Designing and Interpreting COVID-19 Diagnostics: Mathematics, Visual Logistics, and Low Prevalence

Predictive Value ◽

Clinical Performance ◽

Geometric Mean ◽

High Sensitivity ◽

False Positives ◽

Predictive Values ◽

Minimum Requirements ◽

Sensitivity Specificity ◽

Low Prevalence

ABSTRACT Context. Coronavirus infectious disease-19 (COVID-19) diagnostics require understanding of how predictive values depend on sensitivity, specificity, and especially, low prevalence. Clear expectations, high sensitivity and specificity, and manufacturer disclosure will facilitate excellence of tests. Objectives. To derive mathematical equations for designing and interpreting COVID-19 tests, assess Food and Drug Administration (FDA) Emergency Use Authorization and Health Canada minimum requirements, establish sensitivity and specificity tiers, and enhance clinical performance in low prevalence settings. Design. PubMed and other sources generated articles on COVID-19 testing and prevalence. EndNote X9.1 consolidated references. Mathematica and open access software helped prove equations, perform recursive calculations, graph multivariate relationships, and visualize patterns, including a new relationship, predictive value geometric mean-squared. Results. Derived equations were used to illustrate shortcomings of COVID-19 diagnostics in low prevalence. Visual logistics helped establish sensitivity/specificity tiers. FDA/Canada's 90% sensitivity, 95% specificity minimum requirements generate excessive false positives at low prevalence. False positives exceed true positives at <5.3% prevalence, or if sensitivity is improved to 100% and specificity to 98%, at <2% prevalence. Recursive testing improves predictive value. Three tiers emerged from these results. With 100% sensitivity, physicians can select desired predictive values, then input local prevalence, to determine suitable specificity. Conclusions. Understanding low prevalence impact will help healthcare providers meet COVID-19 needs for effective testing. Laypersons should receive clinical performance disclosure when submitting specimens. Home testing needs to meet the same high standards as other tests. In the long run, it will be more cost-effective to improve COVID-19 POC tests rather than repeat testing multiple times.

The Impact of Increasing Prevalence, False Omissions, and Diagnostic Uncertainty on Coronavirus Disease 2019 (COVID-19) Test Performance

Archives of Pathology & Laboratory Medicine ◽

10.5858/arpa.2020-0716-sa ◽

2021 ◽

Author(s):

Gerald J. Kost

Keyword(s):

Test Performance ◽

Influenza A ◽

Geometric Mean ◽

False Positives ◽

Test Quality ◽

False Negatives ◽

Predictive Values ◽

Sensitivity Specificity ◽

Tier 3 ◽

The Impact

ABSTRACT Context. Coronavirus disease 2019 (COVID-19) test performance depends on predictive values in settings of increasing disease prevalence. Geospatially distributed diagnostics with minimal uncertainty facilitate efficient point-of-need strategies. Objectives. To use original mathematics to interpret COVID-19 test metrics; assess Food and Drug Administration Emergency Use Authorizations and Health Canada targets; compare predictive values for multiplex, antigen, polymerase chain reaction kit, point-of-care antibody, and home tests; enhance test performance; and improve decision-making. Design. PubMed/newsprint generated articles documenting prevalence. Mathematica and open access software helped perform recursive calculations, graph multivariate relationships, and visualize performance by comparing predictive value geometric mean-squared patterns. Results. Tiered sensitivity/specificity comprise: T1) 90%, 95%; T2) 95%, 97.5%; and T3) 100%, ≥99%. Tier 1 false negatives exceed true negatives at >90.5% prevalence; false positives exceeded true positives at <5.3% prevalence. High sensitivity/specificity tests reduce false negatives and false positives yielding superior predictive values. Recursive testing improves predictive values. Visual logistics facilitate test comparisons. Antigen test quality falls off as prevalence increases. Multiplex severe acute respiratory syndrome (SARS)-CoV-2)*Influenza A/B*Respiratory-Syncytial Virus (RSV) testing performs reasonably well compared to Tier 3. Tier 3 performance with a Tier 2 confidence band lower limit will generate excellent performance and reliability. Conclusions. The overriding principle is select the best combined performance and reliability pattern for the prevalence bracket. Some public health professionals recommend repetitive testing to compensate for low sensitivity. More logically, improved COVID-19 assays with less uncertainty conserve resources. Multiplex differentiation of COVID-19 from Influenza A/B-RSV represents an effective strategy if seasonal flu surges next year.

Clinical Performance of the Spot Vision Photo Screener before and after Induction of Cycloplegia in Children

Journal of Ophthalmology ◽

10.1155/2019/5329121 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Konuralp Yakar

Keyword(s):

Positive Predictive Value ◽

Negative Predictive Value ◽

Predictive Value ◽

Clinical Performance ◽

High Specificity ◽

Screening Criteria ◽

Predictive Values ◽

Before And After ◽

Sensitivity Specificity ◽

Vision Screener

Aim. To compare the clinical performance of the Spot Vision Screener used to detect amblyopia risk factors (ARFs) in children before and after induction of cycloplegia; the children were referred because they met the screening criteria of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS). Methods. The Spot Vision Screener and a standard autorefractometer were used to examine 200 eyes of 100 children aged 3–10 years, before and after cycloplegia induction, in terms of ARFs. Sensitivity, specificity, and positive and negative predictive values for the detection of significant refractive errors were measured using the AAPOS referral criteria. It was explored that Spot Screener data were affected by cycloplegia. The extent of agreement between cycloplegic/noncycloplegic photoscreening data and cycloplegic autorefraction measurements was assessed using Wilcoxon and Spearman correlation analyses. Results. The Spot’s sensitivity was improved from 60.9% to 85.3% and specificity from 94.9% to 87.4% with cycloplegia compared to cycloplegic standard autorefractometer results. The positive predictive value of Spot was 75.7%, and the negative predictive value was 90.4% without cycloplegia. With cycloplegia, the positive predictive value of Spot was 63.6% and the negative predictive value was 95.8%. Conclusions. The Spot Screener afforded moderate sensitivity and high specificity prior to cycloplegia. The sensitivity and negative predictive value improved after induction of cycloplegia. Examiners should be aware of the effects of cycloplegia on their findings.

Evaluation of a Rapid Kit for Detection of IgM against Leptospira in Human

Canadian Journal of Infectious Diseases and Medical Microbiology ◽

10.1155/2019/5763595 ◽

2019 ◽

Vol 2019 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

Mohan Rao ◽

Fairuz Amran ◽

Nadia Aqilla

Keyword(s):

Predictive Value ◽

Clinical Manifestations ◽

Rapid Test ◽

Febrile Illness ◽

High Sensitivity ◽

Confirmatory Test ◽

Standard Laboratory ◽

Test Efficiency ◽

Introduction. Leptospirosis is an acute febrile illness, known for its protean clinical manifestations and the challenge in differentiating from other infectious diseases. Standardized confirmatory test is antibody dependent and not accessible by the suburban community. This study measures efficiency of an immune-chromatographic assay, Leptocheck WB, in detecting acute leptospirosis. Methods. A total of 142 sera were used for kit evaluation. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated by comparing rapid kit results with gold standard laboratory, microscopic agglutination test (MAT). Results. We found this rapid kit to have a sensitivity and specificity of 66.6% and 78.9%, respectively, whereas the PPV and NPV of the kit appeared to be 73.3% and 73.2%, respectively. Discussion. Test efficiency of this rapid kit is reasonable. It is specific in detecting leptospiral antibody and assures clinician of accurate diagnosis by having higher PPV and NPV. It is prompt and efficient in comparison with conventional methods in assisting differential diagnosis. High sensitivity and specificity leptospirosis rapid test is indeed a crucial measure to assist the diagnosis of acute undifferentiated febrile illnesses.

Inflammation and infiltration: can the radiologist draw a line? MRI versus CT to accurately assess medullary involvement in parosteal osteosarcoma

The International Journal of Biological Markers ◽

10.1177/1724600819900516 ◽

2020 ◽

Vol 35 (1_suppl) ◽

pp. 31-36 ◽

Cited By ~ 2

Author(s):

Maria Pilar Aparisi Gómez ◽

Alberto Righi ◽

Costantino Errani ◽

Giancarlo Facchini ◽

Marco Gambarotti ◽

...

Keyword(s):

Predictive Value ◽

Histological Analysis ◽

High Sensitivity ◽

Inflammatory Change ◽

Parosteal Osteosarcoma ◽

Predictive Values ◽

Exact Test ◽

Preserve Function ◽

Magnetic Resonance Imaging Mri ◽

Cancer causes inflammation as it progresses through healthy tissue. The differentiation of tumoral growth from the surrounding inflammatory change is paramount in planning surgeries seeking to preserve function. This retrospective study aims at illustrating how a careful use of imaging (computed tomography (CT)/magnetic resonance imaging (MRI)) can help to draw the line between infiltration and inflammation. Out of 72 cases of parosteal osteosarcoma in our institution we selected 22 which had pretreatment imaging, and out of those, 14 that had both MRI and CT. Using Fisher’s exact test, we evaluated the performance of each technique on accurately diagnosing medullary tumor infiltration, using histological analysis as a gold standard. All cases (14/14) demonstrated medullary abnormality on MRI, but only 6/14 (42.9%) demonstrated abnormality on CT. The 8/14 cases with MRI abnormality but no CT abnormality (57.1%) showed inflammation with no tumoral cells present on histological analysis. In the cases where the two examinations showed medullary abnormality (6/14) histology demonstrated tumoral infiltration. MRI demonstrated high sensitivity and negative predictive value, but low specificity and low positive predictive value and accuracy (P=1). CT demonstrated high sensitivity, specificity, high positive and negative predictive values and accuracy (P = 0.000333). MRI is highly sensitive for the detection of medullary abnormality but lacks specificity for tumor invasion. Correlation with CT is recommended in all cases of positive MR to add specificity for tumors. The adequate use of the two imaging methods allows to differentiate between inflammatory change and tumoral infiltration in POS, relevant for surgical planning.

Sensitivity and Specificity of Sheard and Percival’s Criteria for the Diagnosis of Young People with Near-heterophoria

Open Access Macedonian Journal of Medical Sciences ◽

10.3889/oamjms.2021.6399 ◽

2021 ◽

Vol 9 (B) ◽

pp. 1128-1134

Author(s):

Saif Hassan Alrasheed ◽

Amel Mohamed Yousif ◽

Majid A. Moafa ◽

Abd Elaziz Mohamed Elmadina ◽

Mohammad Alobaid

Keyword(s):

Young People ◽

Negative Predictive Value ◽

Binocular Vision ◽

Predictive Value ◽

High Sensitivity ◽

The Other ◽

Cross Sectional ◽

Predictive Values ◽

Low Sensitivity

BACKGROUND: Sheard and Percival assumed that symptoms from latent strabismus can be avoided if the relevant fusional vergence is adequate to support the heterophoria. AIM: The aim of the study was to determine the sensitivity and specificity of Sheard’s and Percival’s criterion for the diagnosis of heterophoria. METHODS: A cross-sectional hospital-based study was performed at Al-Neelain Eye Hospital Khartoum, Sudan from February to October 2019. Heterophoria was measured using Maddox Wing and fusional vergence using a prism bar. Thereafter, Sheard’s and Percival’s criteria were used for the diagnosis of heterophoria. RESULTS: A total of 230 participants (age = 15–30 years; mean age = 19.34 ± 3.325 years) were recruited for this study. The Sheard’s criteria showed a high sensitivity of 87.2% and a low specificity of 8.0% for the diagnosing of exophoria, with positive and negative predictive values of 65.5% and 26%, respectively. The criteria showed a relatively low sensitivity of 77.8% and a specificity of 9.0% in the diagnosis of esophoria, with a positive and negative predictive values of 56% and 20%, respectively. Percival criteria showed high sensitivity 84.2% and low specificity 9.1% in diagnosing esophoria, with a positive and negative predictive value of 61.5% and 25%, respectively. On the other hand, the criteria showed low sensitivity 67.4% and specificity 13.8% in diagnosing exophoria, with positive and negative predictive value 61.9% and 17%, respectively. CONCLUSION: Sheard’s and Percival’s criteria are useful in diagnosing binocular vision problems. Sheard’s criteria are accurate in diagnosing near exophoria and Percival’s criteria are more accurate in diagnosing near esophoria. Therefore, these criteria provide good clues and predictions for the diagnosis of binocular vision problems.

An Evaluation of the Arcus Corneae For Age Estimation

Academic Forensic Pathology ◽

10.1177/1925362119891708 ◽

2019 ◽

Vol 9 (3-4) ◽

pp. 155-162

Author(s):

Boonsak Hanterdsith

Keyword(s):

Predictive Value ◽

Interobserver Reliability ◽

High Sensitivity ◽

Diagnostic Value ◽

Cross Sectional Study ◽

Likelihood Ratios ◽

Chi Square ◽

Cross Sectional ◽

Predictive Values ◽

Although the arcus corneae (AC) has long been used as an age indicator for forensic purposes, its diagnostic value has not been evaluated. To evaluate the AC as a predictor of chronological age, the author has studied the correlation of AC with respect to age of the deceased. A cross-sectional study was conducted of 342 Thai corpses at the Maharat Nakhon Ratchasima Hospital, Thailand. AC was graded into three levels: no AC, incomplete ring, and complete ring. One-way analysis of variance, chi-square test, binomial logistic regression, sensitivity, specificity, predictive values, and likelihood ratios were used for analysis. The Cohen’s kappa was used to determine the intraobserver and interobserver reliability. The prevalence of AC and the probability of complete AC were significant higher in corpses aged 60 years and above than in those under 60 years. Consequently, this study confirmed that the prevalence of AC was significantly correlated with the age of Thai individuals. If the complete AC is used as an indicator of age of 60 years and above, complete AC has high sensitivity (92.56%) but low specificity (72.85%), low positive predictive value (65.12%), but high negative predictive value (94.71%). For diagnostic value, the presence of AC can be used for age screening but not for absolute confirmation. The absence of AC indicates young age, incomplete AC indicates middle age, and complete AC indicates old age. The high intraobserver and interobserver reliability provides assurance of the value of AC as a means to estimate personal age.

Monofrequency electrical impedance mammography (EIM) diagnostic system in breast cancer screening

BMC Cancer ◽

10.1186/s12885-020-07283-5 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Blanca Murillo-Ortiz ◽

Abraham Hernández-Ramírez ◽

Talia Rivera-Villanueva ◽

David Suárez-García ◽

Mario Murguía-Pérez ◽

...

Keyword(s):

Breast Cancer ◽

Positive Predictive Value ◽

Negative Predictive Value ◽

Predictive Value ◽

Electrical Impedance ◽

Screening Method ◽

Future Research ◽

Predictive Values ◽

Abstract Background Some evidence has shown that malignant breast tumours have lower electrical impedance than surrounding normal tissues. Electrical impedance could be used as an indicator for breast cancer detection. The purpose of our study was to analyse the sensitivity and specificity of electrical impedance mammography (EIM) and its implementation for the differential diagnosis of pathological lesions of the breast, either alone or in combination with mammography/ultrasound, in 1200 women between 25 and 70 years old. Methods This study is a prospective, cross-sectional epidemiological observational study of serial screening. The women were invited to participate and signed a consent letter. Impedance imaging of the mammary gland was evaluated with the computerized mammography equipment of MEIK electroimpedance v.5.6. (0.5 mA, 50 kHz), developed and manufactured by PKF SIM-Technika®. The successful identification of breast cancer along with the sensitivity, specificity, and positive and negative predictive values of EIM were determined as follows: % sensitivity; % specificity; % positive predictive value (PPV); and % negative predictive value (NPV). Results EIM had a sensitivity of 85% and a specificity of 96%; the positive predictive value was 12%, and the negative predictive value was 99%. Seven cases were biopsy confirmed cancers. Significant correlations between the electrical conductivity index and body mass index (BMI) (p = 0.04) and patient age were observed (p = 0.01). We also observed that the average conductivity distribution increased according to age group (p = 0.001). We used the chi-squared test to assess the interactions between percent density and BMI (normal < 25 kg/m2 (n = 310), overweight 25–29.9 kg/m2 (n = 418) and obese ≥30 (n = 437)) (p < 0.05). The patients with a diagnosis of mammary carcinoma had a BMI of 35.51 kg/m2. Conclusions Our results demonstrate that the use of monofrequency electrical impedance mammography (EIM) in the detection of breast cancer had a sensitivity and specificity of 85 and 96%, respectively. These findings may support future research in the early detection of breast cancer. EIM is a non-radiation method that may also be used as a screening method for young women with dense breasts and a high risk of developing breast cancer.

Prediction of Difficult Tracheal Videolaryngoscopic Intubation Using El-Ganzouri Risk Index

Acta Chirurgica Latviensis ◽

10.1515/chilat-2017-0012 ◽

2017 ◽

Vol 17 (1) ◽

pp. 18-22

Author(s):

Antons Zakalkins ◽

Sigita Kazune

Keyword(s):

Predictive Value ◽

Evaluation Method ◽

Characteristic Curve ◽

Risk Index ◽

Predictive Values ◽

Specificity And Sensitivity ◽

Laryngeal Exposure ◽

Sensitivity Specificity ◽

Induction Of Anaesthesia

Summary Introduction. Unanticipated difficult intubation still exists as a significant problem. El-Ganzouri risk index is a bedside difficult airway evaluation method, which can help determine risk of difficult airways. However, evidence of using of El-Ganzouri risk index in difficult laryngeal visualisation using videolaryngoscopes is limited. Aim of the Study. Determine the specificity and sensitivity of El-Ganzouri multivariate risk index to predict difficult laryngeal exposure using Storz C-MAC videolaryngoscope equipped with D type blade. Material and methods. We conducted a study of 29 patients, which were examined using El-Ganzouri risk index before induction of anaesthesia. After induction of anaesthesia videolaryngoscopy was performed using Storz C-MAC videolaryngoscope equipped with D-blade and laryngeal visualisation was graded using Cormack-Lehane scale. After laryngeal visualisation grading endotracheal tube insertion was performed and numbers of attempts as well as complications during intubation were recorded. Sensitivity, specificity, positive and negative predictive values were calculated, receiver operating characteristic curve and area under curve was obtained. Results. Sensitivity and specificity were 54.2% and 80.0% at El-Ganzouri risk index cut-off value of 2 points. Calculated positive predictive value was 26.7% and negative predictive value was 92.9%. Calculated AUC was 78.3%. Conclusions. El-Ganzouri risk index shows moderate sensitivity and specificity when used with Storz C-MAC videolaryngoscope. It can be used to predict difficult laryngeal visualization during videolaryngoscopic intubation.

Value of Electrical Impedance Scanning (EIS) in the Evaluation of BI-RADS™ III/IV/V-Lesions

Technology in Cancer Research & Treatment ◽

10.1177/153303460500400112 ◽

2005 ◽

Vol 4 (1) ◽

pp. 93-97 ◽

Cited By ~ 13

Author(s):

Thomas Diebold ◽

Volkmar Jacobi ◽

Bernhard Scholz ◽

Conny Hensel ◽

Christine Solbach ◽

...

Keyword(s):

Predictive Value ◽

Clinical Performance ◽

False Negative ◽

High Sensitivity ◽

Mucinous Carcinoma ◽

Patient Acceptance ◽

Electrical Impedance Scanning ◽

Movement Artifacts ◽

Development Center

Two hundred and fifty-six (256) patients (72% preoperative, 28% pre-Mammotome) were prospectively examined with EIS using the TS 2000 (TransScan Research and Development Center, Israel; temporarily distributed by Siemens, Erlangen) with the “LOS”-software (level of suspicion). All exams were performed with the targeted scan probe, the observer knowing all clinical and imaging facts. The area of the lesions was examined with EIS at least with 5 single scans. The evaluation included a scaling of lesions from 1 (surely benign) up to 5 (highly suggestive for malignancy) as well as the additional notification of spots. Results of EIS were based upon the automatic scaling which is provided by the software and were compared with mammography and histology. Furthermore the influence of the histology, size of lesions, and presence/absence of spots on the EIS results were analyzed. Histology revealed benign results in 138 lesions and malignant results in 118 lesions (DCIS=61, ID-Ca=51, IL-Ca=5, mucinous Ca=1). Mammography as expected yielded high values with 91% sensitivity and 62% specificity. Overall sensitivity of EIS was 75.4%, specificity 42.03%, negative predictive value 66.7% and positive predictive value 52.7% (89 TP, 58 TN, 80 FP, 29 FN). EIS was false negative in 20 ID-Ca, 3 IL-Ca, 1 IDL-Ca, 4 DCIS, and 1 mucinous carcinoma. Sensitivity and specificity of EIS did not differ for the different histological differentiations neither for the degree of invasion. Also the additional notification of “spots” didn't show a correlation to malignancy. There were significant differences of the sensitivity of EIS regarding the tumor size. While EIS correctly diagnosed 85% of lesions <10 mm in size, only 64% of lesions >10 mm were detected. Most frequent lesion types for false positives were mastopathy (55/80 FP) and fibroadenoma (21/80 FP). Patient acceptance of EIS was perfect and there were no drop outs because of movement artifacts. In conclusion the “LOS”-software clearly improved the clinical performance of the TS 2000 as compared to the initial software. The high sensitivity of EIS in small cancers which was found in our study may indicate an advantage of this method. However, the overall sensitivity and specificity with this setup of EIS is still far too low. Further improvements especially including the measurement of higher frequencies should be realized.

Evaluation of HSG and SIS Diagnostic Value in Comparison to Hysteroscopy to Detect Intrauterine Abnormalities in Infertile Women in Iran

Austin Journal of Surgery ◽

10.26420/austinjsurg.2021.1272 ◽

2021 ◽

Vol 8 (3) ◽

Author(s):

Nazari L ◽

◽

Boroujeni PT ◽

Keyword(s):

Predictive Value ◽

Gold Standard ◽

Uterine Cavity ◽

High Sensitivity ◽

Diagnostic Odds Ratio ◽

Diagnostic Value ◽

Infertile Women ◽

Intrauterine Abnormalities ◽

Objective: Hysteroscopy is the gold standard in evaluation of uterine cavity. However, being invasive and its possible adverse effects have reduced popularity of hysteroscopy and clinicians have always been looking for a valid alternative for hysteroscopy. In the current study, we aimed to compare diagnostic value of Saline induced Sonography with HSG in diagnosis of intrauterine abnormalities. Material and Method: We performed a retrospective study on 81 infertile women who underwent hysteroscopy, SIS, and HSG at Taleghani infertility center during their IVF treatment course. Polyp, fibroids, adhesion and septate uterus were considered as abnormality. We reported agreement percent, Kappa, sensitivity, specificity, Area Under Curve, Diagnostic Odds Ratio, Positive Predictive Value, and Negative Predictive value for both SIS and HSG. Results: Total agreement between SIS and hysteroscopy was 85.1, while it was 23.4 for HSG. We also observed considerably higher Kappa for SIS (80.1%) than HSG (15.5%). Overall sensitivity and specificity of SIS for diagnosis of all type of anomaly including both uterine abnormalities and Acquired uterine pathologies was 90.1% (95% CI= 80.7, 95.9) and 90.0% (95% CI= 55.5, 99.7). Meanwhile overall sensitivity and specificity of Hysterosalpingography where hysteroscopy was considered as the gold standard was 54.9 (42.7, 66.8) and 50.0 (18.7, 81.3). Conclusion: SIS is more sensitive tools than HSG for diagnosis of intrauterine abnormalities and could be considered one of the best alternative of hysteroscopy. It provides more accurate detail diagnostic information with high sensitivity and specificity.