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Biomedical subjects

D Mossman

Publications and source records attributed to D Mossman.

At least 19 recordsLinked to original sources
PubMed1992

Psychiatry and the homeless mentally ill: a reply to Dr. Lamb.

Homeless mentally ill persons are highly visible subjects of ongoing public discussion and potent symbols of a host of contemporary social problems. They present psychiatry with a scientific challenge that calls for further elucidation of the sources of their mental illness and for fashioning possible solutions to their problems. They also present a moral challenge that requires psychiatrists to acknowledge the cultural, political, legal, and economic context of the mental problems of the homeless in the course of deciding what should be done to help them. H. Richard Lamb has proposed a program of aggressive outreach and psychiatric hospitalization for the homeless mentally ill. The authors believe that his proposal misconstrues the problems and needs of homeless mentally ill individuals; it would also needlessly infringe upon their freedom, further stigmatize them, and probably not help them. The authors offer an alternative understanding of the plight of the homeless mentally ill which places their problems within a larger context of social trends and domestic issues that society has been reluctant to confront. Psychiatrists can help the homeless mentally ill by championing their liberty rights and by focusing public discourse on the broad national need for improved access to medical and psychiatric care.

Attitude of Health Personnel↗
PubMed1992

Diagnostic tests and information theory.

Our previous article showed that the discriminating properties of most diagnostic tests in medicine can be characterized by assuming that tests separate disordered and nondisordered individuals into two overlapping, normal distributions with different means and standard deviations. In this article, we explore the relationship between this way of describing diagnostic tests and the reason that clinicians use them: to gain information about their patients and to reduce diagnostic uncertainty.

Diagnosis, Differential↗
PubMed1992

Comparing diagnostic tests using information theory: the INFO-ROC technique.

We continue our examination of diagnostic tests that are used to assign individuals to one of two mutually exclusive categories, those having or not having a particular disorder. Our last article showed how the information yielded by a test depends on the choice of cutoff and on the patient's pre-test probability of having the disorder. In this article, we demonstrate a method of optimizing a test's information yield that allows us to determine which of several tests gives the most information. Our technique allows us to compare a test's performance with that of a perfect diagnostic test.

Computer Simulation↗
PubMed1992

Balancing risks and benefits: another approach to optimizing diagnostic tests.

In our last two articles, we showed that one can quantify the reduction in uncertainty that results from diagnostic testing, an insight that allowed us to describe a method for optimizing the performance of a test by choosing a cutoff that maximizes its information yield. Although minimizing uncertainty is an important feature of diagnostic testing, there are many situations in which diagnostic tests are most appropriately used to balance risks and benefits associated with the various possible courses of action available to a clinician. This article shows how tests can be used to maximize the "expected utility" associated with a clinical decision.

Humans↗
PubMed1991

"Biological markers" and psychiatric diagnosis: risk-benefit balancing using ROC analysis.

Although the clinical interview retains a central role in psychiatric diagnosis, recent research has suggested that "biological markers" may ultimately increase the precision of clinicians' nosologic and therapeutic decisions. Evaluating and operationalizing diagnostic tests require mathematical techniques that reflect the tests' essential features and limitations, and that guide clinicians in particular clinical situations. In this article we describe a technique that combines signal detection theory and utility-based decision theory, and apply the technique to published data in which sleep architecture was used as a biological marker for depression. We show how outcome utilities influence the optimum REM latency cut-off and show how this relationship is influenced by the prevalence of depression in the population being tested. We also make specific calculations of the practical limits that must be imposed on uncertainties in utilities to operationalize a diagnostic test for a specific clinical situation.

Biomarkers↗
PubMed1991

Predicting length of children's psychiatric hospitalizations: an "ecologic" approach.

This article describes the development and validation of a simple and modestly successful model for predicting inpatient length of stay (LOS) at a state-funded facility providing acute to long term care for children and adolescents in Ohio. Six variables--diagnostic group, legal status at time of admission, attending physician, age, sex, and county of residence--explained 30% of the variation in log10LOS in the subgroup used to create the model, and 26% of log10LOS variation in the cross-validation subgroup. The model also identified LOS outliers with moderate accuracy (ROC area = .68-0.76). The authors attribute the model's success to inclusion of variables that are correlated to idiosyncratic "ecologic" factors as well as variables related to severity of illness. Future attempts to construct LOS models may adopt similar approaches.

Adolescent↗
PubMed1991

Potential HIV exposure in psychiatrically hospitalized adolescent girls.

The authors surveyed 23 psychiatrically hospitalized adolescent girls regarding behavior that involves high risk of HIV infection. Over half (57%) of the girls reported high-risk sexual activities; these girls were more likely to have sexually transmitted diseases, substantial drug abuse histories, and diagnoses of conduct disorder.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Neuropsychiatric decision making: designing nonbinary diagnostic tests.

Most diagnostic tests used in medicine, science, and technology are nonbinary: they are based on quantification of a variable that has a range of possible values. In this article, the authors describe how such tests are designed and characterized. They shall use the concepts developed here in future articles that describe how diagnostic techniques are operationalized for clinical settings.

Blood Platelets↗
PubMed1991

ROC curves, test accuracy, and the description of diagnostic tests.

Clinicians can gain an enhanced understanding of the role of diagnostic tests once they are familiar and comfortable with the descriptions of test performance provided by receiver operating characteristic (ROC) analysis. This article explores the ways that ROC methods quantify test accuracy and describes how ROC methods characterize the distributions of test outcomes in study populations.

Humans↗
PubMed1991

ROC curves and the binormal assumption.

Previous articles in this series have described how receiver operating characteristic (ROC) graphs provide comprehensive graphic representations of the diagnostic performance of non-binary tests and have explained how one constructs "trapezoidal" ROC graphs in which discrete cutoff points are plotted and connected with line segments. In this article, we describe a set of mathematical assumptions that permit the generation of a continuous, smooth ROC curve for a given diagnostic test. These assumptions permit us to characterize a test's performance using a small number of parameters and also to explore properties of diagnostic tests. In this article, we describe a set of mathematical assumptions that can be used to link receiver operating characteristic (ROC) curves to the underlying distribution of values of the diagnostic variable being measured. We will illustrate these assumptions using a diagnostic test that distinguishes alcohol abusers from normal consumers of alcohol and abstainers.

Alcoholism↗
PubMed1990

Optimizing REM latency as a diagnostic test for depression using receiver operating characteristic analysis and information theory.

New diagnostic techniques must be evaluated for their intrinsic accuracy and for their applicability to particular patient groups in specific clinical settings. Using receiver operating characteristic (ROC) analysis and concepts from information theory, we have developed a new mathematical and graphical method that can evaluate, compare, and optimize the performance of diagnostic tests for any value of disorder prevalence. Our analytic method is appropriate to any test that sorts disordered from nondisordered subjects using a continuous or nonbinary diagnostic variable; its characterization of the fundamental properties of such tests thus has important implications for the evaluation and optimization of diagnostic modalities used by clinicians in all medical specialties. We demonstrate our method using published data from five studies that used sleep architecture as a "biological marker" for depression. Our analysis confirms that REM latency is comparable to the dexamethasone suppression test in its ability to discriminate depressed from control subjects. For each of the five studies, we show how optimal REM latency cut-off times may be selected so that diagnostic information yield is maximized, and we compare the ability of each study to detect depressed subjects in populations where the prevalence of affective disorder can be specified.

Adult↗
PubMed1990

Do serum dexamethasone levels improve the DST?

Some investigators have reported that dexamethasone suppression test (DST) accuracy might be improved by incorporating dexamethasone concentrations ([dex]) into test results. Using receiver operating characteristic methods, we evaluated data from four studies in which cortisol and dexamethasone levels were measured simultaneously at one or more times after drug ingestion. We compared DST accuracy using cortisol alone with various diagnostic indices incorporating [dex]. In none of the 21 comparisons did the [dex] factor enhance diagnostic performance.

Depressive Disorder↗
PubMed1990

Improving state-funded child psychiatric care: reducing protracted hospitalizations through changes in treatment planning.

In late 1986, Millcreek Psychiatric Center for Children changed several of its treatment practices in an attempt to decrease needlessly prolonged hospitalizations. The changes included initiating discharge planning shortly after admission, increasing contacts with community and judicial agencies, improving family therapy services, and educating the community about appropriate use of hospital treatments. The fraction of children hospitalized more than 180 days decreased significantly, as did the average length of stay. Mental health professionals should keep community agencies informed about the nature and limitations of inpatient treatment and about children's needs for adequate after-care services.

Adolescent↗
PubMed1990

Introduction to neuropsychiatric decision making: binary diagnostic tests.

This is the first in a series of articles that provide a guide to the understanding and effective use of diagnostic tests in clinical and research endeavors. In this article, we briefly describe some general properties of diagnostic tests. We then focus our attention on binary diagnostic tests, i.e., tests that have only two outcomes, positive or negative. Even though most medical literature assumes that all diagnostic tests are binary, truly binary tests are actually quite rare. Studying them, however, provides a convenient way to familiarize ourselves with important decision-making nomenclature.

Alzheimer Disease↗