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Results for “diagnostic optimization”

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PubMed1993

[The optimal diagnostic approach in myocardial infarct].

In the submitted review the authors discuss rational criteria for the diagnosis of myocardial infarction, indications for thrombolysis, coronarography and possibly PTCA, the method of indirect (non-invasive) assessment of an occluded coronary artery and the most frequent mistakes in the diagnosis of infarction. Essential examinations in the acute stage of myocardial infarction are: case-history, ECG, CK-MB (possibly echocardiography). For indication of thrombolysis of acute PTCA case-history and ECG (or echocardiography) are sufficient. Indications of early coronarography before discharge from hospital: postinfarction angina pectoris, malignant arrhythmia (except on the first day), haemodynamic instability, evidence of myocardial ischaemia (restricted symptoms) during a maximal load before discharge.

Humans↗
PubMed1985

Diagnostic tests in breast cancer. Clinical strategies based on diagnostic probabilities.

Optimal diagnostic strategies used in screening for breast cancer and evaluating breast masses depend on the likelihood of malignancy, findings at physical examination, and the accuracy of tests and procedures. Results from published series, in conjunction with calculations of the probability of malignancy based on test results, indicate that only mammography is needed for screening. A clinical sequence for evaluating palpable breast masses should include a combination of mammography, ultrasound examination, and needle aspiration. In patients with negative findings, the probability of cancer will be sufficiently low to obviate the need for immediate surgical biopsy. However, if there are positive findings, or the initial clinical likelihood of malignancy is high, excision of the mass is indicated.

Adult↗
PubMed1989

Evaluation and optimization of diagnostic tests using receiver operating characteristic analysis and information theory.

We describe a mathematical technique and an associated computer program for comparing, evaluating and optimizing diagnostic tests. The technique combines receiver operating characteristic (ROC) analysis with information theory and cost-benefit analysis to accomplish this. The program is menu driven and highly interactive; it generates 13 possible user-determined ASCII disk files which can be easily converted to graphs. These graphs allow the user to make detailed comparisons among various diagnostic tests for all values of disorder prevalence, and also provide guidelines for cut-off selection in order to optimize tests. These techniques are applied to three published studies of the enzyme screening assay for diagnosis of infection with the HIV virus. We show how graphs produced by this program can be used to compare and optimize these diagnostic tests. The program is written for an IBM-compatible microcomputer running on a DOS operating system.

Clinical Laboratory Techniques↗
PubMed1999

Optimizing the diagnostic criteria for standard (250-microg) and low dose (1-microg) adrenocorticotropin tests in the assessment of adrenal function.

ACTH stimulation is the standard test for assessment of adrenal function. It was suggested that the low dose (1 microg) would be more sensitive for detecting mild secondary adrenal insufficiency than the usual dose of 250 microg. The aim of this study was to find the optimal diagnostic criteria and to compare standard dose test (SDT) with the low dose test (LDT). A group of patients treated with corticosteroids for the 6 months was considered to have hypothalamo-pituitary-adrenal impairment. Studies were performed in 14 corticosteroid-treated and 28 control subjects in random order on 2 consecutive days. Tests were analyzed using the receiver operating characteristic curve method. The best test was cortisol increment at 15 min of the LDT. It was significantly better than the cortisol concentration at 15 min of the SDT, the best test during the SDT (receiver operating characteristic curve area and 95% confidence interval: LDT, 0.997 and 0.956-0.999; SDT, 0.827 and 0.662-0.929; P = 0.0113). For the cortisol increment at 15 min of the LDT at 100% sensitivity, the diagnostic value was 100 mmol/L, and the specificity was 96%. Therefore, the LDT is superior to the standard dose test in the assessment of secondary adrenal insufficiency.

Adrenal Cortex Hormones↗
PubMed1994

Pediatricians' diagnostic approach to pharyngitis and impact of CLIA 1988 on office diagnostic tests.

OBJECTIVE: To determine the factors associated with an optimal diagnostic approach to a child with pharyngitis, characterize office laboratory methods for throat swab culture and group A streptococcal rapid antigen testing, and assess the potential impact of the Clinical Laboratory Improvement Amendments (CLIA) of 1988 on the performance of these tests. DESIGN AND SETTING: Mailed survey to all board-certified primary care pediatricians from seven western states with telephone follow-up for nonrespondents. OUTCOME MEASURES: Differences in practice characteristics and use of office laboratory tests for physicians who usually (> 80%) diagnose pharyngitis using a recommended approach vs those who follow this approach less often (< 50%); characteristics of physicians who indicate that they intend to discontinue office throat culture because of CLIA and those who will continue to perform this test also are compared. RESULTS: Responses from 531 pediatricians were analyzed. Forty-four percent diagnosed pharyngitis appropriately for more than 80% of patients, and 17% did so for fewer than 50%. Optimal diagnosis was significantly more common among physicians who cultured throat swabs in their office (relative risk, 1.40; 95% confidence interval, 1.19 to 1.66) and less common among solo practitioners (relative risk, 0.71; 95% confidence interval, 0.56 to 0.88). Factors that may decrease the sensitivity of office throat culture include short duration of incubation (59%), lack of quality control (51%), and limited education of the persons reading results (6%). With implementation of CLIA, 24% of pediatricians reported that they already have discontinued or will discontinue office throat culture, and 23% have discontinued or will discontinue antigen detection testing for group A streptococci. Those most likely to stop office culture include solo practitioners and practitioners who do not currently perform quality control of culture methods. CONCLUSIONS: Office culture for group A streptococci is strongly associated with an optimal diagnostic approach. Implementation of CLIA regulations may substantially decrease the number of physicians who perform this test. The balance between potential improvements in the quality of office culture with CLIA implementation and the decreased availability of this test needs to be assessed.

Antigens, Bacterial↗
PubMed1989

[Optimalization of diagnostic choices].

The sensitivity and specificity of diagnostic tests and the Gold Standard are introduced. An optimization method for diagnosis, based on the utility function is presented. It is emphasized that the conclusions reached in practice depend on the numerical values subjectively assigned to some parameters. A careful application of such methods is recommended.

Diagnosis↗
PubMed1996

HPV infection and disease in men.

Penile HPV infection and disease are very common in sexually active men, and may be manifest in many forms. Treatment of clinically detectable lesions is advisable not only to relieve symptoms but also to prevent the spread of HPV infection to new sexual partners. Treatment of subclinical disease is more controversial but also may be advisable in some cases given the evidence that these lesions may also harbor infectious virus. In addition, subclinical disease may demonstrate intraepithelial neoplasia, which if left untreated may progress to invasive cancer in a small number of cases. Anal HPV infection and ASIL are very common in high-risk homosexual and bisexual men, particularly among those who are HIV positive. Parallels with cervical HPV infection and disease suggest that anal HSIL may be precancerous, and indeed anal cancer may be as common or more common in this high-risk group as cervical cancer is in women. Further studies are needed to elucidate the natural history of ASIL, the role of immunosuppression in progression to invasive cancer, optimal diagnostic methods, and optimal treatment regimens. Like cervical cancer, anal cancer may be a preventable disease, and implementation of a well-targeted screening program similar to that in place for cervical disease should be considered in the future when appropriate supporting data become available.

Adult↗
PubMed1980

Optimization of diagnostic discrimination applied to the amniotic fluid lecithin/sphingomyelin ratio.

An unrecognized disparity frequently separates the intuitive reliance placed on laboratory information by those who produce it and those who use it. To harmonize these dissimilar perceptions requires quantitative measures of the information contained in laboratory data. The assay of the lecithin/sphingomyelin ratio in amniotic fluid is used as an example to analyze the discriminatory ability of a test. This assay can be optimized from the different viewpoints of sensitivity, specificity, diagnostic effectiveness or value. In each case test results are interpreted in the light of different factors and so the optimal decision threshold to separate positive from negative results may vary. Appreciation of this concept would endow the interpretation of laboratory tests with the same flexibility traditionally available to other clinical information.

Amniotic Fluid↗
PubMed1987

Chronic cholecystitis. An analysis of diagnostic strategies.

To define the optimal diagnostic approach for suspected chronic cholecystitis comprehensive management strategies were developed. Using a computer model, the frequency of appropriate surgery, inappropriate surgery, complications, death, and medical costs were compared in populations of patients with various disease prevalences. The optimal strategy began with ultrasonography, followed by an oral cholecystogram when the ultrasonogram was inconclusive. Oral cholecystogram also was employed when additional diagnostic studies failed to provide another explanation for the patient's symptoms. Compared with strategies using only ultrasonography or oral cholecystography, the combination strategy lowered the frequency of inappropriate surgery from 7.1 to 4.4% and direct medical costs from $1,877 to $1,766 per patient in a population with a 20% prevalence of chronic cholecystitis. The differences persisted at higher prevalences of cholecystitis and when sensitivities and specificities of the tests were varied over ranges reported in the literature. Diagnostic accuracy and direct medical costs could be improved by a more frequent interpretation of subtle abnormal ultrasonographic findings as inconclusive and by a more liberal use of oral cholecystography. This analysis demonstrates that a strategy combining ultrasonography and oral cholecystography is superior to the use of either test alone and is cost-efficient.

Cholecystitis↗
PubMedDate not supplied

[Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis].

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.

Child, Preschool↗
PubMed1997

BANTER: a Bayesian network tutoring shell.

We present an educational tool for bringing the information contained in a Bayesian network to the end user in an easily intelligible form. The BANTER shell is designed to tutor users in evaluation of hypotheses and selection of optimal diagnostic procedures. BANTER can be used with any Bayesian network containing nodes that can be classified into hypotheses, observations, and diagnostic procedures. The system enables one to present various types of queries to the network, to test one's ability to select optimal diagnostic procedures, and the request explanations. We describe the system's capabilities by illustrating how it functions with two structurally different network models of real-world medical problems.

Adult↗
PubMed1985

Differential diagnosis and the competing-hypotheses heuristic. A practical approach to judgment under uncertainty and Bayesian probability.

Evaluating the same diagnostic information across the plausible competing diagnoses is a practical strategy (ie, heuristic) to guide decision making in the face of uncertainty. The prevalence of use of this competing-hypotheses heuristic by 89 first-year house officers was examined in three simulated patient cases. Results indicated that only a minority (24%) of the house officers selected optimal diagnostic information consistent with this Bayesian heuristic across all three cases. Almost all (97%) of the house officers selecting optimal diagnostic information were able to identify the most probable diagnosis specified by Bayes' theorem, while only a chance number (53%) of house officers selecting nonoptimal information were able to identify the most probable diagnosis. The competing-hypotheses heuristic is discussed within the context of diagnostic problem-solving models derived from the literature on medical decision making and clinicopathological conference case records. It is suggested that the heuristic, which does not necessitate any mathematical calculations, may be useful as a complement to clinical judgment.

Bayes Theorem↗
PubMed1998

Choosing a diagnostic cut-off for cannabis dependence.

AIM: While cannabis dependence has been increasingly recognized, there is little research on the measurement issues involved in operationalizing the dependence syndrome for this drug. This paper aimed to investigate the diagnostic utility and appropriate diagnostic cut-offs of three short dependence measures among long-term cannabis users. SETTING AND PARTICIPANTS: Two hundred long-term, regular cannabis users were recruited and interviewed in Sydney, Australia. MEASUREMENTS: Receiver Operating Characteristic analyses compared the diagnostic performance of the short University of Michigan CIDI, a measure of ICD-10 dependence and the Severity of Dependence Scale against the "gold standard" of moderate or more severe DSM-III-R cannabis dependence, as diagnosed by the Substance Abuse Module of the CIDI. FINDINGS: The measures were of equal utility in diagnosing at least moderate DSM-III-R cannabis dependence. While the optimal diagnostic cut-offs for the short University of Michigan CIDI and the ICD-10 dependence measure remained unchanged from those conventionally applied, a more liberal cut-off was optimal for the Severity of Dependence Scale. The amended prevalence of cannabis dependence was 77% using the short University of Michigan CIDI, 72% by the ICD-10 measure and 62% by the Severity of Dependence Scale. CONCLUSIONS: The three instruments were able to diagnose cannabis dependence at levels substantially better than chance. They were generally robust in terms of the optimal diagnostic cut-off in a population of long-term cannabis users. This paper provides guidelines for choosing optimal cut-offs within different contexts.

Adolescent↗
PubMed1999

Multiobjective genetic optimization of diagnostic classifiers with implications for generating receiver operating characteristic curves.

It is well understood that binary classifiers have two implicit objective functions (sensitivity and specificity) describing their performance. Traditional methods of classifier training attempt to combine these two objective functions (or two analogous class performance measures) into one so that conventional scalar optimization techniques can be utilized. This involves incorporating a priori information into the aggregation method so that the resulting performance of the classifier is satisfactory for the task at hand. We have investigated the use of a niched Pareto multiobjective genetic algorithm (GA) for classifier optimization. With niched Pareto GA's, an objective vector is optimized instead of a scalar function, eliminating the need to aggregate classification objective functions. The niched Pareto GA returns a set of optimal solutions that are equivalent in the absence of any information regarding the preferences of the objectives. The a priori knowledge that was used for aggregating the objective functions in conventional classifier training can instead be applied post-optimization to select from one of the series of solutions returned from the multiobjective genetic optimization. We have applied this technique to train a linear classifier and an artificial neural network (ANN), using simulated datasets. The performances of the solutions returned from the multiobjective genetic optimization represent a series of optimal (sensitivity, specificity) pairs, which can be thought of as operating points on a receiver operating characteristic (ROC) curve. All possible ROC curves for a given dataset and classifier are less than or equal to the ROC curve generated by the niched Pareto genetic optimization.

Algorithms↗
PubMed1988

Mammary Paget's disease and intraductal carcinoma. Histologic, histochemical, and immunocytochemical comparison.

This study of mammary Paget's disease was carried out with the objects of clarifying its histogenesis and of determining optimal diagnostic measures. Ten consecutive cases of mammary Paget's disease with their underlying ductal carcinomas were compared. Histologic, histochemical, and immunocytochemical examination mainly supported the hypothesis that mammary Paget's disease is an extension of mammary ductal carcinoma into the overlying nipple epithelium. However, two of our ductal carcinomas stained strongly with S-100 protein, while Paget's disease was uniformly negative with this antibody. The significance of this finding is not known. Optimal diagnostic accuracy is obtained by using a combination of routinely stained sections along with a panel of immunocytochemical stains. Nipple wedge biopsy may demonstrate both intraduct carcinoma and Paget's disease, and is thus a superior biopsy technique.

Biopsy↗
PubMed1986

Computer-aided diagnostic strategy selection.

Determination of the optimal diagnostic work-up strategy for the patient is becoming a major concern for the practicing physician. Overlap of the indications for various diagnostic procedures, differences in their invasiveness or risk, and high costs have made physicians aware of the need to consider the choice of procedure carefully, as well as its relation to management actions available. In this article, the author discusses research approaches that aim toward development of formal decision analytic methods to allow the physician to determine optimal strategy; clinical algorithms or rules as guides to physician decisions; improved measures for characterizing the performance of diagnostic tests; educational tools for increasing the familiarity of physicians with the concepts underlying these measures and analytic procedures; and computer-based aids for facilitating the employment of these resources in actual clinical practice.

Artificial Intelligence↗
PubMed1984

A sequential protocol for the optimization of diagnostic procedures in hepatology.

The aim of this paper is to present a sequential protocol to be used in clinical practice for the detection of liver diseases, based on clinical history, physical examination, and laboratory investigation. The evaluation of the protocol efficacy was carried out on a sample of 288 subjects (92 normal, and 196 affected by various liver alterations) by comparing the obtained results with reference classifications independently performed on the basis of all available subject records (including many more laboratory tests than the ones used in the protocol). A cost-benefit analysis was also carried out, based on the resident population of Regione Piemonte, comparing the protocol with two other simpler ones. Results show that the proposed protocol allows a considerable reduction of costs, showing a high estimated efficacy for clinical use.

Adolescent↗
PubMed1994

Using directly acquired digital ECG data to optimize the diagnostic criteria for anterior myocardial infarction.

The use of a newly developed method of directly transferring digital data from Marquette electrocardiogram (ECG) systems (Milwaukee, Wisconsin) to personal computers for subsequent storage and analysis is illustrated. This method can eliminate the slowness and inaccuracy associated with measuring relevant ECG parameters from analog tracings and manually entering the data into a computer. In this study, the new method was used to derive ECG criteria for anterior myocardial infarction and to compare their performances to those of the current Marquette 12SL diagnostic program and of a group of cardiologists who had also interpreted the ECGs. Using angiographic data, 82 normal subjects and 55 patients with anterior myocardial infarction were identified. The digital ECG data from the patients in each group were transferred to a personal computer and frequency distributions of these data were generated. From these frequency distributions, the ECG criteria that most reliably separated the two groups were identified. The diagnostic performance of the best of these empirically derived criteria appears clinically superior to the performances of both the 12SL program and the cardiologists who had also interpreted the ECGs.

Adult↗