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Operator Characteristic (operator + characteristic)
Kinds of Operator Characteristic Terms modified by Operator Characteristic Selected AbstractsA PCA-based modelling technique for predicting environmental suitability for organisms from presence recordsDIVERSITY AND DISTRIBUTIONS, Issue 1-2 2001M. P. Robertson We present a correlative modelling technique that uses locality records (associated with species presence) and a set of predictor variables to produce a statistically justifiable probability response surface for a target species. The probability response surface indicates the suitability of each grid cell in a map for the target species in terms of the suite of predictor variables. The technique constructs a hyperspace for the target species using principal component axes derived from a principal components analysis performed on a training dataset. The training dataset comprises the values of the predictor variables associated with the localities where the species has been recorded as present. The origin of this hyperspace is taken to characterize the centre of the niche of the organism. All the localities (grid-cells) in the map region are then fitted into this hyperspace using the values of the predictor variables at these localities (the prediction dataset). The Euclidean distance from any locality to the origin of the hyperspace gives a measure of the ,centrality' of that locality in the hyperspace. These distances are used to derive probability values for each grid cell in the map region. The modelling technique was applied to bioclimatic data to predict bioclimatic suitability for three alien invasive plant species (Lantana camara L., Ricinus communis L. and Solanum mauritianum Scop.) in South Africa, Lesotho and Swaziland. The models were tested against independent test records by calculating area under the curve (AUC) values of receiver operator characteristic (ROC) curves and kappa statistics. There was good agreement between the models and the independent test records. The pre-processing of climatic variable data to reduce the deleterious effects of multicollinearity, and the use of stopping rules to prevent overfitting of the models are important aspects of the modelling process. [source] The Glasgow Blatchford scoring system enables accurate risk stratification of patients with upper gastrointestinal haemorrhageINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 7 2010R. Srirajaskanthan Summary Background:, Upper gastrointestinal (UGI) haemorrhage is a frequent cause of hospital admission. Scoring systems have been devised to identify those at risk of adverse outcomes. We evaluated the Glasgow Blatchford score's (GBS) ability to identify the need for clinical and endoscopic intervention in patients with UGI haemorrhage. Methods:, A retrospective observational study was performed in all patients who attended the A&E department with UGI haemorrhage during a 12-month period. Patients were separated into low and high risk categories. High risk encompassed patients who required blood transfusions, operative or endoscopic interventions, management on high dependency or intensive care units, and those who re-bled, represented with further bleeding, or who died. Results:, A total of 174 patients were seen with UGI bleeding. Eight of them self-discharged and were excluded. Of the remaining 166, 94 had a ,low risk' bleed, and 72 ,high risk'. The GBS was significantly higher in the high risk (median = 10) than in the low risk group (median 1, p < 0.001). To assess the validity of the GBS at separating low and high risk groups, receiver-operator characteristic (ROC) curves were plotted. The GBS had an area under ROC curve of 0.96 (95% CI 0.95,1.00). When a cut-off value of , 3 was used, sensitivity and specificity of GBS for identifying high risk bleeds was 100% and 68%. Thus at a cut-off value of , 2 the GBS is useful for distinguishing those patients with a low risk UGI bleed. Conclusions:, The GBS accurately identifies low risk patients who could be managed safely as outpatients. [source] Long-Term Fracture Prediction by DXA and QUS: A 10-Year Prospective Study,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2006Alison Stewart PhD Abstract This study investigated the ability of DXA and QUS to predict fractures long term when measured around the time of the menopause. We found both DXA and QUS are able to predict both any fracture and "osteoporotic" fractures and that QUS can predict independently of BMD. Introduction: There are now many treatments available for prevention of osteoporotic fracture. To be cost-effective, we need to target those most at risk. This study examines the ability of DXA and QUS to predict fractures in an early postmenopausal population of women. Materials and Methods: We prospectively measured 3883 women who had been randomly selected from a community-based register. At baseline, they were measured using DXA of spine and hip (Norland XR-26) and QUS of the heel (Walker Sonix UBA 575). Follow-up had a mean of 9.7 ± 1.1 (SD) years. All incident fractures were identified and validated by examination of X-ray reports, and these were compared with those without fracture in a Cox-regression model to calculate hazard ratios (HRs). Results: We found adjusted HRs for any fracture per 1 SD reduction in spine BMD to be 1.61 (1.42-1.83), whereas neck of femur BMD was 1.54 (1.34-1.75). Areas under the curve (AUC) for a receiver operator characteristic (ROC) analysis were 0.62 for spine BMD and 0.59 for neck BMD. In a subgroup where QUS was also measured, the HR for a 1 SD reduction in BMD was 1.69 (1.29-2.22) for spine BMD and 1.55 (1.17-2.06) for neck BMD. The HR for a 1 SD reduction in broadband ultrasound attenuation (BUA) was 1.53 (1.19-1.96), and 1.44 (1.12-1.86) when further adjusted for neck BMD. The AUCs were 0.63 for spine BMD, 0.59 for neck BMD, and 0.62 for BUA. When only osteoporotic fractures were examined, the HRs increased in all situations. BUA showed the highest HR of 2.25 (1.51-3.34), and when further adjusted for neck BMD was 2.12 (1.38-3.28). Conclusions: In conclusion, it may be possible to scan women around the time of the menopause to predict future fractures. It seems that, for "osteoporotic" fractures, BUA may be an improved predictor of fractures in comparison with DXA, because the relative risk is highest for BUA, and independent of BMD. [source] Measuring diagnostic and predictive accuracy in disease management: an introduction to receiver operating characteristic (ROC) analysisJOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 2 2006Ariel Linden DrPH MS Abstract Diagnostic or predictive accuracy concerns are common in all phases of a disease management (DM) programme, and ultimately play an influential role in the assessment of programme effectiveness. Areas, such as the identification of diseased patients, predictive modelling of future health status and costs and risk stratification, are just a few of the domains in which assessment of accuracy is beneficial, if not critical. The most commonly used analytical model for this purpose is the standard 2 × 2 table method in which sensitivity and specificity are calculated. However, there are several limitations to this approach, including the reliance on a single defined criterion or cut-off for determining a true-positive result, use of non-standardized measurement instruments and sensitivity to outcome prevalence. This paper introduces the receiver operator characteristic (ROC) analysis as a more appropriate and useful technique for assessing diagnostic and predictive accuracy in DM. Its advantages include; testing accuracy across the entire range of scores and thereby not requiring a predetermined cut-off point, easily examined visual and statistical comparisons across tests or scores, and independence from outcome prevalence. Therefore the implementation of ROC as an evaluation tool should be strongly considered in the various phases of a DM programme. [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] Lung function and exhaled nitric oxide levels in infants developing chronic lung diseasePEDIATRIC PULMONOLOGY, Issue 2 2007Olivia Williams MRCPCH Abstract Chronic lung disease (CLD) is a common outcome of neonatal intensive care. To determine whether the results of serial exhaled nitric oxide (eNO) measurements during the perinatal period differed between infants who did and did not develop CLD. In addition, we wished to assess whether eNO results were more predictive of CLD development than lung function test results or readily available clinical data (gestational age and birthweight). The patients were 24 infants with a median gestational age of 27 (range 25,31) weeks. Measurements of eNO levels, functional residual capacity (FRC), and compliance of the respiratory system (CRS) were attempted on postnatal days 1, 3, 5, 7, 14, and 28 days. The 12 infants who developed CLD were of significantly lower birthweight and gestational age than the rest of the cohort; in addition, they had lower median FRC (P,<,0.02) and CRS (P,<,0.02) results, but not higher eNO levels, in the first week after birth. Construction of receiver operator characteristic (ROC) curves demonstrated that the CRS and FRC results on Day 3 were the best predictors of CLD development; the areas under the ROC curves were 0.94 and 0.91, respectively. Early lung function test results, but not eNO levels, are useful in predicting CLD development, but are not significantly better than birthweight. Pediatr Pulmonol. 2007; 42:107,113. © 2006 Wiley-Liss, Inc. [source] Automatic generation and evaluation of sparse protein signatures for families of protein structural domainsPROTEIN SCIENCE, Issue 1 2005Matthew J. Blades Abstract We identified key residues from the structural alignment of families of protein domains from SCOP which we represented in the form of sparse protein signatures. A signature-generating algorithm (SigGen) was developed and used to automatically identify key residues based on several structural and sequence-based criteria. The capacity of the signatures to detect related sequences from the SWISSPROT database was assessed by receiver operator characteristic (ROC) analysis and jack-knife testing. Test signatures for families from each of the main SCOP classes are described in relation to the quality of the structural alignments, the SigGen parameters used, and their diagnostic performance. We show that automatically generated signatures are potently diagnostic for their family (ROC50 scores typically >0.8), consistently outperform random signatures, and can identify sequence relationships in the "twilight zone" of protein sequence similarity (<40%). Signatures based on 15%,30% of alignment positions occurred most frequently among the best-performing signatures. When alignment quality is poor, sparser signatures perform better, whereas signatures generated from higher-quality alignments of fewer structures require more positions to be diagnostic. Our validation of signatures from the Globin family shows that when sequences from the structural alignment are removed and new signatures generated, the omitted sequences are still detected. The positions highlighted by the signature often correspond (alignment specificity >0.7) to the key positions in the original (non-jack-knifed) alignment. We discuss potential applications of sparse signatures in sequence annotation and homology modeling. [source] The Accuracy of Computed Tomography in the Diagnosis of Chronic RhinosinusitisTHE LARYNGOSCOPE, Issue 1 2003Neil Bhattacharyya MD Abstract Objective To determine the sensitivity, specificity, and diagnostic accuracy of paranasal sinus computed tomography (CT) in the diagnosis of chronic rhinosinusitis (CRS). Study Design Prospective dual cohort study. Methods One hundred seventy-one consecutive patients undergoing endoscopic sinus surgery for CRS were evaluated with CT and staged according to the Lund system. Histopathological findings from sinus specimens were reviewed and graded. A second contemporaneous control group of 130 patients undergoing CT of the sinus regions for other reasons but without a diagnosis of CRS was also staged. Sensitivity, specificity, and the receiver,operator characteristic were determined for the sinus CT in the diagnosis of CRS. Positive and negative predictive values were also computed. Results In the disease-positive group of patients with CRS, the mean Lund score was 9.8 (95% confidence interval, 9.0,10.6). The mean inflammatory grade on histopathological study was 2.3 (range, 0,4). For the control group (without disease), the mean Lund score was 4.3 (95% confidence interval, 3.5,5.0). The AUC for the receiver,operator characteristic was 0.802 (P <.001). Selecting a Lund score cut-off value of greater than 2 as abnormal, the sinus CT exhibited sensitivity and specificity of 94% and 41%, respectively. Increasing the cut-off value to 4 changed the sensitivity and specificity to 85% and 59%, respectively. Conclusions The paranasal sinus CT scan exhibits good sensitivity and above-average specificity for the diagnosis of CRS. When added to the history and physical findings, CT may add to the diagnostic accuracy of CRS. [source] Clinical Implications of QRS Duration and QT Peak Prolongation in Patients with Suspected Coronary Disease Referred for Elective Cardiac CatheterizationANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2008M. Nadeem Attar M.D., M.R.C.P. Background: The electrocardiogram (ECG) remains a simple, universally available, and prognostically powerful investigation in heart failure, and acute coronary syndromes. We sought to assess the prognostic utility of clinical, angiographic, and simple ECG parameters in a large cohort of patients undergoing elective cardiac catheterization (CC) for known or suspected coronary artery disease. Methods: Consecutive consenting patients undergoing CC for coronary disease were enrolled at a single tertiary center. Patient data, drug therapy, catheter reports, and ECG recordings were prospectively recorded in a validated electronic archive. The primary outcome measure was death or nonfatal myocardial infarction (MI) over 1 year or until percutaneous or cardiac surgical intervention. Independent prognostic markers were identified using the Cox proportional hazard model. Results: A total of 682 individuals were recruited of whom 17(2.5%) died or suffered a nonfatal MI in 1 year. In multivariate analysis QRS duration (ms) (HR 1.03 95% CI 1.01,1.05, P = 0.003), extent of coronary disease (HR 2.01 95% CI 1.24,3.58, P = 0.006), and prolonged corrected QT peak interval in lead I (HR 1.02 95% CI 1.00,1.03, P = 0.044) were independently associated with death or nonfatal MI. Receiver-operator characteristic (ROC) analysis for the multivariate model against the primary end point yielded an area under the curve of 0.759 (95% CI 0.660,0.858), P < 0.001. Conclusions: QRS duration and QT peak are independently associated with increased risk of death or nonfatal MI in stable patients attending for coronary angiography. [source] Prospective Validation of the Pediatric Appendicitis Score in a Canadian Pediatric Emergency DepartmentACADEMIC EMERGENCY MEDICINE, Issue 7 2009Maala Bhatt MD Abstract Objectives:, Clinical scoring systems attempt to improve the diagnostic accuracy of pediatric appendicitis. The Pediatric Appendicitis Score (PAS) was the first score created specifically for children and showed excellent performance in the derivation study when administered by pediatric surgeons. The objective was to validate the score in a nonreferred population by emergency physicians (EPs). Methods:, A convenience sample of children, 4,18 years old presenting to a pediatric emergency department (ED) with abdominal pain of less than 3 days' duration and in whom the treating physician suspected appendicitis, was prospectively evaluated. Children who were nonverbal, had a previous appendectomy, or had chronic abdominal pathology were excluded. Score components (right lower quadrant and hop tenderness, anorexia, pyrexia, emesis, pain migration, leukocytosis, and neutrophilia) were collected on standardized forms by EPs who were blinded to the scoring system. Interobserver assessments were completed when possible. Appendicitis was defined as appendectomy with positive histology. Outcomes were ascertained by review of the pathology reports from the surgery specimens for children undergoing surgery and by telephone follow-up for children who were discharged home. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated. The overall performance of the score was assessed by a receiver operator characteristic (ROC) curve. Results:, Of the enrolled children who met inclusion criteria (n = 246), 83 (34%) had pathology-proven appendicitis. Using the single cut-point suggested in the derivation study (PAS 5) resulted in an unacceptably high number of false positives (37.6%). The score's performance improved when two cut-points were used. When children with a PAS of ,4 were discharged home without further investigations, the sensitivity was 97.6% with a NPV of 97.7%. When a PAS of ,8 determined the need for appendectomy, the score's specificity was 95.1% with a PPV of 85.2%. Using this strategy, the negative appendectomy rate would have been 8.8%, the missed appendicitis rate would have been 2.4%, and 41% of imaging investigations would have been avoided. Conclusions:, The PAS is a useful tool in the evaluation of children with possible appendicitis. Scores of ,4 help rule out appendicitis, while scores of ,8 help predict appendicitis. Patients with a PAS of 5,7 may need further radiologic evaluation. [source] A novel diagnostic monoclonal antibody specific for Helicobacter pylori CagA of East Asian typeAPMIS, Issue 12 2009AIKO YASUDA Molecular biological and epidemiological studies have suggested that Helicobacter pylori producing East Asian CagA protein variant is more virulent than that producing Western CagA. In the present study, we developed and validated an enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody specifically recognizing East Asian CagA-positive H. pylori. A total of 32 H. pylori strains were tested and the data were subjected to receiver-operator characteristic (ROC) curve analysis. The accuracy of the test, determined by calculating the area under the curve, was 0.96, which indicated a high level of accuracy. At the ROC optimized cutoff, the sensitivity and specificity of our ELISA method were 88.0% and 100%, respectively. The validated ELISA showed good performance in terms of sensitivity and specificity. These results suggest that this test is suitable for the diagnostic detection of East Asian CagA carrying strains. We also analyzed the localization of the CagA protein in H. pylori -infected gastric mucosa with fluorescence immunohistochemistry, and found that CagA protein expression was up-regulated by adhesion to epithelial cells. [source] Multicenter Validation of the Philadelphia EMS Admission Rule (PEAR) to Predict Hospital Admission in Adult Patients Using Out-of-hospital DataACADEMIC EMERGENCY MEDICINE, Issue 6 2009Zachary F. Meisel MD Abstract Objectives:, The objective was to validate a previously derived prediction rule for hospital admission using routinely collected out-of-hospital information. Methods:, The authors performed a multicenter retrospective cohort study of 1,500 randomly selected, adult patients transported to six separate emergency departments (EDs; three community and three academic hospitals in three separate health systems) by a city-run emergency medical services (EMS) system over a 1-year period. Patients younger than 18 years or who bypassed the ED to be evaluated by trauma, obstetric, or psychiatric teams were excluded. The score consisted of six weighted elements that generated a total score (0,14): age , 60 years (3 points); chest pain (3); shortness of breath (3); dizzy, weakness, or syncope (2); history of cancer (2); and history of diabetes (1). Receiver operator characteristic (ROC) curves for the decision rule and admission rates were calculated among individual hospitals and for the entire cohort. Results:, A total of 1,102 patients met inclusion criteria. The admission rate for the entire cohort was 40%, and individual hospital admission rates ranged from 28% to 57%. Overall, 34% had a score of ,4, and 29% had a score of ,5. Area under the ROC curve (AUC) for the combined cohort was 0.83 for all admissions and 0.72 for intensive care unit (ICU) admissions; AUCs at individual hospitals ranged from 0.72 to 0.85. The admission rate for a score of ,4 was 77%; for a score of ,5 the admission rate was 80%. Conclusions:, The ability of this EMS rule to predict the likelihood of hospital admission appears valid in this multicenter cohort. Further studies are needed to measure the impact and feasibility of using this rule to guide decision-making. [source] Evaluation of various POSSUM models for predicting mortality in patients undergoing elective oesophagectomy for carcinomaBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 9 2007F. Lai Background: The aim of the study was to validate the use of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM), Portsmouth (P) POSSUM and upper gastrointestinal (O) POSSUM models in patients undergoing elective thoracic oesophagectomy for carcinoma. Methods: The observed in-hospital mortality rates in 545 patients undergoing elective thoracic oesophagectomy for squamous cell carcinoma of the oesophagus in all public hospitals in Hong Kong was compared with rates predicted by POSSUM, P-POSSUM and O-POSSUM. The discriminatory power of these models was assessed using receiver,operator characteristic (ROC) curve analysis. Results: The observed mortality rate was 5·5 per cent, whereas rates predicted by POSSUM, P-POSSUM and O-POSSUM were 15·0, 4·7 and 10·9 per cent respectively. P-POSSUM showed no lack of fit (P = 0·814), but POSSUM (P < 0·001) and O-POSSUM (P = 0·002) showed lack of fit against observed mortality. POSSUM overpredicted mortality across nearly all risk groups, whereas O-POSSUM overpredicted mortality in patients with low physiological scores and in older patients. POSSUM (area under ROC curve 0·776) and P-POSSUM (0·776) showed equally good discriminatory power but O-POSSUM (0·676) was inferior. Conclusion: P-POSSUM provided the most accurate prediction of in-hospital mortality in this group of patients who had elective oesophagectomy. Copyright © 2007 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] A risk score for predicting perioperative blood transfusion in liver surgeryBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2007C. Pulitanò Background: It would be desirable to predict which patients are most likely to benefit from preoperative autologous blood donation. This aim of this study was to develop a point scoring system for predicting the need for blood transfusion in liver surgery. Methods: The medical records of 480 consecutive patients who underwent hepatic resection were analysed. The data set was split randomly into a derivation set of two-thirds and a validation set of one-third. Univariable analysis was carried out to determine the association between clinicopathological factors and blood transfusion. Significant variables were entered into a multiple logistic regression model, and a transfusion risk score (TRS) was developed. The accuracy of the system was validated by calculating the area under the receiver,operator characteristic (ROC) curve. Results: Factors associated with blood transfusion in multivariable analysis included preoperative haemoglobin concentration below 12·5 g/dl, largest tumour more than 4 cm, need for exposure of the vena cava, need for an associated procedure, and cirrhosis. Each variable was assigned one point, and the total score was compared with the transfusion status of each patient in the validation set. The TRS accurately predicted the likelihood of blood transfusion. In the validation set the area under the ROC curve was 0·89. Conclusion: Use of the TRS could lead to substantial saving by improving the cost-effectiveness of the autologous blood donation programme. Copyright © 2007 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] Comparative study of left colonic Peritonitis Severity Score and Mannheim Peritonitis IndexBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 5 2006S. Biondo Background: Prognostic evaluation of patients with left colonic perforation is useful in predicting mortality. The aims of this prospective study were to determine the prognostic value of the left colonic Peritonitis Severity Score (PSS) and to compare it with the Mannheim Peritonitis Index (MPI). Methods: One-hundred and fifty-six patients underwent emergency operation for distal colonic peritonitis. The PSS and MPI were calculated for each patient. The Spearman rank correlation coefficient was used to measure the association between the two scores. The predictive power of the two scoring systems and their differences were studied using the area under the receiver-operator characteristic (ROC) curve. Results: Forty-one patients died (26·3 per cent). The relationship between scores and mortality was statistically significant for each scoring system (P < 0·001). The Spearman rank correlation coefficient for the correlation between the MPI and PSS was 0·55 (P < 0·001). There was no difference between areas under the ROC curves for the two systems. Conclusion: The PSS and MPI are both well validated scoring systems for left colonic peritonitis. Their routine use might allow stratification of patients according to mortality risk. Copyright © 2006 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] Glasgow Aneurysm Score as a predictor of immediate outcome after surgery for ruptured abdominal aortic aneurysmBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 11 2004S. J. Korhonen Background: The aim of the study was to assess the value of the Glasgow Aneurysm Score in predicting postoperative death after repair of a ruptured abdominal aortic aneurysm (AAA). Methods: Between 1991 and 1999, 836 patients underwent surgery for ruptured AAA. Their operative risk at presentation was evaluated retrospectively using the Glasgow Aneurysm Score, based on data from the nationwide Finnvasc registry. Results: The operative mortality rate was 47·2 per cent (395 of 836); 164 patients (19·6 per cent) had cardiac complications and 164 (19·6 per cent) required intensive care treatment for more than 5 days. Predictors of postoperative death in univariate analysis were: coronary artery disease (P = 0·005), preoperative shock (P < 0·001), age (P < 0·001), and the Glasgow Aneurysm Score (P < 0·001). In multivariate analysis the predictors were: preoperative shock (odds ratio (OR) 2·13 (95 per cent confidence interval (c.i.) 1·45 to 3·11); P < 0·001) and the Glasgow Aneurysm Score (for an increase of ten units: OR 1·81 (95 per cent c.i. 1·54 to 2·12); P < 0·001). Receiver,operator characteristic (ROC) curves showed that the best cut-off value of the Glasgow Aneurysm Score in predicting postoperative death was 84 (area under the curve 0·75 (95 per cent c.i. 0·72 to 0·78), standard error 0·17; P < 0·001). The operative mortality rate was 28·2 per cent (114 of 404) in patients with a Glasgow Aneurysm Score of 84 or less, compared with 65·0 per cent (281 of 432) in those with a score greater than 84 (P < 0·001). Conclusion: The Glasgow Aneurysm Score predicted postoperative death after repair of ruptured AAA in this series. Copyright © 2004 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] Systemic levels of plasmin,antiplasmin complexes are correlated with the expansion rate of small abdominal aortic aneurysmsBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2001J. S. Lindholt Background: The cystatine proteolytic system, the serine proteolytic system and the metallodependent proteolytic system have all been reported to be involved in the matrix degradation of the aortic wall, causing abdominal aortic aneurysm (AAA). Plasmin is a common activator of all three systems and could theoretically be involved in the pathogenesis of AAA by activating all three systems. However, plasmin is immediately inactivated by antiplasmin, forming plasmin,antiplasmin (PAP) complexes when it reaches the circulation. This study was designed to assess whether the systemic levels of PAP complex in conservatively treated patients with AAA could be related to the natural history of AAA. Methods: In 1994, 112 of 141 men with AAA (greater than 3 cm) diagnosed by population screening were interviewed, examined, and had blood samples taken and prepared for serum and ethylenediamine tetra-acetic acid plasma by a standard method. The serum and plasma were frozen at , 21°C until analysis. Of the 112 patients, 99 were followed with annual control scans and blood pressure measurements for 1,5 (mean 2·5) years, and were referred for operation if the AAA exceeded 5 cm in diameter. Of the 99 patients, a random sample of 70 had their level of PAP complexes determined (Dade Behring, Rødovre, Denmark). Furthermore, the level of serum elastin peptides (SEPs) was determined by enzyme-linked immunosorbent assay. Spearman's rank sum correlation test, multivariate linear regression analysis and receiver,operator characteristic (ROC) curve analysis were used for statistical analysis (SPSS 10.0; SPSS, Chicago, Illinois, USA). Results: The level of PAP complex was positively correlated with annual expansion rate (r = 0·29, P = 0·01), but not with the initial AAA size (r = 0·17, P = 0·16) or SEP (r = 0·04, P = 0·77). The significant association to expansion persisted after adjustment for initial AAA size, SEP and smoking. Furthermore, the level of PAP complex was significantly predictive for AAAs expanding to operation recommendable size (area under ROC curve 65 per cent), with an optimal sensitivity and specificity of 65 and 67 per cent respectively. SEP level was also significantly predictive for AAAs expanding to operation recommendable size (area under ROC curve 56 per cent), with an optimal sensitivity and specificity of 56 and 57 per cent. Conclusion: The progression of AAA seems to be caused by a general activation of the proteolytic systems involving plasmin and not by genetic or environmental factors causing increased activation of specific proteases or decreased activity of their specific inhibitors. Furthermore, the level of PAP complex in patients with an aneurysm seems to have a better and independently predictive value of the natural history of AAA, compared with the best serological predictor known to date, the serum level of elastin peptides. © 2001 British Journal of Surgery Society Ltd [source] Benchmarks and control charts for surgical site infectionsBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2000T. L. Gustafson Background Although benchmarks and control charts are basic quality improvement tools, few surgeons use them to monitor surgical site infection (SSI). Obstacles to widespread acceptance include: (1) small denominators, (2) complexities of adjusting for patient risk and (3) scepticism about their true purpose (cost cutting, surgical privilege determination or improving outcomes). Methods The application of benchmark charts (using US national SSI rates as limits) and control charts (using facility rates as limits) was studied in 51 hospitals submitting data to the AICE National Database Initiative. SSI rates were risk adjusted by calculating a new statistic, the standardized infection ratio (SIR), based on the risk index suggested by the Centers for Disease Control National Nosocomial Infection Surveillance Study. Fourteen different types of control chart were examined and 115 suspiciously high or low monthly rates were flagged. Participating hospital epidemiologists investigated and classified each flag as ,a real problem' (potentially preventable) or ,not a problem' (beyond the control of personnel at this facility). Results None of the standard, widely recommended, control charts studied showed practical value for identifying either preventable rate increases or outbreaks (clusters due to a single organism). On the other hand, several types of risk-adjusted control chart based on the SIR correctly identified most true opportunities for improvement. Sensitivity, specificity and receiver,operator characteristic (ROC) analysis revealed that the XmR chart of monthly SIRs would be useful in hospitals with smaller surgical volumes (ROC area = 0·732, P = 0·001). For larger hospitals, the most sensitive and robust SIR chart for real-time monitoring of surgical infections was the mXmR chart (ROC area = 0·753, P = 0·0005). © 2000 British Journal of Surgery Society Ltd [source] Correlation of Optic Nerve Sheath Diameter with Direct Measurement of Intracranial PressureACADEMIC EMERGENCY MEDICINE, Issue 2 2008Heidi Harbison Kimberly MD Abstract Background:, Measurements of the optic nerve sheath diameter (ONSD) using bedside ultrasound (US) have been shown to correlate with clinical and radiologic signs and symptoms of increased intracranial pressure (ICP). Objectives:, Previous literature has identified 5 mm as the ONSD measurement above which patients exhibit either clinical or radiologic signs of elevated ICP. The goals of this study were to evaluate the association between ONSD and ICP and to validate the commonly used ONSD threshold of 5 mm using direct measurements of ICP as measured by ventriculostomy. Methods:, A prospective blinded observational study was performed using a convenience sample of adult patients in both the emergency department (ED) and the neurologic intensive care unit (ICU) who had invasive intracranial monitors placed as part of their clinical care. Ocular USs were performed with a 10,5 MHz linear probe. Emergency physicians (EPs) with previous ocular US experience performed ONSD measurements while blinded to the contemporaneous ICP reading obtained directly from invasive monitoring. The association between ONSD and ICP was assessed with the Spearman rank correlation coefficient, and a receiver operator characteristic (ROC) curve was created to determine the optimal ONSD cutoff to detect ICP > 20 cm H2O. Results:, Thirty-eight ocular USs were performed on 15 individual patients. Spearman rank correlation coefficient of ONSD and ICP was 0.59 (p < 0.0005) demonstrating a significant positive correlation. An ROC curve was created to assess the ability of ONSD to distinguish an abnormal ICP greater than 20 cm H2O. The area under the ROC curve was 0.93 (95% confidence interval [CI] = 0.84 to 0.99). Based on inspection of the ROC curve, ONSD > 5 mm performed well to detect ICP > 20 cm H2O with a sensitivity of 88% (95% CI = 47% to 99%) and specificity of 93% (95% CI = 78% to 99%). Conclusions:, Using an ROC curve the authors systematically confirmed the commonly used threshold of ONSD > 5 mm to detect ICP > 20 cm H2O. This study directly correlates ventriculostomy measurements of ICP with US ONSD measurements and provides further support for the use of ONSD measurements as a noninvasive test for elevated ICP. [source] A CRITICAL LOOK AT PAP ADEQUECY: ARE OUR CRITERIA SATISFACTORY?CYTOPATHOLOGY, Issue 2006D.R. Bolick Liquid based Pap (LBP) specimen adequacy is a highly documented, yet poorly understood cornerstone of our GYN cytology practice. Each day, as cytology professionals, we make adequacy assessments and seldom wonder how the criteria we use were established. Are the criteria appropriate? Are they safe? What is the scientific data that support them? Were they clinically and statistically tested or refined to achieve optimal patient care? In this presentation, we will take a fresh look at what we know about Pap specimen adequacy and challenge some of the core assumptions of our daily practice. LBP tests have a consistent, well-defined surface area for screening, facilitating the quantitative estimates of slide cellularity. This provides an unprecedented opportunity to establish reproducible adequacy standards that can be subjected to scientific scrutiny and rigorous statistical analysis. Capitalizing on this opportunity, the TBS2001 took the landmark step to define specimen adequacy quantitatively, and set the threshold for a satisfactory LBP at greater than 5,000 well visualized squamous epithelial cells. To date, few published studies have attempted to evaluate the validity or receiver operator characteristics for this threshold, define an optimal threshold for clinical utility or assess risks of detection failure in ,satisfactory' but relatively hypocellular Pap specimens. Five years of cumulative adequacy and cellularity data of prospectively collected Pap samples from the author's laboratory will be presented, which will serve as a foundation for a discussion on ,Pap failure'. A relationship between cellularity and detection of HSIL will be presented. Risk levels for Pap failure will be presented for Pap samples of different cellularities. The effect of different cellularity criterion on unsatisfactory Pap rates and Pap failure rates will be demonstrated. Results from this data set raise serious questions as to the safety of current TBS2001 adequacy guidelines and suggest that the risk of Pap failure in specimens with 5,000 to 20 000 squamous cells on the slide is significantly higher than those assumed by the current criteria. TBS2001 designated all LBP to have the same adequacy criterion. Up to this point, it has been assumed that ThinPrep, SurePath, or any other LBP would be sufficiently similar that they should have the same adequacy criteria. Data for squamous cellularity and other performance characteristics of ThinPrep and SurePath from the author's laboratory will be compared. Intriguing data involving the recently approved MonoPrep Pap Test will be reviewed. MonoPrep clinical trial data show the unexpected finding of a strong correlation between abundance of endocervical component and the detection of high-grade lesions, provoking an inquiry of a potential new role for a quantitative assessment of the transition zone component. The current science of LBP adequacy criteria is underdeveloped and does not appear to be founded on statistically valid methods. This condition calls us forward as a body of practitioners and scientists to rigorously explore, clarify and define the fundamental nature of cytology adequacy. As we forge this emerging science, we will improve diagnostic performance, guide the development of future technologies, and better serve the patients who give us their trust. Reference:, Birdsong GG: Pap smear adequacy: Is our understanding satisfactory? Diagn Cytopathol. 2001 Feb; 24(2): 79,81. [source] Fluid therapy in acute myocardial infarction: evaluation of predictors of volume responsivenessACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009J. SNYGG Background: Static vascular filling pressures suffer from poor predictive power in identifying the volume-responsive heart. The use of dynamic arterial pressure variables, including pulse pressure variation (PPV) has instead been suggested to guide volume therapy. The aim of the present study was to evaluate the performance of several clinically applicable haemodynamic parameters to predict volume responsiveness in a pig closed chest model of acute left ventricular myocardial infarction. Methods: Fifteen anaesthetized, mechanically ventilated pigs were studied following acute left myocardial infarction by temporary coronary occlusion. Animals were instrumented to monitor central venous (CVP) and pulmonary artery occlusion (PAOP) pressures and arterial systolic variations (SPV) and PPV. Cardiac output (CO) was measured using the pulmonary artery catheter and by using the PiCCO® monitor also giving stroke volume variation (SVV). Variations in the velocity time integral by pulsed-wave Doppler echocardiography were determined in the left (,VTILV) and right (,VTIRV) ventricular outflow tracts. Consecutive boluses of 4 ml/kg hydroxyethyl starch were administered and volume responsiveness was defined as a 10% increase in CO. Results: Receiver,operator characteristics (ROC) demonstrated the largest area under the curve for ,VTIRV [0.81 (0.70,0.93)] followed by PPV [0.76 (0.64,0.88)] [mean (and 95% CI)]. SPV, ,VTILV and SVV did not change significantly during volume loading. CVP and PAOP increased but did not demonstrate significant ROC. Conclusion: PPV may be used to predict the response to volume administration in the setting of acute left ventricular myocardial infarction. [source] Prevalence of ROPS-equipped tractors on minority operated farms in the US,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 5 2009John R. Myers MS Abstract Background Tractor overturns kill an average of 100 farmers and farm workers per year. Roll-over protective structures (ROPS) are a proven intervention, but are not on a sufficient number of tractors in the US to reduce these deaths. Little has been reported on ROPS use by racial minority farm operators. Methods Data from the NIOSH OISPA survey were used to assess ROPS prevalence rates from a random sample of racial minority farm operators for the year 2003, and ROPS prevalence rates from a random sample of all US farms for the year 2004. Results ROPS prevalence rates on minority farming operations follow similar patterns to ROPS prevalence rates on all US farms. A low prevalence of ROPS on farms was associated with operators over the age of 65 years, farms with small acreages, and farms operated on a part-time basis. The race of the operator had little impact on ROPS prevalence rates. Conclusions Factors such as acreage, farm operator age, region of the US, and full- or part-time farming status influence ROPS prevalence rates on farms more than the race of the operator. Understanding how ROPS prevalence differs across these farm and farm operator characteristics has the potential to efficiently target areas for ROPS promotion programs across the US. Am. J. Ind. Med. 52:408,418, 2009. © 2009 Wiley-Liss, Inc. [source] Predictors of Long-Term Risk for Heart Failure Hospitalization after Acute Myocardial InfarctionANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2010Juha S. Perkiömäki M.D. Background: Data on the value of baseline brain natriuretic peptide (BNP) and autonomic markers in predicting heart failure (HF) hospitalization after an acute myocardial infarction (AMI) are limited. Methods: A consecutive series of patients with AMI without a previous history of HF (n = 569) were followed up for 8 years. At baseline, the patients had a blood sample for determination of BNP, a 24-hour Holter recording for evaluating heart rate variability (HRV) and heart rate turbulence (HRT), and an assessment of baroreflex sensitivity (BRS) using phenylephrine test. Results: During the follow-up, 79 (14%) patients were hospitalized due to HF. Increased baseline BNP, decreased HRV, HRT, and BRS had a significant association with HF hospitalization in univariate comparisons (P < 0.001 for all). After adjusting with all the relevant clinical parameters, BNP, HRV, and HRT still significantly predicted HF hospitalization (P < 0.001 for BNP and for the short-term scaling exponent ,1, P < 0.01 for turbulence slope). In the receiver operator characteristics curve analysis, the area under the curve for BNP was 0.77, for the short-term scaling exponent ,1 0.69, for turbulence slope 0.71, and for BNP/standard deviation of all N-N intervals ratio 0.80. Conclusion: Baseline increased BNP and impaired autonomic function after AMI yield significant information on the long-term risk for HF hospitalization. Ann Noninvasive Electrocardiol 2010;15(3):250,258 [source] The Six-item Screener to Detect Cognitive Impairment in Older Emergency Department PatientsACADEMIC EMERGENCY MEDICINE, Issue 7 2008Scott T. Wilber MD Abstract Background:, Cognitive impairment due to delirium or dementia is common in older emergency department (ED) patients. To prevent errors, emergency physicians (EPs) should use brief, sensitive tests to evaluate older patient's mental status. Prior studies have shown that the Six-Item Screener (SIS) meets these criteria. Objectives:, The goal was to verify the performance of the SIS in a large, multicenter sample of older ED patients. Methods:, A prospective, cross-sectional study was conducted in three urban academic medical center EDs. English-speaking ED patients ,65 years old were enrolled. Patients who received medications that could affect cognition, were too ill, were unable to cooperate, were previously enrolled, or refused to participate were excluded. Patients were administered either the SIS or the Mini-Mental State Examination (MMSE), followed by the other test 30 minutes later. An MMSE of 23 or less was the criterion standard for cognitive impairment; the SIS cutoff was 4 or less for cognitive impairment. Standard operator characteristics of diagnostic tests were calculated with 95% confidence intervals (CIs), and a receiver operating characteristic curve was plotted. Results:, The authors enrolled 352 subjects; 111 were cognitively impaired by MMSE (32%, 95% CI = 27% to 37%). The SIS was 63% sensitive (95% CI = 53% to 72%) and 81% specific (95% CI = 75% to 85%). The area under the receiver operating characteristic curve was 0.77 (95% CI = 0.72 to 0.83). Conclusions:, The sensitivity of the SIS was lower than in prior studies. The reasons for this lower sensitivity are unclear. Further study is needed to clarify the ideal brief mental status test for ED use. [source] A novel algorithm to improve pathologic stage prediction of clinically organ-confined muscle-invasive bladder cancerCANCER, Issue 7 2009David Margel MD Abstract BACKGROUND: An algorithm was created to predict pathologic stage in patients with clinically organ-confined muscle-invasive bladder cancer. METHODS: The sample consisted of 133 consecutive patients scheduled to undergo cystectomy. To develop a tool to predict nonorgan-confined disease before surgery, principal component analysis (PCA) was applied. Patients were stratified into a training set (n = 89) and a validation set (n = 44), and 7 parameters were evaluated: levels of carcinoembryonic antigen, cancer antigen (CA) 125, and carbohydrate antigen (CA) 19-9; clinical stage; presence of hydronephrosis; presence of carcinoma in situ; and initial tumor size >3 cm. PCA was applied to the training set to determine the weight of each parameter. A PCA score was generated for each patient in the set, and a cutoff defining nonorgan-confined disease was established. The accuracy of the cutoff was quantified by the area under the receiver operator characteristics curve (AUC). The model was then applied to the validation set without recalculation; the AUC and the positive and negative predictive values of the validation set were calculated. RESULTS: On pathologic evaluation, 71 patients (53%) were found to have organ-confined tumors and 62 patients (47%) had extravesical disease. The AUC was 0.85 in the training group (95% confidence interval [95% CI], 0.71-0.97) and 0.84 in the validation group (95% CI, 0.75-0.93). The positive and negative predictive values in the validation group were 88% (95% CI, 71%-96%) and 94% (95% CI, 71%-99%), respectively. CONCLUSIONS: The newly devised, internally validated, algorithm was 85% accurate in predicting nonorgan-confined bladder disease before cystectomy. Further external validation in a large cohort was recommended as still necessary. Cancer 2009. © 2009 American Cancer Society. [source] | |||||||||||||