Use Of Receiver Operating Characteristic Curves Research Articles

Clinical validation of image-based AI predictive biomarkers for precision neoadjuvant triple-negative breast cancer treatment (PEAR-TNBC).

TPS627 Background: Triple-negative breast cancer (TNBC) has the worst prognosis of all breast cancer subtypes, with a 5-year recurrence rate of 30% in patients with localized disease. Pathological Complete Response (pCR) strongly predicts the risk of recurrence and death, which are reduced by approximately 80% in patients who achieve a pCR following neoadjuvant treatment. There are multiple treatment regimens available for TNBC patients in the neoadjuvant setting but no biomarkers to match patients to treatments. Giving ineffective treatment leads to worse outcomes for patients and additional burden on healthcare systems. Pear Bio has developed a functional precision medicine test coupling an organ-on-a-chip with a computer vision (CV) pipeline through which an individual patient’s response to different treatments can be monitored simultaneously ex vivo. Each microtumor’s response is monitored using time-lapse 3D microscopy. A proprietary CV pipeline quantifies the responses (e.g. tumor cell viability, culture size). Lab test responses are correlated to the clinical outcomes of the patients to identify biomarkers with high predictive accuracy. This generates multiple CV-based biomarkers with potential predictive value. PEAR-TNBC (NCT05435352) is a prospective, observational UK-wide trial aimed at assessing the test’s accuracy in predicting pCR in TNBC patients in the neoadjuvant setting. The study recruits patients with early TNBC (N=54) who are willing to undergo an additional core needle biopsy prior to starting neoadjuvant therapy. The assay is run in parallel with the patient’s treatment and the treating oncologist is blind to the results of the Pear Bio test. Methods: The study has 2 cohorts (A and B), each recruiting at least 20 evaluable patients. To be eligible, patients need to have ≥10mm tumor, stage I-III, TNBC, with planned neoadjuvant treatment followed by surgery and be willing to undergo a study-specific core needle biopsy procedure. Cohort B also requires a 40mL blood sample. To be evaluable, eligible patients’ samples must be successfully cultured in the 3D ex vivo assay and they must complete at least 4 cycles of neoadjuvant chemotherapy prior to surgery. Cohort A recruitment began on 05/27/22 and has recruited 20 evaluable patients, through 5 sites. Cohort B accrual will begin upon completion of Cohort A. The primary endpoint is the accuracy of the Pear test in predicting pCR, defined as specificity, with secondary outcomes as sensitivity, and positive and negative predictive values. Novel aspects include a focus on specificity (i.e. accurately predicting patients who will not achieve pCR) combined with the use of Receiver-operating characteristic curves to define optimal cutoffs for the CV biomarkers. Future trials will aim to run the test prior to therapy selection, guiding the choice of regimen to assess the test’s ability to increase pCR rates. Clinical trial information: NCT05435352 .

Evaluation of diagnostic accuracy of physical examination and MRI for ligament and meniscus injuries

Surgical planning shall be based on thorough physical examination and radiological findings during patient evaluation. The use of computational methods in the evaluation of diagnostic tests may facilitate the decision-making process as well as reduce treatment costs. Conventional X-ray is a modality of choice for bone visualisation however, it is not suitable for soft tissue evaluation. MRI is a tool designated for soft tissue examination however, its accuracy is debated in the literature. This study was performed to evaluate the diagnostic accuracy of MRI in most common knee injuries in comparison to physical examination. The evaluation of selected diagnostic methods used in the evaluation of ligaments and meniscus was carried out based on statistical indicators and ROC (Receiver Operating Characteristic) curves. The indicators were determined using Statistica and Matlab software. 69 patients were enrolled in the study, who were previously scheduled for arthroscopic knee surgery. Each patient underwent a closed protocol physical evaluation prior to surgery. MRI reports were collected and stored. Diagnostic accuracy was evaluated with the use of ROC curves. Physical examination presented greater diagnostic accuracy than MRI in ACL tears. The same dependency was found in lateral and medial meniscal tears. MRI showed AUC of 0.835 for MM, 0.788 for LM, and 0.870 for ACL, respectively. The physical examination had the greatest diagnostic accuracy in comparison with ACL tears, where AUC for the Lachman test reached 0,902. Apley test was most accurate for LM tears with AUC reaching 0,842, while the McMurray test was the most accurate for MM lesions. MRI is a preferable addition to a thorough physical examination.

Evaluation of the diagnostic accuracy of MRI in detection of knee cartilage lesions using Receiver Operating Characteristic curves

Medical treatment, and especially surgical procedures, is carefully planned and executed based on various diagnostic methods. Physical examination provides preliminary information about the patient’s health; however, when orthopaedic surgery is concerned, more accurate radiological evaluation is necessary. MRI is perceived as a state-of-the-art radiological modality. In this study, we have evaluated MRI efficiency in detecting chondral lesions in the knee joint requiring surgical treatment. The evaluation of selected diagnostic methods used in the assessment of joint cartilage damage was carried out based on statistical indicators and ROC (Receiver Operating Characteristic) curves. The indicators were determined using Statistica and Matlab software. 95. patients underwent knee arthroscopy subsequently after performing MRI for various intraarticular lesions. Chondral lesions estimated with the use of the ICRS scale were divided into two groups, one requiring surgical treatment ICRS grade 3-4, and selected for conservative treatment ICRS grade 0-2. Results were evaluated with the use of ROC curves. MFC was the most common lesion site, where chondral lesions requiring surgical intervention were found in nearly 50% of patients. LTC was affected only in 9 patients, which was the rarest location for chondral lesions. The diagnostic efficiency for each anatomical location was evaluated. The highest diagnostic accuracy was found on MFC followed by LTC. The lowest diagnostic accuracy was found for PFJ. The AUC ranged from 0.8438 for MFC to 0.55 for PFJ. LFC and MTC showed similar accuracy with AUC respectively 0.6419 and 0. 6623. To sum up, MRI is a gold standard for cartilage evaluation, however, its accuracy differs among various anatomical locations, therefore requires a thorough assessment prior to surgical planning.

ROC Curves for the Statistical Analysis of Microarray Data.

A receiver operating characteristic (ROC) curve is a graphical plot that illustrates the diagnostic ability of a binary classifier as a function of its discrimination threshold. This chapter is an overview on the use of ROC curves for microarray data. The notion of ROC curve and its motivation is introduced in Subheading 1. Relevant scientific contributions concerning the use of ROC curves for microarray data are briefly reviewed in Subheading 2. The special case with covariates is considered in Subheading 3. Two relevant aspects are reviewed in this section: the use of LASSO techniques for selecting and combining relevant markers and how to correct for multiple testing when a large number of markers are available. Finally, some conclusions are included.

Use of ROC curves for early warning of landslide displacement rates in response to precipitation (Piagneto landslide, Northern Apennines, Italy)

Active landslides are generally characterized by variations in displacement rate in response to cumulated precipitation. Velocities that are only exceeded in a limited number of days during the year might be considered as critical events, since they might determine, or prelude to, a significant evolution of the landslide. The purpose of this paper is to present a novel approach based on the use of receiver operating characteristic (ROC) curves for assessing cumulated precipitation thresholds that can provide early warning for the occurrence of critical events such as the exceedance of rare displacement rates. The approach has been developed and tested in the Piagneto landslide, an active complex rock slide—debris slide in the Northern Apennines of Italy, for which a 5-year continuous surveying monitoring dataset is available. On the basis of the first 4 years of monitoring data (training dataset), threshold curves relating cumulative precipitation (mm) to precipitation moving windows (days) have been generated by using different benchmarks that, in literature, are used to estimate the maximum predictive performance of ROC curves. These threshold curves have been successfully validated using the last 1 year of monitoring data (validation dataset). They have then been used to simulate how they might help defining different early warning levels in due advance. The proposed methodology can be replicated in any landslide for which a monitoring dataset that includes recurrent acceleration events in response to precipitation is available.

Admission hyperglycemia in patients with acute coronary syndrome complicated by cardiogenic shock.

Many reports shoed that for patients with acute coronary syndrome (ACS) increased admission blood glucose (ABG) level is associated with adverse outcomes. Although scientific reports on this issue are still inconsistent, many recent studies confirm that hyperglycemia is also an unfavorable prognostic factor in patients with ACS complicated by cardiogenic shock (CS). The aim of this study is to determine if hyperglycemia on admission can be a predictor of in-hospital death in patients with ACS complicated by CS. The study population consisted of 40 patients with ACS complicated by CS admitted to the Intensive Cardiac Therapy Clinic from January 2010 to May 2013 and treated with primary percutaneous coronary intervention. A control group was selected among patients with uncomplicated ACS. Patients with CS had significantly higher levels of ABG (15.4 ± 6.26 vs. 7.97 ± ± 2.28 mmol/L, p < 0.01) in comparison with the control group. There was no statistically significant correlation between the level of glucose on admission and in-hospital mortality. Average ABG in patients who survived and in those who died were respectively 15.42 ± 5.61 vs. 15.40 ± 6.87 mmol/L, p > 0.05. Comparison in groups depending on ABG level and calculations with use of receiver-operating characteristics curves showed no relationship between the level of ABG and patients' deaths. Hyperglycemia on admission is a clinical feature of patients with ACS who develop CS, however its prognostic value requires further studies.

Evaluating the social determinants of teenage pregnancy: a temporal analysis using a UK obstetric database from 1950 to 2010

BackgroundTeenage pregnancy is a known social problem which has been previously described using a number of deprivation measures. This study aimed to explore the temporal patterns of teenage pregnancy in...

The incorporation of ICT in higher education. The contribution of ROC curves in the graphic visualization of differences in the analysis of the variables

AbstractThis paper has focused on the productive use of information and communications technology (ICT) by university students and its influence on academic performance. The objective is to determine whether a comparison of successful and non‐successful students (in relation to academic achievements) versus the variables studied (linked to the process of ICT incorporation) can help us to establish contextual and behavioral patterns associated with good academic performance. This differential analysis is carried out by making basic statistical comparisons (student's t‐test). The data analysis is completed by applying receiver operating characteristic curves, a methodology of new application in the area of education. The sample was composed of 1194 students enrolled in 40 different subjects at various universities in two countries, Mexico and Spain. Students gave a very positive appraisal of the value of ICTs to support the teaching process, but they express an intermediate level of satisfaction with the teaching conditions in subjects, which are using the support of these technologies. Moreover, there is a clear relation between high scores in the variables associated with the processes of incorporation of ICT (satisfaction with teaching, higher levels of competence in ICT, less training needs in ICT, more favorable attitudes toward their integration in training processes) and achieving higher academic qualifications.Practitioner NotesWhat is already known about this topic The incorporation of information and communications technology (ICT) into teaching and learning processes is going on at the university as a whole. A number of researches have been developed to know the influence of different variables (personal, organizational, ...) in the integration of ICT and its impact on academic success. The results do not show clear evidence about how certain variables help to improve achievements in ICT‐mediated contexts, although most studies consider relevant variables as teaching conditions, students’ competence in ICT, ICT assessment for learning and students’ attitudes toward ICT. What this paper adds Analysis of the impact of the aforementioned variables on students’ academic success on two related cultural contexts (Salamanca and Chihuahua), both in a similar process of incorporating ICT. In terms of methodology, the use of receiver operating characteristic (ROC) curves to plot the differences in the variables studied between groups of successful and unsuccessful academic achievements. Implications for practice and/or policy Knowledge of the importance of studied variables on the academic success in developing training programs to meet their training needs and achieve the improved skills of students. Assessment of ICT by students as academic self‐learning tools. To suggest the use of ROC curves to express graphically the differences between groups for the study variables in the field of educational research.

A transfer of technology from engineering: use of ROC curves from signal detection theory to investigate information processing in the brain during sensory difference testing.

This article reviews a beneficial effect of technology transfer from Electrical Engineering to Food Sensory Science. Specifically, it reviews the recent adoption in Food Sensory Science of the receiver operating characteristic (ROC) curve, a tool that is incorporated in the theory of signal detection. Its use allows the information processing that takes place in the brain during sensory difference testing to be studied and understood. The review deals with how Signal Detection Theory, also called Thurstonian modeling, led to the adoption of a more sophisticated way of analyzing the data from sensory difference tests, by introducing the signal-to-noise ratio, d′, as a fundamental measure of perceived small sensory differences. Generally, the method of computation of d′ is a simple matter for some of the better known difference tests like the triangle, duo–trio and 2-AFC. However, there are occasions when these tests are not appropriate and other tests like the same–different and the A Not–A test are more suitable. Yet, for these, it is necessary to understand how the brain processes information during the test before d′ can be computed. It is for this task that the ROC curve has a particular use.

Receiver operating characteristic (ROC) curves and the definition of threshold levels to diagnose coronary artery disease on electrocardiographic stress testing. Part II: The use of ROC curves in the choice of electrocardiographic stress test markers of ischaemia

A common problem in diagnostic medicine, when performing a diagnostic test, is to obtain an accurate discrimination between 'normal' cases and cases with disease, owing to the overlapping distributions of these populations. In clinical practice, it is exceedingly rare that a chosen cut point will achieve perfect discrimination between normal cases and those with disease, and one has to select the best compromise between sensitivity and specificity by comparing the diagnostic performance of different tests or diagnostic criteria available. Receiver operating characteristic (or receiver operator characteristic, ROC) curves allow systematic and intuitively appealing descriptions of the diagnostic performance of a test and a comparison of the performance of different tests or diagnostic criteria. This review will analyse the basic principles underlying ROC curves and their specific application to the choice of optimal parameters on exercise electrocardiographic stress testing. Part II will be devoted to the comparative analysis of various parameters derived from exercise stress testing for the diagnosis of underlying coronary artery disease.

Receiver operating characteristic (ROC) curves and the definition of threshold levels to diagnose coronary artery disease on electrocardiographic stress testing. Part I: The use of ROC curves in diagnostic medicine and electrocardiographic markers of ischaemia

A common problem in diagnostic medicine, when performing a diagnostic test, is to obtain an accurate discrimination between 'normal' cases and cases with disease, owing to the overlapping distributions of these populations. In clinical practice, it is exceedingly rare that a chosen cut point will achieve perfect discrimination between normal cases and those with disease, and one has to select the best compromise between sensitivity and specificity by comparing the diagnostic performance of different tests or diagnostic criteria available. Receiver operating characteristic (or receiver operator characteristic, ROC) curves allow systematic and intuitively appealing descriptions of the diagnostic performance of a test and a comparison of the performance of different tests or diagnostic criteria. This review will analyse the basic principles underlying ROC curves and their specific application to the choice of optimal parameters on exercise electrocardiographic (ECG) stress testing. Part I will focus on theoretical description and analysis along with reviewing the common problems related to the diagnosis of myocardial ischaemia by means of exercise ECG stress testing. Part II will be devoted to applying ROC curves to available diagnostic criteria through the analysis of ECG stress test parameters.

Standards for Reporting Prognostic Tumor Marker Studies

Technologic and scientific advances have led to an explosion in the number of new tumor markers being studied for the early detection and prognosis of cancer. It is imperative that the design and results of tumor marker studies are reported in a comprehensive manner so that they can be evaluated critically. However, this is often not the case. This problem motivated the Statistics Subcommittee of the National Cancer Institute-European Organization for Research and Treatment of Cancer working group on cancer diagnostics to develop guidelines, referred to as REMARK, for the reporting of tumor marker studies. In this issue of Journal of Clinical Oncology, McShane et al present these REMARK guidelines for the reporting of prognostic tumor marker studies. These guidelines are similar in spirit to the Consolidated Standards of Reporting Trials initiative for randomized clinical trials and Standards for Reporting of Diagnostic Accuracy statement for diagnostic accuracy studies. The REMARK contains 20 recommendations about the reporting of the study design, statistical analysis methods, preplanned hypotheses, patient and specimen characteristics, and assay methods for tumor marker studies. The guidelines are intended for studies of prognostic markers, which McShane et al define to be markers that “have an association with some clinical outcome” and which “may be considered in the clinical management of a patient.” As an excellent example of how a prognostic marker study should be reported, Dome et al in this issue of Journal of Clinical Oncology report the results of a study investigating the prognostic significance of telomerase expression level in patients with favorable histology Wilms’ tumor. It clearly adheres to the reporting guidelines outlined in REMARK. The REMARK guidelines were developed primarily for studies evaluating a single tumor marker while possibly adjusting for other known prognostic factors. However, the guidelines should also be applicable to studies of a small number of tumor markers such as in the study by Dome et al of expression levels of TERT mRNA and TERC/hTR in patients with favorable histology in a Wilms’ tumor. However, the guidelines are not suggested for studies of a large number of candidate markers that could be obtained, for example, from protein mass spectrometry profiles or gene expression arrays, because the guidelines do not discuss the additional statistical considerations required for high-dimensional data. Biomarkers are increasingly being developed to detect tumors early enough that treatment is likely to be successful. Five phases of biomarker development for early detection of cancer have been proposed. Specifically, preclinical exploratory studies (phase 1), clinical assay development for clinical disease (phase 2), retrospective longitudinal repository studies (phase 3), prospective screening studies (phase 4), and cancer control studies (phase 5). The REMARK guidelines appear to be most relevant to phase 2 and 3 biomarker studies. In these phases the receiver operating characteristic (ROC) curve can be used to estimate the ability of a continuous biomarker to predict or classify the patients who are likely and those who are not likely to have the outcome. A ROC curve is a graphical display of the tradeoffs of the true-positive rate (ie, sensitivity) and false-positive rate (ie, 1 specificity) corresponding to all possible binary tests that can be formed from a continuous biomarker. Baker provides a useful description of the use of ROC curves in the evaluation of early detection biomarkers. The disappointing performance of markers that were initially shown to have a strong association with outcome in part may be because a marker that is strongly associated with outcome may not be effective for predicting those who are likely and those who are not likely to have the outcome. Pepe et al note that a marker with an odds ratio as high as 3 will be a poor predictor of risk. The classification ability of a continuous marker should be assessed using ROC curves, whereas sensitivity and specificity can be used for dichotomous markers. The use of the REMARK guidelines will allow tumor marker studies to be evaluated critically as well as interpreted JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 23 NUMBER 36 DECEMBER 2

Receiver-operator characteristic curves for the ultrasonographic prediction of small-for-gestational-age fetuses in low-risk pregnancies

OBJECTIVE: Our purpose was to assess the accuracy of third-trimester ultrasonographic biometry in the diagnosis of small-for-gestational age fetuses in a low-risk obstetric population. STUDY DESIGN: A total of 1000 low-risk pregnancies were prospectively examined at 31 weeks' gestation. The diagnostic accuracy of the fetal abdominal circumference and estimated fetal weight according to 24 formulas in the literature were evaluated by the use of receiver-operator characteristic curves. RESULTS: The incidence of a birth weight <10th percentile was 8.2%. The diagnostic accuracies of abdominal circumference and estimated fetal weight were remarkably similar. None of the 24 formulas performed significantly better than the measurement of the abdominal circumference. At a specificity of 90%, 46% of infants with a birth weight <10th percentile and five of six cases with adverse perinatal outcomes were predicted. CONCLUSION: In a low-risk obstetric population third-trimester ultrasonographic biometry has limited value in predicting small-for-gestational-age fetuses, and estimation of fetal weight does not carry an advantage over measurement of the abdominal circumference. The optimal cutoff value remains uncertain. However, by accepting a 10% false-positive rate, half of small-for-gestational-age fetuses and most perinatal complications could be recognized. (A M J O BSTET G YNECOL 1996;174:1037-42.)

Determination of sixty percent or greater carotid artery stenosis by duplex Doppler ultrasonography

The Asymptomatic Carotid Atherosclerosis Study, demonstrating the benefit of carotid endarterectomy for symptom-free patients with 60% or greater carotid artery stenosis, has given rise to the need for development of screening parameters for detection of these lesions. Traditional duplex categories (50% to 79%, 80% to 99%) are not applicable. We sought to develop duplex criteria for determination of 60% or greater carotid artery stenosis by comparison with arteriography. The duplex scans and arteriograms of 110 patients (210 carotid arteries), obtained within 1 month of each other, were reviewed by blinded readers. Arteriographic stenosis was determined by the method of the Asymptomatic Carotid Atherosclerosis Study. Duplex measurements of peak systolic velocity (PSV) and end-diastolic velocity (EDV) were recorded, and ratios of velocities in the internal and common carotid arteries (ICA, CCA) were calculated. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy were determined, and receiver-operator characteristic curves were generated. Interobserver agreement for measurement of arteriographic stenosis was "almost perfect" (kappa = 0.86). The criteria determined for detection of 60% or greater stenosis were as follows: PSVICA > 170 cm/sec (sensitivity 98%, specificity 87%, PPV 88%, NPV 98%, accuracy 92%), EDVICA > 40 cm/sec (sensitivity 97%, specificity 52%, PPV 86%, NPV 86%, accuracy 86%), PSVICA/PSVCCA > 2.0 (sensitivity 97%, specificity 73%, PPV 78%, NPV 96%, accuracy 76%), EDVICA/EDVCCA > 2.4 (sensitivity 100%, specificity 80%, PPV 88%, NPV 100%, accuracy 88%). If all of the above criteria were met, 100% accuracy was achieved. It is concluded that 60% or greater carotid artery stenosis can be reliably determined by duplex criteria. The use of receiver-operator characteristic curves allows the individualization of duplex criteria appropriate to specific clinical situations of patient screening for lesions (high sensitivity and NPV) or use as a sole preoperative imaging modality (high PPV). Individual vascular laboratories must validate their own results.

The diagnostic value of urinary pyridinium cross-links of collagen, serum total alkaline phosphatase, and urinary calcium excretion in neoplastic bone disease.

Bone metastases strongly affect skeletal metabolism by both their growth and their paracrine activities. However, so far no specific laboratory marker has been found to signal the spread of neoplastic disease to bone. We performed a cross-sectional study of 153 cancer patients and an equal number of healthy controls matched for sex and age, in which we determined serum levels of calcium and total alkaline phosphatase (TAP) as well as the fasting urinary excretion of calcium (uCa) and of the collagen cross-links pyridinoline (uPYD) and deoxypyridinoline (uDPD). The aim of the study was to analyze the diagnostic validity of the biochemical parameters measured with regard to neoplastic bone involvement. In the cancer group, 98 patients had overt bone metastases, as judged from radiographic and radioisotopic bone imaging. The remaining 55 patients were also in an advanced stage of disease, but there was no evidence of malignant bone involvement. In comparison to healthy controls, patients both with and without metastatic bone disease had significantly higher levels of TAP, uPYD, and uDPD (P < 0.0001). Only in cancer patients with bone metastases was the median serum calcium level higher than in the healthy controls (P < 0.02). uCa was the same in cancer patients and the control group. Within the collective of cancer patients, individuals with skeletal metastases had higher levels of serum calcium (P < 0.05), TAP (P < 0.01), and uPYD and uDPD (both P < 0.0001), than patients without evidence of malignant bone disease. uCa did not differ between the 2 groups of cancer patients. The cancer patients were then stratified into 4 subgroups according to the serum calcium level (< or = 2.6 mmol/L >) and the absence or evidence of bone metastases. This stratification revealed that in patients with bone metastases, uPYD and uDPD levels were similar in normocalcemic and hypercalcemic subjects, whereas in hypercalcemic patients, uCa levels significantly exceeded those in normocalcemic patients. When the efficacy of TAP, uCa, uPYD, and uDPD in discriminating between patients with and without bone metastases was evaluated by use of receiver-operating characteristic curves and stepwise multivariate regression analysis, uPYD was found to have the highest diagnostic validity. Using 50 mumol PYD/mol creatinine (i.e. the upper limit of normal range) as the cut-off level, the sensitivity of uPYD was 88.7%, whereas the specificity was only 41.8% (odds ratio, 5.598; 95% confidence interval, 2.547-12.306).(ABSTRACT TRUNCATED AT 400 WORDS)

Receiver operating characteristic curves: a basic understanding.

Receiver operating characteristic (ROC) is one form of an objective measurement that can be used to compare newer imaging technologies against human observer performance (the ability of the expert radiologist). Use of ROC curves allows one to account for a continuum of radiologic interpretations when calculating sensitivity and specificity for an imaging modality and avoids the inaccuracies that arise from assuming that imaging findings are absolutely normal or abnormal. An ROC curve is generated by plotting sensitivity on the y axis as a function of [1-specificity] on the x axis for a continuum of diagnostic criteria. ROC curves allow visual analysis of the trade offs between the sensitivity and the specificity of a test with regard to the variable diagnostic criteria used by radiologists. Because ROC curve analysis is gaining wide acceptance in medical literature, an explanation of ROC methods with the use of simple examples is necessary to increase the knowledge and understanding of practicing radiologists.

ROC Curve Analysis: An Example Showing the Relationships Among Serum Lipid and Apolipoprotein Concentrations in Identifying Patients with Coronary Artery Disease

Clinical accuracy, defined as the ability to discriminate between states of health, is the fundamental property of any diagnostic test or system. It is readily expressed as clinical sensitivity and specificity, and elegantly represented by the receiver operating characteristic (ROC) curve. To demonstrate the use of ROC curves, we reexamine a study of the ability of serum lipid and apolipoprotein measures to discriminate among degrees of coronary artery disease in patients undergoing coronary angiography. ROC curve analysis reveals that none of these indexes is highly accurate, but demonstrates a modest increase in the accuracy of apolipoprotein over lipid indexes.

ROC curves for the initial assessment of new diagnostic tests.

New diagnostic tests are mainly evaluated by determining the sensitivity and specificity of the test. These test characteristics were originally meant to be used in making diagnoses. For evaluative purposes their usefulness is weakened by their susceptibility to selection and their dependence on the cut-off points that are used for test positivity. The plotting of a receiver operating characteristic (ROC) curve might be a solution to these problems. Furthermore, the ROC curve yields a measure for the diagnostic power of the test expressed in one number instead of two, namely the area under the curve (AUC). Finally, the ROC curve and its AUC permit easy comparison of different tests and the performance of different interpreters of one test. The construction and use of ROC curves are described and illustrated with data of a case-referent investigation into the relationship between iron status parameters and the presence of acute myocardial infarction. The AUCs of ferritin and serum iron, 0.61 and 0.68 respectively, are too low to suggest meaningful usefulness in clinical practice.

Four assay methods for glycated hemoglobin compared as screening tests for diabetes mellitus: the Islington Diabetes Survey.

We assessed the utility of four methods of glycated hemoglobin assay (agar gel electrophoresis with Schiff base, agar gel electrophoresis with prior removal of Schiff base, boronate affinity chromatography, and isoelectric focusing) as screening tests for diabetes mellitus, studying 223 subjects undergoing an oral glucose-tolerance test after fasting and 2 h after ingestion of 75 g of glucose. Assessment of glucose tolerance status according to the 1980 World Health Organization diagnostic criteria indicated that 13 subjects (5.8%) had diabetes, 48 (21.5%) had impaired glucose tolerance, and nine (4.0%) could not be classified (six of these because of missing values). Use of receiver-operating characteristic curves to compare the assays as screening tests showed the affinity chromatography assay to be superior. Assays for glycated hemoglobin after fasting had better precision than post-glucose-load assays as screening tests, and test characteristics of glycated hemoglobin assays on fasting subjects were similar to those of the blood-glucose estimation after fasting. We conclude that measurement of glycated hemoglobin may be a useful screening test for diabetes, and that such measurement of stable glycated hemoglobin is as accurate as measurement of fasting blood-glucose in screening for diabetes. For this use, we found methods that measure stable glycated hemoglobin superior to that measuring both stable and labile Schiff-base fractions.

The use of ROC curves in testing the proficiency of individuals in classifying pneumoconiosis.

During a test of the ability to classify the profusion characteristics of pneumoconiosis recorded in chest radiographs, a constant decision criterion level needs to be maintained or false conclusions regarding the observer's receiver operating characteristic (ROC) curve may result.