Project description:Many experimental and clinical trials have investigated the dental application of probiotics, although the evidence concerning the effects of probiotic supplements is conflicting. We aimed to examine whether sponsorship in trials about dental applications of probiotics is associated with biased estimates of treatment effects. Overall, 13 meta-analyses involving 48 randomized controlled trials (23 with high risk of sponsorship bias, 25 with low risk) with continuous outcomes were included. Effect sizes were calculated from differences in means of first reported continuous outcomes, divided by the pooled standard deviation. For each meta-analysis, the difference in standardized mean differences between high-risk and low-risk trials was estimated by random effects meta-regression. Differences in standardized mean differences (DSMDs) were then calculated via meta-analyses in a random effects meta-analysis model. A combined DSMD of greater than zero indicated that high-risk trials showed more significant treatment effects than low-risk trials. The results show that trials with a high risk of sponsorship bias showed more significant intervention effects than did low-risk trials (combined DSMD, 0.06; 95% confidence interval, 0.3 to 0.9; p < 0.001), with low heterogeneity among meta-analyses (I2 = 0%; between-meta-analyses variance τ2 = 0.00). Based on our study, high-risk clinical trials with continuous outcomes reported more favorable intervention effects than did low-risk trials in general.
Project description:BackgroundRandomised controlled trials (RCTs) are considered the gold standard form of evidence for assessing treatment efficacy, but many factors can influence their reliability including methodological quality, reporting quality and funding source. The aim of this study was to examine the relationship between funding source and positive outcome reporting in veterinary RCTs published in 2011 and to assess the risk of bias in the RCTs identified.MethodsA structured search of PubMed was used to identify feline, canine, equine, bovine and ovine clinical trials examining the efficacy of pharmaceutical interventions published in 2011. Funding source and outcomes were extracted from each RCT and an assessment of risk of bias made using the Cochrane risk of bias tool.ResultsLiterature searches returned 972 papers, with 86 papers (comprising 126 individual RCTs) included in the analysis. There was found to be a significantly higher proportion of positive outcomes reported in the pharmaceutical funding group (P) compared to the non-pharmaceutical (NP) and 'no funding source stated' (NF) groups (P = 56.9%, NP = 34.9%, NF = 29.1%, p < 0.05). A high proportion of trials had an unclear risk of bias across the five criteria examined.ConclusionsWe found evidence that veterinary RCTs were more likely to report positive outcomes if they have pharmaceutical industry funding or involvement. Consistently poor reporting of trials, including non-identification of funding source, was found which hinders the use of the available evidence.
Project description:ObjectiveTo explore the risk of industry sponsorship bias in a systematically identified set of placebo controlled and active comparator trials of statins.DesignSystematic review and network meta-analysis.EligibilityOpen label and double blind randomised controlled trials comparing one statin with another at any dose or with control (placebo, diet, or usual care) for adults with, or at risk of developing, cardiovascular disease. Only trials that lasted longer than four weeks with more than 50 participants per trial arm were included. Two investigators assessed study eligibility.Data sourcesBibliographic databases and reference lists of relevant articles published between 1 January 1985 and 10 March 2013.Data extractionOne investigator extracted data and another confirmed accuracy.Main outcome measureMean absolute change from baseline concentration of low density lipoprotein (LDL) cholesterol.Data synthesisStudy level outcomes from randomised trials were combined using random effects network meta-analyses.ResultsWe included 183 randomised controlled trials of statins, 103 of which were two-armed or multi-armed active comparator trials. When all of the existing randomised evidence was synthesised in network meta-analyses, there were clear differences in the LDL cholesterol lowering effects of individual statins at different doses. In general, higher doses resulted in higher reductions in baseline LDL cholesterol levels. Of a total of 146 industry sponsored trials, 64 were placebo controlled (43.8%). The corresponding number for the non-industry sponsored trials was 16 (43.2%). Of the 35 unique comparisons available in 37 non-industry sponsored trials, 31 were also available in industry sponsored trials. There were no systematic differences in magnitude between the LDL cholesterol lowering effects of individual statins observed in industry sponsored versus non-industry sponsored trials. In industry sponsored trials, the mean change from baseline LDL cholesterol level was on average 1.77 mg/dL (95% credible interval -11.12 to 7.66) lower than the change observed in non-industry sponsored trials. There was no detectable inconsistency in the evidence network.ConclusionsOur analysis shows that the findings obtained from industry sponsored statin trials seem similar in magnitude as those in non-industry sources. There are actual differences in the effectiveness of individual statins at various doses that explain previously observed discrepancies between industry and non-industry sponsored trials.
Project description:BackgroundThe sponsorship mix of trials relevant to young people with cancer has not been reported. Understanding this sponsorship mix may have implications for policies and regulations related to pediatric cancer drug development.MethodsWe analyzed sponsorship of interventional trials first opened in the United States from 2007 to 2018 using the ClinicalTrials.gov registry. A total of 51 781 trials across non-oncology disciplines and 18 431 oncology trials were classified according to lower age of eligibility (≥18 years vs < 18 years). Studies were stratified according to sponsorship (industry vs non-industry). Trial characteristics were compared by sponsorship category. Trends in sponsorship were tracked over time.ResultsWithin oncology trials for patients ≥ 18 years, sponsorship was 33% industry and 67% non-industry. Among oncology trials that included patients < 18 years, sponsorship was 16.6% industry and 83.4% non-industry (P < .001). 15.5% of industry-sponsored trials in non-oncology disciplines included patients < 18 years, whereas only 5.2% of industry-sponsored oncology trials were open to patients < 18 years (P < .001). Relative to trials with non-industry sponsors, there was a statistically significant increase in industry sponsorship of oncology trials that included patients < 18 years over time (P < .001). Trial characteristics differed significantly according to sponsor type regardless of age of eligibility.ConclusionsInterventional oncology trials that include patients < 18 years are less likely to be industry-sponsored compared to oncology trials exclusively in patients ≥ 18 years. Compared to other medical disciplines, a smaller proportion of industry-sponsored oncology trials included patients < 18 years. Trial sponsorship is associated with differential trial characteristics, such as trial duration and number of patients enrolled, regardless of age.
Project description:ObjectiveTo identify scientific publications that result from food industry-funded projects on human health and to characterize their research topics to assess the potential for bias in the research agenda.DesignCross-sectional analysis.Setting/SubjectsFood industry-supported projects related to human health were identified from food company websites; publications resulting from the food industry-sponsored projects were identified through a PubMed search.ResultsOf ten companies analysed, only two (Coca-Cola and the Mars Center for Cocoa Health Science) provided a list of research projects with sufficient detail for analysis. Among the 204 publications resulting from thirty-seven disclosed research projects, the most common topic was physical activity (40·7 %), while highly processed foods were analysed in 10·8 % of the publications. Twenty-two publications (10·8 %) focused on research integrity or research methods.ConclusionsPublications resulting from Coca-Cola- and Mars-sponsored research appear to skew the evidence towards solutions that favour industry interests by focusing on food components that can be manipulated and marketed by food companies. These food industry-funded publications can also distract from nutrition as a health issue by diverting public and policy attention to physical activity. Shaping the debate around scientific methods can be another strategy that corporations use for their benefit to raise doubts about the methods used in non-industry sponsored research.
Project description:ObjectiveTo measure the rate of non-publication and assess possible publication bias in clinical trials of electronic health records.MethodsWe searched ClinicalTrials.gov to identify registered clinical trials of electronic health records and searched the biomedical literature and contacted trial investigators to determine whether the results of the trials were published. Publications were judged as positive, negative, or neutral according to the primary outcome.ResultsSeventy-six percent of trials had publications describing trial results; of these, 74% were positive, 21% were neutral, and 4% were negative (harmful). Of unpublished studies for which the investigator responded, 43% were positive, 57% were neutral, and none were negative; the lower rate of positive results was significant (p<0.001).ConclusionThe rate of non-publication in electronic health record studies is similar to that in other biomedical studies. There appears to be a bias toward publication of positive trials in this domain.
Project description:ObjectiveTo examine the relationship between the funding source of cost-effectiveness analyses of healthcare interventions published in Spain and study conclusions.DesignDescriptive cross-sectional study.LocationScientific literature databases (until December 2014).Participants (analysis units)Cohort of cost-effectiveness analysis of healthcare interventions published in Spain between 1989-2014 (n=223) presenting quality-adjusted life years (QALYs) as the outcome measure.Main measurementsThe relationship between qualitative conclusions of the studies and the type of funding source were established using Fisher's exact test in contingency tables. Distributions of the incremental cost-effectiveness ratios by source of funding in relation to hypothetical willingness to pay thresholds between €30,000-€50,000 per QALY were explored.ResultsA total of 136 (61.0%) studies were funded by industry. The industry-funded studies were less likely to report unfavorable or neutral conclusions than studies non-funded by industry (2.2% vs. 23.0%; P<.0001), largely driven by studies evaluating drugs (0.9% vs. 21.4%; P<.0001). The incremental cost-effectiveness ratios in studies funded by industry were more likely to be below the hypothetical willingness to pay threshold of €30,000 (73.8% vs. 56.3%; P<.0001) and €50,000 (89.4% vs. 68.2%; P<.0001) per QALY.ConclusionsThis study reveals a potential sponsorship bias in cost-effectiveness analyses of healthcare interventions. Studies funded by industry could be favoring the efficiency profile of their products.
Project description:BackgroundClinical trials are the hallmark of evidence-based medicine, but recruitment is often challenging, especially in stroke trials investigating patients not being able to give informed consent. In some nations, ethics committees will not approve of inclusion in a clinical study via consent of a legal representative. The ethical dilemma of including or excluding those patients has not been properly addressed, as there is little data on the effect of stroke characteristics on the ability to give informed consent.MethodsTo examine differences between patients able and unable to consent at inclusion to an acute stroke trial, we conducted a post-hoc analysis of monitoring records from a multicentric interventional trial. These records listed patients who gave informed consent by themselves and those who needed a legal representative to do so. This exemplary STRAWINSKI trial aimed at improving stroke outcome by biomarker-guided antibiotic treatment of stroke associated pneumonia and included patients within 40 h after stroke onset, suffering from MCA infarctions with an NIHSS score > 9 at admission. Standard descriptive and associative statistics were calculated to compare baseline characteristics and outcome measures between patients who were able to consent and those who were not.ResultsWe identified the person giving consent in 228 out of 229 subjects. Patients with inability to consent were older (p < 0.01), suffered from more left-hemispheric (p < 0.01) and more severe strokes (NIHSS, p < 0.01), were more likely to die during hospitalisation (p < 0.01) or have unfavourable outcome at discharge (mRS, p < 0.01), to develop fever (p < 0.01) and tended to be more susceptible to infections (p = 0.06) during the acute course of the disorder.ConclusionsDemographics, stroke characteristics and outcomes significantly affect stroke patients in their ability to consent. Where selection criteria and primary outcome measures of a trial are significantly affected by ability to consent, excluding patients unable to consent might be unethical.Trial registrationURL http://www.clinicaltrials.gov . Unique identifier: NCT01264549 .
Project description:A phase II trial is conducted to investigate if an experimental therapy is efficacious enough to proceed to a large-scale phase III trial or not. In spite of the fast progress in design and analysis methods, single-arm two-stage design is still the most popular for phase II cancer clinical trials. In this review article, we discuss two design and analysis methods that are popularly used for phase II clinical trials, but that can cause serious bias. One is about using the sample proportion as the estimator of the true response rate from single-arm two-stage trials. For a two-stage design with a futility interim test, the sample proportion is negatively biased by ignoring the two-stage design. The other is about the design and analysis of single-arm phase II trials for patient populations consisting of multiple sub-populations with different response rates. In this case, a standard design method is to project the prevalence of each subpopulation and select a standard two-stage design based on the expected response rate for the whole population. By using an unstratified statistical testing in this case, the standard analysis method can be seriously biased if the observed prevalence is very different from the projected one. In this paper, we review appropriate design and analysis methods that are proposed to avoid these sources of bias.
Project description:BackgroundAmong various design aspects, the choice of randomization procedure have to be agreed on, when planning a clinical trial stratified by center. The aim of the paper is to present a methodological approach to evaluate whether a randomization procedure mitigates the impact of bias on the test decision in clinical trial stratified by center.MethodsWe use the weighted t test to analyze the data from a clinical trial stratified by center with a two-arm parallel group design, an intended 1:1 allocation ratio, aiming to prove a superiority hypothesis with a continuous normal endpoint without interim analysis and no adaptation in the randomization process. The derivation is based on the weighted t test under misclassification, i.e. ignoring bias. An additive bias model combing selection bias and time-trend bias is linked to different stratified randomization procedures.ResultsVarious aspects to formulate stratified versions of randomization procedures are discussed. A formula for sample size calculation of the weighted t test is derived and used to specify the tolerated imbalance allowed by some randomization procedures. The distribution of the weighted t test under misclassification is deduced, taking the sequence of patient allocation to treatment, i.e. the randomization sequence into account. An additive bias model combining selection bias and time-trend bias at strata level linked to the applied randomization sequence is proposed. With these before mentioned components, the potential impact of bias on the type one error probability depending on the selected randomization sequence and thus the randomization procedure is formally derived and exemplarily calculated within a numerical evaluation study.ConclusionThe proposed biasing policy and test distribution are necessary to conduct an evaluation of the comparative performance of (stratified) randomization procedure in multi-center clinical trials with a two-arm parallel group design. It enables the choice of the best practice procedure. The evaluation stimulates the discussion about the level of evidence resulting in those kind of clinical trials.