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PubMedDate not supplied

Predictive value of sequential testing in screening for silent myocardial ischemia in asymptomatic middle-aged men (the ECCIS Project).

The accuracy of sequential testing in the noninvasive diagnosis of coronary artery disease has been established in the symptomatic clinical populations, while little is known about its value when applied to low prevalence groups, such as totally asymptomatic men. To evaluate the accuracy of noninvasive sequential testing in the diagnosis of silent myocardial ischemia, data were collected from exercise electrocardiogram, 201Tl perfusion scintigraphy and radionuclide angiography for 62 totally asymptomatic middle-aged men who underwent coronary arteriography because they were positive for two or more markers of myocardial ischemia as determined by a diagnostic screening of a nonbiased population consisting of 4,842 presumably healthy men aged 40-59 years (the ECCIS Project). The predictive value of serial testing procedures for significant coronary artery obstruction was 35%. Predictive values of an abnormal electrocardiogram associated with either an abnormal 201Tl scintigram, an abnormal isotopic ventriculography, or both were 33, 38 and 31%, respectively. In asymptomatic middle-aged men, there is at least a 50% likelihood that an abnormal radionuclide test is a false-positive result, and the positive predictive value is not enhanced by the concordance of an abnormal 201Tl scintigraphy with an abnormal isotopic ventriculography. Thus, the application of noninvasive sequential testing in screening for asymptomatic coronary artery disease is limited by its low predictive value in accordance with the Bayesian probability theory.

Adult↗
PubMed1993

The mathematics of measurement: sensitivity, specificity and predictive value of available tests.

The correct clinical interpretation of any laboratory marker requires a good knowledge of its positive and negative predictive values, which are calculated from the sensitivity and the specificity of the test and from the prevalence of the disease. This means that we need a good assay technique in the case of biochemical tests, and a well defined reference sample (control subjects), with the ability to distinguish between a diseased and a healthy subject. In the field of alcohol abuse markers, each of these notions presents some degree of difficulty. There is no perfect solution, and a compromise has to be agreed upon.

Alcoholism↗
PubMed1992

[Value of signal-averaged electrocardiogram in ventricular arrhythmia without apparent heart disease].

Signal-averaged electrocardiography was performed in 132 subjects with various ventricular arrhythmias without clinically apparent heart disease and compared with the results obtained in a series of 45 normal subjects. The latter enabled definition of the following criteria of normality: QRS duration after averaging < 113 ms; Simson vector of the last 40 ms (RMS40) > or = 17 microV; low amplitude signal duration over 40 microV < 38 ms for a high pass bidirectional filter of 40-300 Hz. Complementary investigations (echo or angiography), performed in all cases, showed underlying abnormalities in 26 patients: 13 right ventricular dysplasias, 7 cardiomyopathies, 3 mitral valve prolapses and 3 minor congenital heart defects. These investigations were normal in the remaining 106 subjects. Of the 26 patients with cardiac disease, 15 had 3 criteria of positivity for late ventricular potentials, 6 had 2 criteria and the other 5 had no criteria of late ventricular potentials. Therefore, 81% of cases with cardiac disease had at least 2 diagnostic criteria of late ventricular potentials whereas only 4% of those without cardiac disease, and in the control group, had criteria of positivity (p < 0.001). Using these criteria, the predictive value of signal-averaged electrocardiography for the detection of underlying cardiac disease was good when 2 criteria are required for diagnosis of late ventricular potentials: sensitivity 81%, specificity 96%; predictive value of a positive test 78%, predictive value of a negative test 97%. Signal-averaged electrocardiography is therefore a good non-invasive method of diagnosing underlying cardiac disease in patients with ventricular arrhythmias without clinically apparent heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Accuracy and safety of transvaginal sonographic placental localization.

Transvaginal sonographic localization of the placenta was performed in 100 patients suspected of having placenta previa. Except in one patient, the diagnosis was confirmed at cesarean delivery in all cases of placenta previa found by sonography before delivery, resulting in a 93.3% predictive value of a positive test. The predictive value of a negative test was 97.6%; in two patients a low-insertion placenta diagnosed by sonography was found to be a placenta previa at delivery. The sensitivity and specificity of the technique were 87.5 and 98.8%, respectively. Although in some instances transvaginal sonography was performed during vaginal hemorrhage, aggravation of bleeding was never observed. Transvaginal sonographic localization of the placenta proved to be an accurate and safe diagnostic procedure.

Cesarean Section↗
PubMedDate not supplied

The predictive value of the postcoital test for auto- and isoimmunity to spermatozoa.

Twenty eight infertile couples with sperm antibodies were used in the study. The immunologic factors in the husbands and wives were compared with the results of the post coital test. The results of the study showed that the post coital test had a predictive value of 75% for male auto-immunity to sperm while only 37% of the females with sperm antibodies had a poor post coital test. It was concluded that the post-coital test is an important screening predictor of auto-immunity to spermatozoa.

Antibodies↗
PubMed2006

Estimating the predictive value of the Test of Memory Malingering: an illustrative example for clinicians.

Recent years have witnessed an explosion in the amount of research literature dedicated to the identification of symptom exaggeration and/or malingering in neuropsychological assessments. Additionally, there is now a growing literature devoted to estimating the base rates of symptom exaggeration/malingering in a range of populations and settings. However, very little literature has been devoted to estimating the positive predictive value (PPV) or negative predictive value (NPV) of these assessment devices and/or strategies. The current project was conducted to provide an illustrative example of how to use the research literature to calculate both PPV and NPV in everyday clinical practice. When the Word Memory Test (WMT) was used as the "gold standard" to which the Test of Memory Malingering (TOMM) was compared, the TOMM achieved very high PPV (.98) and acceptable NPV (.78). How to incorporate the strategy used into clinical practice is discussed.

Female↗
PubMed1996

The MICRAL test for diabetic microalbuminuria: predictive values as a function of prevalence.

The MICRAL test is an immunospecific dipstick for detection of low concentrations of albumin in urine (microalbuminuria). The test is intended to be used for screening in an ambulatory setting. The utility of the test depends on its ability to accurately predict which patients will be classified as either microalbuminuric or normoalbuminuric by means of a standard laboratory method for determination of albumin in urine. We have analysed data from studies with a total of 2904 samples of urine from diabetic patients. The data are from our own study (190 samples) and from a selected set of 10 publications. The results from standard laboratory measurements of albumin in urine were used as " gold standards". The sensitivity and specificity as calculated from the pooled data were 83.2 and 92.3%, respectively. The predictive values were calculated using simulated changes in the prevalence of microalbuminuria (MAU). At a prevalence of MAU of 1% the predictive value of a negative test is 99.9% but that of a positive test only 9.8%. At a prevalence of MAU of 80% the positive predictive value is 97.7% and the negative predictive value 57.9%. In general, any change in the prevalence will lead to a change in the predictive values. Thus the prevalence of MAU in the given clinical setting is a decisive factor in determining the utility of the MICRAL test.

Albuminuria↗
PubMed2006

The predictive value of exercise testing for survival among 75-year-old men and women.

All 75-year-olds born in 1914 and living in the city of Jyväskylä, central Finland (n=388) were invited to study the predictive value of exercise test for mortality. Subjects who entered the laboratory (n=295) were to have a standard pre-test evaluation and perform a cycle ergometer exercise test. Subjects with complete background, exercise-test status and mortality data (n=282) were divided into three groups according to exercise-test status: a non-exercise test group (n=79), an exercise-test termination group (n=95), and an exercise-test completion group (n=108). Mortality was followed up for 9 years. The multivariate hazard ratio (HR) for death among the non-exercise test group compared with exercise-test completion group was 1.87 (CI 1.19-2.94). The multivariate HR for death among the exercise-test termination group compared with the exercise-test completion group was 0.95 (CI 0.58-1.54). High cycling power (W/kg body weight) in the exercise-test completion group was associated with a decreased risk for death with a multivariate HR 0.14 (CI 0.05-0.38). Performing an exercise test serves information on the risk of death that is incremental to clinical data and traditional risk factors of death in elderly people.

Aged↗
PubMed2002

Five-year outcome of normal pressure hydrocephalus with or without a shunt: predictive value of the clinical signs, neuropsychological evaluation and infusion test.

BACKGROUND: Between 1993-1995, 51 patients under 75 years of age with clinical symptoms and CT-based diagnosis of normal pressure hydrocephalus were investigated prospectively in order to clarify the value of neuropsychological tests, clinical symptoms and signs and infusion test in the differential diagnosis and prediction of outcome in normal pressure hydrocephalus. METHODS: Patients had a thorough neurological examination, and neuropsychological evaluation. A 24-hour intraventricular ICP-measurement, infusion test, neurophysiological investigations and MRI study were performed, and a cortical biopsy was obtained. The ICP measurement defined the need for a shunt. All 51 patients were re-examined three and twelve months later. The final follow-up was accomplished five years postoperatively. FINDINGS: 25 of the patients needed a shunt operation. One year after a shunt placement 72% of these patients had a good recovery concerning activities of daily living, 58% benefited in their urinary incontinence and 57% walked better. During the 5 years of follow-up 8 patients with shunt and 9 without shunt had died. Positive effect of shunting remained. Only one neuropsychological test, recognition of words test, distinguishes the patients with the need for a shunt. Simple mini mental examination test was not different in those who improved. In the postoperative follow-up patients with shunt showed no change in neuropsychological tests even if they were subjectively better. The infusion test was of no value in diagnosing NPH. The 16 patients with Alzheimer's disease did worse after one year than those without pathological changes, but the mortality was not increased. INTERPRETATION: Specific neuropsychological tests are of little value in diagnosing NPH. Mini-Mental status examination was neither of value in diagnosing NPH nor in prediction of the outcome. In this study the infusion test did not improve diagnostic accuracy of NPH, but shunt placement relieves urinary incontinence and walking disability in patients with increased ICP. The patients with positive Alzheimer diagnosis on biopsy did not improve.

Aged↗
PubMed2004

[Modelling sensitivity, specificity and predictive values of hematuria testing using reagent sticks in the diagnosis of Schistosoma haematobium infection].

Since its recognition as an effective tool to identify Schistosoma haematobium infection, haematuria detection has been used in several large scale control programs. However, large variations in performance between age groups, gender, prevalence and areas were observed. Correlation between the degree of haematuria and the intensity of infection and between intensity of infection with age and/or gender could partly explained these variations. Other factors, such as the circadian cycles and day-to-day variations of haematuria and egg excretion, a concomitant presence of blood in urine for another reason than schistosomiasis and the intrinsic characteristics of the reagents strips also contribute to the observed variations. This study assessed the influence of age, gender and intensity of infection taken together on the performance of the diagnostic test by fitting logistic regression models. During a socio-economic study of schistosomiasis, carried out between 1989 and 1991 in a rice-growing area located in Mali, West Africa, haematuria was detected by reagent strips among 2,873 six-year-old and more subjects randomly chosen from 14 villages. The "gold standard" of infection was provided by the parasite egg counts. Laboratory quality controls were implemented. Observed sensitivities, specificities, positive and negative predictive values were calculated by the standard two-by-two tables. The influence of age, gender, intensity of infection, measured in a continuous scale, on these parameters were studied by fitting two logistic models. The first one modelled sensitivity and specificity The second one modelled predictive values. Goodness-of-fit tests were performed. Large variations in the observed values of sensitivities, specificities and predictive values by age and gender were observed. The best fitted model for sensitivity and specificity included infection status, age, gender, intensity and an age by gender interaction. For the predictive values, the best model included haematuria, age, and an haematuria by age interaction. Given the large variations in the performances across the covariates strata defined by cross-tabulation of the age/gender and intensity categories, this modelling approach provided a more realistic appraisal of the performances than using overall values obtained from a general two- by-two table. It allowed to assess the effect of the covariates of interest on the performances of the test and provided an adjustment of the performances on these covariates. The best fitted model was able to provide estimates of sensitivity for each age/gender stratum as a function of the intensity of infection, which could not be done by using the two-by-two table approach. A decrease in sensitivity adjusted for intensity of infection above 10 years of age among males is discussed. This modelling approach also uses all the information available and not only the data from the stratum of interest.

Adolescent↗
PubMed1992

Effect of instructions on isokinetic trunk strength testing variability, reliability, absolute value, and predictive validity.

Although isokinetic strength testing has been in use for more than two decades, and numerous studies have addressed isokinetic performance of the lumbar spine, the effect of instructions on isokinetic trunk strength has not been studied. In a sample of 30 healthy women, this study examined the effect of "high-demand" instructions on lumbar strength performance. High-demand instructions were found to have a substantial positive effect on performance variability, reliability, absolute magnitude, and validity. Under these conditions, isokinetic trunk strength was found to be predictive of performance in a frequent lifting-lowering task.

Adult↗
PubMed1986

Predictive value of electrophysiologic testing in the treatment of drug-refractory ventricular arrhythmias with amiodarone.

The value of serial electrophysiologic testing in predicting the outcome of patients receiving amiodarone is controversial. Thirty-six patients with drug-refractory sustained ventricular tachyarrhythmias underwent serial electrophysiologic drug testing. All patients had inducible sustained ventricular tachyarrhythmias off any antiarrhythmic medication. After an oral amiodarone loading regimen there was no change in inducibility in 23 patients (group I), whereas ventricular tachycardia was made more difficult to induce in 5 patients, i.e. sustained ventricular tachycardia was only inducible using a basic drive which was 40 bpm faster than during control (group II). In the remaining 8 patients, induction of ventricular tachycardia was suppressed (group III). During follow-up of 11 +/- 12.3 months, 6 patients in group I had a recurrence of ventricular tachycardia and 2 died suddenly, whereas the course of groups II and III patients was uneventful (P less than 0.03, Breslow; P less than 0.01, Mantel-Cox). The predictive accuracy of the response to serial electrophysiologic testing during amiodarone therapy was 64%, the sensitivity was 46% and the specificity 100%. Thus, serial electrophysiologic drug testing is useful in determining prognosis and predicts the long-term response to amiodarone therapy in patients with ventricular tachyarrhythmias using a graded stimulation protocol.

Amiodarone↗
PubMed1985

[Prognostic value of symptom-limited ergometry 3 weeks after acute myocardial infarct].

96 patients, under 70 years of age, underwent symptom-limited (maximal) exercise testing in the 3rd week after an acute myocardial infarction when neither cardiac insufficiency, angina pectoris (post-infarction) nor malignant arrhythmias were present. A further 29 patients, who could not be exercised because of the reasons mentioned, had a significantly higher frequency of coronary events during the 14 month observation period than those patients who could be exercised (55% vs. 23%, P = 0.05). When signs of (reversible) ischaemia occurred during exercise testing (angina pectoris, ST-segment depression greater than 0.1 mV), the one-year prognosis was significantly worse than in patients having no ischaemia. By means of this test the occurrence of a "coronary event" can be forecasted with high sensitivity (92%) but low specificity (46%). Thus, the negative test ("predictive value" 94%) is suitable for recognising patients with low spontaneous risk thus sparing them from further invasive investigations.

Adult↗
PubMed2000

Comparisons of predictive values of binary medical diagnostic tests for paired designs.

Positive and negative predictive values of a diagnostic test are key clinically relevant measures of test accuracy. Surprisingly, statistical methods for comparing tests with regard to these parameters have not been available for the most common study design in which each test is applied to each study individual. In this paper, we propose a statistic for comparing the predictive values of two diagnostic tests using this paired study design. The proposed statistic is a score statistic derived from a marginal regression model and bears some relation to McNemar's statistic. As McNemar's statistic can be used to compare sensitivities and specificities of diagnostic tests, parameters that condition on disease status, our statistic can be considered as an analog of McNemar's test for the problem of comparing predictive values, parameters that condition on test outcome. We report on the results of a simulation study designed to examine the properties of this test under a variety of conditions. The method is illustrated with data from a study of methods for diagnosis of coronary artery disease.

Biometry↗
PubMed1981

Predictive value of lymphocytotoxic test and platelet aggregometry for the effect of transfused platelet concentrates.

Sera of patients with thrombocytopenic diathesis before platelet transfusion were evaluated using donor's platelets in the aggregometry test the donor's lymphocytes in the lymphocytotoxicity test. In most cases the results of both tests were in agreement, although sometimes, despite strongly positive results of LCTT, the Agr was negative. Both tests showed a similar value for the prediction of the effectiveness of platelet concentrates: Agr in 80% and LCTT in 71% of cases.

Blood Transfusion↗
PubMedDate not supplied

Biomedical testing of the kidney for persons exposed to hazardous substances in the environment.

To identify kidney injury and dysfunction among persons exposed to hazardous substances in the environment, a battery of biomarker tests has been identified for systematic public health use. The standardized use of tests for conducting field epidemiology studies was reviewed in a 1995 joint American-European workshop, and recommended tests were selected by the Agency for Toxic Substances and Disease Registry (ATSDR) and the Centers for Disease Control and Prevention (CDC). These tests would be useful in conducting public health activities but are not recommended in a manner that would suggest changes in routine clinical practice. The tests selected include serum creatinine, urine analysis, urinary albumin, retinol-binding protein, N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), and osmolality. Urinary creatinine was also included to adjust for urine concentration. The tests were chosen for use not only in epidemiologic field studies but also clinically oriented population screening and case studies of persons exposed to hazardous substances at waste sites. Studies using the battery may address the relationship between kidney damage and dysfunction and exposures to hazardous substances, especially in susceptible populations including children. Also, longitudinal studies should be conducted to evaluate the long-term health implications of abnormal tests and to measure the tests' predictive value for renal injury. These studies could evaluate the continuum of renal dysfunction as expressed by persistent decrements in glomerular filtration to the development of end-stage renal disease.

Biomarkers↗