scholarly journals El dilema del vigilante. Valoración de pruebas diagnósticas.

2018 ◽  
Vol 10 (8) ◽  
pp. 4
Author(s):  
Manuel Molina
Keyword(s):  
Diagnostic Tests ◽  
Area Under The Curve ◽  
Roc Curves ◽  
Likelihood Ratios ◽  
Predictive Values ◽  
Significant Parameter ◽  
Quantitative Results ◽  
Sensitivity Specificity

Existen una serie de parámetros que caracterizan las pruebas diagnósticas, como son la sensibilidad, la especificidad, los valores predictivos y los cocientes de probabilidad. Solo estos últimos nos permiten el cálculo de la probabilidad del paciente de presentar la enfermedad, con independencia de la prevalencia en la población. Para caracterizar las pruebas con resultado cuantitativo se utilizan las curvas ROC, cuyo parámetro más significativo es el área bajo la curva. ABSTRACT There are a series of parameters that characterize the diagnostic tests, such as sensitivity, specificity, predictive values and likelihood ratios. Only the latter allow us to calculate the patient's probability of presenting the disease, regardless of the prevalence in the population. To characterize the tests with quantitative results, the ROC curves are used, whose most significant parameter is the area under the curve.

The Interpretation of Test Results

2000 ◽  
Vol 4 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Michael Binder ◽  
Stephan Dreiseitl
Keyword(s):  
Decision Making ◽  
Receiver Operating Characteristic ◽  
Diagnostic Tests ◽  
Operating Characteristic ◽  
Roc Curves ◽  
Test Results ◽  
Likelihood Ratios ◽  
Clinical Routine ◽  
Predictive Values ◽  
Sensitivity Specificity

Background: Dermatologists need to interpret an increasing number of research studies and diagnostic tests. Understanding the techniques for interpreting test results and making decisions based upon those tests represent important tools for decision making for both clinicians and researchers. Objective: This article focuses briefly on the key parameters of diagnostic tests: sensitivity, specificity, prevalence, predictive values, likelihood ratios, and the concept of receiver-operating-characteristic (ROC) curves. A simple example is presented in a step-by-step manner. Conclusion: The principles of interpreting test results are easy to learn and applicable in daily clinical routine. Therefore, dermatologists should be familiar with the concepts outlined in this paper.

scholarly journals Value and Diagnostic Efficacy of Fetal Morphology Assessment Using Ultrasound in A Poor-Resource Setting

Diagnostics ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 109 ◽  
Author(s):  
Ukweh ◽  
Ugbem ◽  
Okeke ◽  
Ekpo
Keyword(s):  
Predictive Value ◽  
Performance Metrics ◽  
Area Under The Curve ◽  
Youden Index ◽  
Likelihood Ratios ◽  
Diagnostic Efficacy ◽  
Predictive Values ◽  
Resource Setting ◽  
Post Test ◽  
Sensitivity Specificity

Background: Ultrasound is operator-dependent, and its value and efficacy in fetal morphology assessment in a low-resource setting is poorly understood. We assessed the value and efficacy of fetal morphology ultrasound assessment in a Nigerian setting. Materials and Methods: We surveyed fetal morphology ultrasound performed across five facilities and followed-up each fetus to ascertain the outcome. Fetuses were surveyed in the second trimester (18th–22nd weeks) using the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) guideline. Clinical and surgical reports were used as references to assess the diagnostic efficacy of ultrasound in livebirths, and autopsy reports to confirm anomalies in terminated pregnancies, spontaneous abortions, intrauterine fetal deaths, and still births. We calculated sensitivity, specificity, positive and negative predictive values, Area under the curve (AUC), Youden index, likelihood ratios, and post-test probabilities. Results: In total, 6520 fetuses of women aged 15–46 years (mean = 31.7 years) were surveyed. The overall sensitivity, specificity, and AUC were 77.1 (95% CI: 68–84.6), 99.5 (95% CI: 99.3–99.7), and 88.3 (95% CI: 83.7–92.2), respectively. Other performance metrics were: positive predictive value, 72.4 (95% CI: 64.7–79.0), negative predictive value, 99.6 (95% CI: 99.5–99.7), and Youden index (77.1%). Abnormality prevalence was 1.67% (95% CI: 1.37–2.01), and the positive and negative likelihood ratios were 254 (95% CI: 107.7–221.4) and 0.23 (95% CI: 0.16–0.33), respectively. The post-test probability for positive test was 72% (95% CI: 65–79). Conclusion: Fetal morphology assessment is valuable in a poor economics setting, however, the variation in the diagnostic efficacy across facilities and the limitations associated with the detection of circulatory system anomalies need to be addressed.

Abstract TP325: Lack of Early Improvement Predicts Poor Clinical Outcome Following Acute Intracerebral Hemorrhage

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Vignan Yogendrakumar ◽  
Eric E Smith ◽  
Andrew M Demchuk ◽  
RIchard I Aviv ◽  
David Rodriguez-Luna ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Area Under The Curve ◽  
Roc Curves ◽  
Predictive Values ◽  
Early Improvement ◽  
Poor Outcome ◽  
Using Data ◽  
Definition Of ◽  
Sensitivity Specificity ◽  
The Cost

Background: Early Neurological Worsening (ENW) is common after ICH, and predicts poor outcome. However, there is limited data as to what degree of ENW best relates to outcome. We used two ICH cohorts to refine and validate a definition of ENW that best predicted 90-day outcomes. Methods: We generated receiver operating characteristic (ROC) curves for the association between 24-hour NIHSS change and ICH outcomes using data from the VISTA collaboration. Primary outcome was poor outcome at 90 days (mRS 4-6); secondary outcomes were other mRS cutpoints (mRS 2-6, 3-6, 5-6, 6). We tested the commonly used NIHSS≥4 definition and in addition employed Youden’s J Index to select optimal cutpoints and calculated sensitivity, specificity, and predictive values. Independent predictors of poor outcome were determined via multivariable logistic regression. Definitions were validated in the prospectively collected PREDICT-ICH cohort. Results: Using 552 patients from the VISTA cohort, ROC curves of 24hr NIHSS change had an area under the curve of 0.75. NIHSS change of ≥0 at 24hrs was seen in 46.4%. Youden’s method showed an optimum cutoff at -0.5. Based on this, ENW defined as >0 (Sens 43%, Spec 91%, PPV 83%, aOR 7.13 [CI:4.05-12.55]), ≥0 (Sens 65%, Spec 73%, PPV 70%, aOR 5.05 [CI:3.25-7.85]), or ≥-1 (Sens 78%, Spec 59%, PPV 65%, aOR 6.04 [CI:3.75-9.71]) all accurately predicted poor outcome. PPV increased with higher NIHSS cutoffs, but at the cost of lower sensitivities. Regression confirmed that all definitions independently predicted outcome at all mRS cutpoints. ENW definitions reproduced well in the validation cohort of 275 patients. Conclusion: All NIHSS cut-offs for ENW predict clinical outcome, regardless of outcome definition. In particular, lack of clinical improvement at 24 hours (i.e. NIHSS is the same or higher) robustly predicted poor outcome, but may not be sufficiently reliable to determine clinical management.

scholarly journals Clinicians' guide to evaluating diagnostic and screening tests in psychiatry

2004 ◽  
Vol 10 (6) ◽  
pp. 446-454 ◽  
Author(s):  
James Warner
Keyword(s):  
Diagnostic Tests ◽  
Critical Appraisal ◽  
Evidence Base ◽  
Psychiatric Practice ◽  
Screening Tests ◽  
Clinical Settings ◽  
Likelihood Ratios ◽  
Predictive Values ◽  
Incorrect Diagnosis ◽  
Sensitivity Specificity

The emphasis on the evidence base of treatments may diminish awareness that critical appraisal of research into other aspects of psychiatric practice is equally important. There is a risk that diagnostic tests may be inappropriate in some clinical settings or the results of a particular test may be over-interpreted, leading to incorrect diagnosis. This article outlines the method of critically evaluating the validity of articles about diagnostic and screening tests in psychiatry and discusses concepts of sensitivity, specificity and predictive values. The use of likelihood ratios in improving clinical certainty that a disease is present or absent is examined.

scholarly journals Diagnosis of asthma in children: the contribution of a detailed history and test results

2019 ◽  
Vol 54 (6) ◽  
pp. 1901326 ◽  
Author(s):  
Carmen C.M. de Jong ◽  
Eva S.L. Pedersen ◽  
Rebeca Mozun ◽  
Myrofora Goutaki ◽  
Daniel Trachsel ◽  
...  
Keyword(s):  
Diagnostic Tests ◽  
Area Under The Curve ◽  
Forced Expiratory Volume ◽  
Predictive Values ◽  
Detailed History ◽  
Provocation Tests ◽  
Skin Prick Tests ◽  
Asthma In Children ◽  
Few Data ◽  
Sensitivity Specificity

IntroductionThere are few data on the usefulness of different tests to diagnose asthma in children.AimWe assessed the contribution of a detailed history and a variety of diagnostic tests for diagnosing asthma in children.MethodsWe studied children aged 6–16 years referred consecutively for evaluation of suspected asthma to two pulmonary outpatient clinics. Symptoms were assessed by parental questionnaire. The clinical evaluation included skin-prick tests, measurement of exhaled nitric oxide fraction (FeNO), spirometry, bronchodilator reversibility and bronchial provocation tests (BPT) by exercise, methacholine and mannitol. Asthma was diagnosed by the physicians at the end of the visit. We assessed diagnostic accuracy of symptoms and tests by calculating sensitivity, specificity, positive and negative predictive values and area under the curve (AUC).ResultsOf the 111 participants, 80 (72%) were diagnosed with asthma. The combined sensitivity and specificity was highest for reported frequent wheeze (more than three attacks per year) (sensitivity 0.44, specificity 0.90), awakening due to wheeze (0.41, 0.90) and wheeze triggered by pollen (0.46, 0.83) or by pets (0.29, 0.99). Of the diagnostic tests, the AUC was highest for FeNO measurement (0.80) and BPT by methacholine (0.81) or exercise (0.74), and lowest for forced expiratory volume in 1 s (FEV1) (0.62) and FEV1/forced vital capacity ratio (0.66), assessed by spirometry.ConclusionThis study suggests that specific questions about triggers and severity of wheeze, measurement of FeNO and BPT by methacholine or exercise contribute more to the diagnosis of asthma in school-aged children than spirometry, bronchodilator reversibility and skin-prick tests.

scholarly journals Sensitivity, Specificity, Predictive Values, and Accuracy of Three Diagnostic Tests to Predict Inferior Alveolar Nerve Blockade Failure in Symptomatic Irreversible Pulpitis

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Daniel Chavarría-Bolaños ◽  
Laura Rodríguez-Wong ◽  
Danny Noguera-González ◽  
Vicente Esparza-Villalpando ◽  
Mauricio Montero-Aguilar ◽  
...  
Keyword(s):  
Diagnostic Tests ◽  
Inferior Alveolar Nerve ◽  
Roc Curves ◽  
Cross Sectional Study ◽  
Anesthetic Technique ◽  
Cross Sectional ◽  
Predictive Values ◽  
Anesthetic Failure ◽  
Sensitivity Specificity ◽  
Irreversible Pulpitis

Introduction.The inferior alveolar nerve block (IANB) is the most common anesthetic technique used on mandibular teeth during root canal treatment. Its success in the presence of preoperative inflammation is still controversial. The aim of this study was to evaluate the sensitivity, specificity, predictive values, and accuracy of three diagnostic tests used to predict IANB failure in symptomatic irreversible pulpitis (SIP).Methodology.A cross-sectional study was carried out on the mandibular molars of 53 patients with SIP. All patients received a single cartridge of mepivacaine 2% with 1 : 100000 epinephrine using the IANB technique. Three diagnostic clinical tests were performed to detect anesthetic failure. Anesthetic failure was defined as a positive painful response to any of the three tests. Sensitivity, specificity, predictive values, accuracy, and ROC curves were calculated and compared and significant differences were analyzed.Results.IANB failure was determined in 71.7% of the patients. The sensitivity scores for the three tests (lip numbness, the cold stimuli test, and responsiveness during endodontic access) were 0.03, 0.35, and 0.55, respectively, and the specificity score was determined as 1 for all of the tests. Clinically, none of the evaluated tests demonstrated a high enough accuracy (0.30, 0.53, and 0.68 for lip numbness, the cold stimuli test, and responsiveness during endodontic access, resp.). A comparison of the areas under the curve in the ROC analyses showed statistically significant differences between the three tests (p<0.05).Conclusion.None of the analyzed tests demonstrated a high enough accuracy to be considered a reliable diagnostic tool for the prediction of anesthetic failure.

scholarly journals Evaluation of PORT/PSI and SOFA scores in predicting in-hospital mortality of patients with COVID-19

2021 ◽  
Vol 1 ◽  
pp. e1196
Author(s):  
José M. Alanís-Naranjo ◽  
Salvador Hernández-Sandoval ◽  
Víctor M. Anguiano-Álvarez ◽  
Eduardo F. Hammeken-Larrondo ◽  
Gabriela Olguín-Contreras ◽  
...  
Keyword(s):  
Hospital Mortality ◽  
Sofa Score ◽  
Area Under The Curve ◽  
Roc Curves ◽  
Prognostic Scores ◽  
Limited Information ◽  
Good Tool ◽  
Predictive Values ◽  
Study Population ◽  
Sensitivity Specificity

Introduction: There is limited information analyzing the utility of different prognostic scores in predicting in-hospital mortality among patients with COVID-19. This study aimed to evaluate the performance of PORT/PSI and SOFA scores in predicting the in-hospital mortality of patients with COVID-19. Material and methods: This was an observational, analytical, and retrospective study that included consecutive patients hospitalized for COVID-19 from April 1, 2020, to May 31, 2020. The study population was characterized, and ROC analysis was performed and used to calculate the area under the curve of PORT/PSI and SOFA scores as well as the sensitivity, specificity, and predictive values. Results: A total of 151 patients were included, with a median age of 52 years (IQR 45-64); 69.5% were men, with a median BMI of 29.3 kg/m2 (IQR 25.5-34.7). Of the total, 102 patients died during hospitalization (67.5%). The areas under the ROC curves for predicting in-hospital mortality were 0.74 (95% CI 0.67-0.81) for the SOFA score and 0.85 (95% CI 0.78-0.90) for the PORT/PSI score. When compared, the PORT/PSI score predicted mortality significantly better than the SOFA score (p: 0.01). Conclusions: The PORT/PSI score is a good tool to predict in-hospital mortality in patients with COVID-19.

scholarly journals Diagnostic testing: an emergency medicine perspective

CJEM ◽  
2002 ◽  
Vol 4 (05) ◽  
pp. 348-354 ◽  
Author(s):  
Andrew Worster ◽  
Grant Innes ◽  
Riyad B. Abu-Laban
Keyword(s):  
Diagnostic Tests ◽  
Diagnostic Testing ◽  
Test Results ◽  
Emergency Physicians ◽  
Likelihood Ratios ◽  
Predictive Values ◽  
The Core ◽  
Core Concepts ◽  
Sensitivity Specificity ◽  
Test Probability

ABSTRACT: Emergency physicians use diagnostic tests extensively, and the ability to order and interpret test results appropriately is a critical skill. An understanding of sensitivity, specificity, predictive values and likelihood ratios, as well as an awareness of the importance of pre-test probability, is essential. The purpose of this article is to explain, in a straightforward and clinically applicable manner, the core concepts related to diagnostic testing.

scholarly journals Establishment and Characterization of an Empirical Biomarker SS/PV-ROC Plot Using Results of the UBC® Rapid Test in Bladder Cancer

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 729 ◽  
Author(s):  
Peter Oehr ◽  
Thorsten Ecke
Keyword(s):  
Bladder Cancer ◽  
Roc Curve ◽  
Predictive Value ◽  
Area Under The Curve ◽  
Rapid Test ◽  
Roc Curves ◽  
Threshold Value ◽  
Control Group ◽  
Predictive Values ◽  
Sensitivity Specificity

Background: This investigation included both a study of potential non-invasive diagnostic approaches for the bladder cancer biomarker UBC® Rapid Test and a study including comparative methods about sensitivity–specificity characteristic (SS-ROC) and predictive receiver operating characteristic (PV-ROC) curves that used bladder cancer as a useful example. Methods: The study included 289 urine samples from patients with tumors of the urinary bladder, patients with non-evidence of disease (NED) and healthy controls. The UBC® Rapid Test is a qualitative point of care assay. Using a photometric reader, quantitative data can also be obtained. Data for pairs of sensitivity/specificity as well as positive/negative predictive values were created by variation of threshold values for the whole patient cohort, as well as for the tumor-free control group. Based on these data, sensitivity–specificity and predictive value threshold distribution curves were constructed and transformed into SS-ROC and PV-ROC curves, which were included in a single SS/PV-ROC plot. Results: The curves revealed TPP-asymmetric improper curves which cross the diagonal from above. Evaluation of the PV-ROC curve showed that two or more distinct positive predictive values (PPV) can correspond to the same value of a negative predictive value (NPV) and vice versa, indicating a complexity in PV-ROC curves which did not exist in SS-ROC curves. In contrast to the SS-ROC curve, the PV-ROC curve had neither an area under the curve (AUC) nor a range from 0% to 100%. Sensitivity of the qualitative assay was 58.5% and specificity 88.2%, PPV was 75.6% and NPV 77.3%, at a threshold value of approximately 12.5 µg/L. Conclusions: The SS/PV-ROC plot is a new diagnostic approach which can be used for direct judgement of gain and loss of predictive values, sensitivity and specificity according to varied threshold value changes, enabling characterization, comparison and evaluation of qualitative and quantitative bioassays.

Discriminating Malignancy in Thyroid Nodules: The Nomogram Versus the Kwak and ACR TI-RADS

2020 ◽  
Vol 163 (6) ◽  
pp. 1156-1165
Author(s):  
Juan Xiao ◽  
Qiang Xiao ◽  
Wei Cong ◽  
Ting Li ◽  
Shouluan Ding ◽  
...  
Keyword(s):  
Thyroid Nodules ◽  
Characteristic Curve ◽  
Area Under The Curve ◽  
Diagnostic Study ◽  
Diagnostic Efficiency ◽  
Training Set ◽  
Multivariable Logistic Regression Model ◽  
Predictive Values ◽  
Validation Set ◽  
Sensitivity Specificity

Objective To develop an easy-to-use nomogram for discrimination of malignant thyroid nodules and to compare diagnostic efficiency with the Kwak and American College of Radiology (ACR) Thyroid Imaging, Reporting and Data System (TI-RADS). Study Design Retrospective diagnostic study. Setting The Second Hospital of Shandong University. Subjects and Methods From March 2017 to April 2019, 792 patients with 1940 thyroid nodules were included into the training set; from May 2019 to December 2019, 174 patients with 389 nodules were included into the validation set. Multivariable logistic regression model was used to develop a nomogram for discriminating malignant nodules. To compare the diagnostic performance of the nomogram with the Kwak and ACR TI-RADS, the area under the receiver operating characteristic curve, sensitivity, specificity, and positive and negative predictive values were calculated. Results The nomogram consisted of 7 factors: composition, orientation, echogenicity, border, margin, extrathyroidal extension, and calcification. In the training set, for all nodules, the area under the curve (AUC) for the nomogram was 0.844, which was higher than the Kwak TI-RADS (0.826, P = .008) and the ACR TI-RADS (0.810, P < .001). For the 822 nodules >1 cm, the AUC of the nomogram was 0.891, which was higher than the Kwak TI-RADS (0.852, P < .001) and the ACR TI-RADS (0.853, P < .001). In the validation set, the AUC of the nomogram was also higher than the Kwak and ACR TI-RADS ( P < .05), each in the whole series and separately for nodules >1 or ≤1 cm. Conclusions When compared with the Kwak and ACR TI-RADS, the nomogram had a better performance in discriminating malignant thyroid nodules.

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