968 resultados para Regression-analysis
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PURPOSE: To describe the safety, complications, and liver regeneration associated with the left liver after embolization of the right portal vein (PV) in patients with hepatocellular carcinoma (HCC) developed in the setting of advanced liver fibrosis and cirrhosis. MATERIALS AND METHODS: Forty patients (31 men, nine women; mean age, 62 years) with HCC underwent PV embolization over a 4-year period. Embolization was performed from a left PV percutaneous access with use of n-butyl cyanoacrylate (NBCA) mixed with iodized oil. Computed tomography (CT) volumetry was performed before and 1 month after PV embolization to measure the left lobe volume as well as the functional liver ratio defined by the ratio between the left lobe and the total liver volume minus tumoral volume. PV pressure and liver enzyme levels were compared before and 1 month after the procedure and complications were registered. Factors potentially affecting regeneration (age, sex, diabetes, chemoembolization, functional liver ratio before PV embolization, and Knodell histologic score) were evaluated by one-way and stepwise regression analysis. RESULTS: PV embolization could be achieved successfully in all cases. Two patients had partial PV thrombosis on the 1-month follow-up CT and two patients developed transient ascites after PV embolization. The left lobe volume increase was 41% +/- 32% after PV embolization and the functional liver ratio increased from 28% +/- 10% to 36% +/- 10% (P < .0001). Hypertrophy of the left lobe was greater in patients with a low functional liver ratio before PV embolization and those with an F3 fibrosis score. Other factors had no influence on left lobe regeneration. CONCLUSION: PV embolization with use of NBCA is feasible in patients with advanced fibrosis and cirrhosis. Hypertrophy of the left lobe of the liver after PV embolization has a statistically significant correlation with lower functional liver ratio and lower degrees of fibrosis.
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OBJECTIVE: Mild neurocognitive disorders (MND) affect a subset of HIV+ patients under effective combination antiretroviral therapy (cART). In this study, we used an innovative multi-contrast magnetic resonance imaging (MRI) approach at high-field to assess the presence of micro-structural brain alterations in MND+ patients. METHODS: We enrolled 17 MND+ and 19 MND- patients with undetectable HIV-1 RNA and 19 healthy controls (HC). MRI acquisitions at 3T included: MP2RAGE for T1 relaxation times, Magnetization Transfer (MT), T2* and Susceptibility Weighted Imaging (SWI) to probe micro-structural integrity and iron deposition in the brain. Statistical analysis used permutation-based tests and correction for family-wise error rate. Multiple regression analysis was performed between MRI data and (i) neuropsychological results (ii) HIV infection characteristics. A linear discriminant analysis (LDA) based on MRI data was performed between MND+ and MND- patients and cross-validated with a leave-one-out test. RESULTS: Our data revealed loss of structural integrity and micro-oedema in MND+ compared to HC in the global white and cortical gray matter, as well as in the thalamus and basal ganglia. Multiple regression analysis showed a significant influence of sub-cortical nuclei alterations on the executive index of MND+ patients (p = 0.04 he and R(2) = 95.2). The LDA distinguished MND+ and MND- patients with a classification quality of 73% after cross-validation. CONCLUSION: Our study shows micro-structural brain tissue alterations in MND+ patients under effective therapy and suggests that multi-contrast MRI at high field is a powerful approach to discriminate between HIV+ patients on cART with and without mild neurocognitive deficits.
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Objective: To assess the relationship between parental occupational exposure to organic solvents, and the risk of anencephaly in Mexico. Methods: A case-control study was conducted based on the registers of the Epidemiological Surveillance System for Neural Tube Defects in Mexico; 151 cases of anencephaly of ≥20 weeks’ gestation were included. A control, born alive and without any apparent congenital malformations at birth, was selected for each case in the same maternity service in which the case was born. Information on occupational exposures, lifestyle habits, reproductive history, use of medicines, supplementation with multivitamins and folic acid, was obtained by a general questionnaire; a food frequency questionnaire was also applied to obtain information of daily intake of folate and other B vitamins. Occupational exposure to organic solvents was based on job title as a proxy for exposure and analysed considering two critical periods around conception. Results: In logistic regression analysis, the odds of having a child with anencephaly was higher if the mother or the father was occupationally exposed to organic solvents during the periconceptional period, or when both parents or at least one of them were occupationally exposed during this period with an adjusted odds ratio of 2.97 (95% CI 1.36 to 6.52). Conclusions: The results support the hypothesis that both maternal and paternal occupational exposure to organic solvents can increase the probability of having a child with anencephaly.
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Background: Cardiovascular diseases are ranked among the leading causes of death in the industrialized countries. This study is aimed at ascertaining the mortality trends by ischemic heart disease (IHD) and cerebrovascular diseases (CVD) in Andalusia within the 1975-2004 period. Method: Based on the official IHD and CVD death statistics and the related populations, the gross rates (GR) and age-adjusted rates (TS) and the Potential Years of Life Lost (PYLL) were calculated. To quantify the trends and their change points, a joinpoint regression analysis was made. Results: The number of IHD deaths for females rose from 2,086 deaths in 1975 to 3,336 in 2004, the TS having dropped from 74.29 to 50.94 deaths/100,000 females, the PYLL having dropped from 173.65 years to 90.56 years/100,000 females. The number of deaths for males rose from 2,854 deaths in 1975 to 4,085 in 2004, the TS having dropped from 147, 67 to 104.96 deaths /100,000 males. The PYLL showed a like behaviour from the first to the last year of the series, showing values of 716.46 and 460.04 years / 100,000 males. For the IHD in females, the number of deaths in absolute numbers dropped from 4,712 to 4,221, the TS having dropped from 166.00 to 62.08 deaths in females, and the PYLL from 338.08 to 87.63 years / 100,000 females. For males, the number of deaths dropped from 3,714 to 2,951, the TS from 206.88 deaths /100,000 males in 1975 to 76.12 /100,000 males in 2004, and the PYLL dropping from 533.12 to 182.38 years / 100,000 males. Conclusions: The trend in mortality due to IHD was not constant either among females or males, although it has always been a downward trend, the drop being statistically significant. The drop in the CVD has been such a major one that both the absolute numbers and the gross rates are lower for the most recent years that the first years in the series studied despite the aging of Andalusia’s population.
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In contrast to some extensively examined food mutagens, for example, aflatoxins, N-nitrosamines and heterocyclic amines, some other food contaminants, in particular polycyclic aromatic hydrocarbons (PAH) and other aromatic compounds, have received less attention. Therefore, exploring the relationships between dietary habits and the levels of biomarkers related to exposure to aromatic compounds is highly relevant. We have investigated in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort the association between dietary items (food groups and nutrients) and aromatic DNA adducts and 4-aminobiphenyl-Hb adducts. Both types of adducts are biomarkers of carcinogen exposure and possibly of cancer risk, and were measured, respectively, in leucocytes and erythrocytes of 1086 (DNA adducts) and 190 (Hb adducts) non-smokers. An inverse, statistically significant, association has been found between DNA adduct levels and dietary fibre intake (P = 0·02), vitamin E (P = 0·04) and alcohol (P = 0·03) but not with other nutrients or food groups. Also, an inverse association between fibre and fruit intake, and BMI and 4-aminobiphenyl-Hb adducts (P = 0·03, 0·04, and 0·03 respectively) was observed. After multivariate regression analysis these inverse correlations remained statistically significant, except for the correlation adducts v. fruit intake. The present study suggests that fibre intake in the usual range can modify the level of DNA or Hb aromatic adducts, but such role seems to be quantitatively modest. Fibres could reduce the formation of DNA adducts in different manners, by diluting potential food mutagens and carcinogens in the gastrointestinal tract, by speeding their transit through the colon and by binding carcinogenic substances.
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OBJECTIVES: To test whether the Global Positioning System (GPS) could be potentially useful to assess the velocity of walking and running in humans. SUBJECT: A young man was equipped with a GPS receptor while walking running and cycling at various velocity on an athletic track. The speed of displacement assessed by GPS, was compared to that directly measured by chronometry (76 tests). RESULTS: In walking and running conditions (from 2-20 km/h) as well as cycling conditions (from 20-40 km/h), there was a significant relationship between the speed assessed by GPS and that actually measured (r = 0.99, P < 0.0001) with little bias in the prediction of velocity. The overall error of prediction (s.d. of difference) averaged +/-0.8 km/h. CONCLUSION: The GPS technique appears very promising for speed assessment although the relative accuracy at walking speed is still insufficient for research purposes. It may be improved by using differential GPS measurement.
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BACKGROUND Available screening tests for dementia are of limited usefulness because they are influenced by the patient's culture and educational level. The Eurotest, an instrument based on the knowledge and handling of money, was designed to overcome these limitations. The objective of this study was to evaluate the diagnostic accuracy of the Eurotest in identifying dementia in customary clinical practice. METHODS A cross-sectional, multi-center, naturalistic phase II study was conducted. The Eurotest was administered to consecutive patients, older than 60 years, in general neurology clinics. The patients' condition was classified as dementia or no dementia according to DSM-IV diagnostic criteria. We calculated sensitivity (Sn), specificity (Sp) and area under the ROC curves (aROC) with 95% confidence intervals. The influence of social and educational factors on scores was evaluated with multiple linear regression analysis, and the influence of these factors on diagnostic accuracy was evaluated with logistic regression. RESULTS Sixteen neurologists recruited a total of 516 participants: 101 with dementia, 380 without dementia, and 35 who were excluded. Of the 481 participants who took the Eurotest, 38.7% were totally or functionally illiterate and 45.5% had received no formal education. Mean time needed to administer the test was 8.2+/-2.0 minutes. The best cut-off point was 20/21, with Sn = 0.91 (0.84-0.96), Sp = 0.82 (0.77-0.85), and aROC = 0.93 (0.91-0.95). Neither the scores on the Eurotest nor its diagnostic accuracy were influenced by social or educational factors. CONCLUSION This naturalistic and pragmatic study shows that the Eurotest is a rapid, simple and useful screening instrument, which is free from educational influences, and has appropriate internal and external validity.
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Interaction effects are usually modeled by means of moderated regression analysis. Structural equation models with non-linear constraints make it possible to estimate interaction effects while correcting formeasurement error. From the various specifications, Jöreskog and Yang's(1996, 1998), likely the most parsimonious, has been chosen and further simplified. Up to now, only direct effects have been specified, thus wasting much of the capability of the structural equation approach. This paper presents and discusses an extension of Jöreskog and Yang's specification that can handle direct, indirect and interaction effects simultaneously. The model is illustrated by a study of the effects of an interactive style of use of budgets on both company innovation and performance
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Several methods have been suggested to estimate non-linear models with interaction terms in the presence of measurement error. Structural equation models eliminate measurement error bias, but require large samples. Ordinary least squares regression on summated scales, regression on factor scores and partial least squares are appropriate for small samples but do not correct measurement error bias. Two stage least squares regression does correct measurement error bias but the results strongly depend on the instrumental variable choice. This article discusses the old disattenuated regression method as an alternative for correcting measurement error in small samples. The method is extended to the case of interaction terms and is illustrated on a model that examines the interaction effect of innovation and style of use of budgets on business performance. Alternative reliability estimates that can be used to disattenuate the estimates are discussed. A comparison is made with the alternative methods. Methods that do not correct for measurement error bias perform very similarly and considerably worse than disattenuated regression
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Objective: Microalbuminuria (MAU) is a marker of early kidney injury and cardiovascular risk. We assessed the association of MAU with plasma adiponectin, leptin and hsCRP, as inflammatory markers, accounting for hypertension, diabetes and obesity. Design and methods: Population based, cross-sectional study in Caucasian subjects aged 35 to 75 years in Lausanne, Switzerland. MAU, measured on spot morning urine, was used either as a continuous (MAU) or dichotomized variable (MA defined as MAU >2.5 and >3.5 mg/mmol creatinine in men and women, respectively). Results: The 2955 women (age 53.3 ± 10.7, mean ± SD years) had mean body mass index (BMI) 24.9 ± 4.5 kg/m. The 2479 men (age 53.1 ± 10.8 years) had mean BMI 27.0 ± 3.9 kg/m². Median hsCRP was 1.3 and 1.3 mg/L, median adiponectin 6.2 and 10.6 mg/mL in men and women, respectively. MA prevalence was 4.9% in women and 9.8% in men. In multivariate regression analysis adjusting for potential confounders (age, sex, hypertension, diabetes, eGFR, BMI, percent fat mass, insulin and smoking), log-transformed MAU was positively associated with hsCRP (P <0.001) and adiponectin (P = 0.002), but not with leptin. The association of adiponectin with MAU was stronger in subjects with low hsCRP, and vice versa (P interaction <0.001). Conclusion: Adiponectin and hsCRP are significant positive determinants of MAU, independently of diabetes, hypertension and fat mass. A negative interaction between hsCRP and adiponectin was found for their effect on MAU. Whether hyperadiponectinemia represents an adequate protective response to vascular stress or has negative causal impact on the development of MAU should be assessed in further studies.
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BACKGROUND Increasing trend and geographical variations in the use of caesarean section suggest the influence of non-clinical factors. The objective was to describe the use of caesarean section in the Andalusian region in Spain by exploring the role of social, clinical, and health services variables. METHODS A cross-sectional study was carried out using vital statistics. It involves all births occurred in Andalusia during the period of 2007-2009. The dependent variable was the use of caesarean section and the set of covariates were classified into three groups: those with a clinical meaning, those related to the health services organization, and those with a social significance. Multivariate logistic regressions were used. RESULTS In the data set of 293,558 births, the prevalence of caesarean delivery was 24.8%. The multivariate analysis highlights the labour complications as the clinical variable with the highest odds ratio (OR=19.36). Regarding the health services variables, the odds of experiencing a caesarean delivery were 55% higher on weekdays than on weekends. Cádiz was the province with the highest OR for caesarean section (comparison between Cádiz and Almería: OR=1,21) where the ratio between births in public and private hospitals was 3.7. The frequency of caesarean section was 34% higher in women with third level education than those with no education. CONCLUSIONS Labour complication is the most influential variable for caesarean section. Caesarean birth rate is above the accepted standards for all social classes and increases with educational level. Inter-provincial differences reflect different patterns with regard to the use of private medicine.
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BACKGROUND: Positron emission tomography (PET) during the cold pressor test (CPT) has been used to assess endothelium-dependent coronary vasoreactivity, a surrogate marker of cardiovascular events. However, its use remains limited by cardiac PET availability. As multidetector computed tomography (MDCT) is more widely available, we aimed to develop a measurement of endothelium-dependent coronary vasoreactivity with MDCT and similar radiation burden as with PET. METHODS AND RESULTS: A study group of 18 participants without known cardiovascular risk factor (9F/9M; age 60±6 years) underwent cardiac PET with (82)Rb and unenhanced ECG-gated MDCT within 4h, each time at rest and during CPT. The relation between absolute myocardial blood flow (MBF) response to CPT by PET (ml·min(-1)·g(1)) and relative changes in MDCT-measured coronary artery surface were assessed using linear regression analysis and Spearman's correlation. MDCT and PET/CT were analyzed in all participants. Hemodynamic conditions during CPT at MDCT and PET were similar (P>0.3). Relative changes in coronary artery surface because of CPT (2.0-21.2%) correlated to changes in MBF (-0.10-0.52ml·min(-1)·g(1)) (ρ=0.68, P=0.02). Effective dose was 1.3±0.2mSv for MDCT and 3.1mSv for PET/CT. CONCLUSIONS: Assessment of endothelium-dependent coronary vasoreactivity using MDCT CPT appears feasible. Because of its wider availability, shorter examination time and similar radiation burden, MDCT could be attractive in clinical research for coronary status assessment.
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BACKGROUND: Knowledge of the number of recent HIV infections is important for epidemiologic surveillance. Over the past decade approaches have been developed to estimate this number by testing HIV-seropositive specimens with assays that discriminate the lower concentration and avidity of HIV antibodies in early infection. We have investigated whether this "recency" information can also be gained from an HIV confirmatory assay. METHODS AND FINDINGS: The ability of a line immunoassay (INNO-LIA HIV I/II Score, Innogenetics) to distinguish recent from older HIV-1 infection was evaluated in comparison with the Calypte HIV-1 BED Incidence enzyme immunoassay (BED-EIA). Both tests were conducted prospectively in all HIV infections newly diagnosed in Switzerland from July 2005 to June 2006. Clinical and laboratory information indicative of recent or older infection was obtained from physicians at the time of HIV diagnosis and used as the reference standard. BED-EIA and various recency algorithms utilizing the antibody reaction to INNO-LIA's five HIV-1 antigen bands were evaluated by logistic regression analysis. A total of 765 HIV-1 infections, 748 (97.8%) with complete test results, were newly diagnosed during the study. A negative or indeterminate HIV antibody assay at diagnosis, symptoms of primary HIV infection, or a negative HIV test during the past 12 mo classified 195 infections (26.1%) as recent (< or = 12 mo). Symptoms of CDC stages B or C classified 161 infections as older (21.5%), and 392 patients with no symptoms remained unclassified. BED-EIA ruled 65% of the 195 recent infections as recent and 80% of the 161 older infections as older. Two INNO-LIA algorithms showed 50% and 40% sensitivity combined with 95% and 99% specificity, respectively. Estimation of recent infection in the entire study population, based on actual results of the three tests and adjusted for a test's sensitivity and specificity, yielded 37% for BED-EIA compared to 35% and 33% for the two INNO-LIA algorithms. Window-based estimation with BED-EIA yielded 41% (95% confidence interval 36%-46%). CONCLUSIONS: Recency information can be extracted from INNO-LIA-based confirmatory testing at no additional costs. This method should improve epidemiologic surveillance in countries that routinely use INNO-LIA for HIV confirmation.
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BACKGROUND. Exposure to xenoestrogens during pregnancy may disturb the development and function of male sexual organs. OBJECTIVE. In this study we aimed to determine whether the combined effect of environmental estrogens measured as total effective xenoestrogen burden (TEXB) is a risk factor for male urogenital malformations. METHODS. In a case-control study, nested in a mother-child cohort (n = 702) established at Granada University Hospital, we compared 50 newborns with diagnosis of cryptorchidism and/or hypospadias with 114 boys without malformations matched by gestational age, date of birth, and parity. Controls did not differ from the total cohort in confounding variables. TEXB and levels of 16 organochlorine pesticides were measured in placenta tissues. Characteristics of parents, pregnancy, and birth were gathered by questionnaire. We used conditional and unconditional regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS. TEXB from organohalogenated compounds was detectable in 72% and 54% of case and control placentas, respectively. Compared with controls, cases had an OR for detectable versus non-detectable TEXB of 2.82 (95% CI, 1.10-7.24). More pesticides were detected in cases than in controls (9.34 +/- 3.19 vs. 6.97 +/- 3.93). ORs for cases with detectable levels of pesticides, after adjusting for potential confounders in the conditional regression analysis, were o,p'-DDT (OR = 2.25; 95% CI, 1.03-4.89), p,p'-DDT (OR = 2.63; 95% CI, 1.21-5.72), lindane (OR = 3.38; 95% CI, 1.36-8.38), mirex (OR = 2.85; 95% CI, 1.22-6.66), and endosulfan alpha (OR = 2.19; 95% CI, 0.99-4.82). Engagement of mothers in agriculture (OR = 3.47; 95% CI, 1.33-9.03), fathers' occupational exposure to xenoestrogens (OR = 2.98; 95% CI, 1.11-8.01), and history of previous stillbirths (OR = 4.20; 95% CI, 1.11-16.66) were also associated with risk of malformations. CONCLUSIONS We found an increased risk for male urogenital malformations related to the combined effect of environmental estrogens in placenta.
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Levels of circulating cardiac troponin I (cTnI) or T are correlated to extent of myocardial destruction after an acute myocardial infarction. Few studies analyzing this relation have employed a second-generation cTnI assay or cardiac magnetic resonance (CMR) as the imaging end point. In this post hoc study of the Efficacy of FX06 in the Prevention of Mycoardial Reperfusion Injury (F.I.R.E.) trial, we aimed at determining the correlation between single-point cTnI measurements and CMR-estimated infarct size at 5 to 7 days and 4 months after a first-time ST-elevation myocardial infarction (STEMI) and investigating whether cTnI might provide independent prognostic information regarding infarct size at 4 months even taking into account early infarct size. Two hundred twenty-seven patients with a first-time STEMI were included in F.I.R.E. All patients received primary percutaneous coronary intervention within 6 hours from onset of symptoms. cTnI was measured at 24 and 48 hours after admission. CMR was conducted within 1 week of the index event (5 to 7 days) and at 4 months. Pearson correlations (r) for infarct size and cTnI at 24 hours were r = 0.66 (5 days) and r = 0.63 (4 months) and those for cTnI at 48 hours were r = 0.67 (5 days) and r = 0.65 (4 months). In a multiple regression analysis for predicting infarct size at 4 months (n = 141), cTnI and infarct location retained an independent prognostic role even taking into account early infarct size. In conclusion, a single-point cTnI measurement taken early after a first-time STEMI is a useful marker for infarct size and might also supplement early CMR evaluation in prediction of infarct size at 4 months.