Fate of Registered Studies From London, Ontario
Abstract
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 modified Poisson regression was used to assess the association between enrollment size and publication. Time to publication was assessed using multiple linear regression.
Results: Of the registered studies (n = 2446), only 38% were published and 30% with their planned primary outcome. Median time to publication post-start was 53 months [IQR: 36, 75]. Factors associated with publication were randomized design, prospective registration, industry funding, drug study, and enrollment size (p < 0.05). Factors associated with shorter time to publication were positive results, prospective registration, and industry funding, while drug studies were associated with longer time to publication (p < 0.05). Surgical studies seemed to have decreased chances of publication and lengthened time to publication but was not statistically significant in either case.
Conclusions: A substantial proportion of clinical trials from London, Ontario remained unpublished. The factors predictive of non-publication and time to publication suggest potential avenues for increasing publication rates.