Factors Associated with Findings of Published Trials of Drug–Drug Comparisons: Why Some Statins Appear More Efficacious than Others

Leiden University, Leyden, South Holland, Netherlands
PLoS Medicine (Impact Factor: 14.43). 06/2007; 4(6):e184. DOI: 10.1371/journal.pmed.0040184
Source: PubMed


Published pharmaceutical industry-sponsored trials are more likely than non-industry-sponsored trials to report results and conclusions that favor drug over placebo. Little is known about potential biases in drug-drug comparisons. This study examined associations between research funding source, study design characteristics aimed at reducing bias, and other factors that potentially influence results and conclusions in randomized controlled trials (RCTs) of statin-drug comparisons.
This is a cross-sectional study of 192 published RCTs comparing a statin drug to another statin drug or non-statin drug. Data on concealment of allocation, selection bias, blinding, sample size, disclosed funding source, financial ties of authors, results for primary outcomes, and author conclusions were extracted by two coders (weighted kappa 0.80 to 0.97). Univariate and multivariate logistic regression identified associations between independent variables and favorable results and conclusions. Of the RCTs, 50% (95/192) were funded by industry, and 37% (70/192) did not disclose any funding source. Looking at the totality of available evidence, we found that almost all studies (98%, 189/192) used only surrogate outcome measures. Moreover, study design weaknesses common to published statin-drug comparisons included inadequate blinding, lack of concealment of allocation, poor follow-up, and lack of intention-to-treat analyses. In multivariate analysis of the full sample, trials with adequate blinding were less likely to report results favoring the test drug, and sample size was associated with favorable conclusions when controlling for other factors. In multivariate analysis of industry-funded RCTs, funding from the test drug company was associated with results (odds ratio = 20.16 [95% confidence interval 4.37-92.98], p < 0.001) and conclusions (odds ratio = 34.55 [95% confidence interval 7.09-168.4], p < 0.001) that favor the test drug when controlling for other factors. Studies with adequate blinding were less likely to report statistically significant results favoring the test drug.
RCTs of head-to-head comparisons of statins with other drugs are more likely to report results and conclusions favoring the sponsor's product compared to the comparator drug. This bias in drug-drug comparison trials should be considered when making decisions regarding drug choice.

Download full-text


Available from: Kirby Lee, Nov 05, 2015
  • Source
    • "El 96% de los autores que apoyaban los bloqueadores de los canales de calcio tenían relaciones económicas con los productores de estos fármacos, comparado con el 60% de los autores que se mostraban " neutrales " y el 37% de los que se mostraban críticos. Con posterioridad, han sido numerosos los estudios que han documentado una asociación entre conflictos de interés y conclusiones " pro-industria " , especialmente en ensayos clínicos aleatorizados (Yaphe y otros, 2001; Kjaergard y Als-Nielsen, 2002; Als- Nielsen y otros, 2003; Montgomery y otros, 2004; 3 Perlis y otros, 2005; Ridker y Torres, 2006; Etter y otros, 2007; Peppercorn y otros, 2007; Tungaraza y Poole, 2007; Bero y otros, 2007). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Resumen: Los vínculos profesionales y financieros entre la industria farmacéutica y las personas e instituciones que llevan a cabo investigación, formación y práctica médicas pueden provocar que intereses individuales o corporativos influyan en la toma de decisiones y en el juicio profesional. Esta situación de posible conflicto de intereses amenaza la integridad de la investigación, la objetividad de la educación médica, la calidad de la atención al paciente y, de forma más general, la confianza pública en la medicina. Una estrategia para proteger la integridad de la investigación y mantener la confianza pública es la comunicación de los posibles conflictos de interés de los autores cuando publican los resultados en las revistas científicas. El presente trabajo analiza las políticas editoriales de declaración de conflictos de interés de las 16 revistas de orientación clínica publicadas en España incluidas en el JCR del año 2011. Los resultados ponen de manifiesto que la mayoría de revistas incluyen en sus instrucciones para autores al menos una mención a la necesidad de declarar los conflictos de interés y ofrecen algún tipo de descripción de estas situaciones, si bien se trata de definiciones laxas sobre las relaciones económicas que se deben declarar, y sin que especifiquen el alcance de las relaciones personales. En la mayor parte de los casos no existen formularios estándar de declaración de conflictos de interés, no se determina el tiempo durante el que puede considerarse que una relación es susceptible de generarlo, no se indica quién y cómo evaluará las declaraciones, ni se indica si las declaraciones se publicarán en los artículos. Palabras clave: Biomedicina; conflictos de interés; industria farmacéutica; políticas editoriales; revistas clínicas. Conflict of interest disclosure policies in clinically oriented Spanish biomedical journals Abstract: Professional and financial ties between the pharmaceutical industry and persons and institutions carrying out research, conducting medical training, and practicing medicine can lead to individual or corporate interests influencing decision-making and professional judgment. These conflicts of interest threaten the integrity of research, the objectivity of medical education, the quality of patient care and, more generally, public confidence in medicine. A strategy to protect research integrity and maintain public trust is for authors to communicate their possible conflicts of interest in the studies they publish. This paper analyses the editorial policies of the 16 clinically oriented biomedical journals published in Spain that were included in the JCR in 2011, in relation to authors' conflict of interest declarations. Results show that, in their instructions to authors, most journals mention the need to disclose possible conflicts of interest and offer some sort of description of such situations. However, the definitions are lax concerning which economic relations should be declared and do not specify the extent of personal relationships. In most cases there is no standard form for declaring conflicts of interest; there is no indication of the period of time during which a relationship can be considered likely to generate a conflict; there is no indication of who will evaluate these statements and how they will be evaluated; and there is no indication as to whether these statements will be published in the articles.
    Full-text · Article · Sep 2015 · Revista española de Documentación Científica
    • "In contrast to findings from other studies (Flacco et al., 2015; Lundh et al., 2012), sponsored trials did not show higher internal validity than non-sponsored trials, with risk of detection bias being significantly higher in sponsored trials. Such risk has been shown to have great potential impact on results and could heavily distort findings of sponsored compared with non-sponsored studies (Bero et al., 2007; Rattinger and Bero, 2009). However, given that most material class combinations performed similar in sponsored and non-sponsored trials, the effect of such potential bias on dental restorative trials (where examiner blinding is oftentimes not fully possible) might be limited. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Industry sponsorship was found to potentially introduce bias into clinical trials. We assessed the effects of industry sponsorship on the design, comparator choice, and findings of randomized controlled trials on dental restorative materials. A systematic review was performed via MEDLINE, CENTRAL, and EMBASE. Randomized trials on dental restorative and adhesive materials published 2005 to 2015 were included. The design of sponsored and nonsponsored trials was compared statistically (risk of bias, treatment indication, setting, transferability, sample size). Comparator choice and network geometry of sponsored and nonsponsored trials were assessed via network analysis. Material performance rankings in different trial types were estimated via Bayesian network meta-analysis. Overall, 114 studies were included (15,321 restorations in 5,232 patients). We found 21 and 41 (18% and 36%) trials being clearly or possibly industry sponsored, respectively. Trial design of sponsored and nonsponsored trials did not significantly differ for most assessed items. Sponsored trials evaluated restorations of load-bearing cavities significantly more often than nonsponsored trials, had longer follow-up periods, and showed significantly increased risk of detection bias. Regardless of sponsorship status, comparisons were mainly performed within material classes. The proportion of trials comparing against gold standard restorative or adhesive materials did not differ between trial types. If ranked for performance according to the need to re-treat (best: least re-treatments), most material combinations were ranked similarly in sponsored and nonsponsored trials. The effect of industry sponsorship on dental restorative trials seems limited.
    No preview · Article · Sep 2015 · Journal of dental research
    • "The largest elephant in the room is the failure of toxicology as a field to examine its own biases in terms of conflicts of interest (LaDou et al. 2010). Bero and others have demonstrated that the source of the piper's pay in research, from clinical trials to tobacco studies, introduces a predictable risk of bias in results and conclusions (Barnes and Bero 1998;Bero et al. 2007;Lundh et al. 2012). For this reason, conflict of interest (COI) was recently proposed as an independent item in the assessment of risk of bias in the Cochrane review process (Bero 2013). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The most essential goal of medicine and public health is to prevent harm [primum non nocere]. This goal is only fully achieved with primary prevention, which requires us to identify and prevent harms prior to human exposure through research and testing that does not involve human subjects. For that reason, public health policies place considerable reliance on nonhuman toxicological studies. But toxicology as a field has often not produced efficient and timely evidence for decision making in public health. In response to this, the US National Research Council called for the adoption of evidence-based methods and systematic reviews in regulatory decision making. EPA, FDA and the European Food Safety Agency have recently endorsed these methods in their assessments of safety and risk. In this article we summarize challenges and problems in current practices in toxicology as applied to decision making. We compare these practices with the principles and methods utilized in evidence based medicine and healthcare, with emphasis on the record of the Cochrane Collaboration. We propose a stepwise strategy to support the development, validation, and application of evidence based toxicology (EBT). We discuss current progresses in this field produced by the Office of Health Assessment and Translation of the National Toxicology Program (OHAT) and Navigation Guide works. We propose that adherence to the Cochrane principles is a fundamental prerequisite for the development and implementation of EBT. The adoption of evidence based principles and methods will enhance the validity, transparency, efficiency and acceptance of toxicological evidence, with benefits in terms of reducing delays and costs for all stakeholders (researchers, consumers, regulators, industry).
    No preview · Article · Jun 2015 · Environmental Health Perspectives
Show more