A Gray Zone Assigned to Inconclusive Results of Quantitative Diagnostic Tests: Application to the Use of Brain Natriuretic Peptide for Diagnosis of Heart Failure in Acute Dyspneic Patients

Coste, Joël; Jourdain, Patrick; Pouchot, J.

doi:10.1373/clinchem.2006.072280

Cited by 48 publications

(40 citation statements)

References 27 publications

(15 reference statements)

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“…For BNP, concentrations Ͻ100 ng/L have been shown to have a strong negative predictive value for ADHF, whereas values Ͼ500 ng/L strongly predict ADHF (16 ). Values of 100 -500 ng/L were considered intermediate (17 ).…”

Section: Blood Samples and Assaysmentioning

confidence: 99%

Lack of Diagnostic and Prognostic Utility of Circulating Plasma Myeloperoxidase Concentrations in Patients Presenting with Dyspnea

et al. 2009

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Section: Blood Samples and Assaysmentioning

confidence: 99%

Lack of Diagnostic and Prognostic Utility of Circulating Plasma Myeloperoxidase Concentrations in Patients Presenting with Dyspnea

et al. 2009

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“…Clinical examples of continuous inconclusive index test resultsExamples of continuous inconclusive test results Diagnostic scenarioNo heart failure: 0-167 ng/L; inconclusive result: 167-462 ng/L; heart failure: 462-5000 ng/L Brain natriuretic peptide (BNP) for diagnosis of heart failure in patients with acute dyspnoea33 No sepsis: <0.5 µg/L; inconclusive result: 0.5-20 µg/L; sepsis: >20 µg/L Procalcitonin for diagnosis of early onset neonatal sepsis34 Monitor annually: eGFR ≥60; inconclusive result: eGFR 30-59; refer: eGFR <30 Management of patients with diabetes in primary care with chronic kidney disease using eGFR eGFR=estimated glomerular filtration rate.For personal use only: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribe…”

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confidence: 99%

Diagnostic accuracy studies: how to report and analyse inconclusive test results

Shinkins

Thompson

Mallett

et al. 2013

BMJ

110

120

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Failure to report inconclusive test results can lead to misleading conclusions regarding the accuracy and clinical usefulness of a diagnostic tool. We show that these results are often overlooked in research on test accuracy and provide guidance on suitable approaches to reporting and analysing these problematic results. The results of studies on diagnostic test accuracy are often reported as a 2×2 classification matrix, in which test results are presented as a dichotomy and a reference standard is used to categorise individuals as with or without disease. This facilitates the calculation of many popular statistics used to summarise the discriminatory performance of tests (such as sensitivity and specificity, positive and negative likelihood ratios, and positive and negative predictive values). Restricting test results to be either positive or negative, however, fails to represent the reality of how they are used in clinical practice 1 ; in many cases, the results from a given diagnostic test do not exclusively fall into these "positive" and "negative" categories. Bethany ShinkinsAlthough most test results provide useful information for diagnostic decision making, there is often a subset of results that are relatively uninformative and lead to an "inconclusive" diagnostic outcome. For example, the "normal" range on a standard biomarker is typically based on statistics that try to minimise the number of false classifications. As most biomarkers are far from perfect discriminators, however, results that fall close to the lower and upper limits of "normality" provide minimal information about the disease status of the patient and are therefore "inconclusive." In most cases inconclusive test results require extra attention from clinicians, such as repeating the test or using more costly (in terms of invasiveness, time, and expense) diagnostic tools. All of these outcomes, coupled with the inevitable delay in diagnosis and clinical decision making, directly affect patient care.In this paper we have focused on clinical scenarios in which there are two disease categories-disease present and disease absent-and discuss the reporting and analysis of inconclusive results produced by a single index test-that is, the diagnostic test under evaluation. Although this is a common scenario in research on diagnostic test accuracy, this is often a simplification of the actual clinical question. In practice, diagnostic tests are often used to distinguish between multiple diseases or different levels of severity, such as different staging in diagnosis of cancer. Additionally, the diagnostic process might involve a pathway of multiple tests rather than a single test. Inconsistent reporting of inconclusive test results in research on diagnostic accuracyWe wanted to explore whether inconclusive results are consistently reported in diagnostic accuracy research. The STARD (STAndards for the Reporting of Diagnostic accuracy studies) statement-a reporting guideline encouraging high quality reporting of diagnostic accuracy studies-recommends...

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“…The cut-off value cannot be used directly as a threshold value to separate diseased from health patients: even the goldstandard ELISA bench kit presents an uncertainty zone (0.9 < Abs < 1.1, in the present case) in which it is not possible to dene patient's status. 32,33 Then, it is necessary to create a three-zone partition to provide a condence interval also for the new diagnostic test: diseased, non-diseased, and an inconclusive outcome region in between, known as the gray zone. 32 Analysis of the positive likelihood ratio (LR+) and negative likelihood ratio (LRÀ) can be used to create this zone, 32,33 as well as numerical factors on standard deviation (SD), or even a tolerance percentage on the cut-off value.…”

Section: Performance Assessment Of Paper-based Elisamentioning

confidence: 99%

Improved assessment of accuracy and performance indicators in paper-based ELISA

et al. 2017

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Paper-based devices are an excellent match for low-cost point-of-care testing (POCT) tools. Their userfriendliness, portability, and short time of analysis, coupled with ease of local manufacture make these devices the best option for inexpensive diagnostic testing tools. However, despite all their positive features, these low-cost diagnostic devices must present good performance indicators, such as sensitivity, specificity, and accuracy. We developed and validated a paper-based ELISA for toxoplasmosis diagnosis through the detection of Toxoplasma gondii immunoglobulin G (IgG) antibodies in 100 human serum samples. From among the different ways to define the cut-off value, we chose Youden's J index (cut-off ¼ 21.73 A.U.), which presented a higher sensitivity value. Our paper-based assay presented a sensitivity of 0.96, a specificity of 0.87, and a gray zone comprising 16 samples (AE15% of the cut-off value, with 3 false positive outputs). The accuracy of the test was estimated by using ROC curves (AUC ¼ 0.97). We also created a macro in Microsoft Excel® to estimate the accuracy of the test (m-Accuracy) based on a non-parametric method, which evidenced a value ¼ 0.88, which classifies our test as moderately to highly accurate. We also provide the m-Accuracy macro for download and the paperbased microplate designs for printing, in order to collaborate with the scientific community and facilitate further studies using this platform. The improvement of these diagnostic tools can bring this technology for those who need it, contributing to population health and well-being.

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A Gray Zone Assigned to Inconclusive Results of Quantitative Diagnostic Tests: Application to the Use of Brain Natriuretic Peptide for Diagnosis of Heart Failure in Acute Dyspneic Patients

Cited by 48 publications

References 27 publications

Lack of Diagnostic and Prognostic Utility of Circulating Plasma Myeloperoxidase Concentrations in Patients Presenting with Dyspnea

Lack of Diagnostic and Prognostic Utility of Circulating Plasma Myeloperoxidase Concentrations in Patients Presenting with Dyspnea

Diagnostic accuracy studies: how to report and analyse inconclusive test results

Improved assessment of accuracy and performance indicators in paper-based ELISA

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