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Pilot trials in thrombosis: Purpose and pitfalls.

ABSTRACT: Randomized controlled trials provide important evidence to guide clinical practice. These full-scale trials are expensive, time consuming and many are never successfully completed. Well conducted pilot studies help with full-scale trial design, assessment and optimization of feasibility, and can avoid the waste of resources associated with starting a full-scale trial that will not succeed. They also provide an opportunity for capacity growth and mentorship of new investigators. It is important to appreciate that the usual goal of a pilot trial is assessment of feasibility and refinement of trial design rather than to gain preliminary evidence of efficacy. Indeed, using event rates from a pilot trial to calculate sample sizes can be misleading in therapeutic trials. Misconceptions exist that pilot trials are just "small trials," are easy to perform, and are not worthy of publication. While, in the past, many pilot trials were poorly conducted and not followed by a full-scale trial, by following the recommendations in the "CONSORT 2010 statement: extension to randomized pilot and feasibility trials," high-quality pilot trials can be performed and reported that will greatly improve the chances of successfully completing a practice-changing trial. We propose that pilot trials are a valuable investment and describe the TRIM-Line pilot trial (NCT03506815), a pilot study assessing the feasibility of a randomized controlled trial investigating primary thromboprophylaxis with rivaroxaban in patients with malignancy and central venous catheters, as an illustrative example of how a pilot trial in the area of thrombosis should be designed.

SUBMITTER: Ikesaka R

PROVIDER: S-EPMC6046600 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Pilot trials in thrombosis: Purpose and pitfalls.

Ikesaka Rick R Langlois Nicole N Carrier Marc M Kearon Clive C Le Gal Grégoire G

Research and practice in thrombosis and haemostasis 20180613 3

Randomized controlled trials provide important evidence to guide clinical practice. These full-scale trials are expensive, time consuming and many are never successfully completed. Well conducted pilot studies help with full-scale trial design, assessment and optimization of feasibility, and can avoid the waste of resources associated with starting a full-scale trial that will not succeed. They also provide an opportunity for capacity growth and mentorship of new investigators. It is important t ...[more]

PMID: 30046762

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Project description:ImportancePotential research participants may assume that randomized trials comparing new interventions with older interventions always hypothesize greater efficacy for the new intervention, as in superiority trials. However, antibiotic trials frequently use "noninferiority" hypotheses allowing a degree of inferior efficacy deemed "clinically acceptable" compared with an older effective drug, in exchange for nonefficacy benefits (eg, decreased adverse effects). Considering these different benefit-harm trade-offs, proper informed consent necessitates supplying different information on the purposes of superiority and noninferiority trials.ObjectiveTo determine the degree to which the study purpose is explained to potential participants in randomized clinical trials of antibiotics and the degree to which study protocols justify their selection of noninferiority hypotheses and amount of "clinically acceptable" inferiority.Design and settingCross-sectional analysis of study protocols, statistical analysis plans (SAPs), and informed consent forms (ICFs) from clinical study reports submitted to the European Medicines Agency. The ICFs were read by both methodologists and patient investigators.Main outcomes and measuresProtocols and SAPs were used as the reference standard to determine prespecified primary hypothesis and record rationale for selection of noninferiority hypotheses and noninferiority margins. This information was cross-referenced against ICFs to determine whether ICFs explained the study purpose.ResultsWe obtained trial documents from 78 randomized trials with prespecified efficacy hypotheses (6 superiority, 72 noninferiority) for 17 antibiotics conducted between 1991 and 2011 that enrolled 39 407 patients. Fifty were included in the ICF analysis. All ICFs contained sections describing study purpose; however, none consistently conveyed study hypothesis to both methodologists and patient investigators. Methodologists found that 1 of 50 conveyed a study purpose. Patient investigators found that 11 of 50 conveyed a study purpose, 7 accurately and 4 inaccurately compared with the reference standard. Seventy-one of 72 noninferiority trial protocols or SAPs provided no rationale for selection of noninferiority hypothesis. None provided a clinical rationale for the chosen amount of decreased efficacy.Conclusions and relevancePatients were not accurately informed of study purpose, which raises questions regarding the ethics of informed consent in antibiotic trials. Noninferiority and superiority trials entail different benefit-harm trade-offs that must be conveyed for ethical informed consent.

Project description:Introduction: Peri-operative window trials, using molecular biomarkers as surrogate endpoints for treatment response, offer investigators a uniqueopportunity to obtain intact tumor samples at 2 different time-points and thus evaluate potential biomarkers over a short period of time. Here we report results of a pilot trial designed to determine if treatment-mediated changes in gene expression can be detected after a 10-day exposure to anastrozole in estrogen receptor (ER)-positive breast cancer compared to untreated controls. Methods: Paired tumor samples (biopsy and surgical) were obtained from 26 postmenopausal women with ER-positive breast cancer. Patients were assigned anastrozole (1mg/dy) for 10 days immediately prior to surgery (13 cases) or no treatment (13 controls). 502 cancer-related genes were examined by the DASL FFPE-based cDNA array (moderated t-test, p ≤ .005). Surrogate biomarkers reflecting changes in gene expression were examined by immunohistochemistry (IHC) (Wilcoxon rank-based test, p < .05). Results: Sufficient RNA was available from 19 paired samples (8 controls, 11 cases). There was no difference in age, tumor size, grade, or baseline biomarker expression between groups. Within each group, 18 genes, reflecting roles in proliferation, angiogenesis, and apoptosis showed differential expression over time from biopsy to surgery (p < 0.005). Dysregulation of estrogen-related genes was present only in the treated group. Comparison between groups identified 5 genes that were significantly dysregulated between controls and treated cases (BAG1/ING1/ERBB4/IFNGR1/TFDP1). Reduction in Ki-67 index was observed in 7 (54%) treated cases in 1 (7.7%) control patient. Conclusions: Short-term (10-day) exposure to anastrozole resulted in significant dysregulation of 18 out of 502 cancer-related genes, and Ki-67 was reduced in 54% of cases. However, the local effects of wound healing may represent a confounding factor in the interpretation of peri-operative window trials as exposed by the changes in gene expression and the increased Ki-67 index in the control group. Prospective, paired tumor samples (biopsy and surgical) were obtained from 26 postmenopausal women with ER-positive breast cancer. Patients were assigned anastrozole (1mg/dy) for 10 days immediately prior to surgery (13 cases) or no treatment (13 controls). 502 cancer-related genes were examined by the DASL FFPE-based cDNA array. Sufficient RNA for gene expression analysis was obtained from 19/26 (73%) FFPE paired (biopsy and surgery) samples (8 controls, 11 anastrozole-treated patients

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Pilot trials in thrombosis: Purpose and pitfalls.

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Pilot trials in thrombosis: Purpose and pitfalls.

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