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Clinical Epidemiology

Western University

Electronic Thesis and Dissertation Repository

Publication bias

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Spin And Distortion In Surgical Trials, Andrea Mataruga Apr 2022

Spin And Distortion In Surgical Trials, Andrea Mataruga

Electronic Thesis and Dissertation Repository

Research problem: Randomized controlled trials (RCTs) are essential; however, their validity can be threatened through distortion or spin. This study quantifies publication bias and distorted outcome reporting.

Methodology: All surgical RCTs registered on ClinicalTrials.gov from 1997-2017 were identified and a sample was obtained through random and intentional selection. Failure to publish (proportion of studies that remain unpublished), outcome distortion (changing intended outcomes), and spin (distorted presentation) were explored. Comparisons were made for positive versus negative studies and for high-income (HICs) versus low-middle income countries (LMICs).

Results: In total, 13,761 RCTs were registered (median enrollment size = 96, 94% from …


Fate Of Registered Studies From London, Ontario, Alex Bi Feb 2022

Fate Of Registered Studies From London, Ontario, Alex Bi

Electronic Thesis and Dissertation Repository

Introduction: Lack of study publication leads to bias in the scientific literature. It is important to better understand this phenomenon and find methods for mitigation.

Research Question: How many clinical trials registered on ClinicalTrials.gov in London, Ontario are started, completed, and published?

Methods: Data from all studies in the ClinicalTrials.gov registry associated with London, Ontario were collected, from registry conception until the end of 2017. We determined whether these registered studies were published by July 2020 and whether their first publication included their planned primary outcome at all. Main factors associated with non-publication were assessed using multivariable log-binomial regression. Multivariable …