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Postgraduate Medical Journal Apr 2005
Topics: Causality; Clinical Trials as Topic; Sensitivity and Specificity; Treatment Outcome
PubMed: 15811880
DOI: 10.1136/pgmj.2004.026807 -
European Heart Journal Jul 2011The assessment of treatment effects from observational studies may be biased with patients not randomly allocated to the experimental or control group. One way to... (Review)
Review
The assessment of treatment effects from observational studies may be biased with patients not randomly allocated to the experimental or control group. One way to overcome this conceptual shortcoming in the design of such studies is the use of propensity scores to adjust for differences of the characteristics between patients treated with experimental and control interventions. The propensity score is defined as the probability that a patient received the experimental intervention conditional on pre-treatment characteristics at baseline. Here, we review how propensity scores are estimated and how they can help in adjusting the treatment effect for baseline imbalances. We further discuss how to evaluate adequate overlap of baseline characteristics between patient groups, provide guidelines for variable selection and model building in modelling the propensity score, and review different methods of propensity score adjustments. We conclude that propensity analyses may help in evaluating the comparability of patients in observational studies, and may account for more potential confounding factors than conventional covariate adjustment approaches. However, bias due to unmeasured confounding cannot be corrected for.
Topics: Analysis of Variance; Bias; Clinical Trials as Topic; Confounding Factors, Epidemiologic; Humans; Propensity Score; Treatment Outcome
PubMed: 21362706
DOI: 10.1093/eurheartj/ehr031 -
Pain Physician 2009Diagnosis is a critical component of health care. The world of diagnostic tests is highly dynamic. New tests are developed at a fast pace and technology of existing... (Review)
Review
Diagnosis is a critical component of health care. The world of diagnostic tests is highly dynamic. New tests are developed at a fast pace and technology of existing tests is continuously being improved. However, clinicians, policy makers, and patients routinely face a range of questions regarding diagnostic tests. Well designed diagnostic test accuracy studies can help in making these decisions, provided that they transparently and fully report their participants, tests, methods, and results (as facilitated). For example, by the standards for the reporting of diagnostic accuracy studies (STARD) statement. Exaggerated and biased results from poorly designed and reported diagnostic test studies can trigger their premature dissemination and lead physicians into making incorrect treatment decisions. Thus, a diagnostic test is useful only to the extent that it distinguishes between conditions or disorders that might otherwise be confused. While almost any test can differentiate healthy persons from severely affected ones, appropriate diagnostic tests should differentiate mild and moderate forms of disease. Shortcomings in a study design and interpretation can affect estimates of diagnostic accuracy. Thus, quality diagnostic studies are essential in medicine in general and interventional pain management in particular. The STARD initiative was developed to improve the accuracy and completeness in the reporting of studies of diagnostic accuracy and provide guidance to assist in reducing the potential for bias in the study and to evaluate a study's generalizability. In the practice of interventional pain management, in addition to diagnostic tests which include laboratory tests, imaging tests, and physical examination, diagnostic interventional techniques are crucial. Interventional techniques as a diagnostic tool in painful conditions is important due to multiple challenging clinical situations, which include the purely subjective nature of pain and underdetermined and uncertain pathophysiology in most painful spinal conditions. Precision diagnostic blocks are used to clarify these challenging clinical situations in order to determine the pathophysiology of clinical pain, the site of nociception, and the pathway of afferent neural signals. Part 5 of evidence-based medicine (EBM) in interventional pain management describes the various aspects of diagnostic accuracy studies.
Topics: Clinical Protocols; Clinical Trials as Topic; Data Interpretation, Statistical; Diagnosis, Differential; Diagnostic Tests, Routine; Evidence-Based Medicine; Humans; Pain; Practice Guidelines as Topic; Predictive Value of Tests; Reproducibility of Results; Research Design
PubMed: 19461821
DOI: No ID Found -
Annals of Oncology : Official Journal... Dec 2004Transcriptional profiling technologies that simultaneously measure the expression of thousands of mRNA species represent a powerful new clinical research tool. Similar... (Review)
Review
Transcriptional profiling technologies that simultaneously measure the expression of thousands of mRNA species represent a powerful new clinical research tool. Similar to previous laboratory analytical methods including immunohistochemistry, PCR and in situ hybridization, this new technology may also find its niche in routine diagnostics. Outcome predictors discovered by these methods may be quite different from previous single-gene markers. These novel tests will probably combine the information embedded in the expression of multiple genes with mathematical prediction algorithms to formulate classification rules and predict outcome. The performance of machine learning-algorithm-based diagnostic tests may improve as they are trained on larger and larger sets of samples, and several generations of tests with improving accuracy may be introduced sequentially. Several gene-expression profiling-technology platforms are mature enough for clinical testing. The most important next step that is needed for further progress is the development and validation of multigene predictors in prospectively designed clinical trials to determine the true accuracy and clinical value of this new technology. This manuscript reviews methodological and statistical issues relevant to clinical trial design to discover and validate multigene predictors of response to therapy.
Topics: Clinical Trials as Topic; Endpoint Determination; Gene Expression Profiling; Genetic Markers; Humans; In Situ Hybridization; Neoplasms; Oligonucleotide Array Sequence Analysis; Polymerase Chain Reaction; Predictive Value of Tests; Prognosis; Research Design; Treatment Outcome
PubMed: 15550577
DOI: 10.1093/annonc/mdh466 -
Trials May 2015Some reasons for registering trials might be considered as self-serving, such as satisfying the requirements of a journal in which the researchers wish to publish their...
Some reasons for registering trials might be considered as self-serving, such as satisfying the requirements of a journal in which the researchers wish to publish their eventual findings or publicising the trial to boost recruitment. Registry entries also help others, including systematic reviewers, to know about ongoing or unpublished studies and contribute to reducing research waste by making it clear what studies are ongoing. Other sources of research waste include inconsistency in outcome measurement across trials in the same area, missing data on important outcomes from some trials, and selective reporting of outcomes. One way to reduce this waste is through the use of core outcome sets: standardised sets of outcomes for research in specific areas of health and social care. These do not restrict the outcomes that will be measured, but provide the minimum to include if a trial is to be of the most use to potential users. We propose that trial registries, such as ISRCTN, encourage researchers to note their use of a core outcome set in their entry. This will help people searching for trials and those worried about selective reporting in closed trials. Trial registries can facilitate these efforts to make new trials as useful as possible and reduce waste. The outcomes section in the entry could prompt the researcher to consider using a core outcome set and facilitate the specification of that core outcome set and its component outcomes through linking to the original core outcome set. In doing this, registries will contribute to the global effort to ensure that trials answer important uncertainties, can be brought together in systematic reviews, and better serve their ultimate aim of improving health and well-being through improving health and social care.
Topics: Clinical Trials as Topic; Endpoint Determination; Humans; Practice Guidelines as Topic; Registries; Research Design; Treatment Outcome
PubMed: 25971905
DOI: 10.1186/s13063-015-0738-6 -
Circulation Jul 2019Heart failure with preserved ejection fraction (HFpEF) is common, yet there is currently no consensus on how to define HFpEF according to various society and clinical...
BACKGROUND
Heart failure with preserved ejection fraction (HFpEF) is common, yet there is currently no consensus on how to define HFpEF according to various society and clinical trial criteria. How clinical and hemodynamic profiles of patients vary across definitions is unclear. We sought to determine clinical characteristics, as well as physiologic and prognostic implications of applying various criteria to define HFpEF.
METHODS
We examined consecutive patients with chronic exertional dyspnea (New York Heart Association class II to IV) and ejection fraction ≥50% referred for comprehensive cardiopulmonary exercise testing with invasive hemodynamic monitoring. We applied societal and clinical trial HFpEF definitions and compared clinical profiles, exercise responses, and cardiovascular outcomes.
RESULTS
Of 461 patients (age 58±15 years, 62% women), 416 met American College of Cardiology/American Heart Association (ACC/AHA), 205 met European Society of Cardiology (ESC), and 55 met Heart Failure Society of America (HFSA) criteria for HFpEF. Clinical profiles and exercise capacity varied across definitions, with peak oxygen uptake of 16.2±5.2 (ACC/AHA), 14.1±4.2 (ESC), and 12.7±3.1 mL·kg·min (HFSA). A total of 243 patients had hemodynamic evidence of HFpEF (abnormal rest or exercise filling pressures), of whom 222 met ACC/AHA, 161 met ESC, and 41 met HFSA criteria. Over a mean follow-up of 3.8 years, the incidence of cardiovascular outcomes ranged from 75 (ACC/AHA) to 298 events per 1000 person-years (HFSA). Application of clinical trial definitions of HFpEF similarly resulted in distinct patient classification and prognostication.
CONCLUSIONS
Use of different HFpEF classifications variably enriches for future cardiovascular events, but at the expense of not including up to 85% of individuals with physiologic evidence of HFpEF. Comprehensive phenotyping of patients with suspected heart failure highlights the limitations and heterogeneity of current HFpEF definitions and may help to refine HFpEF subgrouping to test therapeutic interventions.
Topics: Adult; Aged; Clinical Trials as Topic; Cohort Studies; Dyspnea; Exercise Test; Exercise Tolerance; Female; Heart Failure; Humans; Male; Middle Aged; Stroke Volume; Treatment Outcome
PubMed: 31132875
DOI: 10.1161/CIRCULATIONAHA.118.039136 -
Trials Aug 2022Diabetic macular ischaemia (DMI) is a complication of diabetic retinopathy that leads to irreversible vision loss. DMI is characterised by reduced retinal vessel density...
HORNBILL: a phase I/IIa trial examining the safety, tolerability and early response of BI 764524 in patients with diabetic retinopathy and diabetic macular ischaemia-rationale, study design and protocol.
BACKGROUND
Diabetic macular ischaemia (DMI) is a complication of diabetic retinopathy that leads to irreversible vision loss. DMI is characterised by reduced retinal vessel density and enlargement of the foveal avascular zone (FAZ). Despite its clinical burden, there is no formal consensus on the definition of DMI, and no approved treatment. Semaphorin 3A (Sema3A) is an axonal guidance molecule that blocks revascularisation of the ischaemic retina. Sema3A modulation is therefore a promising mechanism of action for the treatment of ischaemic eye diseases. BI 764524 is an intravitreal anti-Sema3A ischaemia modulator agent.
METHODS
HORNBILL (NCT04424290) is a phase I/IIa trial comprising a non-randomised, open-label, single rising dose (SRD) part and a randomised, masked, sham-controlled multiple dose (MD) part to investigate the safety, tolerability and early biological response of ischaemia modulator BI 764524 in adults (≥18 years) with DMI. DMI will be defined using optical coherence tomography angiography (OCTA) as either any degree of disruption in the retinal vascularity (SRD) or a FAZ of ≥0.5 mm (MD). Subjects in the SRD part will receive 0.5, 1.0 or 2.5 mg of BI 764524; the maximum tolerated dose will then be used in the MD part. A minimum of 12 subjects will be enrolled into the SRD part; planned enrollment is 30 for the MD part. The primary endpoint of the SRD part is the number of subjects with dose-limiting adverse events (AEs) until day 8. The primary endpoint of the MD part is the number of subjects with drug-related AEs from baseline to end of study, and secondary endpoints include change from baseline in the size of the FAZ, best-corrected visual acuity and central retinal thickness.
DISCUSSION
DMI is a poorly defined condition with no treatment options. HORNBILL is the first clinical trial to assess a treatment for DMI and to use OCTA as a means to define and examine DMI. The OCTA data generated in this trial could form the basis of formal diagnostic criteria for DMI. Furthermore, the novel mechanism of action (Sema3A modulation) explored in this trial has the potential to revolutionise the treatment landscape for patients with DMI.
TRIAL REGISTRATION
ClinicalTrials.gov NCT04424290 ; EudraCT 2019-004432-28. Registered on 9 June 2020.
Topics: Adult; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Diabetes Mellitus; Diabetic Retinopathy; Fluorescein Angiography; Humans; Ischemia; Macula Lutea; Randomized Controlled Trials as Topic; Tomography, Optical Coherence; Visual Acuity
PubMed: 35978329
DOI: 10.1186/s13063-022-06527-y -
Association between trial registration and treatment effect estimates: a meta-epidemiological study.BMC Medicine Jul 2016To increase transparency in research, the International Committee of Medical Journal Editors required, in 2005, prospective registration of clinical trials as a...
BACKGROUND
To increase transparency in research, the International Committee of Medical Journal Editors required, in 2005, prospective registration of clinical trials as a condition to publication. However, many trials remain unregistered or retrospectively registered. We aimed to assess the association between trial prospective registration and treatment effect estimates.
METHODS
This is a meta-epidemiological study based on all Cochrane reviews published between March 2011 and September 2014 with meta-analyses of a binary outcome including three or more randomised controlled trials published after 2006. We extracted trial general characteristics and results from the Cochrane reviews. For each trial, we searched for registration in the report's full text, contacted the corresponding author if not reported and searched ClinicalTrials.gov and the International Clinical Trials Registry Platform in case of no response. We classified each trial as prospectively registered (i.e. registered before the start date); retrospectively registered, distinguishing trials registered before and after the primary completion date; and not registered. Treatment effect estimates of prospectively registered and other trials were compared by the ratio of odds ratio (ROR) (ROR <1 indicates larger effects in trials not prospectively registered).
RESULTS
We identified 67 meta-analyses (322 trials). Overall, 225/322 trials (70 %) were registered, 74 (33 %) prospectively and 142 (63 %) retrospectively; 88 were registered before the primary completion date and 54 after. Unregistered or retrospectively registered trials tended to show larger treatment effect estimates than prospectively registered trials (combined ROR = 0.81, 95 % CI 0.65-1.02, based on 32 contributing meta-analyses). Trials unregistered or registered after the primary completion date tended to show larger treatment effect estimates than those registered before this date (combined ROR = 0.84, 95 % CI 0.71-1.01, based on 43 contributing meta-analyses).
CONCLUSIONS
Lack of trial prospective registration may be associated with larger treatment effect estimates.
Topics: Bias; Biomedical Research; Clinical Protocols; Clinical Trials as Topic; Humans; Meta-Analysis as Topic; Publications; Research Design; Treatment Outcome
PubMed: 27377062
DOI: 10.1186/s12916-016-0639-x -
Kidney International Jun 2013Clinical trials in nephrology have focused on achieving targets, supplementing deficiencies, and correcting excesses in order to improve patient outcomes. The majority... (Review)
Review
Clinical trials in nephrology have focused on achieving targets, supplementing deficiencies, and correcting excesses in order to improve patient outcomes. The majority of interventions have failed to demonstrate benefit and some have caused harm. It may be that therapies aiming to 'normalize' parameters may actually disturb evolutionary adaptation, thus causing harm. By refocusing on the physiology of disease, and complexity of adaptation, we may design better trials. We review successful and unsuccessful trials in nephrology and other disciplines and suggest a set of principles by which to design future clinical trials:(1) acknowledge heterogeneity of chronic kidney disease populations and appropriately characterize populations for studies; (2) develop better validated biomarkers (through proteomics, genomics, and metabolomics) to identify responders and nonresponders to interventions; (3) design interventions that mimic physiological processes without collateral detrimental effects; (4) reconsider the status of the randomized-controlled trial as the only 'gold standard' and perform large-scale pragmatic trials comparing current care with the intervention(s) of interest, and (5) broaden nephrology research culture so that the majority of patients are enrolled into observational cohorts and intervention studies, which foster greater knowledge acquisition and dissemination. Improved understanding of pathophysiological mechanisms, in conjunction with more innovative but stringent clinical trial design, will ultimately lead to improved patient outcomes.
Topics: Clinical Trials as Topic; Diffusion of Innovation; Disease Progression; Health Services Research; Humans; Kidney Diseases; Nephrology; Patient Outcome Assessment; Patient Selection; Quality Indicators, Health Care; Research Design; Translational Research, Biomedical; Treatment Outcome
PubMed: 23515054
DOI: 10.1038/ki.2013.91 -
Stroke Sep 2013
Review
Topics: Brain; Brain Ischemia; Clinical Trials as Topic; Humans; Neuroimaging; Stroke
PubMed: 23860298
DOI: 10.1161/STROKEAHA.113.002015