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Biomedical subjects

E L Spitznagel

Publications and source records attributed to E L Spitznagel.

At least 73 records · Page 4Linked to original sources
PubMed1987

The predictive validity of lay Diagnostic Interview Schedule diagnoses in the general population. A comparison with physician examiners.

A clinical reexamination by psychiatrists is a useful comparison for exploring lay Diagnostic Interview Schedule-derived psychiatric diagnoses in general population surveys, but as a validity standard psychiatric reexamination is less than ideal. There are many potential sources of disagreement that have nothing to do with the validity of either the lay or the psychiatrist examination. Another approach to comparing lay and psychiatrist diagnoses is to examine their relative predictive power. We describe such a comparison using outcome variables derived from the one-year follow-up examination of Epidemiologic Catchment Area respondents done at the St. Louis site. We examine several outcome variables across nine diagnostic categories. Within the limits of the available data, lay and psychiatrist diagnoses appear to be essentially equal in terms of the number of outcomes better predicted and few of the differences in predictive power approach statistical significance. We discuss the implications of these findings for the analysis of lay interviewer Diagnostic Interview Schedule-derived diagnoses.

Catchment Area, Health↗
PubMed1987

Left globus pallidus abnormality in never-medicated patients with schizophrenia.

Schizophrenia is a severe psychiatric disorder characterized by onset in young adulthood, the occurrence of hallucinations and delusions, and the development of enduring psychosocial disability. The pathophysiology of this disorder remains unknown. Studies of cerebral blood flow and metabolism designed to identify brain abnormalities in schizophrenia have been limited by inadequate methods of anatomical localization and the possibility of persistent medication effects. We have now used positron emission tomography and a validated method of anatomical localization in an attempt to identify abnormalities of regional cerebral blood flow in newly diagnosed never-medicated patients with schizophrenia. An exploratory study of 5 patients and 10 normal control subjects identified abnormally high blood flow in the left globus pallidus of patients with schizophrenia. A replication study of 5 additional patients and 10 additional control subjects confirmed this finding. No other abnormalities were found.

Adolescent↗
PubMed1987

Difficult-to-recruit respondents and their effect on prevalence estimates in an epidemiologic survey.

Generous contact efforts were used to recruit 3,004 respondents into the first wave of the St. Louis Epidemiologic Catchment Area (ECA) project, a psychiatric epidemiologic study of the general population, conducted from 1981-1982. These efforts were analyzed to establish which sociodemographic characteristics or current psychiatric disorders were determinants of difficulty in recruitment. Being young, male, black, a nonrural resident, educated, and full-time employed were the demographic characteristics associated with increased contact efforts. Persons currently meeting criteria for an alcohol disorder required almost 20% more contact attempts than those without the disorder; this difficulty lay both in their being less available for an initial contact and refusing at a higher rate once contacted. An optimal recruitment effort cutoff point is provided, and a method is suggested for detecting that optimal point in the course of ongoing studies.

Adult↗
PubMed1987

Multispectral analysis of MR images of the breast.

Preliminary investigations were conducted into the potential of magnetic resonance (MR) images for tissue classification of the breast on the basis of relative signal intensity. Multispectral techniques originally developed by the National Aeronautics and Space Administration for satellite image analysis were used in sequence selection, image data correction, image standardization, and image interpretation. Numerous sequence combinations with varying repetition times (TR) and echo times (TE) were considered, and a triplet was selected consisting of long TR/long TE, short TR/short TE, and an opposed phase sequence with intermediate TR and TE. Correction to remove system-imposed intensity inhomogeneities was required for all images. Image standardization based on fat and pectoral muscle signals was necessary for intercase comparisons. Multispectral images obtained based on this analysis suggest the feasibility of intensity-based image classification.

Breast Neoplasms↗
PubMed1986

Radiogenic breast cancer effects of mammographic screening.

The radiocarcinogenic implications of published breast-screening policies were compared. With the use of radioepidemiologic data published recently by the National Institutes of Health, expected excess breast cancers were projected. With a base-line mammogram at age 35 and annual mammography after age 40, as few as 150 or as many as 1,000 radiogenic breast cancers were projected for a screening population of 1 million women, depending on the mammographic system employed and the screening schedule.

Adult↗
PubMed1985

A comparison of clinical and diagnostic interview schedule diagnoses. Physician reexamination of lay-interviewed cases in the general population.

We examined the level of agreement between diagnoses derived from data gathered by lay interviewers using the Diagnostic Interview Schedule (DIS) in a general population survey (the Epidemiologic Catchment Area project) and both DIS and clinical diagnoses made by psychiatrists. Overall percent agreement between the lay DIS and the psychiatrists clinical impression ranged from 79% to 96%. The chance-corrected concordance was .60 or better for eight of the 11 diagnoses. Specificities were all 90% or better. Sensitivities were lower, but lay results showed a bias for only two diagnoses: major depression was significantly underdiagnosed and obsessive illness was overdiagnosed. We compared the present results with those of previous studies from clinical settings. We explored possible reasons for disagreement and discussed the implications of the findings for psychiatric epidemiologic research.

Adult↗
PubMed1985

A proposed solution to the base rate problem in the kappa statistic.

Because it corrects for chance agreement, kappa (kappa) is a useful statistic for calculating interrater concordance. However, kappa has been criticized because its computed value is a function not only of sensitivity and specificity, but also the prevalence, or base rate, of the illness of interest in the particular population under study. For example, it has been shown for a hypothetical case in which sensitivity and specificity remain constant at .95 each, that kappa falls from .81 to .14 when the prevalence drops from 50% to 1%. Thus, differing values of kappa may be entirely due to differences in prevalence. Calculation of agreement presents different problems depending on whether one is studying reliability or validity. We discuss quantification of agreement in the pure validity case, the pure reliability case, and those studies that fall somewhere between. As a way of minimizing the base rate problem, we propose a statistic for the quantification of agreement (the Y statistic), which can be related to kappa but which is completely independent of prevalence in the case of validity studies and relatively so in the case of reliability.

Epidemiologic Methods↗
PubMed1985

Staging parameters for cancers of the head and neck: a multi-factorial analysis.

Utilizing a multi-variate computer based analysis technique, the 1,400 case head and neck tumor registry of Washington University was examined for possible staging variables as an alternative to the current TNM system. Site, age, characteristics of surgical margins, and absence of neck node metastasis were identified as being predictive of nonrecurrence of cancer. A computer model utilizing the variables was compared to the current TNM system and found to be somewhat better (71.2% vs. 65.2%) in accuracy of prediction of nonrecurrence of cancer. Further analysis suggests that future improvements in predictive ability of the model will have to await the identification of new variables such as those that might arise from the current work in areas of flow cytometry or human stem cell cultures.

Computers↗
PubMed1984

Utilization patterns of health maintenance organization disenrollees.

This article addresses several questions about the effect of disenrollment on the start-up phenomenon in health maintenance organizations that were raised in a recent exchange of articles and comments in this journal. The results show that disenrollees, like continuous enrollees, go through a start-up phase of utilization that decreases over duration of membership to a stable lower level. The study also differentiates between voluntary and involuntary disenrollees, both of which go through start-ups. The different characteristics of the start-ups of both groups of disenrollees are contrasted with those of continuous enrollees. The implications of these findings for planners and administrators are discussed, and a future research agenda is recommended.

Adult↗
PubMed1983

Heterogeneity in schizophrenia: a cluster-analytic approach.

Despite agreement that chronic schizophrenia is clinically heterogeneous, no system of subclassification has received general acceptance. Most methods for defining subgroups have relied either on course or symptom type alone. Using cluster analysis on patients rated on a broad range of items derived from commonly employed explicit diagnostic criteria, we were able to define two reasonably distinct groups. The first and larger group was characterized by later onset, good premorbid adjustment, and well-organized delusions; the second by poor premorbid adjustment, early onset, family history of schizophrenia, and symptoms such as bizarre behavior, incoherent speech, and blunted effect. Two different clustering programs yielded similar profiles. Analysis of computer-simulated data indicated that such good agreement would occur by chance less than one time in a hundred. Furthermore, the groupings remained stable when extra cases were added to the sample, and affected family members showed a significant tendency to occur in the same cluster. Although an etiological distinction between the subtypes cannot be inferred, we suggest that this form of classification provides a potentially useful starting point for further biological and genetic research.

Adult↗
PubMed1982

Plasma epinephrine and norepinephrine levels during anesthesia: enflurane-N2O-O2 compared with fentanyl-N2O-O2.

During intra-abdominal surgery, plasma levels of norepinephrine in peripheral venous blood were higher in 11 patients who received fentanyl-nitrous oxide-oxygen than in 10 patients who received enflurane-nitrous oxide-oxygen [703 +/- 95 vs 463 +/- 38 (SEM) pg/ml]. At the same time, systolic blood pressure (143 +/- 6 vs 121 +/- 4 torr), mean blood pressure (108 +/- 4 vs 98 +/- 3 torr), and pulse rate (87 +/- 3 vs 98 +/- 4 beats per minute) also differed significantly (p less than 0.05); plasma levels of epinephrine (235 +/- 61 vs 113 +/- 21) did not. These values did not differ significantly between the two groups before induction of anesthesia, after induction but before skin incision, or in the recovery room. These data support the concept that enflurane anesthesia blocks the sympathetic response to surgical stress more effectively than low dose fentanyl anesthesia.

Adult↗
PubMed1980

Morphological and biochemical studies on the development of cholinergic properties in cultured sympathetic neurons. I. Correlative changes in choline acetyltransferase and synaptic vesicle cytochemistry.

Under certain culture conditions, neonatal rat superior cervical ganglion neurons display not only a number of expected adrenergic characteristics but, paradoxically, also certain cholinergic functions such as the development of hexamethonium-sensitive synaptic contacts and accumulation of choline acetyltransferase (ChAc). The purpose of this study was to determine whether the entire population of cultured neurons was aquiring cholinergic capabilities, or whether this phenomenon was restricted to a subpopulation. After 1--6 and 8 wk in culture, neurons were fixed in KMnO4 after incubation in norepinephrine and prepared for electron microscopy analysis of synaptic vesicle content to determine whether vesicles were dense cored or clear. ChAc, acetylcholinesterase (AChE), and DOPA-decarboxylase (DDC) activities were assayed in sister cultures. In the period from 1 to 8 wk in culture, the average ChAc activity per neuron increased 1,100-fold, and the DDC and AChE activities increased 20- and 30-fold, respectively. After 1 wk in culture, 48 of 50 synaptic boutons contained predominantly dense-cored vesicles, but by 8 wk the synaptic vesicle population was predominantly of the clear type. At intermediate times, the vesicle population in many boutons was mixed. The morphology of the synaptic contacts on neuronal surfaces was that characteristic of autonomic systems, with no definite clustering of the vesicles adjacent to the area of contact. Increased vesicle size correlated with increasing age in culture and the presence of a dense core. Considering these data along with available physiological studies, we conclude that these cultures contain one population of neurons that is initially adrenergic. Over time, under conditions of this culture system, this population develops cholinergic mechanisms. That a neuron may, at a given time, express both cholinergic and adrenergic mechanisms is suggested by the approximately equal numbers of clear and dense-cored vesicles in the boutons found at the intermediate times.

Acetylcholinesterase↗
PubMed1978

ASA physical status classifications: a study of consistency of ratings.

The American Society of Anesthesiologists' (ASA) Physical Status Classification was tested for consistency of use by a questionnaire sent to 304 anesthesiologists. They were requested to classify ten hypothetical patients. Two hundred fifty-five (77.3 percent) responded to two mailings. The mean number of patients rated consistently was 5.9. Four patients elicited wide ranges of responses. Age, obesity, previous myocardial infarction, and anemia provoked controversy. There was no significant difference in responses from different regions of the country. Academic anesthesiologists rated a greater number identical than did those in private practice (P less than 0.01). There was no difference in ratings between those who used the classification for billing purposes and those who did not. The ASA Physical Status Classification is useful but suffers from a lack of scientific precision.

Adult↗
PubMedDate not supplied

Importance of hemodynamic factors in the prognosis of symptomatic carotid occlusion.

CONTEXT: The relative importance of hemodynamic factors in the pathogenesis and treatment of stroke in patients with carotid artery occlusion remains controversial. OBJECTIVE: To test the hypothesis that stage II cerebral hemodynamic failure (increased oxygen extraction measured by positron emission tomography [PET]) distal to symptomatic carotid artery occlusion is an independent risk factor for subsequent stroke in medically treated patients. DESIGN AND SETTING: Prospective, blinded, longitudinal cohort study of patients referred from a group of regional hospitals between 1992 and 1996. PATIENTS: From 419 subjects referred, 81 with previous stroke or transient ischemic attack in the territory of an occluded carotid artery were enrolled. All were followed up to completion of the study, with average follow-up of 31.5 months. MAIN OUTCOME MEASURES: Telephone contact every 6 months recorded the subsequent occurrence of all stroke, ipsilateral ischemic stroke, and death. RESULTS: Stroke occurred in 12 of 39 patients with stage II hemodynamic failure and in 3 of 42 patients without (P = .005); stroke was ipsilateral in 11 of 39 patients with stage II hemodynamic failure and in 2 of 42 patients without (P = .004). Six deaths occurred in each group (P = .94). The age-adjusted relative risk conferred by stage II hemodynamic failure was 6.0 (95% confidence interval [CI], 1.7-21.6) for all stroke and 7.3 (95% CI, 1.6-33.4) for ipsilateral stroke. CONCLUSIONS: Stage II hemodynamic failure defines a subgroup of patients with symptomatic carotid occlusion who are at high risk for subsequent stroke when treated medically. A randomized trial evaluating surgical revascularization in this high-risk subgroup is warranted.

Aged↗