Elbow Valgus Stress Radiography in an Uninjured Population

1998 ◽  
Vol 26 (3) ◽  
pp. 425-427 ◽  
Author(s):  
Guy A. Lee ◽  
Stephen D. Katz ◽  
Mark D. Lazarus
Keyword(s):  
False Positive ◽  
False Positive Rate ◽  
Stress Radiography ◽  
Valgus Stress ◽  
Stress Radiographs ◽  
Significant Difference ◽  
Positive Rate ◽  
Positive Assessment ◽  
Valgus Instability ◽  
The Difference

Valgus instability of the elbow joint is a clinical diagnosis. However, many authors describe valgus stress radiographs as an aid in making this diagnosis. We studied valgus stress radiographs of 20 men (40 elbows) and 20 women (40 elbows), none with a history of elbow trauma or instability. The medial ulnohumeral distance was measured with no stress, valgus stress by gravity, and an applied valgus stress of 25 N (approximately 5 pounds). Measurements were made with the elbow positioned in extension and in 30° of flexion. The increase in medial ulnohumeral gapping with either gravity or 5 pounds of stress was statistically significant at both extension and 30° of flexion compared with the unstressed condition. The difference in ulnohumeral gapping between gravity stress and 5 pounds of valgus stress in extension and in 30° of flexion was also significant. We found no differences with regard to hand dominance or sex. We conclude that uninjured elbows have significant medial ulnohumeral gapping on valgus stress radiography. Although this is an important tool in diagnosing valgus instability of the elbow, it may yield a false-positive assessment of valgus instability. Valgus stress radiographs comparing contralateral elbows may reduce the false-positive rate since there appears to be no significant difference in medial ulnohumeral gapping between the two elbows.

Impact of Including or Removing Nuchal Translucency Measurement on the Detection and False-Positive Rates of First-Trimester Down Syndrome Screening

2015 ◽  
Vol 40 (3) ◽  
pp. 214-218 ◽  
Author(s):  
Emmanuel Spaggiari ◽  
Isabelle Czerkiewicz ◽  
Corinne Sault ◽  
Sophie Dreux ◽  
Armelle Galland ◽  
...  
Keyword(s):  
Down Syndrome ◽  
False Positive ◽  
False Positive Rate ◽  
Method Comparison ◽  
First Trimester ◽  
Nuchal Translucency ◽  
Routine Practice ◽  
Detection Rates ◽  
Significant Difference ◽  
Positive Rate

Introduction: First-trimester Down syndrome (DS) screening combining maternal age, serum markers (pregnancy-associated plasma protein-A and beta-human chorionic gonadotropin) and nuchal translucency (NT) gives an 85% detection rate for a 5% false-positive rate. These results largely depend on quality assessment of biochemical markers and of NT. In routine practice, despite an ultrasound quality control organization, NT images can be considered inadequate. The aim of the study was to evaluate the consequences for risk calculation when NT measurement is not taken into account. Material and Method: Comparison of detection and false-positive rates of first-trimester DS screening (PerkinElmer, Turku, Finland), with and without NT, based on a retrospective study of 117,126 patients including 274 trisomy 21-affected fetuses. NT was measured by more than 3,000 certified sonographers. Results: There was no significant difference in detection rates between the two strategies including or excluding NT measurement (86.7 vs. 81.8%). However, there was a significant difference in the false-positive rates (2.23 vs. 9.97%, p < 0.001). Discussion: Sonographers should be aware that removing NT from combined first-trimester screening would result in a 5-fold increase in false-positive rate to maintain the expected detection rates. This should be an incentive for maintaining quality in NT measurement.

An evaluation of tail paint as an aid or alternative to oestrus detection

1983 ◽  
Vol 37 (2) ◽  
pp. 221-227 ◽  
Author(s):  
M. J. Ducker ◽  
Rosemary A. Haggett ◽  
W. J. Fisher ◽  
Glenys A. Bloomfield ◽  
S. V. Morant
Keyword(s):  
False Positive ◽  
Detection Rate ◽  
False Positive Rate ◽  
Critical Time ◽  
Successful Pregnancy ◽  
Service Period ◽  
Significant Difference ◽  
Positive Rate ◽  
The Mean ◽  
Paint Removal

ABSTRACTOne hundred Friesian heifers were tail-painted between 14 and 21 days after calving. Once a week the paint strip was renewed if any paint had been removed. Over the whole period of observation the ovulation detection rate by definite signs of oestrus was high (0·79), whilst the proportion of silent ovulations detected by tail paint removal was low (0·10). In addition, tail paint was not removed on 0·28 of the occasions when definite oestrus with ovulation occurred and on 0·26 of the occasions when all the paint was removed it was not associated with any reproductive event. In practice, the critical time for tail paint to be effective is during the service period. Again, tail paint identified fewer (P < 0·001) ovulations than definite signs of oestrus (0·66) and had a significantly higher false positive rate (P < 0·001). Month of calving did not affect these results but the accuracy of tail paint declined as the season progressed (P < 0·001). False positive indications were not associated with individual animal characteristics. In a second trial 43 cows were tail-painted and 43 were not. There was no significant difference in the mean number of days from calving to first insemination or successful pregnancy between the two groups. It is concluded that in these trials tail paint was not an effective or reliable aid or alternative to oestrus detection.

scholarly journals Evaluation of Clinical Usefulness of Monocyte Gating Using CD14 and CD64 for Detecting PNH Clone By Flow Cytometry

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4947-4947
Author(s):  
Woo Jae Kwoun ◽  
Jeong-Yeal Ahn ◽  
Ja Young Seo ◽  
Jae Hoon Lee ◽  
Hawk Kim ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
False Positive ◽  
False Positive Rate ◽  
Cell Lineages ◽  
Flow Cytometric ◽  
Significant Difference ◽  
Positive Rate ◽  
A Minor ◽  
Gating Method ◽  
Pnh Clone

Abstract Introduction Flow cytometry is the gold standard in diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) by detecting the absence of glycol-phosphatidyl inositol (GPI)-linked protein expression on red blood cell, granulocyte, and monocyte. The current assays are 4-color analyses of GPI-linked markers such as fluorescein-labeled proaerolysin (FLAER), CD24, CD14, CD59, and CD235a and the lineage markers for granulocyte (CD15) and monocyte (CD64) cells to detect PNH clones. We investigated the utility of CD14/CD64 monocyte gating by comparing with CD45/light scatter (LS) gating in PNH study of the patients with cytopenia and analyzed the types and cell lineages of PNH clone according to the disease groups. Method Total 138 cases were recruited in this study from July 2017 to February 2018 at Gachon University Gil Medical Center in Korea. Flow cytometric analysis was performed with EDTA blood by Beckman Coulter Cytomics FC500 cytometer using gating antibodies such as CD45, CD14, CD15, CD64, CD235a and GPI-linked antibodies such as CD59, CD14, CD24, FLAER. The proportion of monocyte was estimated by CD14/CD64 gating and compared with those using CD45/LS gating. The type of PNH clone was defined according to the size of PNH population. A PNH clone is defined as a PNH population exceeding 1% of the gated cells, a minor PNH clone as between 0.1 and 1%, and rare cells with GPI-deficiency defined as a PNH population less than 0.1%. The types and cell lineages of the PNH clone were analyzed according to the disease groups. Statistical analysis was done using SPSS 17.0 and MedCalc 15.2, and P<0.05 was considered statistically significant. Results Of the 138 cases, PNH clone was detected with 27 cases including 15 cases with a PNH clone and 12 cases with a minor PNH clone. PNH clone was observed in all 8 cases (100%) of PNH cases. Two PNH clone and 4 minor PNH clones were identified in 6 of 16 cases (38%) of acute myeloid leukemia. In 6 of 21 cases (29%) of aplastic anemia (AA) show 5 PNH clones and 1 minor PNH clone. In 5 of 78 cases (6%) of cytopenia(s) only minor PNH clone was observed. The CD45 plus LS gating in monocyte represents a sensitivity of 100%, a specificity of 40.2%, and 60% (73/89) false positive rate in detecting of PNH clone. McNemar test indicates a significant difference between CD14/CD64 and CD45/LS gating methods (P = 0.00). The Bland-Altman plot of monocyte proportion between the two gating methods revealed that CD45/LS gating method was tended to underestimate monocyte proportion and the larger the number of monocytes, the greater the difference in number of monocyte between the two gating methods. The trend of the size of PNH clone in each cell lineage was confirmed by follow-up in three patients with PNH clone. Two patients showed more abrupt changes of PNH clone in monocytes than in red blood cells or in granulocytes. However, in the other patient, a significant trend found in only PNH clone of RBC. Conclusion The types of PNH clone observed in each disease group showed different characteristics. PNH clone was identified in 5 of 6 PNH population detected AA cases, whereas minor PNH clones were observed in all 5 PNH population detected cytopenia cases. Four minor PNH clones and two PNH clones were discovered in 6 PNH population detected AML cases. However, all observed PNH clones observed in AML cases were monocyte. Monocyte gating with CD45 and LS not only underestimated the proportion of monocyte in total WBCs but also showed a high false positive rate of 60% in detecting PNH clone. In contrast, the CD14/CD64 gating method can accurately measure the monocyte population and avoid making a false positive measurement of PNH clone. In addition, in monitoring PNH patients, the measurement of the PNH clone in monocyte tends to be more sensitive to change of PNH clone size than those measured in RBC or granulocytes. In conclusion, the gating using CD14 and CD64 is significantly valuable in flow cytometric diagnosis for detecting the PNH clone in diagnosing new patents as well as monitoring of PNH patients. Disclosures No relevant conflicts of interest to declare.

scholarly journals A method to alleviate false-positive results of the Elecsys HIV combi PT assay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaolan Lu ◽  
Minghong Zhang ◽  
Wen Liu ◽  
Nan Sheng ◽  
Qin Du ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Retrospective Analysis ◽  
False Positive ◽  
False Positive Rate ◽  
Hiv Screening ◽  
Screening Assay ◽  
Positive Serum ◽  
Positive Rate ◽  
The Difference ◽  
Positive Results

AbstractTo explore the effects of urea dissociation on reducing false-positive results of  the Elecsys HIV combi PT assay. A retrospective analysis was used to evaluate the false-positive rate of the Elecsys HIV combi PT assay. Six false-positive sera, six positive sera and six sera from patients with early HIV infection were collected. Dissociation was performed using 1 mol/L, 2 mol/L, 4 mol/L, 6 mol/L, or 8 mol/L urea, and HIV screening assay were then detected to select the appropriate concentration of urea dissociation. Next, 55 false-positive sera and 15 sera from early HIV infection were used to verify the best concentration of urea to achieve dissociation. Retrospective analysis showed that the COI of the Elecsys HIV combi PT assay in false-positive sera ranged from 1.0 to 200.0, and approximately 97.01%(227/234) of false-positive sera were in the range of 1.0–15.0. The avidity index (AI) in positive and false-positive sera decreased as the urea dissociation concentration increased. When the dissociation concentration was 6 mol/L, the AI of false-positive serum was between 0.0234 and 0.2567, and the AI of early HIV infection sera was between 0.4325 and 0.5017. The difference in AI between false-positive and positive samples was significant. When negativity was defined as an AI of less than 0.3970, the sensitivity and specificity were 100.0% and 100.0%, respectively. Urea-mediated dissociation could significantly reduce the false-positive rate of the Elecsys HIV combi PT assay with a low COI. Our findings provided a reference for distinguishing positive and false-positive of the Elecsys HIV combi PT assay.

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 &amp; 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%.

scholarly journals PRATD: A Phased Remote Access Trojan Detection Method with Double-Sided Features

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1894
Author(s):  
Chun Guo ◽  
Zihua Song ◽  
Yuan Ping ◽  
Guowei Shen ◽  
Yuhei Cui ◽  
...  
Keyword(s):  
False Positive ◽  
Detection Method ◽  
False Positive Rate ◽  
True Positive Rate ◽  
Remote Access ◽  
Detection Methods ◽  
Security Threats ◽  
True Positive ◽  
Trojan Detection ◽  
Positive Rate

Remote Access Trojan (RAT) is one of the most terrible security threats that organizations face today. At present, two major RAT detection methods are host-based and network-based detection methods. To complement one another’s strengths, this article proposes a phased RATs detection method by combining double-side features (PRATD). In PRATD, both host-side and network-side features are combined to build detection models, which is conducive to distinguishing the RATs from benign programs because that the RATs not only generate traffic on the network but also leave traces on the host at run time. Besides, PRATD trains two different detection models for the two runtime states of RATs for improving the True Positive Rate (TPR). The experiments on the network and host records collected from five kinds of benign programs and 20 famous RATs show that PRATD can effectively detect RATs, it can achieve a TPR as high as 93.609% with a False Positive Rate (FPR) as low as 0.407% for the known RATs, a TPR 81.928% and FPR 0.185% for the unknown RATs, which suggests it is a competitive candidate for RAT detection.

Evidence for Age-Adjusted D-Dimer to Rule out Pulmonary Embolism: An Institutional Study

2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S5-S5
Author(s):  
Ridin Balakrishnan ◽  
Daniel Casa ◽  
Morayma Reyes Gil
Keyword(s):  
Pulmonary Embolism ◽  
False Positive ◽  
False Positive Rate ◽  
Moderate Risk ◽  
Older Population ◽  
Statistical Measures ◽  
Positive Rate ◽  
Risk Patients ◽  
D Dimer ◽  
Rule Out

Abstract The diagnostic approach for ruling out suspected acute pulmonary embolism (PE) in the ED setting includes several tests: ultrasound, plasma d-dimer assays, ventilation-perfusion scans and computed tomography pulmonary angiography (CTPA). Importantly, a pretest probability scoring algorithm is highly recommended to triage high risk cases while also preventing unnecessary testing and harm to low/moderate risk patients. The d-dimer assay (both ELISA and immunoturbidometric) has been shown to be extremely sensitive to rule out PE in conjunction with clinical probability. In particularly, d-dimer testing is recommended for low/moderate risk patients, in whom a negative d-dimer essentially rules out PE sparing these patients from CTPA radiation exposure, longer hospital stay and anticoagulation. However, an unspecific increase in fibrin-degradation related products has been seen with increase in age, resulting in higher false positive rate in the older population. This study analyzed patient visits to the ED of a large academic institution for five years and looked at the relationship between d-dimer values, age and CTPA results to better understand the value of age-adjusted d-dimer cut-offs in ruling out PE in the older population. A total of 7660 ED visits had a CTPA done to rule out PE; out of which 1875 cases had a d-dimer done in conjunction with the CT and 5875 had only CTPA done. Out of the 1875 cases, 1591 had positive d-dimer results (&gt;0.50 µg/ml (FEU)), of which 910 (57%) were from patients older than or equal to fifty years of age. In these older patients, 779 (86%) had a negative CT result. The following were the statistical measures of the d-dimer test before adjusting for age: sensitivity (98%), specificity (12%); negative predictive value (98%) and false positive rate (88%). After adjusting for age in people older than 50 years (d-dimer cut off = age/100), 138 patients eventually turned out to be d-dimer negative and every case but four had a CT result that was also negative for a PE. The four cases included two non-diagnostic results and two with subacute/chronic/subsegmental PE on imaging. None of these four patients were prescribed anticoagulation. The statistical measures of the d-dimer test after adjusting for age showed: sensitivity (96%), specificity (20%); negative predictive value (98%) and a decrease in the false positive rate (80%). Therefore, imaging could have been potentially avoided in 138/779 (18%) of the patients who were part of this older population and had eventual negative or not clinically significant findings on CTPA if age-adjusted d-dimers were used. This data very strongly advocates for the clinical usefulness of an age-adjusted cut-off of d-dimer to rule out PE.

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