Reporting of statistically significant results at ClinicalTrials.gov for completed superiority randomized controlled trials

Trends in mental health clinical research: Characterizing the ClinicalTrials.gov registry from 2007-2018

While the epidemiologic burden of mental health disorders in the United States has been well described over the past decade, we know relatively little about trends in how these disorders are being studied through clinical research. We examined all US interventional mental health trials submitted to ClinicalTrials.gov between October 1, 2007 and April 30, 2018 to identify trends in trial characteristics, comparisons with non-mental health trials, and trial attributes associated with discontinuation and results reporting. International data were excluded to minimize potential confounding. Over this period, mental health and non-mental health trials grew at similar rates, though Industry and US government-funded trials declined and academic medical center/hospital/other (AMC/Hosp/Oth) funded trials grew faster in mental health research. The proportion of trials with safeguards against bias, including blinding and oversight by data monitoring committees (DMCs), decreased. This occurred during growth in the proportion of trials studying behavioral and non-pharmacological interventions, which often cannot be blinded and do not require DMC oversight. There was concurrent decline in pharmaceutical trials. There was significant growth in trials studying Non-DSM (Diagnostic and Statistical Manual-5) conditions (e.g. suicidality and wellness), as well as substance use, anxiety, and neurocognitive disorders. One in 12 trials was discontinued. Trial discontinuation was associated with industry and AMC/Hosp/Oth funders, pharmaceutical interventions, and lack of DMC oversight. Only 29.9% of completed trials reported results to the registry. Decreased results reporting was associated with behavioral interventions, phase 1 trials, and industry and AMC/Hosp/Oth funders. The main implications of these data are that funding is shifting away from traditional government and industry sources, there is increasing interest in non-pharmacological treatments and Non-DSM conditions, and there are changing norms in trial design characteristics regarding safeguards against bias. These trends can guide researchers and funding bodies when considering the trajectory of future mental health research.

Global mapping of randomised trials related articles published in high-impact-factor medical journals: a cross-sectional analysis

Background

Randomised controlled trials (RCTs) provide the most reliable information to inform clinical practice and patient care. We aimed to map global clinical research publication activity through RCT-related articles in high-impact-factor medical journals over the past five decades.

Methods

We conducted a cross-sectional analysis of articles published in the highest ranked medical journals with an impact factor > 10 (according to Journal Citation Reports published in 2017). We searched PubMed/MEDLINE (from inception to December 31, 2017) for all RCT-related articles (e.g. primary RCTs, secondary analyses and methodology papers) published in high-impact-factor medical journals. For each included article, raw metadata were abstracted from the Web of Science. A process of standardization was conducted to unify the different terms and grammatical variants and to remove typographical, transcription and/or indexing errors. Descriptive analyses were conducted (including the number of articles, citations, most prolific authors, countries, journals, funding sources and keywords). Network analyses of collaborations between countries and co-words are presented.

Results

We included 39,305 articles (for the period 1965–2017) published in forty journals. The Lancet (n = 3593; 9.1%), the Journal of Clinical Oncology (n = 3343; 8.5%) and The New England Journal of Medicine (n = 3275 articles; 8.3%) published the largest number of RCTs. A total of 154 countries were involved in the production of articles. The global productivity ranking was led by the United States (n = 18,393 articles), followed by the United Kingdom (n = 8028 articles), Canada (n = 4548 articles) and Germany (n = 4415 articles). Seventeen authors who had published 100 or more articles were identified; the most prolific authors were affiliated with Duke University (United States), Harvard University (United States) and McMaster University (Canada). The main funding institutions were the National Institutes of Health (United States), Hoffmann-La Roche (Switzerland), Pfizer (United States), Merck Sharp & Dohme (United States) and Novartis (Switzerland). The 100 most cited RCTs were published in nine journals, led by The New England Journal of Medicine (n = 78 articles), The Lancet (n = 9 articles) and JAMA (n = 7 articles). These landmark contributions focused on novel methodological approaches (e.g. the “Bland-Altman method”) and trials on the management of chronic conditions (e.g. diabetes control, hormone replacement therapy in postmenopausal women, multiple therapies for diverse cancers, cardiovascular therapies such as lipid-lowering statins, antihypertensive medications, and antiplatelet and antithrombotic therapy).

Conclusions

Our analysis identified authors, countries, funding institutions, landmark contributions and high-impact-factor medical journals publishing RCTs. Over the last 50 years, publication production in leading medical journals has increased, with Western countries leading in research but with low- and middle-income countries showing very limited representation.

Causes of reporting bias: a theoretical framework

Reporting of research findings is often selective. This threatens the validity of the published body of knowledge if the decision to report depends on the nature of the results. The evidence derived from studies on causes and mechanisms underlying selective reporting may help to avoid or reduce reporting bias. Such research should be guided by a theoretical framework of possible causal pathways that lead to reporting bias. We build upon a classification of determinants of selective reporting that we recently developed in a systematic review of the topic. The resulting theoretical framework features four clusters of causes. There are two clusters of necessary causes: (A) motivations (e.g. a preference for particular findings) and (B) means (e.g. a flexible study design). These two combined represent a sufficient cause for reporting bias to occur. The framework also features two clusters of component causes: (C) conflicts and balancing of interests referring to the individual or the team, and (D) pressures from science and society. The component causes may modify the effect of the necessary causes or may lead to reporting bias mediated through the necessary causes. Our theoretical framework is meant to inspire further research and to create awareness among researchers and end-users of research about reporting bias and its causes.