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Optimal Sensitivity (optimal + sensitivity)
Selected AbstractsA forward application of age associated gray and white matter networks,HUMAN BRAIN MAPPING, Issue 10 2008Adam M. Brickman Abstract To capture patterns of normal age-associated atrophy, we previously used a multivariate statistical approach applied to voxel based morphometry that identified age-associated gray and white matter covariance networks (Brickman et al. [2007]: Neurobiol Aging 28:284,295). The current study sought to examine the stability of these patterns by forward applying the identified networks to an independent sample of neurologically healthy younger and older adults. Forty-two younger and 35 older adults were imaged with standard high-resolution structural magnetic resonance imaging. Individual images were spatially normalized and segmented into gray and white matter. Covariance patterns that were previously identified with scaled subprofile model analyses were prospectively applied to the current sample to identify to what degree the age-associated patterns were manifested. Older individuals were also assessed with a modified version of the Mini Mental State Examination (mMMSE). Gray matter covariance pattern expression discriminated between younger and older participants with high optimal sensitivity (100%) and specificity (90.5%). While the two groups differed in the degree of white matter pattern expression (t (75) = 5.26, P < 0.001), classification based on white matter expression was relatively low (sensitivity = 80% and specificity = 61.9%). Among older adults, chronological age was significantly associated with increased gray matter pattern expression (r (32) = 0.591, P < 0.001) but not with performance on the mMMSE (r (31) = ,0.314, P = 0.085). However, gray matter pattern expression was significantly associated with performance on the mMMSE (r (31) = ,0.405, P = 0.024). The findings suggest that the previously derived age-associated covariance pattern for gray matter is reliable and may provide information that is more functionally meaningful than chronological age. Hum Brain Mapp 2008. © 2007 Wiley-Liss, Inc. [source] Psychometric properties of an interviewer-administered version of the Kessler Psychological Distress scale (K10) among Dutch, Moroccan and Turkish respondentsINTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 3 2009T. Fassaert Abstract The Kessler Psychological Distress scale (K10) is an instrument that is widely used to screen for mental disorders, but information is lacking on its psychometric qualities in non-Western samples. This study used a population-based sample (N = 725) to assess the reliability and validity of the K10 across ethnic groups in an urban area. The results were generally supportive of the K10 as a reliable and valid instrument to screen for anxiety and depression in all three groups. Cronbach's alpha was high (0.93) and the results indicated the existence of a solid single factor structure. Item bias in relation to ethnic background was minor. In each group, there was good criterion validity with respect to one-month DSM-IV diagnosis for depressive and/or anxiety disorder. The results nevertheless highlight the importance of cross-cultural validation, as we found different cut-off values for ethnic subgroups to obtain optimal sensitivity and specificity for detecting depressive and/or anxiety disorders. Copyright © 2009 John Wiley & Sons, Ltd. [source] Screening for Intracranial Stenosis With Transcranial Doppler: The Accuracy of Mean Flow Velocity ThresholdsJOURNAL OF NEUROIMAGING, Issue 1 2002Robert A. Felberg MD ABSTRACT Background. Patients with 50% intracranial arterial stenosis may require more intensive therapies for stroke prevention. Transcranial Doppler (TCD) is a convenient noninvasive screen for intracranial stenosis. The accuracy of different mean flow velocity (MFV) thresholds for determining the degree of stenosis remains uncertain. Methods. The authors prospectively compared the accuracy of TCD criteria and MFV thresholds to magnetic resonance, computed tomography, and digital subtraction angiography in patients with symptoms of recent or remote stroke or transient ischemic attack. Stenosis on angiography was measured as 0%, <50%, or ,50% diameter reduction. Results. Of 136 consecutive patients, 33 (24%) had distal internal carotid artery (ICA), middle cerebral artery (MCA), posterior cerebral artery, or basilar artery stenosis on angiography (14 patients [10%] were excluded due to incomplete TCD examinations, mainly from a lack of temporal windows). TCD showed 31 true-positive, 9 false-positive, 2 false-negative, and 94 true-negative studies. For all vessels, TCD had a sensitivity of 93.9% (confidence interval [CI] = 89%-98%), a specificity of 91.2% (CI = 87%-96%), a positive predictive value (PPV) of 77.5%, and a negative predictive value (NPV) of 97.9%. The trade-off in sensitivity and specificity for MCA MFV thresholds was as follows: MFV ,80 cm/s had a sensitivity of 100%, a specificity of 96.9% (CI = 94%-99%), a PPV of 84%, and an NPV of 100%. MFV,100 cm/s had a sensitivity of 100%, a specificity of 97.9% (CI = 96%-99%), a PPV of 88.8%, and an NPV of 94.9%. MFV,120 cm/s had a sensitivity of 68.7% (CI = 61%-78%), a specificity of 100%, a PPV of 100%, and an NPV of 94.9%. Reasons for false-positive findings include collateralization of flow in the presence of proximal ICA stenosis and prestenotic to stenotic MCA velocity ratios of 1:,2. Conclusion. TCD is both sensitive and specific in identifying ,50% intracranial arterial stenosis. A MFV threshold cutoff of 100 cm/s has an optimal sensitivity and specificity trade-off for ,50% MCA stenosis. To help avoid false-positive results, a prestenotic to stenotic MCA velocity ratio of 1:,2 should be used in addition to the MFV threshold. [source] Skin testing in patients with hypersensitivity reactions to iodinated contrast media , a European multicenter studyALLERGY, Issue 2 2009K. Brockow Background:, Iodinated contrast media cause both immediate and nonimmediate hypersensitivity reactions. The aim of this prospective study was to determine the specificity and sensitivity of skin tests in patients who have experienced such reactions. Methods:, Skin prick, intradermal and patch tests with a series of contrast media were conducted in 220 patients with either immediate or nonimmediate reaction. Positive skin tests were defined according to internationally accepted guidelines. Seventy-one never-exposed subjects and 11 subjects who had tolerated contrast medium exposure, served as negative controls. Results:, Skin test specificity was 96,100%. For tests conducted within the time period from 2 to 6 months after the reaction, up to 50% of immediate reactors and up to 47% of nonimmediate reactors were skin test positive. For immediate reactors, the intradermal tests were the most sensitive, whereas delayed intradermal tests in combination with patch tests were needed for optimal sensitivity in nonimmediate reactors. Contrast medium cross-reactivity was more common in the nonimmediate than in the immediate group. Interestingly, 49% of immediate and 52% of nonimmediate symptoms occurred in previously unexposed patients. Many of these patients were skin test positive, indicating that they were already sensitized at the time of first contrast medium exposure. Conclusions:, These data suggest that at least 50% of hypersensitivity reactions to contrast media are caused by an immunological mechanism. Skin testing appears to be a useful tool for diagnosis of contrast medium allergy and may play an important role in selection of a safe product in previous reactors. [source] Turner syndrome phalangeal screening based on a two-stage linear regression conceptPEDIATRICS INTERNATIONAL, Issue 4 2009Chui-Mei Tiu Abstract Background:, Turner syndrome (TS) is a congenital chromosomal abnormality, resulting in short stature, short fourth metacarpal, and retarded skeletal maturation in children. The existing methods of diagnosis, which include carpal angle, metacarpal sign, and body mass index (BMI), cannot accurately diagnose TS. The authors propose a novel procedure for examining the hand skeleton to distinguish between normal individuals and patients with TS. Methods:, This investigation was divided into two parts. In the first part, existing methods (evaluation of the metacarpal sign, measurement of the carpal angle, and determination of BMI) were used. Examination in the second part was based on the two-stage screening method (TSSM). In the first stage in TSSM, the ratio of the lengths of the distal,middle phalanges of the fifth digit was determined in normal subjects with average range of satisfactory body height and TS patients. A suitable cut-off was found on linear regression and used to divide the plot into TS patients and normal subjects. In the second stage, the normal section was transferred to another group based on bone and chronological ages. A greater number of patients were diagnosed with TS using this method. Finally, four cut-off parameters were determined on linear regression analysis. Results with optimal sensitivity and specificity were automatically obtained. Results:, The combination of TSSM with optimal programming (sensitivity = 0.81 and specificity = 0.91) was satisfactory for diagnosing TS patients. Conclusion:, TSSM can suitably evaluate growth of the hand skeleton to distinguish between normal individuals and patients with TS. [source] Applications of protein microarrays for biomarker discoveryPROTEOMICS - CLINICAL APPLICATIONS, Issue 10-11 2008Niroshan Ramachandran Abstract The search for new biomarkers for diagnosis, prognosis, and therapeutic monitoring of diseases continues in earnest despite dwindling success at finding novel reliable markers. Some of the current markers in clinical use do not provide optimal sensitivity and specificity, with the prostate cancer antigen (PSA) being one of many such examples. The emergence of proteomic techniques and systems approaches to study disease pathophysiology has rekindled the quest for new biomarkers. In particular the use of protein microarrays has surged as a powerful tool for large-scale testing of biological samples. Approximately half the reports on protein microarrays have been published in the last two years especially in the area of biomarker discovery. In this review, we will discuss the application of protein microarray technologies that offer unique opportunities to find novel biomarkers. [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] | |||||||||||||