Thermography in the Diagnosis of DVT

Summary161 consecutively admitted medical patients with the clinical suspicion of acute deep venous thrombosis (DVT) were thermographed and phlebographed in order to study the congruence of these methods. The sensitivity of thermography in the detection of DVT was found to be 99%, whereas the specificity was only 49%.The low specificity is explained by the fact that all thermographs suggestive of DVT were classified as pathologic to keep the sensitivity of the method as high as possible. Patients with dilated veins which may closely resemble DVT on thermography may in these cases give false positive results.Of 76 patients with phlebographically verified DVT, 22% became thermographically normal within 22 days, whereas 78% did not normalize within the mean observation time of 31 days.In another part of the study all medical patients (101) who were residing in our wards during a period of a week were screened by means of thermography. From this unselected group 17 patients were found to have thermographs suggestive of DVT. In 5 of these patients no reason for pathological thermography could be found.Thermography is a cheap and highly sensitive screening method for DVT, but findings of false positives caused by older thromboses and dilated veins are not unusual. The frequency of such false positives may be minimized by performing thermography after exercise.

Download Full-text

Incidence and Characteristics of Vancomycin Nonsusceptible Strains of Methicillin-Resistant Staphylococcus aureus at Hershey Medical Center

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01073-08 ◽

2008 ◽

Vol 52 (12) ◽

pp. 4510-4513 ◽

Cited By ~ 19

Author(s):

Klaudia Kosowska-Shick ◽

Lois M. Ednie ◽

Pamela McGhee ◽

Kathy Smith ◽

Cynthia D. Todd ◽

...

Keyword(s):

Staphylococcus Aureus ◽

False Positive ◽

Methicillin Resistant Staphylococcus Aureus ◽

Medical Center ◽

Screening Method ◽

Brain Heart Infusion ◽

Methicillin Resistant ◽

Repeat Testing ◽

False Positivity ◽

Positive Results

ABSTRACT All 982 methicillin-resistant Staphylococcus aureus strains collected from August 2006 to December 2007 were tested for vancomycin susceptibility by using 3-μg/ml vancomycin brain heart infusion screening plates, a vancomycin Etest, and a vancomycin/teicoplanin macro Etest. Three vancomycin-intermediate Staphylococcus aureus (VISA) (0.3%) and two heterogeneous VISA (0.2%) isolates were identified. The screening method yielded 895 cases of ≤1 colony and 87 positive results (with growth of >1 colony after 48 h); further Etests showed 82/87 isolates with growth on screening plates to be false positive. Repeat testing showed a false-positivity rate of only 15 of the original 87 isolates by plate screening.

Download Full-text

Noninvasiv Screening For Acute Dvt By Means Of Leg Temperature Profiles And Venous Emptying Curves As Compared To Conventional Thermography And Phlebography

10.1055/s-0038-1652468 ◽

1981 ◽

Author(s):

E Nilsson ◽

K Holmgren ◽

H Jacobsson ◽

H Johnsson ◽

S Zetterquist

Keyword(s):

False Positive ◽

Infrared Radiation ◽

Diagnostic Procedure ◽

Varicose Veins ◽

Venous Occlusion ◽

Clinical Suspicion ◽

Diagnostic Sensitivity ◽

Temperature Profiles ◽

Positive Results ◽

Position Indicator

simplified thermographic technique has been developed to provide leg temperature profiles for diagnosis of acute DVT (DevethermR). The temperature profiles are obtained by manual scanning from the foot to the hip with an infrared radiation transducer attached to a position indicator. The diagnosis of DVT is based on side-differences in mean segmental leg temperature.In 200 patients admitted to hospital due to the clinical suspicion of acute DVT, the leg temperature profiles were pathological in 132 of those 140 patients who proved to have DVT at phlebography which means a sensitivity of 94%. False positive results were obtained in cases with e.g. varicose veins or regional infections but these errors could be reduced if the profiles were not only numerically evaluated but also subjected to pattern analyses. A combination with venous emptying curves as obtained from venous occlusion plethysmography further improved the specificity of the noninvasive diagnostic procedure. This combination also proved favourable for the differentiation between proximal and distal leg thromboses as well as acute and old DVT. Some of the patients were investigated with thermography by a scanning camera. The results correlated closely to those obtained with the simplified thermographic technique but without improving the diagnostic sensitivity.

Download Full-text

EVALUATION OF SCREENING TESTS FOR URINARY MUCOPOLYSACCHARIDES

PEDIATRICS ◽

10.1542/peds.52.1.64 ◽

1973 ◽

Vol 52 (1) ◽

pp. 64-68

Author(s):

Iraj Rezvani ◽

P. J. Collipp ◽

Angelo M. DiGeorge

Keyword(s):

False Positive ◽

Screening Test ◽

False Positives ◽

Spot Test ◽

Screening Tests ◽

Paper Test ◽

Normal Children ◽

Great Caution ◽

Turbidity Test ◽

Positive Results

A recently developed spot test, "MPS paper," has been added to other screening tests for urinary mucopolysaccharides. The effectiveness of this test has been compared to that of the cetytrimethylammonium bromide and the acid albumin gross turbidity tests in normal children and in patients with mucopolysaccharidoses. Although all these tests are effective in the detection of excessive mucopolysaccharides in urine, their excessive sensitivity yields many weak false-positives. We found "MPS paper" test to yield 34% false-positive tests, compared to 42% for cetytrimethylammonium bromide and 8% for the acid albumin gross turbidity test. We have concluded that the acid albumin gross turbidity is the most reliable screening test for detection of mucopolysaccharide disorders. "MPS paper" spot test has the advantage of being simple and practical, but weak positive results should be interpreted with great caution; it has the added disadvantage of being the most costly of the screening tests at the present time.

Download Full-text

Pitfalls and Prevention Strategies for Liquid Chromatography-Tandem Mass Spectrometry in the Selected Reaction– Monitoring Mode for Drug Analysis

Clinical Chemistry ◽

10.1373/clinchem.2008.105478 ◽

2008 ◽

Vol 54 (9) ◽

pp. 1519-1527 ◽

Cited By ~ 80

Author(s):

François-Ludovic Sauvage ◽

Jean-Michel Gaulier ◽

Gérard Lachâtre ◽

Pierre Marquet

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Tandem Mass Spectrometry ◽

Relative Abundance ◽

False Positive ◽

Screening Method ◽

Selected Reaction Monitoring ◽

Tandem Mass ◽

Reaction Monitoring ◽

Positive Results

Abstract Background: We observed cases of false-positive results with the use of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Different LC-MS/MS techniques that use the selected reaction-monitoring mode, routinely employed for the analysis and quantification of drugs and toxic compounds in biological matrices, were involved in the false-positive and potentially false-positive results obtained. We sought to analyze the causes of and solutions to this problem. Methods: We used a previously reported LC-MS/MS general unknown screening method, as well as manual spectral investigation in 1 case, to perform verification and identification of interfering compounds. Results: We observed that false-positive results involved: a metabolite of zolpidem that might have been mistaken for lysergic acid diethylamide, benzoylecgonine mistaken for atropine, and clomipramine and 3 phenothiazines that share several common ion transitions. Conclusions: To prevent problems such as those we experienced, we recommend the use of stable-isotope internal standards when possible, relative retention times, 2 transitions or more per compound when possible, and acceptable relative abundance ratios between transitions, with an experience-based tolerance of ±15% for transitions with a relative abundance >10% and with an extension to ±25% for transitions <10% when the concentration is at the limit of quantification. A powerful general unknown screening procedure can help to confirm suspected interferences. Our results indicate that the specificity of screening procedures is questionable for LC-MS/MS analyses performed in the selected reaction-monitoring mode and involving a large number of compounds with only 1 transition per compound.

Download Full-text

Do we cause false positives? An experimental series on droplet or airborne SARS-CoV-2 contamination of sampling tubes during swab collection in a test center

Antimicrobial Resistance and Infection Control ◽

10.1186/s13756-021-00920-z ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Thomas Scheier ◽

Cyril Shah ◽

Michael Huber ◽

Hugo Sax ◽

Barbara Hasse ◽

...

Keyword(s):

Infection Control ◽

False Positive ◽

False Positives ◽

Experimental Series ◽

Airborne Contamination ◽

Rapid Spread ◽

Time Periods ◽

Short Time ◽

Time Frames ◽

Positive Results

AbstractThe rapid spread of the coronavirus disease 2019 pandemic urged immense testing capacities as one cornerstone of infection control. Many institutions opened outpatient SARS-CoV-2 test centers to allow large number of tests in comparatively short time frames. With increasing positive test rates, concerns for a possible airborne or droplet contamination of specimens leading to false-positive results were raised. In our experimental series performed in a dedicated SARS-CoV-2 test center, 40 open collection tubes placed for defined time periods in proximity to individuals were found to be SARS-CoV-2 negative. These findings argue against false-positive SARS-CoV-2 results due to droplet or airborne contamination.

Download Full-text

Women’s conceptual knowledge about breast cancer screening and overdiagnosis in Norway: a cross-sectional study

BMJ Open ◽

10.1136/bmjopen-2021-052121 ◽

2021 ◽

Vol 11 (12) ◽

pp. e052121

Author(s):

Kaitlyn M Tsuruda ◽

Marit B Veierød ◽

Nehmat Houssami ◽

Gunvor G Waade ◽

Gunhild Mangerud ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Mortality ◽

False Positive ◽

Conceptual Knowledge ◽

Breast Cancer Mortality ◽

Mammographic Screening ◽

Mortality Benefit ◽

Cross Sectional ◽

The Mean ◽

Positive Results

ObjectiveTo investigate conceptual knowledge about mammographic screening among Norwegian women.DesignWe administered a cross-sectional, web-based survey. We used multiple-choice questions and a grading rubric published by a research group from Australia.SettingOur Norwegian-language survey was open from April to June 2020 and targeted women aged 45–74 years.Participants2033 women completed our questionnaire. We excluded 13 women outside the target age range and 128 women with incomplete data. Responses from 1892 women were included in the final study sample.Primary and secondary outcome measuresThe questionnaire focused on women’s knowledge about the breast cancer mortality reduction, false positive results and overdiagnosis associated with mammographic screening. The primary outcome was the mean number of marks assigned in each of the three themes and overall. There were three potential marks for questions about breast cancer mortality, one for false positives and six for overdiagnosis.ResultsMost women (91.7%) correctly reported that screened women are less likely to die of breast cancer than non-screened women. 39.7% of women reported having heard of a ‘false positive screening result’ and 86.2% identified the term’s definition; 51.3% of women had heard of ‘overdiagnosis’ and 14.8% identified the term’s definition. The mean score was 2.59 of 3 for questions about breast cancer mortality benefit and 0.93 of 1 for the question about false positive screening results. It was 2.23 of 6 for questions about overdiagnosis.ConclusionsMost participants correctly answered questions about the breast cancer mortality benefit and false positive results associated with screening. The proportion of correct responses to questions about overdiagnosis was modest, indicating that conceptual knowledge about overdiagnosis was lower. Qualitative studies that can obtain in-depth information about women’s understanding of overdiagnosis may help improve Norwegian-language information about this challenging topic.

Download Full-text

Cord Plasma α-Fetoprotein Values and Neonatal Jaundice

PEDIATRICS ◽

10.1542/peds.74.6.1065 ◽

1984 ◽

Vol 74 (6) ◽

pp. 1065-1068 ◽

Cited By ~ 1

Author(s):

K. L. Tan ◽

A. Loganath ◽

A. C. Roy ◽

H. H. Goh ◽

S. M. Karim ◽

...

Keyword(s):

High Risk ◽

False Positive ◽

Neonatal Jaundice ◽

False Negative ◽

Negative Results ◽

Cord Plasma ◽

False Negative Results ◽

The Mean ◽

Glucose 6 Phosphate Dehydrogenase ◽

Positive Results

Umbilical cord plasma α-fetoprotein (AFP) values were determined in 127 infants with hyperbilirubinemia (56 glucose-6-phosphate dehydrogenase (G-6-PD) deficient and 71 G-6-PD normal) and 136 control subjects (73 G-6-PD deficient and 63 G-6-PD normal). The mean α-fetoprotein value of 173 ± 35.2 (SD) mg/L for the group of infants with hyperbilirubinemia was significantly greater than that (122 ± 21.7 mg/L) for the control infants (P < .001). G-6-PD status and sex did not significantly affect the α-fetoprotein values. Using an α-fetoprotein level of 130 mg/L as a "cut-off" value, the incidence of false-positive results was 25.5% and the incidence of false-negative results was 11.8%. This test can be used as a screening procedure to detect infants at high risk for hyperbilirubinemia.

Download Full-text

An Emerging Marker Predicting The Severity of Covid-19: Neutrophil-Lymphocyte Count Ratio

10.53350/pjmhs2115113398 ◽

2021 ◽

Vol 15 (11) ◽

pp. 3398-3399

Author(s):

Ali Hassan ◽

Zulfiqar Ali ◽

Hina Iftikhar ◽

Azhar Graded ◽

Zulfiqar Haider ◽

...

Keyword(s):

Lymphocyte Count ◽

Clinical Symptoms ◽

Smoking History ◽

Laboratory Findings ◽

Count Ratio ◽

Highly Sensitive ◽

Severity Prediction ◽

Severe Group ◽

The Mean ◽

Positive Results

Objective: To assess the efficacy of neutrophil-lymphocyte count ratio in predicting the severity of covid-19 Materials and Methods: The patients with positive results for COVID-19 were shifted to COVID ITC, CMH, Multan. The clinical histories of confirmed patients of COVID-19 during February 2020 to May 2021 were reviewed. The patients were divided into 4 classes, mild, common, severe, and fatal, according to guidelines of COVID-19 i.e., trial version 7. Data was collected regarding age, sex, smoking history, temperature, epidemiological history, clinical symptoms, and laboratory findings of all included patients including NLCR. Results: The mean NLCR of Mild and Severe Group was 2.77±1.23 and 20.31±4.45, respectively, (p=0.000). (Table. II). The area under the curves of NLCR was larger than neut, suggesting the optimal performance of NLCR with cut-off value 5.89. The sensitivity and specificity of NLCR was 85% and 95%, respectively. (Table. III). Conclusion: It can be concluded that an increase in NLCR levels can indicate that the covid-19 disease is moving towards exacerbation. NLCR can be recommended as a novel and highly sensitive and specific indicator for severity prediction in Covid-19 patients. Keywords: Emerging, Marker, Severity, Covid-19, Neutrophils, Lymphocytes, Ratio

Download Full-text

Reducing False-Positive Results in Newborn Screening Using Machine Learning

International Journal of Neonatal Screening ◽

10.3390/ijns6010016 ◽

2020 ◽

Vol 6 (1) ◽

pp. 16 ◽

Cited By ~ 4

Author(s):

Gang Peng ◽

Yishuo Tang ◽

Tina M. Cowan ◽

Gregory M. Enns ◽

Hongyu Zhao ◽

...

Keyword(s):

Machine Learning ◽

Random Forest ◽

Newborn Screening ◽

False Positive ◽

Clinical Laboratory ◽

False Positives ◽

Complex Data ◽

Interpretive Analysis ◽

Chain Acyl ◽

Positive Results

Newborn screening (NBS) for inborn metabolic disorders is a highly successful public health program that by design is accompanied by false-positive results. Here we trained a Random Forest machine learning classifier on screening data to improve prediction of true and false positives. Data included 39 metabolic analytes detected by tandem mass spectrometry and clinical variables such as gestational age and birth weight. Analytical performance was evaluated for a cohort of 2777 screen positives reported by the California NBS program, which consisted of 235 confirmed cases and 2542 false positives for one of four disorders: glutaric acidemia type 1 (GA-1), methylmalonic acidemia (MMA), ornithine transcarbamylase deficiency (OTCD), and very long-chain acyl-CoA dehydrogenase deficiency (VLCADD). Without changing the sensitivity to detect these disorders in screening, Random Forest-based analysis of all metabolites reduced the number of false positives for GA-1 by 89%, for MMA by 45%, for OTCD by 98%, and for VLCADD by 2%. All primary disease markers and previously reported analytes such as methionine for MMA and OTCD were among the top-ranked analytes. Random Forest’s ability to classify GA-1 false positives was found similar to results obtained using Clinical Laboratory Integrated Reports (CLIR). We developed an online Random Forest tool for interpretive analysis of increasingly complex data from newborn screening.

Download Full-text

Highly sensitive qualitative methods for serum choriogonadotropin (hCG): clinical specificity studies.

Clinical Chemistry ◽

10.1093/clinchem/33.5.677 ◽

1987 ◽

Vol 33 (5) ◽

pp. 677-681 ◽

Cited By ~ 3

Author(s):

Z L Bandi ◽

I Schoen ◽

M DeLara

Keyword(s):

False Positive ◽

Quantitative Methods ◽

Analytical Sensitivity ◽

Negative Results ◽

Beta Hcg ◽

Highly Sensitive ◽

Menopausal Women ◽

Pregnancy Testing ◽

Post Menopausal ◽

Positive Results

Abstract We screened six highly sensitive kits, designed for serum pregnancy tests, for false-positive results. The two best were then evaluated more extensively. The "BETA-hCG MAIA-clone" (I) and the "TANDEM ICON" (II) kits gave only negative results for 100 sera from men at 5, 10, and 25 int. units/L (1st IRP). Of 100 serum specimens from post-menopausal women three and 10 were hCG positive by the II and the I reagents, respectively, but only at the 5 int. units (1st IRP) of hCG per liter level of sensitivity. At 10 and 25 int. units/L, all specimens were negative by both tests. The manufacturers of these kits recommend pregnancy testing only at the 25 int. units/L level of analytical sensitivity. By quantitative methods, hCG concentrations in the II positive samples ranged from 6 to 20 int. units/L (1st IRP) and lutropin concentrations were between 130 to greater than 150 int. units/L. The medical records of the corresponding patients did not support the presence of trophoblast or any other hCG-secreting tissues. During 15 months of routine use of the II reagents at an analytical sensitivity of 25 int. units/L (1st IRP) hCG for pregnancy testing (greater than 4000 serum specimens from pre-menopausal women), the staff has not reported to us any suspected false-positive findings.

Download Full-text