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Biomedical subjects

A R Feinstein

Publications and source records attributed to A R Feinstein.

At least 109 records · Page 6Linked to original sources
PubMed1990

A simple procedure for general screening for functional disability in elderly patients.

We propose a short, simple approach that can be used by general internists to routinely screen the functional status of elderly patients in office practice. The approach relies on checking a limited number of targets that are commonly dysfunctional but often unappreciated when conventional histories and physical examinations are done for elderly patients. The new focus is on carefully selected tests of vision, hearing, arm and leg function, urinary incontinence, mental status, instrumental and basic activities of daily living, environmental hazards, and social support systems. Brief questions and easily observed tasks are used to obtain the information needed for a suitable, effective screening while minimizing the time for administration. The approach can be incorporated into routine practice if certain relatively unproductive procedures are eliminated from the routine clinical examination, and particularly if internists are suitably compensated for the additional time.

Aged↗
PubMed1990

Diagnostic criteria and technology as sources for changing incidences of pulmonary diseases.

PURPOSE: To investigate the impact of changes in diagnostic criteria and technology on the rates of occurrence of pulmonary diseases during each of four different calendar years: 1921, 1941, 1961, and 1982. PATIENTS AND METHODS: The medical records were obtained for all patients discharged from Yale-New Haven Hospital during 1921, 1941, 1961, and 1982 with a diagnosis of either pulmonary tuberculosis or primary lung cancer. Each patient's entire clinical course was then thoroughly reviewed, including all available data obtained in the six-month intervals before and after the patient's hospitalization. Critical diagnostic information obtained during life at any time during this one-year period was acceptable as evidence for the diagnosis. RESULTS: According to modern diagnostic criteria, the existing evidence of pulmonary tuberculosis or primary lung cancer often did not justify those diagnoses in patients hospitalized during each of the four survey years. The proportions of justified diagnoses showed a consistent increase over time: 16%, 42%, 53%, and 86%, respectively, for tuberculosis, and 0%, 54%, 93%, and 93%, respectively, for lung cancer. CONCLUSION: The results suggest that some of the statistical changes in occurrence rates for these two pulmonary diseases may be due to temporal improvements in diagnostic precision, not just to environmental changes or therapeutic advances.

Diagnosis, Differential↗
PubMed1990

Indexes and boundaries for "quantitative significance" in statistical decisions.

Boundaries for delta, representing a "quantitatively significant" or "substantively impressive" distinction, have not been established, analogous to the boundary of alpha, usually set at 0.05, for the stochastic or probabilistic component of "statistical significance". To determine what boundaries are being used for the "quantitative" decisions, we reviewed pertinent articles in three general medical journals. For each contrast of two means, contrast of two rates, or correlation coefficient, we noted the investigators' decisions about stochastic significance, stated in P values or confidence intervals, and about quantitative significance, indicated by interpretive comments. The boundaries between impressive and unimpressive distinctions were best formed by a ratio of greater than or equal to 1.2 for the smaller to the larger mean in 546 comparisons, by a standardized increment of greater than or equal to 0.28 and odds ratio of greater than or equal to 2.2 in 392 comparisons of two rates; and by an r value of greater than or equal to 0.32 in 154 correlation coefficients. Additional boundaries were also identified for "substantially" and "highly" significant quantitative distinctions. Although the proposed boundaries should be kept flexible, indexes and boundaries for decisions about "quantitative significance" are particularly useful when a value of delta must be chosen for calculating sample size before the research is done, and when the "statistical significance" of completed research is appraised for its quantitative as well as stochastic components.

Confidence Intervals↗
PubMed1990

A comparison of multivariable mathematical methods for predicting survival--I. Introduction, rationale, and general strategy.

This paper and the two following papers (Parts I-III) report an investigation of performance variability for four multivariable methods: discriminant function analysis, and linear, logistic, and Cox regression. Each method was examined for its performance in using the same independent variables to develop predictive models for survival of a large cohort of patients with lung cancer. The cogent biologic attributes of the patients had previously been divided into five ordinal stages having a strong prognostic gradient. With stratified random sampling, we prepared seven "generating" sets of data in which the five biologic stages were arranged in proportional, uniform, symmetrical unimodal, decreasing exponential, increasing exponential, U-shaped, or bi-modal distributions. Each of the multivariable methods was applied to each of the seven generating distributions, and the results were tested in a separate "challenge" set, which had not been included in any of the generating sets. The research was intended not merely to compare the performance of the multivariable methods, but also to see how their performance would be affected by different statistical distributions of the same cogent biologic attributes. The results, which are presented in the second and third papers, were compared for selection of independent variables and coefficients, and for accuracy in fitting the generating sets and the challenge set.

Cohort Studies↗
PubMed1990

A comparison of multivariable mathematical methods for predicting survival--III. Accuracy of predictions in generating and challenge sets.

This paper concludes a study of "performance variability" when four methods of multivariable analysis--multiple linear regression, discriminant function analysis, multiple logistic regression, and two arrangements of Cox's proportional hazards regression--were applied to the same stratified random samples of "generating sets" containing seven different statistical distributions of cogent biologic attributes in a composite staging system for a large cohort of patients with lung cancer. Each model developed from the generating sets was also applied for predictions in a previously sequestered "challenge set". Across the different generating sets, the multivariable methods showed good agreement with one another in the stepwise choice of first two powerful predictor variables, but not in the sequence of subsequent choices or in the standardized coefficients assigned to the same collection of "forced" variables. In concordance of predictions for individual patients in the generating sets, the overall proportions of disagreement for pairs of methods ranged from 0 to 28%, and kappa values ranged from 0.49 to 1.00. The accuracy of individual predictions showed relatively similar results when the different methods were applied to the same generating set. Across the generating sets, the different methods showed similar total results but substantial variations in predictions for alive and dead patients. When the models from the generating sets were applied for predictions in the challenge set, the results showed an analogous pattern: similar accuracy within models for overall and live/dead predictions, but substantial variations in live/dead predictions across models derived from different generating sources. The results showed that the multivariable methods often had good agreement with one another in predictions for groups but not for individual persons; and that no single method was superior to the others or to the composite staging system. We conclude that multivariable analytic methods may be most effective and consistent if used to find the few most powerful predictor variables, omitting the many other variables that may be "statistically significant" but less cogent. The powerful predictors may sometimes be best constructed, before the analysis begins, as composite variables containing appropriate unions or ordinal arrangements of elemental candidate variables.

Cohort Studies↗
PubMed1990

High agreement but low kappa: I. The problems of two paradoxes.

In a fourfold table showing binary agreement of two observers, the observed proportion of agreement, p0, can be paradoxically altered by the chance-corrected ratio that creates kappa as an index of concordance. In one paradox, a high value of p0 can be drastically lowered by a substantial imbalance in the table's marginal totals either vertically or horizontally. In the second pardox, kappa will be higher with an asymmetrical rather than symmetrical imbalanced in marginal totals, and with imperfect rather than perfect symmetry in the imbalance. An adjustment that substitutes kappa max for kappa does not repair either problem, and seems to make the second one worse.

Models, Statistical↗
PubMed1990

High agreement but low kappa: II. Resolving the paradoxes.

An omnibus index offers a single summary expression for a fourfold table of binary concordance among two observers. Among the available other omnibus indexes, none offers a satisfactory solution for the paradoxes that occur with p0 and kappa. The problem can be avoided only by using ppos and pneg as two separate indexes of proportionate agreement in the observers' positive and negative decisions. These two indexes, which are analogous to sensitivity and specificity for concordance in a diagnostic marker test, create the paradoxes formed when the chance correction in kappa is calculated as a product of the increment in the two indexes and the increment in marginal totals. If only a single omnibus index is used to compared different performances in observer variability, the paradoxes of kappa are desirable since they appropriately "penalize" inequalities in ppos and pneg. For better understanding of results and for planning improvements in the observers' performance, however, the omnibus value of kappa should always be accompanied by separate individual values of ppos and pneg.

Observer Variation↗
PubMed1990

A clinical-severity staging system for patients with lung cancer.

The prognostic staging of cancer in general, and lung cancer in particular, has customarily depended mainly on morphologic distinctions. The gross anatomic extensiveness of cancers is cited with TNM stages that describe the primary tumor (T), spread to regional lymph nodes (N), and metastatic dissemination (M) to distant sites. Microscopic characteristics are cited according to the cancer's cell type (e.g., adenocarcinoma, epidermoid carcinoma) and/or grade of differentiation (e.g., well differentiated, poorly differentiated, anaplastic). Although the clinical manifestations, functional effects, and associated co-morbidity of a cancer are universally recognized as having major prognostic importance, they have not been classified with a standard system of taxonomy. When considered at all, clinical phenomena have been cited with a surrogate index of "performance status" that ignores the underlying clinical dysfunctions while being greatly affected by non-clinical phenomena, such as the patient's psychic status, economic motivations, and system of social support. The current research was done to develop a standard system of taxonomy (or "staging") for the prognostic impact of clinical distinctions in patients with primary lung cancer. Appropriate data were obtained, computer-coded, and analyzed from medical records for the complete clinical course of an inception cohort of 1266 patients who were first treated at either the Yale-New Haven Hospital or the West Haven Veterans Administration Hospital during the interval January 1, 1953-December 31, 1964. The information under analysis included clinical phenomena as well as anatomic extensiveness (TNM stage), microscopic histology, the chronometric duration of the interval from the first symptom of lung cancer to zero time, the iatrotropic reason why the patient sought medical attention, the presence of anemia, the amount of customary cigarette use, and the conventional demographic data for age and gender. The main clinical phenomena were expressed in variables for symptom pattern severity, and co-morbidity. Symptom pattern referred to the existence of specific pulmonic symptoms (e.g., hemoptysis), systemic symptoms (e.g., complaint of weight loss), and metastatic symptoms that might be mediastinal (e.g., superior vena cava syndrome), regional (e.g., the Horner syndrome), or distantly metastatic (e.g., central nervous system). The symptom severity variable included the amount of weight loss, and the existence of severe dyspnea or particularly severe tumor effects (such as mental obtundation, rather than hemiparesis in patients with CNS metastasis). Prognostic co-morbidity was cited for coexisting diseases, such as recurrent myocardial infarctions, that might be more lethal than the lung cancer itself.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1989

Changes in dyspnea-fatigue ratings as indicators of quality of life in the treatment of congestive heart failure.

A new clinical index of dyspnea and fatigue has been applied to rate the condition of patients with congestive heart failure. The index has 3 components, each rated on a scale from 0 to 4, for the magnitude of the task that evokes dyspnea or fatigue, the magnitude of the pace (or effort) with which the task is performed and the associated functional impairment in general activities. The ratings for each component are added to form an aggregated score, which can range from 0, for the worst condition, to 12, for the best. Because dyspnea and fatigue are prime symptoms and sources of clinical distress, the index helps reflect the quality of life in patients with congestive heart failure. In double-blind trials of therapy, changes in the index showed good correlations with patients' self-selected ratings of improvement. The posttherapeutic changes in the index ratings were significantly higher with a new active agent (lisinopril) than with placebo or another active agent (captopril).

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1989

A new prognostic staging system for the acquired immunodeficiency syndrome.

An improved prognostic staging system is needed for patients with the acquired immunodeficiency syndrome (AIDS). To construct such a system, we analyzed the course of 117 consecutive adults who received a diagnosis of AIDS at Yale-New Haven Hospital from 1981 through 1987. The staging system was developed from the data on the first 76 patients, confirmed in the remaining 41 patients, and then applied to the entire cohort. The staging system, which is based on physiologic deficits rather than demographic or diagnostic features, gives one point for each of the following: severe diarrhea or serum albumin level under 2.0 g per deciliter, any neurologic deficit, arterial oxygen tension of 50 mm Hg or less, hematocrit below 30 percent, lymphocyte count below 150 per microliter, white-cell count below 2500, and platelet count below 140,000. The total score determines the presence of Stages I (0 points), II (1 point), or III (2 to 7 points). The three stages had distinctive prognostic gradients in our cohort. For patients in Stages I, II, and III, the median survival times were 11.6, 5.1, and 2.1 months, respectively, with one-year survival rates of 50, 30, and 8 percent. When the staging system was tested with a proportional-hazards model, no other descriptive or laboratory variable added any additional predictive power. Although this new staging system requires further validation in other populations, we believe it will be useful in evaluating new therapies and improving the precision of prognosis in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

New epidemiologic evidence confirming that bias does not explain the aspirin/Reye's syndrome association.

To determine the validity of the aspirin/Reye's syndrome association, we developed an epidemiologic investigation to assess the effects of five potential sources of bias. A case-control study incorporated procedures to avoid temporal precedence and susceptibility bias. These included classifying cases as having monophasic or biphasic patterns of illness and matching for severity of symptoms at zero-time. To evaluate the effect of a potential recall bias, an "alternate-condition" control group was enrolled. A medical record review study was conducted to assess the potential for diagnostic bias, and a blanket surveillance of all hospitals in a region was conducted to evaluate reporting bias. Twenty-four case subjects and 48 matched controls were enrolled. Eight-eight percent of case subjects and only 17% of controls had received aspirin prior to the onset of Reye's syndrome (matched odds ratio, 35; 95% confidence interval, 4.2 to 288). Further analyses demonstrated that the association could not be attributed to the five potential sources of bias.

Adolescent↗