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21,037
result(s) for
"test specificity"
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Comparison of four commercial, automated antigen tests to detect SARS-CoV-2 variants of concern
by
Blum, Helmut
,
Späth, Patricia
,
Kaderali, Lars
in
Amino acids
,
Antigens
,
Antigens, Viral - analysis
2021
A versatile portfolio of diagnostic tests is essential for the containment of the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) pandemic. Besides nucleic acid-based test systems and point-of-care (POCT) antigen (Ag) tests, quantitative, laboratory-based nucleocapsid Ag tests for SARS-CoV-2 have recently been launched. Here, we evaluated four commercial Ag tests on automated platforms and one POCT to detect SARS-CoV-2. We evaluated PCR-positive (
n
= 107) and PCR-negative (
n
= 303) respiratory swabs from asymptomatic and symptomatic patients at the end of the second pandemic wave in Germany (February–March 2021) as well as clinical isolates EU1 (B.1.117), variant of concern (VOC) Alpha (B.1.1.7) or Beta (B.1.351), which had been expanded in a biosafety level 3 laboratory. The specificities of automated SARS-CoV-2 Ag tests ranged between 97.0 and 99.7% (Lumipulse G SARS-CoV-2 Ag (Fujirebio): 97.03%, Elecsys SARS-CoV-2 Ag (Roche Diagnostics): 97.69%; LIAISON
®
SARS-CoV-2 Ag (Diasorin) and SARS-CoV-2 Ag ELISA (Euroimmun): 99.67%). In this study cohort of hospitalized patients, the clinical sensitivities of tests were low, ranging from 17.76 to 52.34%, and analytical sensitivities ranged from 420,000 to 25,000,000 Geq/ml. In comparison, the detection limit of the Roche Rapid Ag Test (RAT) was 9,300,000 Geq/ml, detecting 23.58% of respiratory samples. Receiver-operating-characteristics (ROCs) and Youden’s index analyses were performed to further characterize the assays’ overall performance and determine optimal assay cutoffs for sensitivity and specificity. VOCs carrying up to four amino acid mutations in nucleocapsid were detected by all five assays with characteristics comparable to non-VOCs. In summary, automated, quantitative SARS-CoV-2 Ag tests show variable performance and are not necessarily superior to a standard POCT. The efficacy of any alternative testing strategies to complement nucleic acid-based assays must be carefully evaluated by independent laboratories prior to widespread implementation.
Journal Article
Accuracy of body mass index in diagnosing obesity in the adult general population
2008
Background: Body mass index (BMI) is the most widely used measure to diagnose obesity. However, the accuracy of BMI in detecting excess body adiposity in the adult general population is largely unknown. Methods: A cross-sectional design of 13 601 subjects (age 20-79.9 years; 49% men) from the Third National Health and Nutrition Examination Survey. Bioelectrical impedance analysis was used to estimate body fat percent (BF% ). We assessed the diagnostic performance of BMI using the World Health Organization reference standard for obesity of BF% >25% in men and>35% in women. We tested the correlation between BMI and both BF% and lean mass by sex and age groups adjusted for race. Results: BMI-defined obesity (30 kg m- 2) was present in 19.1% of men and 24.7% of women, while BF% -defined obesity was present in 43.9% of men and 52.3% of women. A BMI30 had a high specificity (men=95% , 95% confidence interval (CI), 94-96 and women=99% , 95% CI, 98-100), but a poor sensitivity (men=36% , 95% CI, 35-37 and women=49% , 95% CI, 48-50) to detect BF% -defined obesity. The diagnostic performance of BMI diminished as age increased. In men, BMI had a better correlation with lean mass than with BF% , while in women BMI correlated better with BF% than with lean mass. However, in the intermediate range of BMI (25-29.9 kg m- 2), BMI failed to discriminate between BF% and lean mass in both sexes. Conclusions: The accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. A BMI cutoff of30 kg m- 2 has good specificity but misses more than half of people with excess fat. These results may help to explain the unexpected better survival in overweight/mild obese patients.
Journal Article
BMI-related errors in the measurement of obesity
2008
Body mass index (BMI) has various deficiencies as a measure of obesity, especially when the BMI measure is based on self-reported height and weight. BMI is an indirect measure of body fat compared with more direct approaches such as bioelectrical impedance. Moreover, BMI does not necessarily reflect the changes that occur with age. The proportion of body fat increases with age, whereas muscle mass decreases, but corresponding changes in height, weight and BMI may not reflect changes in body fat and muscle mass. Both the sensitivity and specificity of BMI have been shown to be poor. Additionally, the relation between BMI and percentage of body fat is not linear and differs for men and women. The consequences of the errors in the measurement of obesity with BMI depend on whether they are differential or nondifferential. Differential misclassification, a potentially greater problem in case-control and cross-sectional studies than in prospective cohort studies, can produce a bias toward or away from the null. Nondifferential misclassification produces a bias toward the null for a dichotomous exposure; for measures of exposure that are not dichotomous, the bias may be away from the null. In short, the use of BMI as a measure of obesity can introduce misclassification problems that may result in important bias in estimating the effects related to obesity.
Journal Article
Species specificity and specificity diversity (SSD) framework: a novel method for detecting the unique and enriched species associated with disease by leveraging the microbiome heterogeneity
2024
Background
Differentiating the microbiome changes associated with diseases is challenging but critically important. Majority of existing efforts have been focused on a community level, but the discerning power of community or holistic metrics such as diversity analysis seems limited. This prompts many researchers to believe that the promise should be downward to species or even strain level—effectively and efficiently identifying unique or enriched species in diseased microbiomes with statistical rigor. Nevertheless, virtually, all species-level approaches such as differential abundance and differential network analysis methods exclusively rely on species abundances without considering species distribution information, while it can be said that distribution is equally, if not more, important than abundance in shaping the spatiotemporal heterogeneity of community compositions.
Results
Here, we fill the gap by developing a novel framework—species specificity and specificity diversity (SSD)—that synthesizes both abundance and distribution information to differentiate microbiomes, at both species and community scales, under different environmental gradients such as the healthy and diseased treatments. The proposed SSD framework consists of three essential elements. The first is species specificity (SS), a concept that reincarnates the traditional specialist-generalist continuum and is defined by Mariadassou et al. (Ecol Lett 18:974-82, 2015). The SS synthesizes a species’ local prevalence (distribution) and global abundance information and attaches specificity measure to each species in a specific habitat (e.g., healthy or diseased treatment). The second element is a new concept to introduce here, the (species) specificity diversity (SD), which is inspired by traditional species (abundance) diversity in community ecology and measures the diversity of specificity (a proxy for metacommunity heterogeneity, essentially) with Renyi’s entropy. The third element is a pair of statistical tests based on the principle of permutation tests.
Conclusions
The SSD framework can (
i
) identify and catalogue lists of unique species (US), significantly enriched species (ES) in each treatment based on SS and specificity permutation (SP) test and (
ii
) measure the holistic differences between assemblages (or treatments) based on SD and specificity diversity permutation (SDP) test. Both capacities can be enabling technologies for general comparative microbiome research including risk assessment, diagnosis, and treatment of microbiome-associated diseases.
Journal Article
A four-stage evaluation of the Paediatric Yorkhill Malnutrition Score in a tertiary paediatric hospital and a district general hospital
by
Gerasimidis, Konstantinos
,
Wright, Charlotte M.
,
Macleod, Isobel
in
accuracy
,
anthropometric measurements
,
Biological and medical sciences
2010
Paediatric in-patients are at high risk of malnutrition but validated paediatric screening tools suitable for use by nursing staff are scarce. The present study aimed to assess the diagnostic accuracy of the new Paediatric Yorkhill Malnutrition Score (PYMS). During a pilot introduction in a tertiary referral hospital and a district general hospital, two research dietitians assessed the validity of the PYMS by comparing the nursing screening outcome with a full dietetic assessment, anthropometry and body composition measurements. An additional PYMS form was completed by the research dietitians to assess its inter-rater reliability with the nursing staff and for comparison with the Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMP) and the Paediatric Subjective Global Nutritional Assessment (SGNA). Of the 247 children studied, the nurse-rated PYMS identified 59 % of those rated at high risk by full dietetic assessment. Of those rated at high risk by the nursing PYMS, 47 % were confirmed as high risk on full assessment. The PYMS showed moderate agreement with the full assessment (κ = 0·46) and inter-rater reliability (κ = 0·53) with the research dietitians. Children who screened as high risk for malnutrition had significantly lower lean mass index than those at moderate or low risk, but no difference in fat. When completed by the research dietitians, the PYMS showed similar sensitivity to the STAMP, but a higher positive predictive value. The SGNA had higher specificity than the PYMS but much lower sensitivity. The PYMS screening tool is an acceptable screening tool for identifying children at risk of malnutrition without producing unmanageable numbers of false-positive cases.
Journal Article
Preliminary Evidence for Internal Structure, Sensitivity, and Specificity of a Brief PTSD and Complex PTSD Measure in Adolescents
by
Campos, Susana
,
Fresno, Andrés
,
Olff, Miranda
in
Adolescent Development
,
Adolescent Psychopathology
,
Adolescents
2023
Early detection of trauma-related psychopathology is fundamental for preventing symptom escalation in adolescents, and this strategy can be carried out by developing accurate measures. The aim of this study is to provide preliminary evidence for the internal structure, construct validity, reliability, sensitivity, and specificity of a brief screening instrument for posttraumatic stress disorder (PTSD) and complex PTSD (C-PTSD) in general population adolescents. 1,501 Chilean adolescents participated by responding to the Brief PTSD scale (BPTSD) along with a battery of additional questionnaires. The internal structure of the eight-item BPTSD was assessed through exploratory and confirmatory factor analyses, while criterion validity was assessed through receiver-operating characteristic (ROC) curves. Confirmatory factor analysis (CFA) demonstrated a two-dimensional internal structure that is in accordance with literature regarding C-PTSD. Our results suggest that BPTSD may measure PTSD with complex features rather than C-PTSD. The scale showed adequate reliability, and criterion validity. The BPTSD is a brief, reliable, and simply-worded measure for PTSD symptoms and C-PTSD features in adolescents.
La détection précoce de psychopathies liées aux traumatismes est fondamentale pour prévenir l'escalade des symptômes chez les adolescents, et cette stratégie peut être réalisée en développant des mesures précises. L'objectif de cette étude est de fournir des preuves préliminaires de la structure interne, de la validité de construction, de la fiabilité, de la sensibilité et de la spécificité d'un bref instrument de dépistage du trouble de stress post-traumatique (PTSD) et du TSPT complexe (C-PTSD) chez des adolescents de la population générale. 1 501 adolescents chiliens ont participé à l'étude en répondant à la brève échelle du TSPT (BPTSD) ainsi qu'à une batterie de questionnaires supplémentaires. La structure interne de l'échelle BPTSD à huit items a été évaluée par des analyses factorielles exploratoires et confirmatoires, tandis que la validité des critères a été évaluée par des courbes de fonction d'efficacité du récepteur (ROC pour receiver-operating characteristic). L'analyse factorielle confirmatoire (CFA) a démontré une structure interne bidimensionnelle qui est en accord avec la littérature concernant le TSPT complexe. Nos résultats suggèrent que le BPTSD pourrait mesurer le TSPT avec des caractéristiques complexes plutôt que le TSPT complexe. L'échelle a montré une fiabilité et une validité de critère adéquates. Le BPTSD est une mesure brève, fiable et simple pour les symptômes du TSPT et les caractéristiques du TSPT complexe chez les adolescents.
Public Significance Statement
PTSD and complex PTSD can be severe in adolescents. Detection of PTSD symptoms is fundamental for early intervention in trauma, but it requires simple yet effective measures. The adjusted BPTSD is a short and reliable measure that assesses PTSD symptoms and complex PTSD features in the general population, adolescents, and young people.
Journal Article
Short communication: Haptoglobin as an early indicator of metritis
2009
The purpose of this study was to determine whether haptoglobin (Hp) could be used as a predictive measure for metritis. Cattle were grouped into 3 health categories based on the condition of vaginal discharge and body temperature after calving: severe metritis (n=12), mild metritis (n=32), and healthy (n=23). Blood was collected and analyzed for Hp concentration on d −20±5, −6±2, −2±1, and d 0 relative to calving, and then every 3 d after calving until d +21. Cows with mild and severe metritis had greater Hp concentrations than healthy cows between d 0 and d +12. Mean (±SE) Hp concentrations peaked on d +3 in the cows with mild metritis (1.06±0.15g/L) and on d +6 in cows with severe metritis (1.62±0.47g/L). Mean concentrations for the healthy group were 0.58±0.12g/L and 0.31±0.08g/L on d +3 and d +6, respectively. Clinical signs of pathological discharge for the mildly and severely metritic cows did not occur until, on average, 8.6±3.9 d and 5.3±1.9 d after calving, respectively. Cows with Hp concentrations ≥1g/L on d +3 were 6.7 times more likely to develop severe or mild metritis; this predictive threshold has a sensitivity of 50% and specificity of 87%. These results indicate that an acute phase inflammatory response precedes clinical metritis and that Hp screening may assist in the early detection of metritis, providing increased opportunities for early treatment and prevention.
Journal Article
Potential Moderators of the Effects of Blood Flow Restriction Training on Muscle Strength and Hypertrophy: A Meta-analysis Based on a Comparison with High-Load Resistance Training
by
Wu, Xueping
,
Geng, Yu
,
Zhang, Meng
in
Blood flow restriction training
,
High-load resistance training
,
Hypertrophy
2024
Background
While it has been examined whether there are similar magnitudes of muscle strength and hypertrophy adaptations between low-load resistance training combined with blood-flow restriction training (BFR-RT) and high-load resistance training (HL-RT), some important potential moderators (e.g., age, sex, upper and lower limbs, frequency and duration etc.) have yet to be analyzed further. Furthermore, training status, specificity of muscle strength tests (dynamic versus isometric or isokinetic) and specificity of muscle mass assessments (locations of muscle hypertrophy assessments) seem to exhibit different effects on the results of the analysis. The role of these influencing factors, therefore, remains to be elucidated.
Objectives
The aim of this meta-analysis was to compare the effects of BFR- versus HL-RT on muscle adaptations, when considering the influence of population characteristics (training status, sex and age), protocol characteristics (upper or lower limbs, duration and frequency) and test specificity.
Methods
Studies were identified through database searches based on the following inclusion criteria: (1) pre- and post-training assessment of muscular strength; (2) pre- and post-training assessment of muscular hypertrophy; (3) comparison of BFR-RT vs. HL-RT; (4) score ≥ 4 on PEDro scale; (5) means and standard deviations (or standard errors) are reported or allow estimation from graphs. In cases where the fifth criterion was not met, the data were requested directly from the authors.
Results
The main finding of the present study was that training status was an important influencing factor in the effects of BFR-RT. The trained individuals may gain greater muscle strength and hypertrophy with BFR-RT as compared to HL-RT. However, the results showed that the untrained individuals experienced similar muscle mass gains and superior muscle strength gains in with HL-RT compared to BFR-RT.
Conclusion
Compared to HL-RT, training status is an important factor influencing the effects of the BFR-RT, in which trained can obtain greater muscle strength and hypertrophy gains in BFR-RT, while untrained individuals can obtain greater strength gains and similar hypertrophy in HL-RT.
Key Points
Training status is an important factor influencing the effects of the BFR-RT.
Trained individuals may obtain greater muscle strength and hypertrophy gains in BFR-RT compared to HL-RT.
Untrained individuals may experience a smaller increase in strength and a similar increase in hypertrophy with BFR-RT compared to HL-RT.
Journal Article
Diagnostic Challenges in Canine Parvovirus 2c in Vaccine Failure Cases
2020
In this study, three different diagnostic tests for parvovirus were compared with vaccination status and parvovirus genotype in suspected canine parvovirus cases. Faecal samples from vaccinated (N17) and unvaccinated or unknown vaccination status (N41) dogs that had clinical signs of parvovirus infection were tested using three different assays of antigen tests, conventional and quantitative PCR tests. The genotype of each sample was determined by sequencing. In addition to the suspected parvovirus samples, 21 faecal samples from apparently healthy dogs were tested in three diagnostic tests to evaluate the sensitivity and specificity of the tests. The antigen test was positive in 41.2% of vaccinated dogs and 73.2% of unvaccinated diseased dogs. Conventional PCR and qPCR were positive for canine parvovirus (CPV) in 82.4% of vaccinated dogs and 92.7% of unvaccinated dogs. CPV type-2c (CPV-2c) was detected in 82.75% of dogs (12 vaccinated and 36 unvaccinated dogs), CPV-2b was detected in 5.17% dogs (one vaccinated and two unvaccinated) and CPV-2a in 1.72% vaccinated dog. Mean Ct values in qPCR for vaccinated dogs were higher than the unvaccinated dogs (p = 0.049), suggesting that vaccinated dogs shed less virus, even in clinical forms of CPV. CPV-2c was the dominant subtype infecting dogs in both vaccinated and unvaccinated cases. Faecal antigen testing failed to identify a substantial proportion of CPV-2c infected dogs, likely due to low sensitivity. The faecal samples from apparently healthy dogs (n = 21) showed negative results in all three tests. Negative CPV faecal antigen results should be viewed with caution until they are confirmed by molecular methods.
Journal Article
Commercial test kits for detection of Lyme borreliosis: a meta-analysis of test accuracy
2016
The clinical diagnosis of Lyme borreliosis can be supported by various test methodologies; test kits are available from many manufacturers. Literature searches were carried out to identify studies that reported characteristics of the test kits. Of 50 searched studies, 18 were included where the tests were commercially available and samples were proven to be positive using serology testing, evidence of an erythema migrans rash, and/or culture. Additional requirements were a test specificity of ≥85% and publication in the last 20 years. The weighted mean sensitivity for all tests and for all samples was 59.5%. Individual study means varied from 30.6% to 86.2%. Sensitivity for each test technology varied from 62.4% for Western blot kits, and 62.3% for enzyme-linked immunosorbent assay tests, to 53.9% for synthetic C6 peptide ELISA tests and 53.7% when the two-tier methodology was used. Test sensitivity increased as dissemination of the pathogen affected different organs; however, the absence of data on the time from infection to serological testing and the lack of standard definitions for \"early\" and \"late\" disease prevented analysis of test sensitivity versus time of infection. The lack of standardization of the definitions of disease stage and the possibility of retrospective selection bias prevented clear evaluation of test sensitivity by \"stage\". The sensitivity for samples classified as acute disease was 35.4%, with a corresponding sensitivity of 64.5% for samples from patients defined as convalescent. Regression analysis demonstrated an improvement of 4% in test sensitivity over the 20-year study period. The studies did not provide data to indicate the sensitivity of tests used in a clinical setting since the effect of recent use of antibiotics or steroids or other factors affecting antibody response was not factored in. The tests were developed for only specific
species; sensitivities for other species could not be calculated.
Journal Article