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Biomedical subjects

D McSherry

Publications and source records attributed to D McSherry.

6 recordsLinked to original sources
PubMed1999

Dynamic and static approaches to clinical data mining.

In sequential diagnosis, the usefulness of a test can be assessed only in the context of a chosen diagnostic strategy, and depends on the evidence provided by previous test results. Choosing the most useful test at each stage of the evidence-gathering process therefore requires a dynamic approach to data analysis. An implementation of such an approach in an intelligent program for sequential diagnosis based on the evidence-gathering strategies used by doctors is described. On the other hand, a static approach to data analysis is appropriate in the discovery of knowledge required, for example, to explain or justify a diagnosis by identifying the most important findings, both positive and negative, on which the diagnosis is based. An algorithm for the discovery of features which always provide evidence in favour of, or against, a diagnosis selected by the data miner is presented. Dominance relationships among features in the data set are also discovered such that if one feature dominates another, it always provides more evidence in favour of the diagnosis, or less evidence against it.

Abdominal Pain↗
PubMed1997

Avoiding premature closure in sequential diagnosis.

An important aspect of diagnostic reasoning is the ability to recognise when there is sufficient evidence to enable a working diagnosis to be made and thus avoid the unnecessary risks and costs of further testing. On the other hand, the reasoner must be careful to avoid the error, known as premature closure, of accepting a diagnosis before it is fully verified. In the absence of a more rigorous approach to verification, a pragmatic approach adopted in many programs for sequential diagnosis is to discontinue testing when the probability of the leading hypothesis reaches an arbitrary threshold. Experimental results are presented to illustrate the potential unreliability of this approach. A more reliable way to avoid premature closure is to discontinue testing only when the lower bound for the probability of the leading hypothesis reaches an acceptably high level. For example, a lower bound of 70% means that its probability can never be less than 70% regardless of any evidence that further testing may reveal. Another reason to discontinue testing may be that further evidence can at best increase the probability of the leading hypothesis by a small amount. For example, if the probability of the leading hypothesis is 72%, with a lower bound of 65% and an upper bound of 75%, further testing may be difficult to justify. As these examples illustrate, a termination strategy informed by upper and lower bounds for the probability of the leading hypothesis may help to avoid both premature closure and undue prolongation of the testing process. Finding upper and lower bounds for the probability of a diagnostic hypothesis as each new piece of evidence is obtained is feasible by existing techniques only when the number of remaining tests is small. However, new techniques are presented which can often produce a dramatic reduction in the computational effort required to find the upper and lower bounds. Based on the independence Bayesian framework, the theory presented extends a probabilistic model of hypothetico-deductive reasoning designed to enable programs for sequential diagnosis in medicine to emulate the reasoning processes of human diagnosticians.

Abdomen, Acute↗
PubMed1986

Albert's test: a neglected test of perceptual neglect.

Disorders of perception are thought to be important in predicting the outcome from stroke, but their exact significance is difficult to define because of lack of standardised terminology and diagnostic methods. In a prospective study of 205 unselected stroke patients, perceptual neglect, assessed by a standardised test battery, was found in 49% of patients with lesions of the non-dominant hemisphere and in 25% with lesions of the dominant hemisphere. One component of the test battery was a simple test described by Albert in which patients cross out lines ruled in a standard fashion on a sheet of paper; this was easy to administer and related closely to neglect diagnosed by the test battery as a whole. Results of Albert's test were a significant predictor of both mortality and functional activity six months after the stroke, independent of the influence of other clinical, neurological, laboratory, and social factors. The full test battery for perceptual neglect was of no significant additional predictive value.

Aged↗
PubMedDate not supplied

Clinical problem solving by computer.

Computer access to the medical literature has become more convenient than ever with MEDLINE and other bibliographical databases available on CD-ROM. The benefits of literature searching by computer include improvements in the quality of medical decision making and cost effectiveness of patient care. However, the results obtained by physicians with amateur searching skills are often inferior to those obtained through the traditional service mediated by a skilled librarian. To ensure that future physicians develop the skills necessary for effective use of the medical literature, it is essential to provide training in literature searching by computer at medical school.

CD-ROM↗
PubMedDate not supplied

Obtaining medical information from the Internet.

The Internet is rapidly expanding as an environment for electronic communication and resource sharing. The World Wide Web, a relatively new service on the Internet, provides access to a wealth of information resources through a simple point-and-click interface. Available resources of interest to physicians include bibliographical and statistical databases, literature reviews, discussion groups, press releases, newsletters, drug information, self-assessment questionnaires, multimedia textbooks, patient simulations, clinical decision aids, educational software, and much more. Access to the Internet is widely available in universities and medical libraries; physicians working at home can gain access from a personal computer linked by a modem to a telephone line, by subscribing to an Internet service provider.

Computer Communication Networks↗