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R M Centor

Publications and source records attributed to R M Centor.

At least 37 records · Page 2Linked to original sources
PubMed1986

Assessing the responsiveness of functional scales to clinical change: an analogy to diagnostic test performance.

One characteristic of newer health or functional status scales which has received little attention is their responsiveness over time to clinical change. In part, this is because methods for assessing this characteristic are crude and not well standardized. We suggest that scales be viewed as "diagnostic tests" for discriminating between improved and unimproved patients. With this perspective, one may construct receiver operating characteristic (ROC) curves describing a scale's ability to detect improvement (or failure to improve) using some external criterion. This method is illustrated using data from a study of acute low back pain, comparing the Sickness Impact Profile, its major subscales, and a shorter, more disease-specific scale. The results demonstrate an advantage of the ROC approach over simple pre- and post-treatment score comparisons in assessing scale responsiveness. They also suggest some advantage for a brief disease-specific scale over the lengthier "generic" SIP.

Adult↗
PubMed1986

Effect of medium and cultivation conditions on comparisons between latex agglutination and culture detection of group A streptococci.

In the laboratory diagnosis of pharyngitis, results from latex agglutination tests (LAT) performed directly on throat swabs are often compared with the isolation of group A beta-hemolytic streptococci (GABHS) from simultaneously obtained swabs cultivated on a variety of media under different atmospheric conditions. In this study, results of an LAT, Directigen, were compared with those of two different media: sheep blood agar (SBA) and group A selective strep agar (ssA). Specimens inoculated on SBA were incubated in three different atmospheres: air, 3 to 5% CO2, and anaerobically. Those inoculated on ssA were incubated in 3 to 5% CO2 only. Isolation of GABHS was confirmed by coagglutination. The standard for true positivity was the isolation of GABHS from at least one of the simultaneous cultures. Comparisons were made with samples from 693 adult patients. GABHS was isolated on at least one of the three cultures in 143 patients, demonstrating an isolation rate of 20.6%. LAT exhibited a sensitivity of 95.1%. SBA incubated in air, in CO2, or anaerobically had sensitivities of 86.2, 85.9, and 93.7%, respectively. The ssA detected 99.3% of the positive specimens. Single SBA culture proved to be inferior to LAT and therefore was a poor standard for measuring LAT performance. Single ssA cultures demonstrated the greatest sensitivity in GABHS detection and therefore could serve as a standard for measuring LAT performance.

Aerobiosis↗
PubMed1986

Throat cultures and rapid tests for diagnosis of group A streptococcal pharyngitis.

This article reviews the use of diagnostic tests to guide management of adults with sore throats. Pharyngitis due to group A beta-hemolytic streptococci represents the major diagnostic concern in these patients. Organisms other than group A streptococci can cause pharyngitis, but their clinical importance and their diagnostic tests have not yet been established. For many years, physicians have used routine throat cultures to diagnose group A streptococcal pharyngitis. Rapid tests have recently been introduced that detect the group A streptococcal antigen on throat swab specimens. Because both tests have high sensitivity and specificity, the choice of tests may depend on test turnaround time. Rapid tests should improve management by decreasing both short-term morbidity and inappropriate use of antibiotics.

Antigens, Bacterial↗
PubMed1986

Transportability of a decision rule for the diagnosis of streptococcal pharyngitis.

Use of existing decision rules could improve management of streptococcal pharyngitis, but the validity of such rules outside their original patient population is not known. We applied a four-item decision rule derived at the Medical College of Virginia, Richmond, to 516 patients at the University of Nebraska, Omaha, to test how accurately it would predict outcome of throat culture. After correction for differences in the prevalence of a positive culture (17% in Virginia, 26% in Nebraska), the rule closely predicted the frequency of positive cultures in five subgroups based on the presence of clinical findings. We conclude that this rule transported well to a different patient population and would have been useful in identifying patients with pharyngitis who had a high likelihood of throat cultures positive for group A streptococci.

Adult↗
PubMed1985

A Visicalc program for estimating the area under a receiver operating characteristic (ROC) curve.

The area under the ROC curve interests us as a method for analyzing discrimination or detectability. One can assess a diagnostic test or probability assessor with respect to its degree of discrimination. The area under the ROC curve gives us the probability of correctly identifying abnormal from normal in a forced-choice, two-alternative problem. Previous methods used for calculating the area involved maximum likelihood estimation on a mainframe or minicomputer. This paper demonstrates an adaptation of a recently published nonparametric method for estimating the area. This adaptation takes advantage of electronic spreadsheet software and may be used on most (if not all) microcomputers. The paper develops the construction of the program needed for the necessary calculations.

Computers↗
PubMed1985

An evaluation of methods for estimating the area under the receiver operating characteristic (ROC) curve.

The area under the receiver operating characteristic (ROC) curve serves as one means for evaluating the performance of diagnostic and predictive test systems. The most commonly used method for estimating the area under an ROC curve utilizes the maximum-likelihood-estimation technique, and a nonparametric method to calculate the area under an ROC curve was recently described. We compared the performance of these two methods. The results for the area under the ROC curve and the standard error of the estimate as calculated by each of the two methods exhibited high correlation. Generally, the nonparametric method yields lower area estimates than the maximum-likelihood-estimation technique. However, these differences generally were small, particularly with ROC curves derived from five or more cutoff points. Consistent results of hypothesis testing of the significance of differences between two ROC curves will be similar, regardless of which method is used, as long as one uses the same estimation technique on the two curves and as long as the two ROC curves being compared are of similar shape.

Computers↗
PubMed1984

Development of the adult respiratory distress syndrome: progressive alteration of neutrophil chemotactic and secretory processes.

Chemotaxis and lysosomal enzyme release in peripheral blood neutrophils taken from patients before, during, and after recovery from the adult respiratory distress syndrome (ARDS) were studied. This allowed for correlation of cellular function with changes in a patient's clinical status. It was found that neutrophils from 8 of 9 patients with the fully developed syndrome exhibited a profound depression of chemotaxis (63% depressed, P = 0.0001) and a fourfold elevation of basal lysosomal enzyme release relative to neutrophils from healthy controls (P = 0.0001). These findings of depression of chemotaxis and enhanced basal enzyme release were also detected in neutrophils taken from 7 of 11 patients in whom clinical risk factors (eg, sepsis, pneumonia) for the syndrome had developed. Following resolution of the adult respiratory distress syndrome, the above changes in neutrophil function resolved in the four patients studied during convalescence. Healthy neutrophils exposed to plasma samples (untreated or zymosan-activated) from control subjects and patients with ARDS could not be distinguished with respect to chemotaxis and enzyme secretion. It is concluded that patients in whom ARDS develops show profound but reversible changes in peripheral neutrophil activity which can be measured following the development of a clinical predisposition for the syndrome. Further, the presence of a humoral substance capable of promoting chemotaxis or enzyme secretion from healthy neutrophils in the untreated plasma of patients suffering from ARDS was not demonstrated. This suggests that alteration of neutrophil activity measured in patients with the fully developed syndrome may be cellular in origin.

Acetylglucosaminidase↗
PubMed1982

Treating sore throats in the emergency room. The importance of follow-up in decision making.

Evaluation and treatment of emergency room patients complaining of sore throats are complicated by an unknown probability of follow-up. Tompkins' analysis of cost-effective sore throat management strategies was modified by adding an expression for variable follow-up rate. The original analysis specified a culture range when the probability of streptococcal infection was between 0.05 and 0.20, while the expanded analysis demonstrates that this range decreases with decreasing follow-up. For follow-up rates of 0.70 or less, all patients would be in either the treatment or no treatment group. This analysis demonstrates the importance of follow-up in out-patient decision making, and illustrates the methodology for including follow-up (and similar factors) in our analyses.

Decision Making↗
PubMed1981

The diagnosis of strep throat in adults in the emergency room.

Adult patients who presented to an urban emergency room complaining of a sore throat had cultures and clinical information recorded. Models were constructed, using logistic regression analysis, of both a positive culture for Group A beta streptococcus and a positive guess by a resident. The model of a positive culture consisted of four variables--tonsillar exudates, swollen tender anterior cervical nodes, lack of a cough, and history of fever. Patients with all 4 variables had a 56% probability of a positive culture; 3 variables, 32%; 2 variables, 15%; 1 variable, 6.5%; and 0 variables, 2.5%. The model of a positive guess by a resident demonstrated an over-reliance on physical exam and an underuse of history. The model of a positive culture allows stratification of patients to assist clinicians in the management strategies.

Adolescent↗
PubMedDate not supplied

Rapid diagnosis of streptococcal pharyngitis in adult emergency room patients.

A rapid latex agglutination slide test for group A beta-hemolytic streptococcal throat infections was prospectively evaluated. Resident physicians, working in an adult non-acute emergency room, recorded clinical data and collected throat swabs from 729 adult patients with sore throats. Research assistants obtained throat swabs from 329 control patients. Sensitivity and specificity, compared with routine cultures, were 96% and 97%, respectively. Analyses of clinical predictions and of test results for control patients, however, suggest that this test may perform better than routine culture. The test provides a rapid, accurate, potentially useful alternative for diagnosing group A beta-hemolytic streptococcal pharyngitis in adults.

Adolescent↗
PubMedDate not supplied

Underdocumentation of benzodiazepine prescriptions in a general medicine clinic.

During a three-month period the authors reviewed the charts of patients prescribed benzodiazepine and non-benzodiazepine medications by 73 housestaff practicing in an ambulatory medical clinic. Compared with non-benzodiazepine prescriptions, benzodiazepine name (p less than 0.001), instructions (p less than 0.001), and targeted problems (p less than 0.0001) were significantly underrecorded. In 11% of the records reviewed there was no indication that a mood disorder had been identified or a benzodiazepine prescribed (p less than 0.0001). Problems targeted for benzodiazepine management were found less frequently in the records of elderly patients than in those of patients less than 65 years of age (p less than 0.05). The authors conclude that many houseofficers significantly underdocument the prescriptions they write for benzodiazepine medications and that this may be a marker of their regard for managing mood disorders with benzodiazepines.

Ambulatory Care Facilities↗
PubMedDate not supplied

Rational decision making based on history: adult sore throats.

Primary care physicians are often required to make preliminary evaluations based only on the patient's history, especially during telephone encounters about sore throats. The authors studied adults with sore throats to determine whether patients can be stratified into higher and lower risks of strep throat by history alone. They first obtained data from 517 patients seen in an emergency room. Providers graded symptoms on a four-point scale (absent, mild, moderate, or severe). Initial analyses showed that prediction based on history should include three variables: fever, difficulty in swallowing, and cough. For ease of computation, these were consolidated into one score, "history" (= fever history + difficulty in swallowing - cough). This score was used to develop a model that predicts the probability of infection with group A beta-hemolytic streptococcus, and the model's performance was tested in two additional patient groups. The predictive accuracy of the "history" score was confirmed in all patient groups, despite differences in providers and disease prevalences. Primary care physicians may use this model to help them make decisions in situations such as telephone encounters without using additional data.

Adult↗
PubMedDate not supplied

What a difference a day makes: a decision analysis of adult streptococcal pharyngitis.

With the availability of group A beta-hemolytic streptococcal (GABHS) antigen detection tests, the management of adult pharyngitis is being reassessed. A decision analytic model was developed which considered four strategies: immediate treatment, no treatment, performing a rapid antigen test, or obtaining a bacterial culture. Patient outcomes were expressed in "well" days, which were reduced by the "sick" days associated with adverse reactions to treatment or complications of GABHS infection. When immediate test results are available, testing is the optimal strategy for probabilities of GABHS between 1 and 49 per cent. This range includes almost all patients, using probability estimates based on clinical criteria. The absolute benefit of testing was 0.1 days. The major advantage of a rapid test is the avoidance of penicillin reactions. Variations in the symptomatic benefits of treatment had minimal effects on the analysis. The analysis supports the use of an antigen test for adult patients with pharyngitis.

Acute Disease↗