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Predictive Test (predictive + test)
Selected AbstractsInformation derived from sensitization test methods: test sensitivity, false positives and false negativesCONTACT DERMATITIS, Issue 1 2007David A. Basketter Predictive toxicology tests for the prospective identification of skin-sensitizing chemicals are well known and have been used for many years. However, of these, only the local lymph node assay (LLNA) has actually undergone formal independent assessment to determine the accuracy of the predictions, particularly with respect to the likelihood of false positives and false negatives. Often, efforts to increase the sensitivity of a test (reducing false negatives) tend to increase the number of false positives. In this short review, these issues are discussed in particular relation to the 3 predictive tests available in regulatory toxicology, the guinea-pig maximization test, the occluded patch test of Buehler and the LLNA. A key perspective is that no predictive test is without limitations; having a good appreciation of these limitations is necessary for making the best use of the information derived from these methods. [source] Strong irritants masquerading as skin allergens: the case of benzalkonium chlorideCONTACT DERMATITIS, Issue 4 2004David A. Basketter Chemicals may possess a number of hazards to human health including the ability to cause skin irritation and contact allergy. Identification and characterization of these properties should fall within predictive toxicology, but information derived from human exposure, including clinical experience, is also of importance. In this context, it is of interest to review the case of benzalkonium chloride, a cationic surfactant. This chemical is a well-known skin irritant, but on occasions it has also been reported to have allergenic properties, typically on the basis of positive diagnostic patch test data. Because the accumulated knowledge concerning the properties of a chemical is employed as the basis for its regulatory classification (e.g. in Europe), as well as for informing the clinical community with respect to the diagnosis of irritant versus allergic contact dermatitis (ACD), it is important to distinguish properly which chemicals are simply irritants from those which are both irritant and allergenic on skin. A review of the information on benzalkonium chloride confirms that it is a significant skin irritant. However, both predictive test results and clinical data lead to the conclusion that benzalkonium chloride is, at most, an extremely rare allergen, except perhaps in the eye, but with many supposed cases of ACD being likely to arise from the misinterpretation of patch test data. As a consequence, this substance should not normally be regarded as, or classified as, a significant skin sensitizer. [source] Allergy assessment of foods or ingredients derived from biotechnology, gene-modified organisms, or novel foodsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 6 2004Lars K. Poulsen Abstract The introduction of novel proteins into foods carries a risk of eliciting allergic reactions in individuals sensitive to the introduced protein and a risk of sensitizing susceptible individuals. No single predictive test exists to perform a hazard assessment in relation to allergenic properties of newly expressed proteins in gene-modified organisms (GMOs). Instead, performance of a weighted risk analysis based on the decision tree approach has been suggested. The individual steps of this analysis comprise sequence homology to known allergens, specific or targeted serum screens for immunoglobulin E (IgE) cross-reactions to known allergens, digestability studies of the proteins in simulated gastric and/or intestinal fluids, and animal studies. These steps are discussed and five examples of risk evaluation of GMOs or novel foods are presented. These include ice-structuring protein derived from fish, microbial transglutaminase, GMO-soybeans, amylase and the Nangai nut. [source] Agreement between clinical examination and quantitative tests of neurologic function among 384 subjects,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 4 2001Kyle Steenland Abstract Background Quantitative neurological tests are often cheaper and easier than clinical examinations, and provide continuous data which may discriminate between exposed and nonexposed groups with more sensitivity than dichotomous (normal/abnormal) examination data. Methods We compare clinical examinations and analogous quantitative tests for arm tremor, postural sway, and vibrotactile sensitivity (finger and toe), for 384 subjects. Results The "abnormal" clinical outcomes studied were relatively common (range, 3,36%), and did not result in impairment of daily activity for affected subjects. All the quantitative tests were reasonably good predictors of the corresponding clinical outcome. The most predictive test was for toe vibrotactile sensitivity. The probability of an abnormal clinical result for those in the worst quartile for the toe test was 0.63, compared with 0.36 for all subjects. Conclusions Our results suggest that certain quantitative tests might be used in epidemiologic studies instead of a physical examination. Am. J. Ind. Med. 39:361,368, 2001. Published 2001 Wiley-Liss, Inc. [source] Original Article: Amniotic fluid lamellar body concentration as a marker of fetal lung maturity at term elective caesarean deliveryAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 4 2010Susan P. WALKER Background:, Caesarean birth, without prior labour, is associated with an increased risk of neonatal respiratory morbidity among term infants. The concentration of lamellar bodies in amniotic fluid reflects pulmonary surfactant production and release, and is thus used in preterm populations as a marker of fetal lung maturity. Whether amniotic fluid lamellar body concentration (AFLBC) may correlate with risk factors for term respiratory distress has not previously been evaluated. Aims:, To determine the relationship between AFLBC and risk factors for respiratory distress following term caesarean birth. Methods:, The AFLBC of 249 women at the time of term caesarean birth was examined for an association with gestational age, gender, presentation and neonatal respiratory distress requiring special care nursery (SCN) admission. Results:, There was a significant increase in AFLBC with gestation. When compared with caesarean deliveries performed during the 37th week of gestation, there was a 50%, 54% and 56% increase in lamellar body concentrations (LBCs) taken during the 38th, 39th and 40th week of gestation respectively (P < 0.05 for all). Female fetuses had a 16% higher LBC than males (P < 0.05). An LBC <100 × 109 mL,1 was associated with increased risk of admission to the SCN with respiratory distress (RR = 5.6; 1.2,26.5, P < 0.05). Conclusion:, Known risk factors for term respiratory distress are reflected in the AFLBC. A significant relationship exists between AFLBC and respiratory morbidity following term caesarean birth. However, the low prevalence of this condition limits the clinical role of AFLBC as a predictive test for term respiratory morbidity. [source] Identification and classification of skin sensitizers: identifying false positives and false negativesCONTACT DERMATITIS, Issue 5 2006David A. Basketter The first step in regulatory evaluation of substances involves the identification of their intrinsic hazards, including the potential for skin sensitization. This is, quite properly, entirely different from assessment of the risks to human health, which might arise from incorporation of substances in products. EU guidance on regulations concerning the classification of skin sensitizers suggests a range of sources of information be deployed in the hazard identification process. These include chemical structure, predictive animal tests, and various types of human data. Where the information is clear-cut, then uncertainties rarely arise. However, for some materials, discordant information arises, perhaps because the substance is on the borderline of test sensitivity and classification (sensitizing materials of insufficient potency do not classified according to the EU scheme), due to conflicting results in predictive tests or for other reasons. In this study, we review data on a number of substances where a classification decision is complicated by such discordances and seek to use these examples to demonstrate how best to make a weight of evidence decision on whether a substance should, or should not, be classified as a skin sensitizer. [source] Prospective validation of P2/MS noninvasive index using complete blood counts for detecting oesophageal varices in B-viral cirrhosisLIVER INTERNATIONAL, Issue 6 2010Beom Kyung Kim Abstract Backgrounds: Periodic endoscopic screening for oesophageal varices (OVs) and prophylactic treatment for high-risk OVs (HOVs; medium/large OVs or small OVs plus red sign/decompensation) are currently recommended for all cirrhotic patients. However, if a simple, noninvasive test is available, many low-risk patients may reliably avoid endoscopy. Aims: We conducted a large-scale validation study of a simple, noninvasive test called P2/MS based on complete blood counts, (platelet count)2/[monocyte fraction (%) × segmented neutrophil fraction (%)], and compared it with other predictive tests for HOVs in B-viral cirrhotic patients. Methods: From 2008 to 2009, we prospectively enrolled 318 consecutive B-viral cirrhotic patients. All underwent endoscopy and laboratory evaluation. Results: An area under the receiver operating characteristic curve of P2/MS was 0.941 for HOVs, comparable with those of the age,spleen platelet ratio index (0.922, P=0.317) and spleen,platelet ratio index (0.922, P=0.324), and better than those of age,platelet index (0.653, P<0.001), aspartate aminotransferase (AST),platelet ratio index (0.871, P<0.006) and AST-alanine aminotransferase ratio (0.644, P<0.001). P2/MS<11 reliably identified 83 patients as having HOVs (94.0% positive predictive value), while at a cutoff of 25 and 179 as not having HOVs (94.4% negative predictive value). Overall, P2/MS reliably determined the likelihood of HOVs in 262 patients (82.4%). These cutoffs were validated internally using bootstrap resampling methods, which showed good agreement. Conclusions: P2/MS is a simple, accurate and economical method, reducing the need for endoscopy in B-viral cirrhosis. Patients with P2/MS<11 should be considered for appropriate prophylactic treatments, while those with P2/MS>25 may avoid endoscopy reliably. [source] First-trimester assessment of placenta function and the prediction of preeclampsia and intrauterine growth restrictionPRENATAL DIAGNOSIS, Issue 4 2010Yan Zhong Abstract Preeclampsia and intrauterine growth restriction (IUGR) are major contributors to perinatal mortality and morbidity worldwide. Both are characterized by impaired trophoblastic invasion of the maternal spiral arteries and their conversion from narrow muscular vessels to wide non-muscular channels. Despite improvement in the understanding of the pathophysiology of these conditions, ability to accurately identify pregnant woman who will develop them is limited. This greatly impairs the development and testing of preventive interventions. While different measures of placental dysfunction have been associated with increased risk for adverse pregnancy outcomes, the ability of any single one to accurately predict these outcomes is poor. Developing predictive tests is further challenged by difficulty in the timing of the measurements, as both the structural and biochemical characteristics of the placenta change with increasing gestational age. The ideal screening test would accurately predict the development of adverse pregnancy outcomes early enough to provide a window for preventive interventions. Improvement in ultrasound technology provides potentially useful novel tools for evaluating placental structure, but measuresments need to be standardized in order to be useful. Maternal serum analyte screening is a noninvasive test of placental biochemical function, but present serum marker alone is not sufficiently accurate to suggest its routine use in clinical practice. The use of first trimester biochemical markers in combination with uterine artery Doppler screening is promising as a potential screening tool. Prospective longitudinal studies using standardized methodology are necessary to further evaluate the choice of parameters and strategies of combination to achieve the best predictive models. Copyright © 2010 John Wiley & Sons, Ltd. [source] | |||||||||||||