Biomedical subjects

J Whitehead

Publications and source records attributed to J Whitehead.

98 records · Page 6Linked to original sources

PubMedDate not supplied

The design of a sequential clinical trial for the comparison of two lung cancer treatments.

The steps in designing a controlled trial to evaluate a new treatment for inoperable carcinoma of the bronchus are described. The principal outcome measure is survival time from treatment allocation, and the duration of the trial is determined by application of the sequential logrank test. The detailed determination of the stopping rule and the arrangements for analyses are described.

Carcinoma, Bronchogenic↗

PubMedDate not supplied

The analysis of a sequential clinical trial for the comparison of two lung cancer treatments.

Methods adopted in the analysis of data from a randomized controlled trial of a new treatment for inoperable lung cancer are described. The trial design employed the sequential logrank test using length of survival from time of randomization as the principal outcome measure. We describe the practical arrangements for regular inspections of the accumulating data as required by the sequential design, and also for more extensive but less formal interim analyses, and present some of the results. On termination of the trial the survival patterns of the two treatment groups were compared using methods of analysis developed specifically to allow for the sequential nature of the trial design. The role of prognostic factors was investigated using fixed sample methods which are approximately independent of the sequential design.

Clinical Trials as Topic↗

PubMedDate not supplied

Sample sizes for phase II and phase III clinical trials: an integrated approach.

In this paper the following problem of clinical research is explored. Several potential new treatments are available for use against a certain disease. These are evaluated in a series of pilot studies which will constitute phase II clinical trials. The most promising will then be compared with a standard treatment in a phase III trial. Of interest will be the number of patients needed for the complete research programme, the proportions of these that should be involved in each phase, and the number of treatments which should be tried. Optimal strategies are found which maximize the probability that the overall programme identifies a treatment which is significantly better than the standard.

Clinical Trials as Topic↗

PubMedDate not supplied

Sequential methods based on the boundaries approach for the clinical comparison of survival times.

The earliest formal sequential procedure, the sequential probability ratio test, involved the plotting of certain test statistics and comparison with straight line parallel boundaries. The boundaries approach can now be used with a wide variety of test statistics, including those appropriate to the analysis of survival data. The boundaries can take various forms, although the use of straight lines still eases the underlying mathematical theory while at least approximating to the requirements of the majority of clinical trials. The implementation of sequential methods needs to be made flexibly and sensitively, with each clinical trial meriting an individualized approach.

Bias↗

PubMedDate not supplied

Sample sizes for phase II clinical trials derived from Bayesian decision theory.

In early phase clinical trials of a new medical treatment, patients are treated to decide whether there is sufficient promise to justify additional studies. A decision theoretic approach is proposed to help determine the number of patients that should be treated. The optimal sample size is obtained by maximizing a utility function which incorporates both the number of 'gained successes' and the costs of treatment. The method extends work of Sylvester and Staquet, and adopts a Bayesian formulation. Numbers of patients in later studies and in eventual routine use of the treatment are taken into account. We allow for the possibility that a later study might lead to an erroneous conclusion. The effects of these various influences on the recommended sampling plan for the early phase clinical trial are explored.

Bayes Theorem↗

PubMedDate not supplied

Bayesian decision procedures for dose determining experiments.

This paper describes the Bayesian decision procedure and illustrates the methodology through an application to dose determination in early phase clinical trials. The situation considered is quite specific: a fixed number of patients are available, to be treated one at a time, with the choice of dose for any patient requiring knowledge of the responses of all previous patients. A continuous range of possible doses is available. The prior beliefs about the dose-response relationship are of a particular form and the gain from investigation is measured in terms of statistical information gathered. How all of these specifications may be varied is discussed. A comparison with the continual reassessment method is made.

Bayes Theorem↗

PubMedDate not supplied

Progressive nonfluent aphasia with dementia: a case report.

We report a patient with progressive nonfluent aphasia and mild dementia. On 9-month follow-up evaluation, there was significant deterioration in both language and cognition. Unlike in Alzheimer's disease, the aphasia was of the Broca's type. In contrast with primary progressive aphasia, a dementia was present and the cognitive and language decline showed a rather rapid course.

Alzheimer Disease↗

PubMedDate not supplied

Newly qualified staff nurses' perceptions of the role transition.

This article describes the findings of a research project that explored the perceptions of staff nurses (who had been qualified for a maximum of 1 year) on the role transition from student nurse to newly qualified staff nurse. A convenience sample of six staff nurses employed by one NHS trust was studied. Data were collected by using audiotaped semistructured interviews. The findings revealed that the transition phase from student nurse to staff nurse is a fraught time and that a perceived lack of knowledge and support during the transition phase was a major cause of anxiety. The research has demonstrated that there is a need for support during the transition phase from student to newly qualified staff nurse. It is recommended that a structured preceptorship programme on qualification is essential (UKCC, 1999).

Adaptation, Psychological↗