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K M Facey

Publications and source records attributed to K M Facey.

6 recordsLinked to original sources
PubMed1996

Comparison of the spending function method and the Christmas tree correction for group sequential trials.

Sequential designs for continuous monitoring can be derived from the theory of a Brownian motion process. In practice, infrequent analyses lead to a discrete monitoring process. In this paper, two methods proposed to correct for discrete monitoring are compared. The methods are used to create procedures similar to both the O'Brien and Fleming test and the triangular test and are compared in terms of the error rates. For the O'Brien and Fleming test, the spending function method is found to achieve the required error rates more accurately than the Christmas tree correction, while for the triangular test, both methods perform as planned.

Clinical Trials as Topic↗
PubMed1992

A sequential procedure for a phase II efficacy trial in hypercholesterolemia.

The design of a phase II placebo-controlled efficacy trial to evaluate a new treatment for hypercholesterolemia using a sequential procedure is presented. The sequential procedure used is the triangular test which offers flexibility of monitoring and allows early stopping even when the null hypothesis is "accepted." The primary response is reduction in total serum cholesterol level, which is assumed to be normally distributed with unknown variance. The treatment difference is parameterized in terms of the standardized difference between the means. The accuracy of the error rates of the triangular test using this parameterization is compared with the test based on the difference between the means.

Cholesterol↗
PubMed1990

An improved approximation for calculation of confidence intervals after a sequential clinical trial.

A method for the calculation of confidence intervals following a sequential clinical trial is proposed which is more accurate than methods based solely on continuous monitoring assumptions, but is not as computationally laborious as previous methods suggested for group sequential trials. The calculation takes account of the excess of the sample path over the boundary at the final inspection of the trial, which may be substantial after group sequential monitoring, and is ignored when continuous monitoring is assumed. Accuracy of such confidence intervals after a triangular test is investigated by simulation of coverage probabilities, individual confidence limit probabilities and p-value curves.

Clinical Trials as Topic↗
PubMedDate not supplied

Statistical shortcomings in licensing applications.

This paper concerns the statistical work carried out with respect to clinical trials conducted for regulatory purposes. Although the general quality of such work has improved markedly over recent years and is now generally high, a number of shortcomings remain. A few of these arise from failure to follow well established statistical practice. Rather more arise from a poor understanding of areas of known statistical disagreement and from the unsatisfactory use of newer and more advanced techniques. Inadequacies in reporting statistical work are commonplace. Examples of all these shortcomings are provided and emphasis is placed on the value of a statistical contribution to overall summaries such as the clinical expert report.

Clinical Trials, Phase II as Topic↗
PubMedDate not supplied

The management of interim analyses in drug development.

The ethical need for interim analyses in long-term trials of life-threatening conditions is well established, but recently there has been increased enthusiasm for the use of interim analyses in other areas of clinical research. Interim analysis is seen as a powerful tool in drug development to help reduce 'time to market' by allowing key decisions to be made earlier on the basis of one or more ongoing clinical trials. However, this goal can only be achieved without serious penalties if interim analyses are properly designed and executed, so that the integrity of the whole drug development programme is maintained. The purpose of this paper is to define procedures for the design and management of clinical trials which involve interim analyses. These procedures are intended to incorporate good clinical and statistical practice, hence maintaining high scientific standards not only of individual trials but also of the overall development programme. Aspects of design, conduct, analysis and dissemination of results are considered, with particular focus on the effective use of data monitoring committees in confirmatory efficacy trials.

Bias↗