scholarly journals The effect of correlations between screening markers on screening performance

2007 ◽  
Vol 14 (3) ◽  
pp. 151-157 ◽  
Author(s):  
J K Morris ◽  
N J Wald
Keyword(s):  
Computer Simulation ◽  
Detection Rate ◽  
Prenatal Screening ◽  
False Positive Rate ◽  
Strong Correlations ◽  
Computer Simulation Study ◽  
Opposite Pattern ◽  
Screening Performance ◽  
Positive Rate ◽  
Highly Correlated

Objectives: It is widely thought that correlations between screening markers will tend to degrade screening performance. We performed a computer simulation study to investigate the quantitative effect of correlations between two markers on screening performance, using prenatal screening for Down's syndrome as an example, although the results apply generally. Methods: Monte Carlo simulation was used to generate values of two hypothetical markers, A and B, in 1000 affected and 1000 unaffected pregnancies. The means, standard deviations and correlations of A and B were varied in five different examples. Results: If markers A and B are, on average, higher in affected than unaffected pregnancies and each marker, individually, has the same detection rate for a given false-positive rate (i.e. the same screening performance), then the screening performance of A and B together tends to decrease as A and B become more positively correlated with each other (within affected or unaffected categories) and tends to increase as A and B become more negatively correlated. If A is, on average, higher in affected pregnancies and B is, on average, lower in affected pregnancies (but again each marker has the same screening performance), the opposite pattern is observed; screening performance increases as A and B become more positively correlated and screening performance decreases as they become more negatively correlated. If A and B have unequal screening performances, modest correlations between A and B have little effect on the screening performance of A and B together, but when the correlations are strong whether positive or negative (with r values greater than about 0.45 or less than −0.45) screening performance progressively increases. Conclusion: Correlations between screening markers considered separately in affected and unaffected pregnancies can either decrease or increase screening performance. In practice, these effects are usually modest, because most screening markers are not highly correlated with each other and the effects become important only with strong correlations, whether positive or negative.

The efficacy of combining several risk factors as a screening test

2005 ◽  
Vol 12 (4) ◽  
pp. 197-201 ◽  
Author(s):  
Nicholas J Wald ◽  
Joan K Morris ◽  
Simon Rish
Keyword(s):  
Risk Factors ◽  
Risk Factor ◽  
False Positive ◽  
Detection Rate ◽  
False Positive Rate ◽  
Individual Risk ◽  
Detection Rates ◽  
Screening Performance ◽  
Positive Rate ◽  
The Individual

Objective: To determine the quantitative effect on overall screening performance (detection rate for a given false-positive rate) of using several moderately strong, independent risk factors in combination as screening markers. Setting: Theoretical statistical analysis. Methods: For the purposes of this analysis, it was assumed that all risk factors were independent, had Gaussian distributions with the same standard deviation in affected and unaffected individuals and had the same screening performance. We determined the overall screening performance associated with using an increasing number of risk factors together, with each risk factor having a detection rate of 10%, 15% or 20% for a 5% false-positive rate. The overall screening performance was estimated as the detection rate for a 5% false-positive rate. Results: Combining the risk factors increased the screening performance, but the gain in detection at a constant false-positive rate was relatively modest and diminished with the addition of each risk factor. Combining three risk factors, each with a 15% detection rate for a 5% false-positive rate, yields a 28% detection rate. Combining five risk factors increases the detection rate to 39%. If the individual risk factors have a detection rate of 10% for a 5% false-positive rate, it would require combining about 15 such risk factors to achieve a comparable overall detection rate (41%). Conclusion: It is intuitively thought that combining moderately strong risk factors can substantially improve screening performance. For example, most cardiovascular risk factors that may be used in screening for ischaemic heart disease events, such as serum cholesterol and blood pressure, have a relatively modest screening performance (about 15% detection rate for a 5% false-positive rate). It would require the combination of about 15 or 20 such risk factors to achieve detection rates of about 80% for a 5% false-positive rate. This is impractical, given the risk factors so far discovered, because there are too few risk factors and their associations with disease are too weak.

Screening for Diabetic Retinopathy in Primary Care: Retinal Photography Alone can Be Used Efficiently and Effectively to Exclude Those with Sight Threatening Lesions

1997 ◽  
Vol 4 (3) ◽  
pp. 174-176 ◽  
Author(s):  
P M S Evans ◽  
T S Purewal ◽  
A Hopper ◽  
H Slater ◽  
D R L Jones ◽  
...  
Keyword(s):  
Primary Care ◽  
Diabetic Retinopathy ◽  
Gold Standard ◽  
Detection Rate ◽  
False Positive Rate ◽  
Poor Quality ◽  
Background Retinopathy ◽  
Screening Performance ◽  
Positive Rate ◽  
Retinal Photography

Background— Good screening performance of retinal photography and ophthalmoscopy together in screening for diabetic retinopathy in primary care have been reported. This study reanalysed the data to evaluate the screening performance of photography alone. Methods— One thousand and ten patients screened by fundal photography and ophthalmoscopy were studied retrospectively. Fundal photographs were quality graded with poor quality pictures being excluded from the analysis. Each patient was reviewed initially by both retinal photographs and ophthalmoscopy by an ophthalmologist, the “gold standard”. Six months later the fundal photographs were reviewed and reported in a blinded manner by the ophthalmologist. Results— Two thousand and fourteen photographs were obtained, of which 162 (8%) had to be excluded because of poor quality. On review of the remaining 18S2 photographs in isolation, of 77 cases of severe retinopathy as determined by the “gold standard”, 67 had severe changes on photography—detection rate 87%. Of the 1775 cases without sight threatening retinopathy only five were judged to have sight threatening changes on photography—false positive rate 0.3%. Considering sight threatening and background retinopathy together, the detection rate was 69% (2S7 of 375) and the false positive rate 1.6% (23 of 1477). Conclusion— Good quality fundal photographs alone seem specific enough to screen for sight threatening diabetic retinopathy, but will underdetect background retinopathy.

Combining Carotid Intima-media Thickness with Carotid Plaque on Screening for Coronary Heart Disease

2009 ◽  
Vol 16 (3) ◽  
pp. 155-159 ◽  
Author(s):  
David S Wald ◽  
Jonathan P Bestwick ◽  
Geraint Morton ◽  
Linda Drummond ◽  
Nick Jenkins ◽  
...  
Keyword(s):  
Coronary Heart Disease ◽  
False Positive ◽  
Carotid Plaque ◽  
Detection Rate ◽  
False Positive Rate ◽  
Intima Media Thickness ◽  
Carotid Imt ◽  
Percentage Points ◽  
Screening Performance ◽  
Positive Rate

Background Ultrasound-detected carotid artery intima-media thickness (IMT) and carotid plaque are possible screening tests for coronary heart disease (CHD) among asymptomatic individuals. Objective To assess the increase in screening performance of combining carotid IMT and plaque compared with each measurement alone in the identification of individuals with CHD. Methods Ultrasound examination of left and right carotid arteries was performed on 100 individuals (median age 57), 55 with a history of CHD (unstable angina or myocardial infarction) and 45 without. IMT measurements were taken from the common carotid artery and plaque was identified above, at and below the carotid bifurcation. Associations between IMT and plaque were determined using logistic regression, and screening performance was assessed from the distributions of IMT and plaque among cases and controls. Results At a false-positive rate of 5%, IMT (cut-off >0.75 mm) identified 30% (95% CI 14–58) of affected individuals. There was an increase in the detection rate of 8 percentage points (1–33%) using IMT and plaque combined compared with IMT alone. As the false-positive increased, the difference in the detection rate increased, up to a maximum of 20 percentage points (5–38%) at a false-positive rate of 20%. The comparison of IMT and plaque combined with plaque alone could only be estimated for the false-positive rate observed using plaque alone (18%); at this point the detection rate was 72% for plaque and 75% for plaque and IMT combined, an increase of 3 percentage points (0–4%). Conclusion In screening for CHD, combining carotid IMT measurement with plaque assessment is better than using either measurement alone, but the improvement in discrimination is not sufficient to make carotid ultrasound screening for CHD worthwhile.

Placental protein-13 (PP13) in combination with PAPP-A and free leptin index (fLI) in first trimester maternal serum screening for severe and early preeclampsia

2017 ◽  
Vol 56 (1) ◽  
Author(s):  
Carin P. De Villiers ◽  
Paula L. Hedley ◽  
Sophie Placing ◽  
Karen R. Wøjdemann ◽  
Anne-Cathrine Shalmi ◽  
...  
Keyword(s):  
Detection Rate ◽  
False Positive Rate ◽  
First Trimester ◽  
Serum Marker ◽  
Maternal Serum ◽  
Maternal Serum Screening ◽  
Discriminatory Ability ◽  
Screening Performance ◽  
Positive Rate ◽  
Placental Protein

AbstractBackground:Placental protein-13 (PP13) is involved in placental invasion and has been suggested as a maternal serum marker of preeclampsia (PE) development. However, the discriminatory ability of PP13 in first trimester has not been completely clarified.Methods:PP13 was measured in first trimester (week 10Results:In severe PE (including HELLP) cases (n=26) the median PP13 concentration was 35.8 pg/mL (range: 17.8–85.5 pg/mL) and in PE pregnancies (n=10) with birth prior to week 34, the median PP13 concentration was 30.6 pg/mL (13.1–50.1 pg/mL), compared to controls with a median of 54.8 pg/mL (range: 15.4–142.6 pg/mL) (p<0.04). The population screening detection rate (DR) for a false-positive rate of 10% for severe PE and HELLP was 26% for PP13, 28% for PP13+PAPP-A, 33% for PP13+fLI, and 40% for PP13+PAPP-A+fLI.Conclusions:PP13 is a marker of severe PE and HELLP syndrome. The screening performance of PP13 can be markedly improved by combining it with fLI and PAPP-A.

scholarly journals Combined First-Trimester Screening in Northern Finland: Experiences of the First Ten Years

2014 ◽  
Vol 8 ◽  
pp. CMRH.S14958
Author(s):  
Merilainen Anna ◽  
Peuhkurinen Sini ◽  
Honkasalo Timppa ◽  
Laitinen Paivi ◽  
Kokkonen Hannaleena ◽  
...  
Keyword(s):  
Detection Rate ◽  
False Positive Rate ◽  
Down's Syndrome ◽  
Down’S Syndrome ◽  
First Trimester ◽  
First Trimester Screening ◽  
Invasive Procedures ◽  
Screening Performance ◽  
Positive Rate ◽  
Trimester Screening

Objective To evaluate the efficacy of first trimester combined screening for Down's syndrome in Northern Finland during the first 10 years of practice. Methods During 1 January 2002 to 31 December 2011, 47,896 women participated voluntarily in combined screening during first trimester. The risk cutoff was 1:250. The study period was divided into two time periods; 2002-2006 and 2007-2011. Results During the first half of the study period, the detection rate (DR) was 77.3% with a 4.9% false-positive rate (FPR). During the latter half, the DR was 77.1% with a 2.8% FPR. Conclusions An important issue is the number of invasive procedures needed to detect one case of Down's syndrome. The screening performance improved markedly in the latter five years period since the FPR lowered from 4.9% to 2.8% and the number of invasive procedures needed to detect one case of Down's syndrome lowered from 15 to 11.

scholarly journals Evaluation of Cell-free Fetal DNA as a Second-Trimester Maternal Serum Marker of Down Syndrome Pregnancy

2003 ◽  
Vol 49 (2) ◽  
pp. 239-242 ◽  
Author(s):  
Antonio Farina ◽  
Erik S LeShane ◽  
Geralyn M Lambert-Messerlian ◽  
Jacob A Canick ◽  
Thomas Lee ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Detection Rate ◽  
False Positive Rate ◽  
Maternal Serum ◽  
Second Trimester ◽  
Fetal Dna ◽  
Screening Performance ◽  
Cell Free Fetal Dna ◽  
Positive Rate ◽  
Screening Marker

Abstract Background: Second-trimester cell-free fetal DNA (studied only in pregnancies with male fetuses) is higher in maternal serum samples from women carrying Down syndrome fetuses than in unaffected pregnancies. In this study we evaluated the potential performance of fetal DNA as a screening marker for Down syndrome. Methods: Data on maternal serum fetal DNA concentrations and the corresponding concentrations of the quadruple serum markers were available from 15 Down syndrome cases, each matched for gestational age and length of freezer storage, with 5 control samples. Analyte values were expressed as multiple(s) of the control or population median. Screening performance of fetal DNA, both alone and when added to estimates of quadruple marker performance, was determined after modeling using univariate and multivariate gaussian distribution analysis. Results: The median fetal DNA concentration in Down syndrome cases was 1.7 times higher than in controls. In univariate analysis, fetal DNA gave a 21% detection rate at a 5% false-positive rate. When added to quadruple marker screening, fetal DNA increased the estimated detection rate from 81% to 86% at a 5% false-positive rate. Conclusions: Cell-free fetal DNA, measured in maternal serum, can modestly increase screening performance above what is currently available in the second trimester. If and when maternal serum fetal DNA can be measured in pregnancies with both male and female fetuses, the utility and cost-effectiveness of adding it as a Down syndrome screening marker should be assessed.

scholarly journals Night-Time Vehicle Sensing in Far Infrared Image with Deep Learning

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Hai Wang ◽  
Yingfeng Cai ◽  
Xiaobo Chen ◽  
Long Chen
Keyword(s):  
Detection Rate ◽  
False Positive Rate ◽  
Infrared Image ◽  
Far Infrared ◽  
Night Vision ◽  
Infrared Sensors ◽  
Night Time ◽  
Detection Rates ◽  
Positive Rate ◽  
And Performance

The use of night vision systems in vehicles is becoming increasingly common. Several approaches using infrared sensors have been proposed in the literature to detect vehicles in far infrared (FIR) images. However, these systems still have low vehicle detection rates and performance could be improved. This paper presents a novel method to detect vehicles using a far infrared automotive sensor. Firstly, vehicle candidates are generated using a constant threshold from the infrared frame. Contours are then generated by using a local adaptive threshold based on maximum distance, which decreases the number of processing regions for classification and reduces the false positive rate. Finally, vehicle candidates are verified using a deep belief network (DBN) based classifier. The detection rate is 93.9% which is achieved on a database of 5000 images and video streams. This result is approximately a 2.5% improvement on previously reported methods and the false detection rate is also the lowest among them.

scholarly journals Rapid and Automatic Detection of Micronuclei in Binucleated lymphocytes Image

2021 ◽  
Author(s):  
Xiang Shen ◽  
Ying Chen ◽  
Chaowen Li ◽  
Fucheng Yang ◽  
Zhanbo Wen ◽  
...  
Keyword(s):  
False Positive ◽  
Detection Rate ◽  
False Positive Rate ◽  
Research Work ◽  
Estimation Method ◽  
Automatic Detection ◽  
Dose Estimation ◽  
Binucleated Cell ◽  
Positive Rate ◽  
Binucleated Lymphocytes

Abstract In terms of radiation biological dose estimation, the cytokinesis block micronucleus (CBMN) assay is the internationally recognized dose estimation method. Due to the subjectivity and the time-consuming of manual detection, it cannot meet the needs of rapid standard assay of CBMN. Therefore, in this research work, we combined the convolutional neural network to design a software that can be used for rapid standard automatic detection of micronuclei in Giemsa stained binucleated lymphocytes image. The software analysis workflow is divided into four stages: cell acquisition, adhesive cell masses segmentation, cell type identification, micronucleus counting. After verification, our algorithm can quickly and effectively detect binucleated cells and micronucleus even when the cytoplasm is blurred, multiple micronucleus are attached to each other, or micronucleus is attached to the nucleus. In the test of a large number of random images, the software reached 99.4% of the manual detection in terms of the detection rate of binucleated cell, and the false positive rate of binucleated cell was 14.7%. In terms of micronucleus detection rate, the software reached 115.1% of manual detection, and its false positive rate was 26.2%. The analysis time of each picture is about 0.3s, an order of magnitude faster than conventional method.

scholarly journals Using a Subtractive Center Behavioral Model to Detect Malware

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Ömer Aslan ◽  
Refik Samet ◽  
Ömer Özgür Tanrıöver
Keyword(s):  
Detection Rate ◽  
Learning Algorithm ◽  
False Positive Rate ◽  
Behavioral Model ◽  
Behavior Patterns ◽  
Test Results ◽  
Malicious Behavior ◽  
Proposed Model ◽  
Positive Rate ◽  
New Generation

In recent years, malware has evolved by using different obfuscation techniques; due to this evolution, the detection of malware has become problematic. Signature-based and traditional behavior-based malware detectors cannot effectively detect this new generation of malware. This paper proposes a subtractive center behavior model (SCBM) to create a malware dataset that captures semantically related behaviors from sample programs. In the proposed model, system paths, where malware behaviors are performed, and malware behaviors themselves are taken into consideration. This way malicious behavior patterns are differentiated from benign behavior patterns. Features that could not exceed the specified score are removed from the dataset. The datasets created using the proposed model contain far fewer features than the datasets created by n-gram and other models that have been used in other studies. The proposed model can handle both known and unknown malware, and the obtained detection rate and accuracy of the proposed model are higher than those of the known models. To show the effectiveness of the proposed model, 2 datasets with score and without score are created by using SCBM. In total, 6700 malware samples and 3000 benign samples are tested. The results are compared with those derived from n-gram and models from other studies in the literature. The test results show that, by combining the proposed model with an appropriate machine learning algorithm, the detection rate, false positive rate, and accuracy are measured as 99.9%, 0.2%, and 99.8%, respectively.

scholarly journals Predicting first-trimester outcome of embryos with cardiac activity in women with recurrent spontaneous abortion

2020 ◽  
Vol 48 (6) ◽  
pp. 030006052091182
Author(s):  
Huixian Li ◽  
Shuang Qin ◽  
Fanfan Xiao ◽  
Yuhong Li ◽  
Yunhe Gao ◽  
...  
Keyword(s):  
Pregnant Women ◽  
False Positive ◽  
Detection Rate ◽  
False Positive Rate ◽  
Cardiac Activity ◽  
First Trimester ◽  
Clinical Indicators ◽  
Early Outcome ◽  
Heart Motion ◽  
Positive Rate

Objective This study was performed to evaluate the capability of routine clinical indicators to predict the early outcome of embryos with cardiac activity in women with recurrent spontaneous abortion (RSA). Methods A retrospective cohort study of pregnant women with a history of RSA in a Chinese tertiary hospital was performed using unadjusted and multivariable logistic regression. Results Of 789 pregnant women with RSA, 625 (79.21%) had ongoing pregnancy, whereas 164 (20.79%) developed abortion before 20 full weeks of gestational age even after embryonic heart motion was detected. The final model had an area under the curve of 0.81 (95% confidence interval, 0.78–0.84) with a sensitivity of 74.39%, a specificity of 76.00%, and a false-positive rate of 52.32% at a fixed detection rate of 90%. Conclusions The combination of multiple routine clinical indicators was valuable in predicting the early outcome of embryos with cardiac activity in viable pregnancies with RSA. However, this model might result in a high false-positive rate with a fixed detection rate of 90%; other markers must be investigated to identify first-trimester RSA once positive embryonic heart motion is established.

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