Gender differences in anxiety-related traits in patients with panic disorder

This study examined gender differences in anxiety-related personality traits in patients with panic disorder with or without agoraphobia (PD+/-AG). Outpatients (101 total) with SCID confirmed PD+/-AG completed the Anxiety Sensitivity Index (ASI), the Trait form of the State-Trait Anxiety Inventory (STAI-T), the NEO Personality Inventory Revised (NEO PI-R), and the Retrospective Self-Report of Inhibition (RSRI) as part of their assessment. Significant gender differences were not detected for the total ASI scores. Females scored significantly higher than males on the Physical Concerns subscale of the ASI, whereas males scored significantly higher than women on the Social Concerns subscale. Women scored higher than men on the Extraversion scale of the NEO PI-R as well as on certain subscales of this domain. Although a significant gender difference was not detected on the Neuroticism subscale, men scored higher on the angry hostility and depression facets of this trait. Significant gender differences were not found for the STAI-T or the RSRI. These findings suggest that gender differences exist among patients with PD+/-AG in the feared consequences of anxiety symptoms as well as in the personality characteristics of extraversion.     

Changes in anxiety sensitivity with pharmacotherapy for panic disorder

Fear of anxiety symptoms (anxiety sensitivity) has been implicated in the etiology and maintenance of panic disorder, and has been shown to improve with cognitive-behavioral treatment. The impact of pharmacotherapy on anxiety sensitivity is less clear. We administered the Anxiety Sensitivity Index (ASI) during a 12-week randomized controlled trial investigating the relative efficacy of paroxetine, paroxetine plus sustained clonazepam, and paroxetine plus brief clonazepam for patients with panic disorder. We found a mean reduction in ASI scores of 9.6 points, which correlated with symptomatic improvement, and did not differ significantly between groups. Our data provides further evidence that pharmacotherapy leads to significant acute reductions in fears of anxiety symptoms in patients with panic disorder, albeit at levels that may be somewhat less than the changes associated with CBT. Implications of these findings are discussed relative to optimizing pharmacologic treatment of panic disorder.     

A long-lasting improvement of somatosensory function after prism adaptation, a case study

Previous studies have observed a reduction of visual and representational neglect symptoms after visuo-manual adaptation to rightward displacing prisms. Recently, improvements have also been observed on somatosensory tasks, such as locating the centre of a haptically explored circle and tactile double simultaneous stimulation. In the current single case study we assessed whether prism adaptation with the ipsilesional hand improved two aspects of contralesional somatosensory function, pressure sensitivity and proprioception. After the first application of prism adaptation improvements in pressure sensitivity and proprioception were observed. A second prism adaptation confirmed the improvements in contralesional somatosensory function. The effects of prism adaptation on position sense were longer lasting than have been reported previously, but consistent with reductions of visual neglect symptoms after prism adaptation. The current findings suggest that prism adaptation can have a non-spatial effect on neglect-related supra-modal deficits.     

"Pop-out" of targets modulated in luminance or colour: the effect of intrinsic and extrinsic uncertainty

Targets defined by attributes such as colour or brightness are said to "pop-out" from a cluttered scene, with little or no dependency on the size of the set to be searched, while search for other attributes can depend strongly on set-size. We measured contrast thresholds for increments and decrements in luminance or colour and show that they increase strongly with set-size (as previously observed for orientation). However, in some conditions, where the potential distractors were not salient visual targets, there was no dependency of set-size at all ("pop-out"). All the data can be modelled by assuming two main sources of uncertainty: the intrinsic uncertainty due to the number of detectors monitored during a specific task and the extrinsic uncertainty introduced by increasing the number of items displayed. The strength of the effect is well explained by a simple signal detection theory "signed-max" model suited for two-tailed tasks [Journal of Vision 2 (8), 559]. The results suggest that "pop-out" is not peculiar to luminance or colour, but may occur in conditions when the intrinsic uncertainty is so high as to saturate the effects of further uncertainty sources.     

Small sample estimation of relative accuracy for binary screening tests

Comparing the accuracy of two screening tests is ideally achieved by administering both tests as well as a gold standard test to all study subjects. In practice, a more ethical screen positive study design is often used, one that requires gold standard determination only for subjects that screen positive on either test under investigation. Although it is not possible to quantify the absolute accuracy of each test with such a design,the relative accuracy of the tests can be estimated. Since relative accuracy estimation has poor small sample properties, adjusted estimators based on adding constants to the observed data have been proposed. The adjusted estimators have the advantage that they yield point and variance estimates of relative accuracy in all settings. However, we show through both theory and numerical examples that adding constants to the data can be beneficial or detrimental to small sample performance. Furthermore, the performance of the adjusted estimator depends not only on the magnitude of the constant but also on parameters that cannot be estimated with data from a screen positive study, making selection of an optimal constant difficult in practice. We also examine the performance of the adjusted estimator using data from a study comparing the accuracy of two screening tests for cervical cancer.     

On simultaneous assessment of sensitivity and specificity when combining two diagnostic tests

Diagnostic tests are seldom adopted in isolation. Few tests have high sensitivity and specificity simultaneously. In these cases, one can increase either the sensitivity or the specificity by combining two component tests under either the 'either positive' rule or the 'both positive' rule. However, there is a tradeoff between sensitivity and specificity when these rules are applied. We propose three statistical procedures to simultaneously assess the sensitivity and specificity when combining two component tests. Measurements of interest include rate difference and rate ratio. Our empirical results demonstrate that (i) the asymptotic test procedures for both measurements and approximate test procedure for rate difference possess inflated type I error rate; (ii) the exact test procedures for both measurements possess deflated type I error rate; and (iii) the approximate (unconditional) test procedure for rate ratio becomes an reliable alternative and nicely controls the actual type I error rate in small to moderate sample sizes. Moreover, the approximate (unconditional) test procedure is computationally less intensive than the exact (unconditional) test procedure. We illustrate our methodologies with a real example from a residual nasopharyngeal carcinoma (RNP) study.     

Testing non-inferiority (and equivalence) between two diagnostic procedures in paired-sample ordinal data

Before adopting a new diagnostic procedure, which is more convenient and less expensive than the standard existing procedure, it is essentially important to assess whether the diagnostic accuracy of the new procedure is non-inferior (or equivalent) to that of the standard procedure. In this paper, we consider the situation where test responses are on an ordinal scale with more than two categories. We give two definitions of non-inferiority, one in terms of the probability of correctly identifying the case for a randomly selected pair of a case and a non-case over all possible cut-off points, and the other in terms of both the sensitivity and specificity directly. On the basis of large sample theory, we develop two simple test procedures for detecting non-inferiority. We further conduct Monte Carlo simulation to evaluate the finite sample performance of these test procedures. We note that the two asymptotic test procedures proposed here can actually perform reasonably well in a variety of situations even when the numbers of studied subjects from the diseased and non-diseased populations are not large. To illustrate the use of the proposed test procedures, we include an example of determining whether the diagnostic accuracy of using a digitized film is non-inferior to that of using a plain film for screening breast cancer. Finally, we note that the extension of these results to accommodate the case of detecting (two-sided) equivalence is simply straightforward.     

Uncertainty and the value of diagnostic information, with application to axillary lymph node dissection in breast cancer

In clinical decision making, it is common to ask whether, and how much, a diagnostic procedure is contributing to subsequent treatment decisions. Statistically, quantification of the value of the information provided by a diagnostic procedure can be carried out using decision trees with multiple decision points, representing both the diagnostic test and the subsequent treatments that may depend on the test's results. This article investigates probabilistic sensitivity analysis approaches for exploring and communicating parameter uncertainty in such decision trees. Complexities arise because uncertainty about a model's inputs determines uncertainty about optimal decisions at all decision nodes of a tree. We present the expected utility solution strategy for multistage decision problems in the presence of uncertainty on input parameters, propose a set of graphical displays and summarization tools for probabilistic sensitivity analysis in multistage decision trees, and provide an application to axillary lymph node dissection in breast cancer.     

Effect of conjugated linoleic acid isomers on insulin resistance and mRNA levels of genes regulating energy metabolism in high-fat-fed rats

OBJECTIVE: We investigated the effects of specific conjugated linoleic acid (CLA) isomers on glucose metabolism and insulin resistance and on mRNA levels of genes important in glucose and lipid metabolism. METHODS: Sprague-Dawley rats were fed for 8 wk on a high-fat diet (45% kcal from fat) or one of three CLA-supplemented diets (1% CLA) containing differing isomers of CLA, including a mixture of CLAs (CLA mix), cis-9, trans-11-CLA (C9,T11-CLA), or trans-10, cis-12-CLA (T10,C12-CLA). RESULTS: Compared with the high-fat group, all the CLA groups had enhanced glucose tolerance. Insulin resistance index was significantly lower in the CLA-treated groups. No significant difference could be observed in the level of serum lipids between groups and in the activities of phosphoenolpyruvate carboxylase, glucose-6-phosphatase, and glucokinase. However, C9,T11-CLA and T10,C12-CLA significantly increased acyl coenzyme A oxidase mRNA in skeletal muscle. In addition, C9,T11-CLA increased hepatic acyl coenzyme A oxidase mRNA and skeletal muscle uncoupling protein-2 mRNA. The CLA mix showed intermediate effects on the levels of these genes. CONCLUSIONS: The addition of all types of CLA to Sprague-Dawley rats fed a high-fat diet can decrease insulin resistance. Possible mechanisms are increased fat oxidation and energy expenditure by increasing acyl coenzyme A oxidase and uncoupling protein-2 mRNA in the liver and/or skeletal muscle.     

The pattern of sesame sensitivity among infants and children

Recently, we found sesame to be a major cause of severe IgE-mediated food allergic reactions among infants and young children in Israel. The purpose of this study was to describe the different patterns of sesame sensitivity. We have identified three subgroups among our patients (n = 32). Group I (n = 23, M/F; 14/9) consisted of cases with IgE-mediated sesame allergy. The mean age of the first allergic reaction was 11.7 months. Although the main clinical manifestation was urticaria/angiedema (n = 14, 60%), anaphylaxis was the presenting symptom in seven (30%) patients; all of them were younger than 1 year. Sixteen (70%) were found to be allergic to other foods, and other atopic diseases were identified in 18 (78%) patients. Three patients 'outgrew' their allergy within 1–2 years. Group II (n = 2) included cases in whom sesame allergy was ruled out based on a negative skin prick test (SPT) together with a negative open oral challenge. Group III (n = 7) consisted of patients that were found to be SPT positive for sesame as part of a screening for other food allergies. Although sesame products have become fashionable in westernized countries, early exposure may cause sesame to share eventually the same 'noteriety and fate' as peanut – a major cause of severe food allergic reactions.