Home About us Contact
|
Home About us Contact | ||
|
|
||
Likelihood Ratio (likelihood + ratio)
Kinds of Likelihood Ratio Terms modified by Likelihood Ratio Selected AbstractsComputation of Likelihood Ratios in Fingerprint Identification for Configurations of Any Number of MinutiæJOURNAL OF FORENSIC SCIENCES, Issue 1 2007Cédric Neumann M.Sc. ABSTRACT: Recent court challenges have highlighted the need for statistical research on fingerprint identification. This paper proposes a model for computing likelihood ratios (LRs) to assess the evidential value of comparisons with any number of minutiæ. The model considers minutiae type, direction and relative spatial relationships. It expands on previous work on three minutiae by adopting a spatial modeling using radial triangulation and a probabilistic distortion model for assessing the numerator of the LR. The model has been tested on a sample of 686 ulnar loops and 204 arches. Features vectors used for statistical analysis have been obtained following a preprocessing step based on Gabor filtering and image processing to extract minutiae data. The metric used to assess similarity between two feature vectors is based on an Euclidean distance measure. Tippett plots and rates of misleading evidence have been used as performance indicators of the model. The model has shown encouraging behavior with low rates of misleading evidence and a LR power of the model increasing significantly with the number of minutiæ. The LRs that it provides are highly indicative of identity of source on a significant proportion of cases, even when considering configurations with few minutiæ. In contrast with previous research, the model, in addition to minutia type and direction, incorporates spatial relationships of minutiæ without introducing probabilistic independence assumptions. The model also accounts for finger distortion. [source] Likelihood ratio for Crohn's disease as a function of Anti- Saccharomyces cerevisiae antibody concentrationINFLAMMATORY BOWEL DISEASES, Issue 1 2010N. Vermeulen No abstract is available for this article. [source] Clinical and biochemical implications of low thyroid hormone levels (total and free forms) in euthyroid patients with chronic kidney diseaseJOURNAL OF INTERNAL MEDICINE, Issue 6 2007J. J. Carrero Abstract., Carrero JJ, Qureshi AR, Axelsson J, Yilmaz MI, Rehnmark S, Witt MR, Bárány P, Heimbürger O, Suliman ME, Alvestrand A, Lindholm B, Stenvinkel P (Karolinska Institutet, Stockholm; and Karo Bio AB, Novum, Huddinge; Sweden). Clinical and biochemical implications of low thyroid hormone levels (total and free forms) in euthyroid patients with chronic kidney disease. J Intern Med 2007; 262: 690,701. Objectives., In this study, we explore the associations of decreased thyroid hormone levels with inflammation, wasting and survival in biochemically euthyroid patients with end-stage renal disease (ESRD). Design., After exclusion of 23 patients with thyroid-stimulating hormone (TSH) values outside the normal range (0.1,4.5 mIU L,1), 187 clinically and biochemically euthyroid incident ESRD stage 5 patients starting dialysis were followed for a median of 20 (range 1,60) months. Measurements of total and free forms of thyroid hormones, s-albumin, hs-CRP, interleukin (IL)-6, vascular adhesion molecule (VCAM)-1 and insulin-like growth factor 1 (IGF-1) were performed at baseline. Results., In this population, 17 out of 210 patients (8%) were defined as subclinically hypothyroid. Multivariate analysis, according to receiver operating characteristic (ROC) curves, showed that mortality was best predicted by total triiodothyronine (T3). When using the cut-off levels derived from ROC, low T3 levels were associated with increased inflammation (higher hs-CRP, IL-6 and VCAM-1) and lower concentration of both s-albumin and IGF-1. Finally, low T3 but not low free triiodothyronine was associated with worse all-cause (Likelihood ratio = 45.4; P < 0.0001) and cardiovascular mortality (Likelihood ratio = 47.8; P < 0.0001) after adjustment for confounding factors. Conclusion., This study showed that low T3 levels are independent predictors of all-cause and also cardiovascular disease mortality in biochemically euthyroid patients, perhaps due to an intimate association with inflammation. Based on these results, the use of T3 levels in studies assessing the relationship between thyroid dysfunction and mortality risk is recommended. [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 57JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003D Cocito BACKGROUND: Since 1991, five sets of electrophysiological criteria for CIDP have been reported. However, until now, receiver operator characteristic (ROC), such as sensitivity and specificity, of only AAN criteria were investigated, showing a high specificity, but intermediate sensitivity. The application of these criteria may be useful in clinical trials, but is inadequate in clinical practice, since they preclude immunomodulating treatment in patients who do not meet them. OBJECTIVE: 1) to evaluate the ROC and predictive value of five different electrophysiological criteria for CIDP (AAN, INCAT, Rotta et al, Nicholas et al. and Saperstein et al.); 2) to identify the most informative electrophysiological features indicative of demyelination by mean of the likelihood ratio; 3) to determine, in our series of cases, a set of minimal electrophysiological criteria (albeit aspecific) enough sensitive for CIDP diagnosis. PATIENTS AND METHODS: 20 patients with sensorimotor polyneuropathy, progressive for at least 2 months, with weakness in least two limbs and documented improvement in strength in response to immunotherapy. Other potential causes were excluded, including diabetes and IgM paraproteinemia with or without anti-MAG reactivity. Twelve patients with axonal polyneuropathy associated with diabetes and 12 patients with amyotrophic lateral sclerosis were included as controls. Nerve conduction studies (NCS) were evaluated according to all five sets of NCS criteria and ROC was calculated. Likelihood ratio for CIDP was evaluated for each set of NCS criteria and for presence of each of the following features in different number of nerves: motor conduction velocities (MCV), conduction blocks/temporal dispersion, distal motor (DML) and F-wave latencies (FWL). MCV, DML and FWL were considered indicative of demyelination if decreased or increased as suggested by AAN criteria. Results will be discussed. [source] A Two-Level Model for Evidence Evaluation in the Presence of Zeros,JOURNAL OF FORENSIC SCIENCES, Issue 2 2010Grzegorz Zadora Ph.D. Abstract:, Likelihood ratios (LRs) provide a natural way of computing the value of evidence under competing propositions. We propose LR models for classification and comparison that extend the ideas of Aitken, Zadora, and Lucy and Aitken and Lucy to include consideration of zeros. Instead of substituting zeros by a small value, we view the presence of zeros as informative and model it using Bernoulli distributions. The proposed models are used for evaluation of forensic glass (comparison and classification problem) and paint data (comparison problem). Two hundred and sixty-four glass samples were analyzed by scanning electron microscopy, coupled with an energy dispersive X-ray spectrometer method and 36 acrylic topcoat paint samples by pyrolysis gas chromatography hyphened with mass spectrometer method. The proposed LR model gave very satisfactory results for the glass comparison problem and for most of the classification tasks for glass. Results of comparison of paints were also highly satisfactory, with only 3.0% false positive answers and 2.8% false negative answers. [source] Literature Review and suggested protocol for managing ultrasound soft markers for Down syndrome: Thickened nuchal fold, echogenic bowel, shortened femur, shortened humerus, pyelectasis and absent or hypoplastic nasal boneJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 3 2007Article first published online: 10 MAY 200, M Bethune Summary Mid-trimester soft markers have been linked with Down syndrome and other aneuploidies. There are many other prenatal screening tests available with better detection rates for Down syndrome than the mid-trimester ultrasound. Many patients confronted with the diagnosis of a soft marker become anxious and may request a diagnostic test (amniocentesis) despite the associated risk of miscarriage. This is also despite the fact that most fetuses with an isolated soft marker are chromosomally normal. The management of a pregnancy with a soft marker must therefore be planned in a manner designed to minimize patient anxiety. Likelihood ratios can be used to modify a patient's ,prior risk' (based on age or prior screening tests) and create a new risk. This calculation may help identify a subset of patients suitable for further investigation. It has been proposed that ,negative' likelihood ratios can be used to reduce a patient's risk if no soft marker is found at a mid-trimester ultrasound. There remain concerns about this approach and further research is required before this approach enters common practice. The published work surrounding the management of thickened nuchal fold, echogenic bowel, shortened femur, shortened humerus, pyelectasis (renal pelvis dilatation) and hypoplastic nasal bone is reviewed. Each soft marker has different associations and individual management plans for each of these soft markers are presented. Although isolated single umbilical artery is not usually considered a soft marker of aneuploidy, a management plan for this common finding is also included. [source] Bayesian analysis of plant disease predictionPLANT PATHOLOGY, Issue 4 2002J. E. Yuen Rule-based systems for the prediction of the occurrence of disease can be evaluated in a number of different ways. One way is to examine the probability of disease occurrence before and after using the predictor. Bayes's Theorem can be a useful tool to examine how a disease forecast (either positive or negative) affects the probability of occurrence, and simple analyses can be conducted without knowing the risk preferences of the targeted decision makers. Likelihood ratios can be calculated from the sensitivity and specificity of the forecast, and provide convenient summaries of the forecast performance. They can also be used in a simpler form of Bayes's Theorem. For diseases where little or no prior information on occurrence is available, most forecasts will be useful in that they will increase or decrease the probability of disease occurrence. For extremely common or extremely rare diseases, likelihood ratios may not be sufficiently large or small to substantially affect the probability of disease occurrence or make any difference to the actions taken by the decision maker. [source] Single and Combined Diagnostic Value of Clinical Features and Laboratory Tests in Acute AppendicitisACADEMIC EMERGENCY MEDICINE, Issue 9 2009Wytze Laméris Abstract Objectives:, The objective was to evaluate the diagnostic accuracy of clinical features and laboratory test results in detecting acute appendicitis. Methods:, Clinical features and laboratory test results were prospectively recorded in a consecutive series of 1,101 patients presenting with abdominal pain at the emergency department (ED) in six hospitals. Likelihood ratios (LRs) and the areas under the receiver operating characteristic curve (AUC) were calculated for the individual features. Variants of clinical presentation, based on different combinations of clinical features, were investigated and the accuracies of combinations of clinical features were evaluated. Results:, The discriminative power (AUC) of the individual features in patients with suspected appendicitis ranged from 0.50 to 0.65. For five of the 23 predictor sets, the accuracy for appendicitis was more than 85%. This accuracy was only found in male patients. The relative frequency of these predictor sets ranged from 2% to 13% of patients with suspected appendicitis. A combination of the clinical features migration of pain to the right lower quadrant (RLQ), and direct tenderness in the RLQ, was present in only 28% (120/422) of clinically suspected patients, of whom no more than 85 patients had appendicitis (71%). A "classical" presentation (combination of migration of pain to the RLQ, tenderness in the RLQ, and rigidity) occurred in only 6% (25/422) of patients with suspected appendicitis and yielded an accuracy of 100% in males but only 46% in females. Conclusions:, The discriminative power (AUC) of individual clinical features and laboratory test results for appendicitis was weak in patients with suspected appendicitis. Combinations of clinical features and laboratory tests with high diagnostic accuracy are relatively infrequent in patients with suspected appendicitis. [source] Accuracy of Ottawa Ankle Rules to Exclude Fractures of the Ankle and Midfoot in Children: A Meta-analysisACADEMIC EMERGENCY MEDICINE, Issue 4 2009Shawn Dowling MD Abstract Objectives:, The objectives were to conduct a systematic review to determine the diagnostic accuracy of the Ottawa Ankle Rules (OAR) to exclude ankle and midfoot fractures in children and the extent to which x-ray use could be reduced without missing significant fractures. Methods:, The authors conducted comprehensive searches of electronic databases and gray literature sources. Independent reviewers applied standard inclusion and exclusion criteria. The criterion standard diagnostic test was an ankle and/or foot x-ray or proxy measure to ensure no missed fractures. Standard 2 × 2 tables were constructed. Sensitivities and specificities were pooled using an approximation of the inverse variance; 95% confidence intervals (95% CIs) were calculated using the exact method. Likelihood ratios (LR ±) and diagnostic odds ratios were combined under DerSimonian and Laird random effects model. Results:, A pooled analysis of 12 studies (N = 3,130) identified 671 fractures (prevalence = 21.4%). Ten studies reported Salter-Harris Type I (SH-I) fractures. The pooled sensitivity was 98.5% (95% CI = 97.3 to 99.2), suggesting that the OAR can be used to rule out a fracture. Four of 10 missed fractures were characterized: 1 SH-I, 1 SH-IV, and 2 "insignificant fractures" (either SH-I or avulsion fractures <3 mm). The pooled estimate for rate of x-ray reduction was 24.8% (95% CI = 23.3% to 26.3%; range = 5% to 44%). Conclusions:, The OAR appear to be a reliable tool to exclude fractures in children greater than 5 years of age presenting with ankle and midfoot injuries. Employing the OAR would significantly decrease x-ray use with a low likelihood of missing a fracture. [source] A Decision Rule for Predicting Bacterial Meningitis in Children with Cerebrospinal Fluid Pleocytosis When Gram Stain Is Negative or UnavailableACADEMIC EMERGENCY MEDICINE, Issue 5 2008Bema K. Bonsu MBChB Abstract Objectives:, Among children with cerebrospinal fluid (CSF) pleocytosis, the task of separating aseptic from bacterial meningitis is hampered when the CSF Gram stain result is unavailable, delayed, or negative. In this study, the authors derive and validate a clinical decision rule for use in this setting. Methods:, This was a review of peripheral blood and CSF test results from 78 children (<19 years) presenting to Children's Hospital Columbus from 1998 to 2002. For those with a CSF leukocyte count of >7/,L, a rule was created for separating bacterial from viral meningitis that was based on routine laboratory tests, but excluded Gram stain. The rule was validated in 158 subjects seen at the same site (Columbus, 2002,2004) and in 871 subjects selected from a separate site (Boston, 1993,1999). Results:, One point each (maximum, 6 points) was assigned for leukocytes >597/,L, neutrophils >74%, glucose <38 mg/dL, and protein >97 mg/dL in CSF and for leukocytes >17,000/mL and bands to neutrophils >11% in peripheral blood. Areas under receiver-operator-characteristic curves (AROCs) for the resultant score were 0.98 for the derivation set and 0.90 and 0.97, respectively, for validation sets from Columbus and Boston. Sensitivity and specificity pairs for the Boston data set were 100 and 44%, respectively, at a score of 0 and 97 and 81% at a score of 1. Likelihood ratios (LRs) increased from 0 at a score of 0 to 40 at a score of ,4. Conclusions:, Among children with CSF pleocytosis, a prediction score based on common tests of CSF and peripheral blood and intended for children with unavailable, negative, or delayed CSF Gram stain results has value for diagnosing bacterial meningitis. [source] Validity of suspected alcohol and drug violations in aviation employeesADDICTION, Issue 10 2010Guohua Li ABSTRACT Aims In the United States, transportation employees who are suspected of using alcohol and drugs are subject to reasonable-cause testing. This study aims to assess the validity of suspected alcohol and drug violations in aviation employees. Methods Using reasonable-cause testing and random testing data from the Federal Aviation Administration for the years 1995,2005, we calculated the positive predictive value (PPV) and positive likelihood ratio (LR+) of suspected alcohol and drug violations. The true status of violations was based on testing results, with an alcohol violation being defined as a blood alcohol concentration of ,0.04 mg/dl and a drug violation as a test positive for marijuana, cocaine, amphetamines, phencyclidine or opiates. Results During the 11-year study period, a total of 2284 alcohol tests and 2015 drug tests were performed under the reasonable-cause testing program. The PPV was 37.7% [95% confidence interval (CI), 35.7,39.7%] for suspected alcohol violations and 12.6% (95% CI, 11.2,14.1%) for suspected drug violations. Random testing revealed an overall prevalence of 0.09% for alcohol violations and 0.6% for drug violations. The LR+ was 653.6 (95% CI, 581.7,734.3) for suspected alcohol violations and 22.5 (95% CI, 19.6,25.7) for suspected drug violations. Conclusion The discriminative power of reasonable-cause testing suggests that, despite its limited positive predictive value, physical and behavioral observation represents an efficient screening method for detecting alcohol and drug violations. The limited positive predictive value of reasonable-cause testing in aviation employees is due in part to the very low prevalence of alcohol and drug violations. [source] Likelihood-based tests for localized spatial clustering of diseaseENVIRONMETRICS, Issue 8 2004Ronald E. Gangnon Abstract Numerous methods have been proposed for detecting spatial clustering of disease. Two methods for likelihood-based inference using parametric models for clustering are the spatial scan statistic and the weighted average likelihood ratio (WALR) test. The spatial scan statistic provides a measure of evidence for clustering at a specific, data-identified location; it can be biased towards finding clusters in areas with greater spatial resolution. The WALR test provides a more global assessment of the evidence for clustering and identifies cluster locations in a relatively unbiased fashion using a posterior distribution over potential clusters. We consider two new statistics which attempt to combine the specificity of the scan statistic with the lack of bias of the WALR test: a scan statistic based on a penalized likelihood ratio and a localized version of the WALR test. We evaluate the power of these tests and bias of the associated estimates through simulations and demonstrate their application using the well-known New York leukemia data. Copyright © 2004 John Wiley & Sons, Ltd. [source] Individual differences in allocation of funds in the dictator game associated with length of the arginine vasopressin 1a receptor RS3 promoter region and correlation between RS3 length and hippocampal mRNAGENES, BRAIN AND BEHAVIOR, Issue 3 2008A. Knafo Human altruism is a widespread phenomenon that puzzled evolutionary biologists since Darwin. Economic games illustrate human altruism by showing that behavior deviates from economic predictions of profit maximization. A game that most plainly shows this altruistic tendency is the Dictator Game. We hypothesized that human altruistic behavior is to some extent hardwired and that a likely candidate that may contribute to individual differences in altruistic behavior is the arginine vasopressin 1a (AVPR1a) receptor that in some mammals such as the vole has a profound impact on affiliative behaviors. In the current investigation, 203 male and female university students played an online version of the Dictator Game, for real money payoffs. All subjects and their parents were genotyped for AVPR1a RS1 and RS3 promoter-region repeat polymorphisms. Parents did not participate in online game playing. As variation in the length of a repetitive element in the vole AVPR1a promoter region is associated with differences in social behavior, we examined the relationship between RS1 and RS3 repeat length (base pairs) and allocation sums. Participants with short versions (308,325 bp) of the AVPR1a RS3 repeat allocated significantly (likelihood ratio = 14.75, P = 0.001, df = 2) fewer shekels to the ,other' than participants with long versions (327,343 bp). We also implemented a family-based association test, UNPHASED, to confirm and validate the correlation between the AVPR1a RS3 repeat and monetary allocations in the dictator game. Dictator game allocations were significantly associated with the RS3 repeat (global P value: likelihood ratio ,2 = 11.73, df = 4, P = 0.019). The association between the AVPR1a RS3 repeat and altruism was also confirmed using two self-report scales (the Bardi,Schwartz Universalism and Benevolence Value-expressive Behavior scales). RS3 long alleles were associated with higher scores on both measures. Finally, long AVPR1a RS3 repeats were associated with higher AVPR1a human post-mortem hippocampal messenger RNA levels than short RS3 repeats (one-way analysis of variance (ANOVA): F = 15.04, P = 0.001, df = 14) suggesting a functional molecular genetic basis for the observation that participants with the long RS3 repeats allocate more money than participants with the short repeats. This is the first investigation showing that a common human polymorphism, with antecedents in lower mammals, contributes to decision making in an economic game. The finding that the same gene contributing to social bonding in lower animals also appears to operate similarly in human behavior suggests a common evolutionary mechanism. [source] Haplotype association analysis for late onset diseases using nuclear family dataGENETIC EPIDEMIOLOGY, Issue 3 2006Chun Li Abstract In haplotype-based association studies for late onset diseases, one attractive design is to use available unaffected spouses as controls (Valle et al. [1998] Diab. Care 21:949,958). Given cases and spouses only, the standard expectation-maximization (EM) algorithm (Dempster et al. [1977] J. R. Stat. Soc. B 39:1,38) for case-control data can be used to estimate haplotype frequencies. But often we will have offspring for at least some of the spouse pairs, and offspring genotypes provide additional information about the haplotypes of the parents. Existing methods may either ignore the offspring information, or reconstruct haplotypes for the subjects using offspring information and discard data from those whose haplotypes cannot be reconstructed with high confidence. Neither of these approaches is efficient, and the latter approach may also be biased. For case-control data with some subjects forming spouse pairs and offspring genotypes available for some spouse pairs or individuals, we propose a unified, likelihood-based method of haplotype inference. The method makes use of available offspring genotype information to apportion ambiguous haplotypes for the subjects. For subjects without offspring genotype information, haplotypes are apportioned as in the standard EM algorithm for case-control data. Our method enables efficient haplotype frequency estimation using an EM algorithm and supports probabilistic haplotype reconstruction with the probability calculated based on the whole sample. We describe likelihood ratio and permutation tests to test for disease-haplotype association, and describe three test statistics that are potentially useful for detecting such an association. Genet. Epidemiol. 2006. © 2006 Wiley-Liss, Inc. [source] Detection of Helicobacter pylori DNA by a Simple Stool PCR Method in Adult Dyspeptic PatientsHELICOBACTER, Issue 4 2005Nazime ABSTRACT Introduction.,Helicobacter pylori is the major agent causing peptic ulcer, gastric cancer and mucosa-associated lymphoid tissue (MALT) gastric lymphoma. A simple stool polymerase chain reaction (PCR) method was performed and compared with the gold standards for the diagnosis of H. pylori infection. Material and methods., A total of 54 adult patients (mean age, 46.41 ± 13.12 years) with dyspeptic symptoms from Gastroenterology at Dokuz Eylül University Hospital between May and November 2003 were included. Two antrum and corpus biopsies were taken from each patient. Infection by H. pylori was defined as positivity and negativity of the gold standards. DNA extraction of stool specimens was done using QIAamp DNA Stool Mini Kit (QIAGEN) and PCR conditions included amplification and reamplification steps using the H. pylori ureA gene specific primers (HPU1, HPU2) and were visualized on 1% agarose gel stained with ethidium bromide. Results., Forty-six of 54 patients (85.2%) were diagnosed positive and eight (14.8%) were negative for H. pylori infection by the gold standard methods. Thirty-two patients were positive (59.3%) and 22 of them (40.7%) were detected negative by stool PCR method. The stool PCR method and gold standard methods showed a statistical difference for the detection of H. pylori infection (p < .0001). Sensitivity, specificity, likelihood ratio, and positive and negative predictive values were 65.22%, 75%, 2.61%, 93.75%, and 27.7%, respectively. Discussion., The PCR on the stool specimens resulted as being a very specific test. We suggest that a simple stool PCR method that we developed can be used to detect H. pylori, virulence genes, and in drug resistance studies either first line diagnostic methods in the laboratory or in the clinical management of dyspeptic patients. [source] Alanine transaminase rather than abdominal ultrasound alone is an important investigation to justify cholecystectomy in patients presenting with acute pancreatitisHPB, Issue 5 2010Kerry Anderson Abstract Objectives:, The aims of this study were to investigate the predictive value of an elevated level of alanine transaminase (ALT) for biliary acute pancreatitis (AP) and to reconsider the role of abdominal ultrasound (AUS). Methods:, All patients admitted to Christchurch Public Hospital with AP between July 2005 and December 2008 were identified from a prospectively collected database. Peak ALT within 48 h of presentation was recorded. Aetiology was determined on the basis of history, AUS and other relevant investigations. Results:, A total of 543 patients met the inclusion criteria. Patients with biliary AP had significantly higher median (range) ALT than those with non-biliary causes (200 units/l [63,421 units/l] vs. 33 units/l [18,84 units/l]; P < 0.001). An ALT level of >300 units/l had a sensitivity of 36%, specificity of 94%, positive predictive value of 87% and positive likelihood ratio of 5.6 for gallstones. An elevated ALT and negative AUS had a probability of 21,80% for gallstones. Conclusions:, An elevated ALT strongly supports a diagnosis of gallstones in AP. Abdominal ultrasound effectively confirms this diagnosis; however, a negative ultrasound in the presence of a raised ALT does not exclude gallstones. In some patients consideration could be given to proceeding to laparoscopic cholecystectomy based on ALT alone. [source] The Use of Impedance Cardiography in Predicting Mortality in Emergency Department Patients With Severe Sepsis and Septic ShockACADEMIC EMERGENCY MEDICINE, Issue 4 2010Anthony M. Napoli MD Abstract Objectives:, Pulmonary artery catheterization poses significant risks and requires specialized training. Technological advances allow for more readily available, noninvasive clinical measurements of hemodynamics. Few studies exist that assess the efficacy of noninvasive hemodynamic monitoring in sepsis patients. The authors hypothesized that cardiac index, as measured noninvasively by impedance cardiography (ICG) in emergency department (ED) patients undergoing early goal-directed therapy (EGDT) for sepsis, would be associated with in-hospital mortality. Methods:, This was a prospective observational cohort study of patients age over 18 years meeting criteria for EGDT (lactate > 4 or systolic blood pressure < 90 after 2 L of normal saline). Initial measurements of cardiac index were obtained by ICG. Patients were followed throughout their hospital course until discharge or in-hospital death. Cardiac index measures in survivors and nonsurvivors are presented as means and 95% confidence intervals (CI). Diagnostic performance of ICG in predicting mortality was tested by receiver operating characteristic (ROC) curve and areas under the ROC curves (AUC) were compared using Wilcoxon test. Results:, Fifty-six patients were enrolled; one was excluded due to an inability to complete data acquisition. The mean cardiac index in nonsurvivors (2.3 L/min·m2, 95% CI = 1.6 to 3.0) was less than that for survivors (3.2, 95% CI = 2.9 to 3.5) with mean difference of 0.9 (95% CI = 0.12 to 1.71). The AUC for ICG in predicting mortality was 0.71 (95% CI = 0.58 to 0.88; p = 0.004). A cardiac index of < 2 L/min·m2 had a sensitivity of 43% (95% CI = 18% to 71%), specificity of 93% (95% CI = 80% to 95%), positive likelihood ratio of 5.9, and negative likelihood ratio of 0.6 for predicting in-hospital mortality. Conclusions:, Early, noninvasive measurement of the cardiac index in critically ill severe sepsis and septic shock patients can be performed in the ED for those who meet criteria for EGDT. There appears to be an association between an initial lower cardiac index as measured noninvasively and in-hospital mortality. ACADEMIC EMERGENCY MEDICINE 2010; 17:452,455 © 2010 by the Society for Academic Emergency Medicine [source] High score on the Relative Stress Scale, a marker of possible psychiatric disorder in family carers of patients with dementiaINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 3 2007Ingun Ulstein Abstract Objective To compare the scores on the Relative Stress Scale (RSS) with those on the General Health Questionnaire (GHQ) and the Geriatric Depression Scale (GDS), and to establish a cut-off score for RSS in order to distinguish carers with symptoms of psychiatric disorders from those without. Methods One hundred and ninety-four carers of 194 patients suffering from dementia according to ICD-10 were included in the study. Burden of care was assessed by the 15-items RSS, and psychiatric symptoms by means of the GHQ-30 and the 30-items GDS. A case score above 5 on GHQ and above 13 on GDS were used to define carers with probable psychiatric morbidity. Sensitivity (SS), specificity (SP), accuracy and likelihood ratio for a positive test (LR+) were calculated for different cut-points of the RSS. Results Fifty-six percent of the carers had a GHQ score above 5, and 22% had a GDS score above 13. A two-step cluster analysis using 192 of the 194 carers, identified three groups of carers; a low risk group for psychiatric morbidity (LRG), 82 carers with GHQ,,,5 and GDS,,,13; a medium risk group (MRG), 69 carers with GHQ,>,5 and GDS,,,13; and a high-risk group (HRG), 40 carers with GHQ,>,5 and GDS,>,13. The optimal RSS cut-off to distinguish between the LRG and the others was,>,23 (SS 0.72, SP 0.82, accuracy 0.76, LR,+,4.0), whereas the optimal cut-off to separate the HRG from the others was,>30 (SS 0.74, SP 0.87, accuracy 0.84, LR,+,5.7). Conclusion The RSS is a useful instrument to stratify carers according to their risk of psychiatric morbidity. Copyright © 2006 John Wiley & Sons, Ltd. [source] Haemoglobinometry in general practiceINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 6 2003S. M. Lewis Summary Haemoglobinometry as a primary point-of-care test is well established. This study was undertaken to assess whether haemoglobinometry by itself provides an adequate haematological screening procedure in general practice. In a series of 500 sequential blood counts received by the central hospital laboratory from local doctors, 405 (81%) had a normal haemoglobin. Full blood counts on these samples showed 15% with one or more blood count parameters outside 2SD of normal reference values, including increased MCV, low MCV with low MCH and MCHC, leucocytosis with neutrophilia, a few cases with neutropenia, lymphopenia, monocytosis or eosinophilia. When the limits were set at 3SD, these abnormalities were found in only 7.6% of the cases. Calculation of test utility gave a positive predictive value of 0.83, a negative predictive value of 0.85, with a likelihood ratio of 14.3 and an overall diagnostic reliability of 84%. It was concluded that haemoglobin alone is a valuable primary screening test and a full blood count is required only when anaemia is present or when the patient's history and clinical signs indicate the need for such further investigation. Using this protocol it is unlikely that any serious error will be made in diagnosing a clinically significant condition; the main limitation is failure to diagnose pre-anaemic iron deficiency. [source] Interpreting DNA Evidence: A ReviewINTERNATIONAL STATISTICAL REVIEW, Issue 3 2003L.A. Foreman Summary The paper provides a review of current issues relating to the use of DNA profiling in forensic science. A short historical section gives the main statistical milestones that occurred during a rapid development of DNA technology and operational uses. Greater detail is then provided for interpretation issues involving STR DNA profiles, including: , methods that take account of population substructure in DNA calculations; , parallel work carried out by the US National Research Council; , the move away from multiple independence testing in favour of experiments that demonstrate the robustness of casework procedures; , the questionable practice of source attribution ,with reasonable scientific certainty'; , the effect on the interpretation of profiles obtained under increasingly sensitive techniques, the LCN technique in particular; , the use of DNA profiles as an intelligence tool; , the interpretation of DNA mixtures. Experience of presenting DNA evidence within UK courts is also discussed. The paper then summarises a generic interpretation framework based on the concept of likelihood ratio within a hierarchy of propositions. Finally the use of Bayesian networks to interpret DNA evidence is reviewed. Résumé Cet article présente un inventaire des questions relativesá l'utilisation du profilage ADN dans la science légale. Une courte section historique décrit les principales étapes statistiques qui ont eu lieu pendant le rapide développement de la technologie ADN et ses utilisations opérationnelles. De plus grands détails sont ensuite donnés pour l'interprétation de questions sur les profils AND STR, ce qui inclut: ,les méthodes qui tiennent compte des sous-structures de population dans les calculs ADN; ,le travail conduit en paralléle par le Conseil de Recherche Nationale des Etats-Unis (NRC); ,l'évolution depuis les tests d'indépendance multiple vers des expériences qui démontrent la robustesse des procédures; ,la pratique contestable de l'attribution de source avec "certitude scientifique raisonnable"; ,l'effet de l'interprétation des profils obtenus sous techniques de plus en plus sensibles, la technique LCN en particulier ,l'utilisation de profils ADN comme outil d'intelligence; ,l'interprétation de mélanges ADN. L'expérience de ce type de preuve dans les tribunaux britanniques sera également présentée et commentée. L'article présentera un cavenas d'interprétation centré sur le concept de rapport de vraisemblance, inscrit dans une hérarchie de propositions. Finalement, l'utilisation de réseaux Bayesien pour interpréter la preuve par ADN sera abordée. [source] Prognosis of stage I pressure ulcers and related factorsINTERNATIONAL WOUND JOURNAL, Issue 4 2006Miwa Sato Abstract The prognosis of stage I pressure ulcers cannot be predicted; therefore, nursing interventions for preventing their deterioration have not been clearly established. This study describes the clinical course of stage I pressure ulcers and prospectively investigates the factors related to their deterioration. Thirty-one stage I pressure ulcers in 30 patients in a long-term care facility were studied, and morphological changes were assessed every day until the ulcers healed or deteriorated. The physiological changes were assessed by ultrasonography and thermography. Twenty ulcers healed, and 11 deteriorated. The characteristics of deterioration were as follows: (1) double erythema; (2) non blanchable erythema across the whole area determined by glass plate compression; (3) erythema away from the tip of the bony prominence; and (4) expanding erythema on the following day. We analysed the sensitivity, specificity, positive predictive value, negative predictive value and positive likelihood ratio for the diagnostic utility of the indicators of deterioration double erythema and distance from the tip of bony prominence, which can be instantly assessed without the use of any special device. The values were 36·4%, 95·0%, 80·0%, 73·1% and 7·28, respectively. These results suggest that clinicians can predict the prognosis of stage I pressure ulcers by initial assessment and provide appropriate care based on the assessment. [source] A Chart-Based Method for Identification of Delirium: Validation Compared with Interviewer Ratings Using the Confusion Assessment MethodJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2005Sharon K. Inouye MD Objectives: To validate a chart-based method for identification of delirium and compare it with direct interviewer assessment using the Confusion Assessment Method (CAM). Design: Prospective validation study. Setting: Teaching hospital. Participants: Nine hundred nineteen older hospitalized patients. Measurements: A chart-based instrument for identification of delirium was created and compared with the reference standard interviewer ratings, which used direct cognitive assessment to complete the CAM for delirium. Trained nurse chart abstractors were blinded to all interview data, including cognitive and CAM ratings. Factors influencing the correct identification of delirium in the chart were examined. Results: Delirium was present in 115 (12.5%) patients according to the CAM. Sensitivity of the chart-based instrument was 74%, specificity was 83%, and likelihood ratio for a positive result was 4.4. Overall agreement between chart and interviewer ratings was 82%, kappa=0.41. By contrast, using International Classification of Diseases, Ninth Revision, Clinical Modification, administrative codes, the sensitivity for delirium was 3%, and specificity was 99%. Independent factors associated with incorrect chart identification of delirium were dementia, severe illness, and high baseline delirium risk. With all three factors present, the chart instrument was three times more likely to identify patients incorrectly than with none of the factors present. Conclusion: A chart-based instrument for delirium, which should be useful for patient safety and quality-improvement programs in older persons, was validated. Because of potential misclassification, the chart-based instrument is not recommended for individual patient care or diagnostic purposes. [source] Fine mapping and detection of the causative mutation underlying Quantitative Trait LociJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 5 2010E. Uleberg Summary The effect on power and precision of including the causative SNP amongst the investigated markers in Quantitative Trait Loci (QTL) mapping experiments was investigated. Three fine mapping methods were tested to see which was most efficient in finding the causative mutation: combined linkage and linkage disequilibrium mapping (LLD); association mapping (MARK); a combination of LLD and association mapping (LLDMARK). Two simulated data sets were analysed: in one set, the causative SNP was included amongst the markers, while in the other set the causative SNP was masked between markers. Including the causative SNP amongst the markers increased both precision and power in the analyses. For the LLD method the number of correctly positioned QTL increased from 17 for the analysis without the causative SNP to 77 for the analysis including the causative SNP. The likelihood of the data analysis increased from 3.4 to 13.3 likelihood units for the MARK method when the causative SNP was included. When the causative SNP was masked between the analysed markers, the LLD method was most efficient in detecting the correct QTL position, while the MARK method was most efficient when the causative SNP was included as a marker in the analysis. The LLDMARK method, combining association mapping and LLD, assumes a QTL as the null hypothesis (using LLD method) and tests whether the ,putative causative SNP' explains significantly more variance than a QTL in the region. Thus, if the putative causative SNP does not only give an Identical-By-Descent (IBD) signal, but also an Alike-In-State (AIS) signal, LLDMARK gives a positive likelihood ratio. LLDMARK detected less than half as many causative SNPs as the other methods, and also had a relatively high false discovery rate when the QTL effect was large. LLDMARK may however be more robust against spurious associations, because the regional IBD is largely corrected for by fitting a QTL effect in the null hypothesis model. [source] Evaluation of the evidential value of physicochemical data by a Bayesian network approachJOURNAL OF CHEMOMETRICS, Issue 7-8 2010Grzegorz Zadora Abstract The growing interest in applications of Bayesian networks (BNs) in forensic science raises the question of whether BN could be used in forensic practice for the evaluation of results from physicochemical analysis of a limited number of observations from flammable liquids (weathered kerosene and diesel fuel) by automated thermal desorption gas chromatography mass spectrometry (ATD-GC/MS), car paints by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) and fibres by microspectrophotometry (MSP) in the visible (VIS) range. Therefore, various simple BN models, which allow the evaluation of both discrete and continuous types of data, were studied in order to address questions raised by the representatives of the administration of justice, concerning the identification and classification of objects into certain categories and/or the association between two items. The results of the evaluation performed by BN models were expressed in the form of a likelihood ratio, which is a well-documented measure of evidential value in the forensic field. From the results obtained, it can be concluded that BN models seem to be promising tool for evaluating physicochemical data. Copyright © 2010 John Wiley & Sons, Ltd. [source] Recommended dietary allowance for vitamin C in the United States is also applicable to a population of young Japanese womenJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2004Hiroshi Ihara Abstract The recommended dietary allowance (RDA) for ascorbic acid (AA) in Canada and the United States has been set for several years at 75 mg/day for women 19,30 years old. Recently this level was questioned, and an increase to 90 mg/day was suggested. For Japanese women in the same age group, we found that the RDA for AA is currently 100 mg/day. Our goal was to determine which RDA is sufficient for maintaining a serum concentration of AA in young Japanese women above the lower reference limit of 7.0 mg/L. We measured serum AA concentrations by an ascorbate oxidase method in 176 healthy Japanese women (19,26 years old). We also performed an ROC analysis to estimate the optimal cutoff value for oral dosage to distinguish individuals with hypovitaminosis-C (<7.0 mg/L) from those with a normal serum AA. We evaluated the Japanese RDA using the 75 or 90 mg/day U.S. RDA and the weight ratio between Japanese and U.S. women, and discovered that the RDA value ranged between 66 and 79 mg/day. From the ROC analysis, we found that the optimal daily dosage of AA is approximately 75 mg/day. This value gave the highest efficiency, sensitivity, negative predictive value, and positive likelihood ratio, and the lowest negative likelihood ratio. Therefore, an RDA of 100 mg/day may be unnecessarily high for young Japanese women. J. Clin. Lab. Anal. 18:305,308, 2004. © 2004 Wiley-Liss, Inc. [source] Model-Free CUSUM Methods for Person FitJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 4 2009Ronald D. Armstrong This article demonstrates the use of a new class of model-free cumulative sum (CUSUM) statistics to detect person fit given the responses to a linear test. The fundamental statistic being accumulated is the likelihood ratio of two probabilities. The detection performance of this CUSUM scheme is compared to other model-free person-fit statistics found in the literature as well as an adaptation of another CUSUM approach. The study used both simulated responses and real response data from a large-scale standardized admission test. [source] Nasogastric Aspiration and Lavage in Emergency Department Patients with Hematochezia or Melena Without HematemesisACADEMIC EMERGENCY MEDICINE, Issue 2 2010Nicholas Palamidessi MD Abstract Objectives:, The utility of nasogastric aspiration and lavage in the emergency management of patients with melena or hematochezia without hematemesis is controversial. This evidence-based emergency medicine review evaluates the following question: does nasogastric aspiration and lavage in patients with melena or hematochezia and no hematemesis differentiate an upper from lower source of gastrointestinal (GI) bleeding? Methods:, MEDLINE, EMBASE, the Cochrane Library, and other databases were searched. Studies were selected for inclusion in the review if the authors had performed nasogastric aspiration (with or without lavage) in all patients with hematochezia or melena and performed esophagogastroduodenal endoscopy (EGD) in all patients. Studies were excluded if they enrolled patients with history of esophageal varices or included patients with hematemesis or coffee ground emesis (unless the data for patients without hematemesis or coffee ground emesis could be separated out). The outcome was identifying upper GI hemorrhage (active bleeding or high-risk lesions potentially responsible for hemorrhage) and the rate of complications associated with the nasogastric tube insertion. Quality of the included studies was assessed using standard criteria for diagnostic accuracy studies. Results:, Three retrospective studies met our inclusion and exclusion criteria. The prevalence of an upper GI source for patients with melena or hematochezia without hematemesis was 32% to 74%. According to the included studies, the diagnostic performance of the nasogastric aspiration and lavage for predicting upper GI bleeding is poor. The sensitivity of this test ranged from 42% to 84%, the specificity from 54% to 91%, and negative likelihood ratios from 0.62 to 0.20. Only one study reported the rate complications associated with nasogastric aspiration and lavage (1.6%). Conclusions:, Nasogastric aspiration, with or without lavage, has a low sensitivity and poor negative likelihood ratio, which limits its utility in ruling out an upper GI source of bleeding in patients with melena or hematochezia without hematemesis. ACADEMIC EMERGENCY MEDICINE 2010; 17:126,132 © 2010 by the Society for Academic Emergency Medicine [source] Resolving Paternity Relationships Using X-Chromosome STRs and Bayesian NetworksJOURNAL OF FORENSIC SCIENCES, Issue 4 2007Didier Hatsch Ph.D. Abstract:, X-chromosomal short tandem repeats (X-STRs) are very useful in complex paternity cases because they are inherited by male and female offspring in different ways. They complement autosomal STRs (as-STRs) allowing higher paternity probabilities to be attained. These probabilities are expressed in a likelihood ratio (LR). The formulae needed to calculate LR depend on the genotype combinations of suspected pedigrees. LR can also be obtained by the use of Bayesian networks (BNs). These are graphical representations of real situations that can be used to easily calculate complex probabilities. In the present work, two BNs are presented, which are designed to derive LRs for half-sisters/half-sisters and mother/daughter/paternal grandmother relationships. These networks were validated against known formulae and show themselves to be useful in other suspect pedigree situations than those for which they were developed. The BNs were applied in two paternity cases. The application of the mother/daughter/paternal grandmother BN highlighted the complementary value of X-STRs to as-STRs. The same case evaluated without the mother underlined that missing information tends to be conservative if the alleged father is the biological father and otherwise nonconservative. The half-sisters case shows a limitation of statistical interpretations in regard to high allelic frequencies. [source] Comparison of three current staging systems for hepatocellular carcinoma: Japan integrated staging score, new Barcelona Clinic Liver Cancer staging classification, and Tokyo scoreJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 3 2008Hobyung Chung Abstract Background and Aim:, Although various staging systems for hepatocellular carcinoma (HCC) have been developed in recent years, there is no worldwide consensus which staging system is best. The aim of the present study was to compare the performance of the currently developed three staging systems: the Japan integrated staging (JIS) score, new Barcelona Clinic Liver Cancer (BCLC) staging classification, and the Tokyo score. Methods:, A total of 290 consecutive patients with HCC before initial treatment at Kinki University between January 1999 and December 2001 were included. The patients were stratified according to the three staging systems, and the performance of the staging systems was compared using survival time as the only outcome measure. Results:, There were significant differences between all stages in the JIS score, while no significant difference was found between stages C and D in the BCLC staging classification and between all the scores, except between scores 0 and 1 and 2 and 3 in the Tokyo score. For all patients (n = 290), the radical treatment group (n = 208) and the non-radical treatment group (n = 82), the likelihood ratio ,2 -test showed the highest value, and the Akaike information criterion value was lowest in the JIS score. Conclusion:, The JIS score provided the best prognostic stratification in a Japanese cohort of HCC patients who were mainly diagnosed at early stages and treated with radical therapies. [source] The Accuracy of Transcranial Doppler in the Diagnosis of Stenosis or Occlusion of the Terminal Internal Carotid ArteryJOURNAL OF NEUROIMAGING, Issue 4 2004Jose C. Navarro MD ABSTRACT Background and Purpose. Transcranial Doppler (TCD) can detect intracranial stenoses and occlusions that can help in the diagnosis and management of ischemic stroke. The accuracy parameters for lesions located in the terminal internal carotid artery (TICA) are less known, unlike other basal cerebral vessels. Patients and Methods. The authors studied consecutive patients referred for TCD who underwent contrast angiography or magnetic resonance angiography. They calculated the sensi tivity, specificity, positive and negative predictive values (PPV and NPV), and likelihood ratios. Results. Forty-three patients had TCD and angiography: mean age was 57 ± 20 years, and 65% were men. Twenty-two patients were diagnosed with TICA stenosis or occlusion on TCD underwent angiography. Four patients had abnormal TCD findings that were not confirmed by angiography. Two of 21 patients with normal TCD showed mod erate (< 50%) stenosis of the TICA and cavernous segment of the internal carotid artery at angiography. Accuracy parameters for TCD were as follows: sensitivity = 90% (confidence interval [CI], 63%-96%), specificity = 83% (CI, 61%-94%), PPV = 82%, NPV = 86%, positive likelihood ratio = 5, and negative likelihood ratio = 0.17. Conclusions. TCD is a sensitive screening tool for the lesions in the TICA. Specificity is likely affected by a wide spectrum of the stenosis severity shown at angiography and time lags between the studies. [source] | ||||||||||||||||||||||||||||||||||||||||||||||