Screening for Lead Poisoning in an Urban Pediatric Clinic Using Samples Obtained by Fingerstick

PEDIATRICS ◽  
1994 ◽  
Vol 94 (2) ◽  
pp. 174-179
Author(s):  
David J. Schonfeld ◽  
Mark R. Cullen ◽  
Petrie M. Rainey ◽  
Anne T. Berg ◽  
David R. Brown ◽  
...  
Keyword(s):  
Lead Poisoning ◽  
False Positive ◽  
Lead Concentration ◽  
Capillary Tube ◽  
Graphite Furnace ◽  
False Positive Rate ◽  
Screening Tests ◽  
Zinc Protoporphyrin ◽  
Pediatric Clinic ◽  
Positive Rate

Objective. To assess the false positive rate of blood (BPb) determinations on sample obtained by fingerstick from children screened in an urban clinic. Method. From a single fingerstick (N = 1573), blood was collected in a capillary tube for determining lead concentration (CPb) by graphite furnace and an additional sample was absorbed onto a filter paper for determining lead concentration (FPb) by atomic absorption spectrophotometry with Delves cup. Zinc protoporphyrin (ZPP) was measured immediately and a confirmatory venous lead (VPb) specimen was obtained at the same visit if the ZPP was ≥35 µg/dL (0.6 µmol/L); children with either a CPb or FPb ≥15 µg/dL (0.7 µmol/L) were later recalled for determining VPb. Results. For the 172 children who had a VPb on the same day as the screening tests, the false positive rates (95% confidence intervals) at a lead threshold of 15 µg/dL (0.7 µmol/L) were: CPb, 13.5% (6.7-20.3); FPb, 19.1% (11.8-26.4). Analyses using all 679 screens with a paired venous specimen (mean delay between screen and venous testing = 30 days) yielded much higher false positive rates (CPb, 31.3%; FPb, 46.0%). Conclusions. Screening for lead poisoning is feasible within an urban pediatric clinic by direct measurement of lead concentration in blood samples obtained by fingerstick. The false positive rate that can be obtained is acceptable given the precision of measuring BPb concentration. Practitioners using a staged screening protocol may incorrectly attribute a higher false positive rate to the screening tests, when much of the error may be due to the temporal variability of BPb resulting from both biologic variability in BPb concentration and intermittent exposures.

Properly collected plasma metanephrines excludes PPGL after false positive screening tests

2021 ◽  
Author(s):  
Gregory A Kline ◽  
Jessica Boyd ◽  
Brenda Polzin ◽  
Adrian Harvey ◽  
Janice L Pasieka ◽  
...  
Keyword(s):  
False Positive ◽  
Adrenal Mass ◽  
Chart Review ◽  
False Positive Rate ◽  
Total Positivity ◽  
Screening Tests ◽  
Positive Rate ◽  
Plasma Metanephrines ◽  
Positive Results ◽  
Urine Metanephrines

Abstract Context False positive results are common for pheochromocytoma/paraganglioma(PPGL) real-world screening. Objective Determine the correlation between screening urine and seated plasma metanephrines in outpatients where PPGL was absent, compared to meticulously prepared and supine-collected plasma metanephrines with age-adjusted references. Design Retrospective cohort study Setting Databases from a single-provider provincial laboratory(2012-2018), a validated PPGL registry and a manual chart review from a specialized endocrine testing unit. Patients PPGL registry data excluded known PPGL cases from the laboratory database. Outpatients having both urine and plasma metanephrines <90 days apart. Methods The correlation between urine and seated plasma measures along with the total positivity rate. All cases of plasma metanephrines drawn in the endocrine unit were reviewed for test indication and test positivity rate. Results There were 810 non-PPGL pairs of urine and plasma metanephrines in the laboratory database; 46.1% of urine metanephrines were reported high. Of seated outpatient plasma metanephrines drawn a median of 5.9 days later, 19.2% were also high (r=0.33 and 0.50 for normetanephrine and metanephrine, respectively). In contrast, the meticulously prepared and supine collected patients(n=139, 51% prior high urine metanephrines) had <3% rate of abnormal high results in patients without known PPGL/adrenal mass. Conclusions There was a poor-to-moderate correlation between urine and seated plasma metanephrines. Up to 20% of those with high urine measures also had high seated plasma metanephrines in the absence of PPGL. Properly prepared and collected supine plasma metanephrines had a false positive rate of <3% in the absence of known PPGL/adrenal mass.

scholarly journals Performance of Fetal Medicine Foundation Software for Pre-Eclampsia Prediction Upon Marker Customization: Cross-Sectional Study (Preprint)

2019 ◽  
Author(s):  
Karina Bilda De Castro Rezende ◽  
Antonio José Ledo Alves Cunha ◽  
Joffre Amim Jr ◽  
Wescule De Moraes Oliveira ◽  
Maria Eduarda Belloti Leão ◽  
...  
Keyword(s):  
High Risk ◽  
False Positive ◽  
False Positive Rate ◽  
Area Under The Curve ◽  
Screening Tests ◽  
Risk Scores ◽  
Cross Sectional ◽  
Fetal Medicine ◽  
Maternal Characteristics ◽  
Positive Rate

BACKGROUND FMF2012 is an algorithm developed by the Fetal Medicine Foundation (FMF) to predict pre-eclampsia on the basis of maternal characteristics combined with biophysical and biochemical markers. Afro-Caribbean ethnicity is the second risk factor, in magnitude, found in populations tested by FMF, which was not confirmed in a Brazilian setting. OBJECTIVE This study aimed to analyze the performance of pre-eclampsia prediction software by customization of maternal ethnicity. METHODS This was a cross-sectional observational study, with secondary evaluation of data from FMF first trimester screening tests of singleton pregnancies. Risk scores were calculated from maternal characteristics and biophysical markers, and they were presented as the risk for early pre-eclampsia (PE34) and preterm pre-eclampsia (PE37). The following steps were followed: (1) identification of women characterized as black ethnicity; (2) calculation of early and preterm pre-eclampsia risk, reclassifying them as white, which generated a new score; (3) comparison of the proportions of women categorized as high risk between the original and new scores; (4) construction of the receiver operator characteristic curve; (5) calculation of the area under the curve, sensitivity, and false positive rate; and (6) comparison of the area under the curve, sensitivity, and false positive rate of the original with the new risk by chi-square test. RESULTS A total of 1531 cases were included in the final sample, with 219 out of 1531 cases (14.30; 95% CI 12.5-16.0) and 182 out of 1531 cases (11.88%; 95% CI 10.3-13.5) classified as high risk for pre-eclampsia development, originally and after recalculating the new risk, respectively. The comparison of FMF2012 predictive model performance between the originally estimated risks and the estimated new risks showed that the difference was not significant for sensitivity and area under the curve, but it was significant for false positive rate. CONCLUSIONS We conclude that black ethnicity classification of Brazilian pregnant women by the FMF2012 algorithm increases the false positive rate. Suppressing ethnicity effect did not improve the test sensitivity. By modifying demographic characteristics, it is possible to improve some performance aspects of clinical prediction tests.

Comparison of Vestibulo-Ocular and Vestibulospinal Screening Tests

1981 ◽  
Vol 89 (5) ◽  
pp. 811-817 ◽  
Author(s):  
F. Owen Black ◽  
Conrad Wall
Keyword(s):  
False Positive ◽  
False Positive Rate ◽  
The Other ◽  
Screening Tests ◽  
Caloric Test ◽  
Positional Nystagmus ◽  
Vestibular Disorder ◽  
Positive Rate ◽  
Peripheral Vestibular Disorder ◽  
Caloric Tests

A comparison of a newly developed vestibulospinal screening test and two vestibulo-ocular screening tests (caloric and rotation) was performed on two groups of patients, one with Meniere's disease (MD) the other with benign paroxysmal positional nystagmus (BPPN) and vertigo. Vestibulospinal screening tests were slightly more sensitive (not statistically significant) than caloric tests for detection of a peripheral vestibular disorder. Caloric, rotation, and vestibulospinal screening tests were specific neither for MD nor BPPN groups. The caloric test false-positive rate for the involved ear was unacceptably high for the BPPN group. The rotation test false-positive rate was the highest of the three tests for both groups. The vestibulospinal test combined with either the caloric or the rotational tests increased the sensitivity for detection of a peripheral vestibular disturbance, particularly for the MD patients.

scholarly journals Performance of Fetal Medicine Foundation Software for Pre-Eclampsia Prediction Upon Marker Customization: Cross-Sectional Study

10.2196/14738 ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. e14738 ◽  
Author(s):  
Karina Bilda De Castro Rezende ◽  
Antonio José Ledo Alves Cunha ◽  
Joffre Amim Jr ◽  
Wescule De Moraes Oliveira ◽  
Maria Eduarda Belloti Leão ◽  
...  
Keyword(s):  
High Risk ◽  
False Positive ◽  
False Positive Rate ◽  
Area Under The Curve ◽  
Screening Tests ◽  
Risk Scores ◽  
Cross Sectional ◽  
Fetal Medicine ◽  
Maternal Characteristics ◽  
Positive Rate

Background FMF2012 is an algorithm developed by the Fetal Medicine Foundation (FMF) to predict pre-eclampsia on the basis of maternal characteristics combined with biophysical and biochemical markers. Afro-Caribbean ethnicity is the second risk factor, in magnitude, found in populations tested by FMF, which was not confirmed in a Brazilian setting. Objective This study aimed to analyze the performance of pre-eclampsia prediction software by customization of maternal ethnicity. Methods This was a cross-sectional observational study, with secondary evaluation of data from FMF first trimester screening tests of singleton pregnancies. Risk scores were calculated from maternal characteristics and biophysical markers, and they were presented as the risk for early pre-eclampsia (PE34) and preterm pre-eclampsia (PE37). The following steps were followed: (1) identification of women characterized as black ethnicity; (2) calculation of early and preterm pre-eclampsia risk, reclassifying them as white, which generated a new score; (3) comparison of the proportions of women categorized as high risk between the original and new scores; (4) construction of the receiver operator characteristic curve; (5) calculation of the area under the curve, sensitivity, and false positive rate; and (6) comparison of the area under the curve, sensitivity, and false positive rate of the original with the new risk by chi-square test. Results A total of 1531 cases were included in the final sample, with 219 out of 1531 cases (14.30; 95% CI 12.5-16.0) and 182 out of 1531 cases (11.88%; 95% CI 10.3-13.5) classified as high risk for pre-eclampsia development, originally and after recalculating the new risk, respectively. The comparison of FMF2012 predictive model performance between the originally estimated risks and the estimated new risks showed that the difference was not significant for sensitivity and area under the curve, but it was significant for false positive rate. Conclusions We conclude that black ethnicity classification of Brazilian pregnant women by the FMF2012 algorithm increases the false positive rate. Suppressing ethnicity effect did not improve the test sensitivity. By modifying demographic characteristics, it is possible to improve some performance aspects of clinical prediction tests.

scholarly journals Integrated Screening for Chromosomal Anomalies: Strategies in Developing Countries

2011 ◽  
Vol 5 (2) ◽  
pp. 133-136
Author(s):  
Narendra Malhotra ◽  
Jai Prakash Rao
Keyword(s):  
False Positive ◽  
Detection Rate ◽  
False Positive Rate ◽  
Screening Tests ◽  
Chromosomal Anomalies ◽  
Ultrasound Screening ◽  
Embryo Viability ◽  
High Detection Rate ◽  
Genetic Syndrome ◽  
Positive Rate

ABSTRACT Ultrasound screening has advantages over maternal serum screening. These include confirmation of embryo viability, accurate assessment of gestational age, early diagnosis of multiple pregnancies and identification of chorionicity, the detection of major structural abnormalities, major defects of the heart and great arteries, skeletal dysplasias and genetic syndrome and measurement of NT thickness in assessing the risk for Down's syndrome. Nuchal translucency (NT) has emerged as the most sensitive ultrasound marker for detection of chromosomal anomalies in the first trimester. However, the use of ultrasound in routine screening still faces problems with reliability and quality control. Combination of maternal age, NT and first and biochemical second-trimester markers is known as the integrated test. A major goal of screening tests is to achieve high detection rate and low false-positive rate at a low cost. The integrated test best meets these criteria. It could achieve a detection rate of 85% for a false-positive rate of 1.2%. It has a much better positive predictive value and, therefore, fewer amniocentesis and fewer losses of normal fetuses. Only screen-positive cases could be taken for invasive testing.

Improving diagnosis of acute appendicitis with atypical findings by Tc-99m HMPAO leukocyte scan

2002 ◽  
Vol 41 (01) ◽  
pp. 37-41 ◽  
Author(s):  
S. Shung-Shung ◽  
S. Yu-Chien ◽  
Y. Mei-Due ◽  
W. Hwei-Chung ◽  
A. Kao
Keyword(s):  
Acute Appendicitis ◽  
False Positive ◽  
False Positive Rate ◽  
Accurate Method ◽  
Clinical Findings ◽  
Pathological Findings ◽  
Lower Quadrant ◽  
Predictive Values ◽  
Positive Rate

Summary Aim: Even with careful observation, the overall false-positive rate of laparotomy remains 10-15% when acute appendicitis was suspected. Therefore, the clinical efficacy of Tc-99m HMPAO labeled leukocyte (TC-WBC) scan for the diagnosis of acute appendicitis in patients presenting with atypical clinical findings is assessed. Patients and Methods: Eighty patients presenting with acute abdominal pain and possible acute appendicitis but atypical findings were included in this study. After intravenous injection of TC-WBC, serial anterior abdominal/pelvic images at 30, 60, 120 and 240 min with 800k counts were obtained with a gamma camera. Any abnormal localization of radioactivity in the right lower quadrant of the abdomen, equal to or greater than bone marrow activity, was considered as a positive scan. Results: 36 out of 49 patients showing positive TC-WBC scans received appendectomy. They all proved to have positive pathological findings. Five positive TC-WBC were not related to acute appendicitis, because of other pathological lesions. Eight patients were not operated and clinical follow-up after one month revealed no acute abdominal condition. Three of 31 patients with negative TC-WBC scans received appendectomy. They also presented positive pathological findings. The remaining 28 patients did not receive operations and revealed no evidence of appendicitis after at least one month of follow-up. The overall sensitivity, specificity, accuracy, positive and negative predictive values for TC-WBC scan to diagnose acute appendicitis were 92, 78, 86, 82, and 90%, respectively. Conclusion: TC-WBC scan provides a rapid and highly accurate method for the diagnosis of acute appendicitis in patients with equivocal clinical examination. It proved useful in reducing the false-positive rate of laparotomy and shortens the time necessary for clinical observation.

Predicting Fetal Chromosome Anomalies in the First Trimester Using Pregnancy Associated Plasma Protein-A: A Comparison of Statistical Methods

1993 ◽  
Vol 32 (02) ◽  
pp. 175-179 ◽  
Author(s):  
B. Brambati ◽  
T. Chard ◽  
J. G. Grudzinskas ◽  
M. C. M. Macintosh
Keyword(s):  
Logistic Regression ◽  
General Population ◽  
Likelihood Ratio ◽  
False Positive ◽  
False Positive Rate ◽  
Ratio Method ◽  
Detection Rates ◽  
Gaussian Distributions ◽  
Positive Rate ◽  
Likelihood Ratio Method

Abstract:The analysis of the clinical efficiency of a biochemical parameter in the prediction of chromosome anomalies is described, using a database of 475 cases including 30 abnormalities. A comparison was made of two different approaches to the statistical analysis: the use of Gaussian frequency distributions and likelihood ratios, and logistic regression. Both methods computed that for a 5% false-positive rate approximately 60% of anomalies are detected on the basis of maternal age and serum PAPP-A. The logistic regression analysis is appropriate where the outcome variable (chromosome anomaly) is binary and the detection rates refer to the original data only. The likelihood ratio method is used to predict the outcome in the general population. The latter method depends on the data or some transformation of the data fitting a known frequency distribution (Gaussian in this case). The precision of the predicted detection rates is limited by the small sample of abnormals (30 cases). Varying the means and standard deviations (to the limits of their 95% confidence intervals) of the fitted log Gaussian distributions resulted in a detection rate varying between 42% and 79% for a 5% false-positive rate. Thus, although the likelihood ratio method is potentially the better method in determining the usefulness of a test in the general population, larger numbers of abnormal cases are required to stabilise the means and standard deviations of the fitted log Gaussian distributions.

Identification of and Correction for Publication Bias: Comment

2019 ◽  
Author(s):  
Amanda Kvarven ◽  
Eirik Strømland ◽  
Magnus Johannesson
Keyword(s):  
Publication Bias ◽  
False Positive ◽  
Large Scale ◽  
Meta Analysis ◽  
False Positive Rate ◽  
Effect Sizes ◽  
Replication Studies ◽  
Moderate Reduction ◽  
Positive Rate ◽  
Meta Analyses

Andrews & Kasy (2019) propose an approach for adjusting effect sizes in meta-analysis for publication bias. We use the Andrews-Kasy estimator to adjust the result of 15 meta-analyses and compare the adjusted results to 15 large-scale multiple labs replication studies estimating the same effects. The pre-registered replications provide precisely estimated effect sizes, which do not suffer from publication bias. The Andrews-Kasy approach leads to a moderate reduction of the inflated effect sizes in the meta-analyses. However, the approach still overestimates effect sizes by a factor of about two or more and has an estimated false positive rate of between 57% and 100%.

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