164 resultados para Multiple comparisons (Statistics)


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Background and purpose: Decision making (DM) has been defined as the process through which a person forms preferences, selects and executes actions, and evaluates the outcome related to a selected choice. This ability represents an important factor for adequate behaviour in everyday life. DM impairment in multiple sclerosis (MS) has been previously reported. The purpose of the present study was to assess DM in patients with MS at the earliest clinically detectable time point of the disease. Methods: Patients with definite (n=109) or possible (clinically isolated syndrome, CIS; n=56) MS, a short disease duration (mean 2.3 years) and a minor neurological disability (mean EDSS 1.8) were compared to 50 healthy controls aged 18 to 60 years (mean age 32.2) using the Iowa Gambling Task (IGT). Subjects had to select a card from any of 4 decks (A/B [disadvantageous]; C/D [advantageous]). The game consisted of 100 trials then grouped in blocks of 20 cards for data analysis. Skill in DM was assessed by means of a learning index (LI) defined as the difference between the averaged last three block indexes and first two block indexes (LI=[(BI-3+BI-4+BI-5)/3-(BI-1+B2)/2]). Non parametric tests were used for statistical analysis. Results: LI was higher in the control group (0.24, SD 0.44) than in the MS group (0.21, SD 0.38), however without reaching statistical significance (p=0.7). Interesting differences were detected when MS patients were grouped according to phenotype. A trend to a difference between MS subgroups and controls was observed for LI (p=0.06), which became significant between MS subgroups (p=0.03). CIS patients who confirmed MS diagnosis by presenting a second relapse after study entry showed a dysfunction in the IGT in comparison to the other CIS (p=0.01) and definite MS (p=0.04) patients. In the opposite, CIS patients characterised by not entirely fulfilled McDonald criteria at inclusion and absence of relapse during the study showed an normal learning pattern on the IGT. Finally, comparing MS patients who developed relapses after study entry, those who remained clinically stable and controls, we observed impaired performances only in relapsing patients in comparison to stable patients (p=0.008) and controls (p=0.03). Discussion: These results raise the assumption of a sustained role for both MS relapsing activity and disease heterogeneity (i.e. infra-clinical severity or activity of MS) in the impaired process of decision making.

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This paper presents reflexions about statistical considerations on illicit drug profiling and more specifically about the calculation of threshold for determining of the seizure are linked or not. The specific case of heroin and cocaine profiling is presented with the necessary details on the target profiling variables (major alkaloids) selected and the analytical method used. Statistical approach to compare illicit drug seizures is also presented with the introduction of different scenarios dealing with different data pre-treatment or transformation of variables.The main aim consists to demonstrate the influence of data pre-treatment on the statistical outputs. A thorough study of the evolution of the true positive rate (TP) and the false positive rate (FP) in heroin and cocaine comparison is then proposed to investigate this specific topic and to demonstrate that there is no universal approach available and that the calculations have to be revaluate for each new specific application.

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Résumé : Le condylome acuminé anal (CAA), transmis par contact sexuel, résulte d'une infection par Human Papilloma Virus (HPV). Son traitement chirurgical est grevé d'un taux de récidive de 4-29%. Le but de cette étude était d'identifier une éventuelle corrélation entre type d'HPV présent dans les CAA excisés chirurgicalement et taux de récidive de la maladie, ? Cette étude rétrospective porte sur 140 patients opérés au Centre Hospitalier Universitaire Vaudois de CAA, entre 1990 et 2005. Le diagnostic lésionnel a été confirmé par un examen histomorphologique. Le(s) type(s) d'HPV présent(s) dans ces lésions a été déterminé par Polymerase Chain Reaction (PCR). Les patients ont donné leur accord à cette analyse et complété un questionnaire. Une éventuelle corrélation entre récidive de CAA, type d'HPV et status HIV a été recherchée. HPV 6 et 11 sont les virus les plus fréquemment découverts (51% et 28%, respectivement) chez les 140 patients (123H/17F). Trente-cinq (25%) d'entre eux ont présenté une récidive. HPV 11 était present chez 19 (41%) sujets. Ceci est statistiquement significatif (P<0.05), en comparaison aux autres HPVs. Il n'y a par contre pas de différence significative entre la fréquence de récidive des 33 (24%) patients HIV-positifs et le reste du collectif. HPV 11 est donc associé à un taux de récidive de CAA significativement élevé. Un suivi strict des patients atteints est nécessaire pour identifier une récidive et la traiter sans délai, notamment lorsque HPV 11 est present. Ces résultats innovateurs soulèvent la question de la nécessité de pratiquer une typisation virale systématique sur les lésions excisées. La justification d'une telle attitude demande toutefois encore d'être confirmée.

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BACKGROUND: To estimate the prevalence of undernutrition among children with profound intellectual and multiple disabilities (PIMD) and to explore its influence on quality of life. METHODS: Seventy-two children with PIMD (47 male; 25 female; age range 2 to 15 years 4 months; mean age 8.6, SD 3.6) underwent an anthropometric assessment, including body weight, triceps skinfold thickness, segmental measures and recumbent length. Undernutrition was determined using tricipital skinfold percentile and z-scores of weight-for-height and height-for-age. The quality of life of each child was evaluated using the QUALIN questionnaire adapted for profoundly disabled children. RESULTS: Twenty-five children (34.7%) were undernourished and seven (9.7%) were obese. Among undernourished children only eight (32 %) were receiving food supplements and two (8%) had a gastrostomy, of which one was still on a refeeding programme. On multivariate analysis, undernutrition was one of the independent predictors of lower quality of life. CONCLUSION: Undernutrition remains a matter of concern in children with PIMD. There is a need to better train professionals in systematically assessing the nutritional status of profoundly disabled children in order to start nutritional management when necessary.

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Tumor necrosis factor (TNF) alpha, interleukins (IL) 2, 4, 6, and 10, and IgG oligoclonal bands (IgG OB) in vitro production was assessed, after whole-blood stimulation with lipopolysaccharide or concanavalin A, in 61 patients presenting with relapsing-remitting, relapsing-progressive, or chronic progressive multiple sclerosis. Multiple sclerosis patients were receiving no treatment or azathioprine (AZA), cyclosporin, cyclophosphamide, subcutaneous interferon (IFN) beta 1 a, or corticosteroids (CST). Statistical correlations significantly showed that: (a) AZA lowers TNF-alpha (P = 0.002) and increases IL-4 production (P = 0.0024), and IFN-beta 1 a increases TNF-alpha and decreases IL-4 levels; (b) CST has a negative effect on TNF-alpha, IL-6, and IL-4 synthesis; and (c) AZA, IFN-beta 1 a, and CST diminish IgG OB synthesis (P = 0.001). Although our study of the dynamics of TNF-alpha, IL-2, IL-4, IL-6, and IL-10 in vitro production generally found no statistically significant correlations (partly explained by the limited number of values in the various groups), IL-6 was shown to drop during the periods surrounding relapse (P = 0.05) in the absence of treatment, while TNF-alpha (P = 0.04) and IL-6 (P < 0.05) dropped before exacerbation in the presence of AZA. In vitro production of TNF-alpha was closely and positively correlated with that of IL-6, independently of clinical features. The enhanced production of IL-10 detected before or at relapse with AZA and IFN-beta 1 a (trends) may interfere with initiation of the immune reaction and with the development of new CNS lesions. Some discrepancies with previously published results stress the difficulties in studying the state of stimulation of different populations of leukocytes by using a variety of in vitro stimuli and in establishing a correlation between mRNA studies and the amount of final or active protein produced.

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Dislocated compound fractures of the proximal humerus are often difficult to treat. The choice of treatment influences the final functional result. From 1984-1991 108 patients with dislocated compound fractures of the proximal humerus were operated with a T-plate osteosynthesis, retrospectively examined and classified according to the Neer-Classification. At an average follow up time of 5 years 72 patients had a clinical and radiological examination. 68% of these patients with 3-fragment fractures and 80% with 4-fragment fractures showed a modest to unsatisfactory result caused by fracture biology, imprecise fracture reduction or poor surgical procedure. Incorrect position of T-plates and inadequate material were distinguishable. The T-plate which was widely used in the late eighties for internal fixation has to be considered a failure for these particular types of fractures and should be limited for Collum chirurgicum fractures.

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Sex allocation data in eusocial Hymenoptera (ants, bees and wasps) provide an excellent opportunity to assess the effectiveness of kin selection, because queens and workers differ in their relatedness to females and males. The first studies on sex allocation in eusocial Hymenoptera compared population sex investment ratios across species. Female-biased investment in monogyne (= with single-queen colonies) populations of ants suggested that workers manipulate sex allocation according to their higher relatedness to females than males (relatedness asymmetry). However, several factors may confound these comparisons across species. First, variation in relatedness asymmetry is typically associated with major changes in breeding system and life history that may also affect sex allocation. Secondly, the relative cost of females and males is difficult to estimate across sexually dimorphic taxa, such as ants. Thirdly, each species in the comparison may not represent an independent data point, because of phylogenetic relationships among species. Recently, stronger evidence that workers control sex allocation has been provided by intraspecific studies of sex ratio variation across colonies. In several species of eusocial Hymenoptera, colonies with high relatedness asymmetry produced mostly females, in contrast to colonies with low relatedness asymmetry which produced mostly males. Additional signs of worker control were found by investigating proximate mechanisms of sex ratio manipulation in ants and wasps. However, worker control is not always effective, and further manipulative experiments will be needed to disentangle the multiple evolutionary factors and processes affecting sex allocation in eusocial Hymenoptera.

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Lung transplantation has evolved from an experimental procedure to a viable therapeutic option in many countries. In Switzerland, the first lung transplant was performed in November 1992, more than ten years after the first successful procedure world-wide. Thenceforward, a prospective national lung transplant registry was established, principally to enable quality control. The data of all patients transplanted in the two Swiss Lung Transplant centres Zurich University Hospital and Centre de Romandie (Geneva-Lausanne) were analysed. In 10 years 242 lung transplants have been performed. Underlying lung diseases were cystic fibrosis including bronchiectasis (32%), emphysema (32%), parenchymal disorders (19%), pulmonary hypertension (11%) and lymphangioleiomyomatosis (3%). There were only 3% redo procedures. The 1, 5 and 9 year survival rates were 77% (95% CI 72-82), 64% (95% CI 57-71) and 56% (95% CI 45-67), respectively. The 5 year survival rate of patients transplanted since 1998 was 72% (95% CI 64-80). Multivariate Cox regression analysis revealed that survival was significantly better in this group compared to those transplanted before 1998 (HR 0.44, 0.26-0.75). Patients aged 60 years and older (HR 5.67, 95% CI 2.50-12.89) and those with pulmonary hypertension (HR 2.01, 95% CI 1.10-3.65) had a significantly worse prognosis The most frequent causes of death were infections (29%), bronchiolitis obliterans syndrome (25%) and multiple organ failure (14%). The 10-year Swiss experience of lung transplantation compares favourably with the international data. The best results are obtained in cystic fibrosis, pulmonary emphysema and parenchymal disorders.

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Significant progress has been made with regard to the quantitative integration of geophysical and hydrological data at the local scale. However, extending the corresponding approaches to the scale of a field site represents a major, and as-of-yet largely unresolved, challenge. To address this problem, we have developed downscaling procedure based on a non-linear Bayesian sequential simulation approach. The main objective of this algorithm is to estimate the value of the sparsely sampled hydraulic conductivity at non-sampled locations based on its relation to the electrical conductivity logged at collocated wells and surface resistivity measurements, which are available throughout the studied site. The in situ relationship between the hydraulic and electrical conductivities is described through a non-parametric multivariatekernel density function. Then a stochastic integration of low-resolution, large-scale electrical resistivity tomography (ERT) data in combination with high-resolution, local-scale downhole measurements of the hydraulic and electrical conductivities is applied. The overall viability of this downscaling approach is tested and validated by comparing flow and transport simulation through the original and the upscaled hydraulic conductivity fields. Our results indicate that the proposed procedure allows obtaining remarkably faithful estimates of the regional-scale hydraulic conductivity structure and correspondingly reliable predictions of the transport characteristics over relatively long distances.

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BACKGROUND: Angiogenesis inhibitors have been developed to block tumour angiogenesis and target vascular endothelial cells. While some of them have already been approved by the health authorities and are successfully integrated into patient care, many others are still under development, and the clinical value of this approach has to be established. OBJECTIVES: To assess the efficacy and toxicity of targeted anti-angiogenic therapies, in addition to chemotherapy, in patients with metastatic colorectal cancer. Primary endpoints are both progression-free and overall survival. Response rates, toxicity and secondary resectability were secondary endpoints. Comparisons were first-line chemotherapy in combination with angiogenesis inhibitor, to the same chemotherapy without angiogenesis inhibitor; and second-line chemotherapy, to the same chemotherapy without angiogenesis inhibitor. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials, MEDLINE, as well as proceedings from ECCO, ESMO and ASCO until November 2008. In addition, reference lists from trials were scanned, experts in the field and drug manufacturers were contacted to obtain further information. SELECTION CRITERIA: Randomized controlled trials on targeted anti-angiogenic drugs in metastatic colorectal cancer (MCRC). DATA COLLECTION AND ANALYSIS: Data collection and analysis was performed, according to a previously published protocol. Because individual patient data was not provided, aggregate data had to be used for the analysis. Summary statistics for the primary endpoints were hazard ratios (HR's) and their 95% confidence intervals. MAIN RESULTS: At present, eligible first line trials for this meta-analysis were available for bevacizumab (5 trials including 3101 patients) and vatalanib (1 trial which included 1168 patients). The overall HR s for PFS (0.61, 95% CI 0.45 - 0.83) and OS (0.81, 95% 0.73 - 0.90) for the comparison of first-line chemotherapy, with or without bevacizumab, confirms significant benefits in favour of the patients treated with bevacizumab. However, the effect on PFS shows significant heterogeneity. For second-line chemotherapy, with or without bevacizumab, a benefit in both PFS (HR 0.61, 95% CI 0.51 - 0.73) and OS (HR 0.75, 95% CI 0.63-0.89) was demonstrated in a single, randomized trial. While differences in treatment-related deaths and 60-day mortality were not significant, higher incidences in grade III/IV hypertension, arterial thrombembolic events and gastrointestinal perforations were observed in the patients treated with bevacizumab. For valatanib, currently available data showed a non-significant benefit in PFS and OS. AUTHORS' CONCLUSIONS: The addition of bevacizumab to chemotherapy of metastatic colorectal cancer prolongs both PFS and OS in first-and second-line therapy.

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Introduction Lesion detection in multiple sclerosis (MS) is an essential part of its clinical diagnosis. In addition, radiological characterisation of MS lesions is an important research field that aims at distinguishing different MS types, monitoring drug response and prognosis. To date, various MR protocols have been proposed to obtain optimal lesion contrast for early and comprehensive diagnosis of the MS disease. In this study, we compare the sensitivity of five different MR contrasts for lesion detection: (i) the DIR sequence (Double Inversion Recovery, [4]), (ii) the Dark-fluid SPACE acquisition schemes, a 3D variant of a 2D FLAIR sequence [1], (iii) the MP2RAGE [2], an MP-RAGE variant that provides homogeneous T1 contrast and quantitative T1-values, and the sequences currently used for clinical MS diagnosis (2D FLAIR, MP-RAGE). Furthermore, we investigate the T1 relaxation times of cortical and sub-cortical regions in the brain hemispheres and the cerebellum at 3T. Methods 10 early-stage female MS patients (age: 31.64.7y; disease duration: 3.81.9y; disability score, EDSS: 1.80.4) and 10 healthy controls (age and gender-matched: 31.25.8y) were included in the study after obtaining informed written consent according to the local ethic protocol. All experiments were performed at 3T (Magnetom Trio a Tim System, Siemens, Germany) using a 32-channel head coil [5]. The imaging protocol included the following sequences, (all except for axial FLAIR 2D with 1x1x1.2 mm3 voxel and 256x256x160 matrix): DIR (TI1/TI2/TR XX/3652/10000 ms, iPAT=2, TA 12:02 min), MP-RAGE (TI/TR 900/2300 ms, iPAT=3, TA 3:47 min); MP2RAGE (TI1/TI2/TR 700/2500/5000 ms, iPAT=3, TA 8:22 min, cf. [2]); 3D FLAIR SPACE (only for patient 4-6, TI/TR 1800/5000 ms, iPAT=2, TA=5;52 min, cf. [1]); Axial FLAIR (0.9x0.9x2.5 mm3, 256x256x44 matrix, TI/TR 2500/9000 ms, iPAT=2, TA 4:05 min). Lesions were identified by two experienced neurologist and radiologist, manually contoured and assigned to regional locations (s. table 1). Regional lesion masks (RLM) from each contrast were compared for number and volumes of lesions. In addition, RLM were merged in a single "master" mask, which represented the sum of the lesions of all contrasts. T1 values were derived for each location from this mask for patients 5-10 (3D FLAIR contrast was missing for patient 1-4). Results & Discussion The DIR sequence appears the most sensitive for total lesions count, followed by the MP2RAGE (table 1). The 3D FLAIR SPACE sequence turns out to be more sensitive than the 2D FLAIR, presumably due to reduced partial volume effects. Looking for sub-cortical hemispheric lesions, the DIR contrast appears to be equally sensitive to the MP2RAGE and SPACE, but most sensitive for cerebellar MS plaques. The DIR sequence is also the one that reveals cortical hemispheric lesions best. T1 relaxation times at 3T in the WM and GM of the hemispheres and the cerebellum, as obtained with the MP2RAGE sequence, are shown in table 2. Extending previous studies, we confirm overall longer T1-values in lesion tissue and higher standard deviations compared to the non-lesion tissue and control tissue in healthy controls. We hypothesize a biological (different degree of axonal loss and demyelination) rather than technical origin. Conclusion In this study, we applied 5 MR contrasts including two novel sequences to investigate the contrast of highest sensitivity for early MS diagnosis. In addition, we characterized for the first time the T1 relaxation time in cortical and sub-cortical regions of the hemispheres and the cerebellum. Results are in agreement with previous publications and meaningful biological interpretation of the data.

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Altruism is a deep and complex phenomenon that is analysed by scholars of various disciplines, including psychology, philosophy, biology, evolutionary anthropology and experimental economics. Much confusion arises in current literature because the term altruism covers variable concepts and processes across disciplines. Here we investigate the sense given to altruism when used in different fields and argumentative contexts. We argue that four distinct but related concepts need to be distinguished: (a) psychological altruism, the genuine motivation to improve others' interests and welfare; (b) reproductive altruism, which involves increasing others' chances of survival and reproduction at the actor's expense; (c) behavioural altruism, which involves bearing some cost in the interest of others; and (d) preference altruism, which is a preference for others' interests. We show how this conceptual clarification permits the identification of overstated claims that stem from an imprecise use of terminology. Distinguishing these four types of altruism will help to solve rhetorical conflicts that currently undermine the interdisciplinary debate about human altruism.