9 months, 1,700 (41%) participants had an outcome event. Compared to event rate at sites with >30 participants (32%), those with 1 to 10 (51%, hazard ratio [HR]: 1.77, 95% confidence interval [CI]: 1.56 to 2.02) and 11 to 30 (42%, HR: 1.44, 95% CI: 1.28 to 1.62) participants per site groups had worse outcomes. This relationship was comparable across regions (p = 0.43). After adjustment for risk factors, participants enrolled at sites with fewer enrollees were at higher risk for adverse outcomes (HR: 1.26, 95% CI: 1.08 to 1.46 for 1 to 10; HR: 1.22, 95% CI: 1.07 to 1.38 for 11 to 30 vs. >30 participant sites). Higher proportion of participants from site with >30 participants completed the protocol (45.5% for <10, 61.7% for 11 to 30, and 68.4% for sites enrolling >30 participants; p < 0.001).Conclusions Baseline characteristics, protocol completion, and outcomes differed significantly among higher versus lower enrolling sites. These data imply that the number of participant enrolled per site may influence trials beyond logistics.

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  • International trials of various pharmacotherapies have sometimes found discordant results in patients enrolled in the United States than seen in overall trial results.

    “International trials of various pharmacotherapies have sometimes found discordant results in patients enrolled in the United States than seen in overall trial results.19–32”
  • The reasons for discordant US results range from low numbers of patients enrolled in the United States to potential differences in background medical management or in patient risk profiles.

    “The reasons range from low numbers of patients enrolled in the United States to potential differences in background medical management or in patient risk profiles.”

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  1. Truelove C. 21st Annual report: belt tightens on big pharma. Med Ad News 2007;26:4 -7.

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Authors
Butler, J., Subacius, H., Vaduganathan, M., Fonarow, G. C., Ambrosy, A. P., Konstam, M. A., Maggioni, A., Mentz, R. J., Swedberg, K., Zannad, F., & Gheorghiade, M.
Affiliations
  • Emory University (US)
  • Northwestern University (US)
  • Harvard University (US)
  • University of California, Los Angeles (US)
  • Stanford University (US)
  • Tufts University (US)
  • Associazione Nazionale Medici Cardiologi Ospedalieri (IT)
  • Duke University (US)
  • University of Gothenburg (SE)
  • Inserm (FR)
Corresponding author
Gheorghiade, Mihai
Venue
Journal of the American College of Cardiology
Publisher
Elsevier BV
Published
2013-02
Volume
61
Issue
5
Pages
571-579
ISSN
0735-1097 (ISSN-L)
OpenAlex
W133383503
Cited by
60
References
24
Citations by year
2025: 1 · 2024: 2 · 2023: 1 · 2021: 3 · 2020: 1 · 2019: 2 · 2018: 5 · 2017: 6 · 2016: 6 · 2015: 13 · 2014: 10 · 2013: 9 · 2012: 1
FWCI
6.79
Type
journal article
Language
en
Open access
Locations
  • Journal of the American College of Cardiology (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Cytokinetics
  • Novartis
  • Otsuka America
  • Medtronic
  • Servier
  • Amgen
  • AstraZeneca
  • Gilead Sciences
Topics
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Heart Failure Treatment and Management
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Ethics in Clinical Research
Keywords
acute heart failure, cardiovascular mortality, heart failure hospitalization, participant characteristics, ACE inhibitors, mineralocorticoid receptor antagonists, ejection fraction, comorbidities, trial outcomes
MeSH terms
Tolvaptan, Aged, Aged, 80 and over, Benzazepines, Clinical Protocols, Double-Blind Method, Europe, Europe, Eastern, Female, Follow-Up Studies, Heart Failure, Hospitalization, Humans, Male, Middle Aged, North America, Prospective Studies, South America, Vasopressins, Survival Rate, Treatment Outcome, Patient Selection, Internationality

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