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Results for “Empirical Approach”

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PubMed2002

Bayesian approach to evaluation of bridging studies.

We address the issue of analysis of clinical data generated by the bridging study conducted in the new region to evaluate the similarity for extrapolation of the foreign clinical data. A bridging study is usually conducted in the new region only after the test product is approved for commercial marketing in the original region due to its proven efficacy and safety. Sufficient information on efficacy, safety, dosage, and dose regimen has already generated in the original region. The empirical Bayesian approach is proposed to synthesize the data generated by the bridging study and foreign clinical data generated in the original region for assessment of similarity between the new and the original regions. A method for sample size determination for the bridging study is also suggested. It can be shown that the total sample size is inversely proportional to the strength of the evidence for the efficacy presented in the original region and the proportion of the patients assigned to receive the test product in the bridging study.

Algorithms↗

PubMed1992

Prediction of the volume of distribution of 7-hydroxycoumarin in man from in vitro and ex vivo data obtained in rat.

The essential parameter to estimate the first dose size of a drug in man is the volume of distribution. For a drug that has never been used in man before, estimates of the volume of distribution can only be obtained from animals and in vitro data. The purpose of this study was to compare various approaches presented in the literature for predicting the volume of distribution at steady state (VSS) and the terminal phase volume of distribution (Vd beta) in man. A lipophilic active metabolite of coumarin, 7-hydroxycoumarin (7OHC), was selected for this investigation. This compound is extensively metabolized in both the central and peripheral compartments. Of the six methods evaluated, only an empirical allometric approach yielded a reasonable estimate of VSS. All methods underestimated VSS and none of the applicable methods were able to predict Vd beta. The reason for this discrepancy may be due to the fact that the calculation of VSS in man was done assuming elimination from the central compartment.

Animals↗

PubMed1995

Scientific and ethical concerns in clinical trials in Alzheimer's patients: the bridging study.

This paper reviews the scientific and ethical issues surrounding the conduct of bridging studies in patients with Alzheimer's disease (AD). Bridging studies, so called because they facilitate the transition from phase I to phase II development, are late phase I safety/tolerance studies which determine the maximum tolerated dose (MTD) in patients before initiating phase II efficacy studies. Determining the MTD in patients is important because we have found that AD patients appear to respond to cholinergic compounds differently from normal volunteers, reaching a different MTD. Preliminary evidence of dose-related efficacy with two cholinergic compounds lends support to our contention that determination of the highest tolerated dose maximizes the potential to detect efficacy. We will review the early clinical development of several cholinergic compounds and make recommendations for the design and conduct of bridging studies based on our experience. A fixed-dose panel design with dosages based on the MTD determined in normal volunteers is recommended. In order to minimize risk to the patients, ensuring that scientific benefits outweigh the risks, a bridging study must be supported by detailed preclinical toxicology, by a clinical research unit that is prepared to handle unexpected contingencies, and by the oversight of a competent, multi-disciplinary review board. Patients should be in good physical health (excluding AD), and a comprehensive informed consent procedure must be instituted. Carefully planned and well run bridging studies represent a scientifically and ethically sound approach to drug development in the Alzheimer's population.

Alzheimer Disease↗

PubMed2003

Changes in the components of moral reasoning during students' medical education: a pilot study.

INTRODUCTION: Many authors are concerned by students' moral reasoning not developing normally during medical education. AIM: This study is concerned with how the components of student' moral reasoning are affected by their medical studies. METHODS: Ninety-two medical students were tested on entry into first year and on finishing third year, to determine evolutionary changes in their moral reasoning. Changes in their use of arguments specific to each stage of moral development were measured. RESULTS: Significant changes were observed in the weighted global score (-18.14 +/- 59.17, P = 2.8%). Changes in global score correlated with changes in stages of moral reasoning. The multivariate structure of moral reasoning was reorganised into two principal components, which, respectively, explained almost 82% (first year) and 72% (third year) of the total variability in scores. Moral reasoning stages characterized by law-and-order and social-contract/legalistic orientations proved important for explaining the variability in students' moral reasoning at the start of medical training, while instrumental-relativist and interpersonal-concordance orientations explained variability post third year. CONCLUSIONS: Students restructure their handling of ethical questions by using arguments with more instrumental-relativist and interpersonal-concordance orientations, rather than those of the more desirable law-and-order or social-contract/legalistic type. To assess better the skills required for moral reasoning, a more sophisticated approach is needed than that of a simple measure of improvement/stagnation/deterioration.

Adult↗

PubMed1992

Alternative approaches to the analysis of binary and categorical repeated measurements.

The purpose of this paper is to describe, illustrate, and compare a number of different approaches to the analysis of repeated binary and categorical data. These approaches include empirical generalized least squares and generalized estimating equations, as well as traditional log-linear modeling methods. It is shown that the interpretation of the parameters in the various models depends critically on the type of model fitted. In particular, we contrast the population-averaged and subject-specific models. Two example data sets are used to illustrate the approaches, and throughout we concentrate on methods that can be easily implemented.

Clinical Trials as Topic↗

PubMed2006

Oncologists' opinions about research ethics committees in Italy: an update, 2004.

While there is general consensus about the basic features of ethical research, the explosion of information from technology, genetics and clinical research, and the desire to accelerate the translation of preliminary findings into clinical research and practice have created space for conflicts between the aims of research, medical ethics and human rights. Research ethics committees (RECs) play a crucial role. In 2004, a short standardized questionnaire was sent to 110 Italian oncologists. The questionnaire explored aspects of the interaction between oncologists and RECs, including reports on personal experience with RECs, and the oncologists' opinions and level of satisfaction with important functions of RECs, such as bureaucratic, ethics, scientific, and educational and training aspects. The findings are compared with those from the previous surveys. Eighty-three out of the 91 oncologists returned the questionnaire. Responders were working in 67 hospitals (60 RECs). The level of satisfaction with REC activities was high for ethical and scientific aspects (87 and 80% were satisfied or very satisfied, respectively); somewhat lower for bureaucratic and secretarial aspects (61%); and much lower for educational and formation activities (33%). Comparison with other surveys does not show any important difference. The main findings of this survey are the stable figures concerning oncologists' opinions and the low ratings given to education and training aspects. This latter finding clearly identifies the need for educational activities, and the possibility of using this approach to foster interactions between RECs and researchers.

Attitude of Health Personnel↗

PubMed2004

Management of implantable cardioverter defibrillators in end-of-life care.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) can prevent premature death from an arrhythmia but may also prolong the dying process and make it more distressing. OBJECTIVE: To describe the frequency, timing, and correlates of discussions about deactivating ICDs. DESIGN: Retrospective cohort study. SETTING: Telephone survey. PARTICIPANTS: Next of kin of patients with ICDs who died of any cause. Of 136 next of kin contacted, 100 (74%) participated. MEASUREMENTS: Incidence of discussions about deactivating ICDs and timing of last shock from ICD. RESULTS: Next of kin reported that clinicians discussed deactivating the ICD in only 27 of the 100 cases. Most discussions occurred in the last few days of life. Family members reported that 8 patients received a shock from their ICD in the minutes before death. LIMITATIONS: This retrospective survey relied on the reports of next of kin. CONCLUSIONS: Next of kin reported that clinicians discussed deactivating ICDs with few patients. Individuals who choose to receive this device should have the opportunity to choose to discontinue it as death approaches.

Aged↗

PubMed1991

From hopeful to hopeless ... when do we write "do not resuscitate"?

The issue of do not resuscitate (DNR) decisions has been the subject of much discussion in the medical literature. To try to understand the factors that may be determinants of the timing of DNR decisions, we reviewed the charts of 70 consecutive burned patients who died between 1986 and 1988. When a DNR decision was written, it was within 48 hours of the patient's death (74% of patients). No statistical difference was found in the sex distribution or in the percentage of body surface area burned in the DNR group and in the resuscitation group. Physicians, nurses, social workers, the hospital attorney, the district attorney, and the coroner of our county were interviewed. The uncertainty of legal guidelines and practical considerations of family expectations preclude a uniform approach to this problem.

Adult↗

PubMed2002

Effects of models of rate evolution on estimation of divergence dates with special reference to the metazoan 18S ribosomal RNA phylogeny.

The molecular clock, i.e., constancy of the rate of evolution over time, is commonly assumed in estimating divergence dates. However, this assumption is often violated and has drastic effects on date estimation. Recently, a number of attempts have been made to relax the clock assumption. One approach is to use maximum likelihood, which assigns rates to branches and allows the estimation of both rates and times. An alternative is the Bayes approach, which models the change of the rate over time. A number of models of rate change have been proposed. We have extended and evaluated models of rate evolution, i.e., the lognormal and its recent variant, along with the gamma, the exponential, and the Ornstein-Uhlenbeck processes. These models were first applied to a small hominoid data set, where an empirical Bayes approach was used to estimate the hyperparameters that measure the amount of rate variation. Estimation of divergence times was sensitive to these hyperparameters, especially when the assumed model is close to the clock assumption. The rate and date estimates varied little from model to model, although the posterior Bayes factor indicated the Ornstein-Uhlenbeck process outperformed the other models. To demonstrate the importance of allowing for rate change across lineages, this general approach was used to analyze a larger data set consisting of the 18S ribosomal RNA gene of 39 metazoan species. We obtained date estimates consistent with paleontological records, the deepest split within the group being about 560 million years ago. Estimates of the rates were in accordance with the Cambrian explosion hypothesis and suggested some more recent lineage-specific bursts of evolution.

Algorithms↗

PubMed2005

Public knowledge and attitudes toward organ donation and transplantation: a cross-cultural study.

OBJECTIVE: The aim of this study was to determine the knowledge, attitudes, awareness, and determinants of organ donation and transplantation in a Qatari population. DESIGN: This is a cross-sectional study to determine the knowledge and attitude toward organ donation in a Peninsula Arabian Gulf country. SETTING: The setting was Primary Health Care (PHC) Centers and community-based study in Qatar. SUBJECTS: A multistage sampling design was used in a representative sample of 1600 Qataris and non-Qataris, including males and females of at least 17 years of age, from October 2003 to May 2004. In this study a 1305 (81.5%) subjects participated, each giving consent for the study. MEASUREMENTS: Participants completed a questionnaire assessing their knowledge, attitudes, and awareness for organ donation. RESULTS: Of 1305 samples, 637 (48.8%) males and 668 females (51.2%) living in urban and semiurban areas agreed to participate and complete the questionnaire. Of these, 762 (58.4%) were Qataris. There was a significant difference between Qataris and non-Qataris with respect to their age, educational level, monthly income, and occupation. In this study, 31.6% of Qataris and 29.8% of non-Qataris had no idea about the organ donation; 37.8% of Qataris and 32.8% of non-Qataris were willing to donate their organs. The majority of subjects preferred donating organs to their close relatives and friends. However, 83.8% of the studied subjects did not agree with an incentive-based approach for donating organs. CONCLUSION: This study showed that people should not be blamed for not being willing to participate in organ donation, but the health system and health education providers are responsible. A more effective approach should be tried regarding health education.

Cross-Cultural Comparison↗

PubMed2001

Evaluating palliative care: facilitating reflexive dialogues about an ambiguous concept.

Palliation is a relatively new concept that is used in connection with the integral care provided to those who are unable to recover from their illness. The specific meaning of the concept has not been clearly defined. This article explores the possibilities offered by a responsive approach to evaluation that can facilitate a reflexive dialogue on this ambiguous concept. In doing so it draws on a case study of a palliative care project in a Dutch health care authority. The article begins with an overview of the characteristics of a responsive approach to evaluation and addresses interpretative, representational and practical dilemmas. It goes on to present a series of dialogues between health professionals, informal caregivers, patients and evaluators. These dialogues take the form of juxtaposed stories, transcribed conversations and interpretations. Finally, the learning experiences are summarised and the appropriateness of the responsive approach to evaluate palliative care is discussed.

Ethics↗

PubMedDate not supplied

Methodological issues associated with studying an illegal act: assisted dying.

The experience of receiving patient requests for assistance in prematurely ending life can represent both an ethical and legal dilemma for nurses in the United States. Similarly, the study of nurses' involvement with such a sensitive topic also poses risks to the study participants, the researcher, and the nursing profession's covenant with society. The purpose of this article is to explore methodological issues and approaches associated with studying an ethically and legally sensitive issue, and to describe application of these approaches to a study of oncology nurses' experiences with receiving requests for assisted dying from terminally ill patients with cancer.

Confidentiality↗

PubMedDate not supplied

Framing the decision: determinants of how women considering multifetal pregnancy reduction as a pregnancy-management strategy frame their moral dilemma.

OBJECTIVE: How people make decisions regarding medical technologies and procedures are affected by how they 'frame' those decisions. Medical frames are characterized by a reliance on statistics regarding outcomes and risk to mother and surviving embryos, emphasize the influence of medical authorities, and are driven by a desire to minimize medical risks. Moral frames, on the other hand, are driven more by a desire to minimize the disruption to antiabortion and antireduction moral precepts, and weight heavily the advice of religious leaders. These frames contest with one another. Our objective is to examine the biographical determinants of frame dominance in this contest as it applies to multigestation pregnancies where selective reduction is being considered as a pregnancy-management strategy. METHODS: For a sample of 55 multigestation women considering multifetal reduction as a pregnancy-management strategy, we develop a distinction between medical and moral frames. Semistructured interviews generated qualitative data that were independently coded by two researchers. These variables were then analyzed using dummy variable regression analysis. RESULTS: Conceptualizing these frames as anchoring opposite ends of a continuum, we show that 40% of the variance in frame dominance can be accounted for by three factors: how involved patients are in religious institutions that have antiabortion norms, whether they have medico-scientific careers, and how pro-reduction their advice has been from fertility specialists and obstetricians prior to coming to the clinic. CONCLUSIONS: The implication of these results for practice include recognizing the wide variation in patient's perceptions of their situations and how these perceptual frames alter how women confront risk-benefit statistics and being flexible in one's approach to counseling patients. This approach can further serve as a model for similar reproductive-health dilemmas.

Career Choice↗

PubMed2006

Average dispersal success: linking home range, dispersal, and metapopulation dynamics to reserve design.

Spatially explicit models for populations are often difficult to tackle mathematically and, in addition, require detailed data on individual movement behavior that are not easily obtained. An approximation known as the "average dispersal success" provides a tool for converting complex models, which may include stage structure and a mechanistic description of dispersal, into a simple matrix model. This simpler matrix model has two key advantages. First, it is easier to parameterize from the types of empirical data typically available to conservation biologists, such as survivorship, fecundity, and the fraction of juveniles produced in a study area that also recruit within the study area. Second, it is more amenable to theoretical investigation. Here, we use the average dispersal success approximation to develop estimates of the critical reserve size for systems comprising single patches or simple metapopulations. The quantitative approach can be used for both plants and animals; however, to provide a concrete example of the technique's utility, we focus on a special case pertinent to animals. Specifically, for territorial animals, we can characterize such an estimate of minimum viable habitat area in terms of the number of home ranges that the reserve contains. Consequently, the average dispersal success framework provides a framework through which home range size, natal dispersal distances, and metapopulation dynamics can be linked to reserve design. We briefly illustrate the approach using empirical data for the swift fox (Vulpes velox).

Animals↗

PubMed1995

Involving consumers in health care decision making.

This paper considers ways of involving consumers in decisions regarding the allocation of scarce health service resources. Specifically, two levels of consumer participation are highlighted and discussed. These are: (1) at the level of deciding whether or not a particular service should be introduced or its scale changed; and (2) at the level of deciding how best to provide a service once it has been decided that the service will be provided. The limitations of the current methods of involving consumers are outlined and two alternative approaches discussed. These are willingness to pay and conjoint analysis.

Community Participation↗

PubMed2004

Study of the involvement of research ethics committees in the constitution and use of biobanks in France.

Concerns are emerging about the protection of individuals who take part in genetic research involving biobanks. We used several items of a questionnaire sent to 48 French research ethics committees (RECs) to investigate the means by which they evaluate the constitution and use of biobanks, and the elements on which conclusions were based. Most RECs felt they should evaluate the constitution of biobanks in protocols, but not all did so in practice. Harmonization of the competence of RECs for evaluating biobanks is required, particularly concerning information, consent, the duration of sample conservation and the communication of research results. Our results, together with those of others, demonstrate the need to develop rules and guidelines based on common ethical approaches, particularly in the European environment.

Bioethical Issues↗

PubMed1998

In search of a new ethic for treating patients with chronic pain: what can medical boards do?

Author argues that a complex "ethic of underprescribing" underlies the continued reluctance of physicians to use opioids to treat chronic pain. She contends that state medical boards are uniquely positioned to promote a new ethic for pain management, but stresses the difficulties for boards in attaining this goal. She thinks success may hinge on whether boards can change their approach to pain management and persuade a skeptical medical community that adopting a risk for underprescribing will serve the long-term interests of patients and the profession.

Analgesics, Opioid↗

PubMedDate not supplied

Nationwide practices for screening and reporting prenatal cocaine abuse: a survey of teaching programs.

Questionnaires surveying policies and opinions about prenatal cocaine abuse were sent to training programs nationwide. Eighty-one pediatric and 81 obstetric programs from 42 states responded. Although respondents favored routinely screening all patients by maternal history (81%) and by urine toxicology (36%), only 64% and 8%, respectively, reported these as established policy. Physicians reporting higher regional prenatal cocaine abuse rates more commonly favored universal perinatal screening (p = .009), but established policies were similar regardless of local prevalence (p = .19). Fifty-two percent of respondents were unaware of their state's requirements for reporting prenatal cocaine abuse. While most physicians favored interventions such as voluntary drug rehabilitation (64%) and family support services (64%), some physicians favored foster care placement for the infants (28%) and involuntary drug rehabilitation (31%). Only 3% felt that criminal prosecution of the mother was appropriate. Policies for managing prenatal cocaine abuse often did not reflect physicians' opinions. A multidisciplinary medical, social, and legal approach is needed to develop effective management policies.

Cocaine↗