Synthesis Analysis of Regression Models with a Continuous Outcome

Synthesis Analysis of Regression Models with a Continuous Outcome Xiao-Hua Zhou 1,2, Nan Hu 2, Guizhou Hu3, and Martin Root3 1 HSR&D Center of Excellence, VA Puget Sound Health Care System, Seattle, WA 98101. 2 Department of Biostatistics, University of Washington, Seattle, WA 98195. 3 BioSignia, Inc., 1822 East NC Highway 54, Suite 350, Durham, NC 27713 To estimate the multivariate regression model from multiple individual studies, it would be challenging to obtain results if the input from individual studies only provide univariate or incomplete multivariate regression information. Samsa et al [1] proposed a simple method to combine coefficients from univariate linear regression models into a multivariate linear regression model, a method known as synthesis analysis. However, the validity of this method relies on the normality assumption of the data, and it does not provide variance estimates. In this paper we propose a new synthesis method that improves on the existing synthesis method by eliminating the normality assumption, reducing bias, and allowing for the variance estimation of the estimated parameters

Effective Action Method for Computing Next to Leading Corrections of O(N)O(N) Models

We compute the corrections of next to leading order in the ${1 \over N}$ expansion to the effective potential of a system described by a Ginzburg-Landau model with $N$ components and quartic interaction, in the case of spontaneous symmetry breaking. The method we apply allows to generalize in a simple way the so-called Self-Consistent Screened Approximation (SCSA).Comment: p. 8, LATEX, DFF 193/9/199

A randomized trial of fish oil omega-3 fatty acids on arterial health, inflammation, and metabolic syndrome in a young healthy population

BACKGROUND: Long chain omega-3 fatty acids from fish oils (O3) are known to have beneficial effects on a number of vascular risk factors in at-risk populations. The effects of a highly bioavailable emulsified preparation on an overweight young adult population are less well known. METHODS: Young adults, age 18–30, with body mass indices (BMIs) greater than 23 (average = 28.1) were administered 1.7 g of O3 per day (N = 30) or safflower oil placebo (N = 27) in an emulsified preparation (Coromega, Inc.) for 4 weeks in a double-blind randomized design. Blood was drawn and anthropometric measurements taken before and after dosing. Hemodynamic measures (central pulse wave velocity, augmentation index, and aortic systolic blood pressure), inflammatory cytokines (IL-6, IL-8, IL-10, and tumor necrosis factor-α), red blood cell and plasma phospholipid fatty acid profiles, fasting serum lipids, glucose, and C-reactive protein were measured. RESULTS: Red cell and plasma phospholipid eicosapentaenoic acid and docosahexaenoic acid concentrations increased over the four weeks of dosing in the O3 group. Dosing with O3 did not affect central pulse wave velocity, augmentation index, or aortic systolic blood pressure. None of the five American Heart Association metabolic syndrome components improved over the dosing period. None of the inflammatory cytokines, C-reactive protein, or lipids (total or LDL cholesterol) improved over the dosing period. CONCLUSIONS: No salutary effects of O3 were observed in hemodynamic, metabolic syndrome criteria or inflammatory markers as a result of this relatively short period of administration in this relatively overweight, but healthy young adult cohort

Combining Information From Multiple Data Sources to Create Multivariable Risk Models: Illustration and Preliminary Assessment of a New Method

A common practice of metanalysis is combining the results of numerous studies on the effects of a risk factor on a disease outcome. If several of these composite relative risks are estimated from the medical literature for a specific disease, they cannot be combined in a multivariate risk model, as is often done in individual studies, because methods are not available to overcome the issues of risk factor colinearity and heterogeneity of the different cohorts. We propose a solution to these problems for general linear regression of continuous outcomes using a simple example of combining two independent variables from two sources in estimating a joint outcome. We demonstrate that when explicitly modifying the underlying data characteristics (correlation coefficients, standard deviations, and univariate betas) over a wide range, the predicted outcomes remain reasonable estimates of empirically derived outcomes (gold standard). This method shows the most promise in situations where the primary interest is in generating predicted values as when identifying a high-risk group of individuals. The resulting partial regression coefficients are less robust than the predicted values

A-CAST: Entwicklung eines Plugin-basierten Tools zur Unfallanalyse mit CAST (Causal Accident Analysis)

Unfälle sind auch in der heutigen Zeit keine Seltenheit. Bei sicherheitskritischen Systemen kann ein Unfall viele Menschenleben kosten. Deshalb sollte aus bereits geschehenen Unfällen gelernt werden. Durch eine Analyse solcher lassen sich mögliche zukünftige Unfälle vermeiden. Eine neue Methode für die Unfallanalyse ist der CAST-Ansatz, welcher auf dem STAMP-Modell basiert. Im Zuge dieser Arbeit wird ein Tool entwickelt, dass die Funktionen der CAST Analyse implementiert und so eine Unterstützung für die Analyse von Unfällen bieten soll

Vitamin A and carotenoid status in rural China

Vitamin A status of 260 groups of twenty five males or twenty five females, aged 3 years,surveyed in twenty four provinces of the People's Republic of China, was assessed by. measuringplasma retinol, retinol binding protein and fl-carotene concentrations. Direct measurements of foodintake over a 3 d period and questionnaire data on the frequency of consumption ofvegetables, fruits,animal products and <lther dietary items were also used. Vitamin A status appeared to be low only inspecific counties but in general was satisfactory or only marginally deficient. Plasma JI-carotene levelswere strikingly low in comparison with Western levels despite generous vegetable consumptionsuggests that intake of vitamin A precursors may have been adequate but not abundant enough tomaintain high circulating plasma levels of fl-carotene. Plasma fl-carotene, for both males and females,was significantly correlated with the frequency of consumption of green vegetables. Plasma retinol, formales, was highly correlated with meat, fish, oil and alcohol consumption expressed both in quantity orfrequency of consumption. Higher levels of plasma retinol, together with lower levels of plasma JIcarotenein males compared with females, suggest that men consume more animal products or mayhave higher retinol requirements and therefore a higher rate of conversion of JI-carotene to retinol

Healthy Eating Index 2005 and selected macronutrients are correlated with improved lung function in humans

A number of dietary components have been associated with lung function. However, a comprehensive measure of a healthy diet has not been compared with lung function. Herein, we test the hypothesis that a healthy overall diet, as assessed by the Healthy Eating Index 2005 (HEI-2005), will be associated with increased lung function. This is an investigation using the Atherosclerosis Risk in Communities Research Materials obtained from the National Heart Lung Blood Institute. The study surveyed dietary habits of 15 567 American subjects from 4 communities in 1987 to1990. Spirometric measures of lung function were also taken at entry to the study and a second time 3 years later.Based on food and nutritional data collected by food frequency questionnaire, an HEI-2005 score was calculated for each subject. This total score, together with its 12 components scores and associated macronutrient, was compared with lung function results by linear regression. Models were controlled for smoking behavior, demographics, and other important covariates. The HEI-2005 total scores were positively associated with forced expiratory volume in 1 second per forced vital capacity (FEV(1)/FVC) at visit 1 (ß = .101 per increase in 1 quintile of HEI-2005) and visit 2 (ß = .140), and FEV(1) as percentage of the predicted FEV(1) at visit 2 (ß = .215) (P < .05). In addition, HEI-2005component scores that represented high intakes of whole grains (ß = .127 and .096); saturated fats (ß = -.091); and solid fats, alcohol, and added sugar (ß = -.109 and -.131) were significantly associated with FEV(1)/FVC at either visit 1 or visit 2. Intakes of total calories (ß =-.082 at visit 1) and saturated fatty acids (ß = -.085 at visit 2) werenegatively associated with FEV(1)/FVC. Dietary polyunsaturated fatty acids (ß = .085 and .116) and long-chain omega-3 fatty acids (ß = .109 and .103), animal protein (ß = .132 and .093), and dietary fiber (ß = .129) were positively associated with lung health. An overall healthy diet is associated with higher lung functio

Use of an Improved Method for Analysis of Urinary Aflatoxin M 1 in a Survey of Mainland China and Taiwan

An improved monoclonal antibody immunoaffinity chromatography/high-pressure liquid chromatography/ftuorescence detection method was developed to measure aftatoxin (AF) exposure by quantifying AFM 1 inhuman and rat urine samples.Analysis of different amounts of various AF metabolites showed that the immunoaffinity resin was highlyselective for aftatoxin 81 (AFB1), AFB2, and AFM 1• Recovery of added AFs increased with the amount of immunoaffinity resin and was virtually complete within the range of 0.01-10 ng of AFM 1 by using 7 ml of resin. The detection limit of this method is 0.5 pglml urine. Rats dosed with tritiated AFB 1 excreted in their urine tritiated AFM., among other AF metabolites, as indicated by chemical derivative confirmation and cochromatography with authentic AFM 1 and agreement of radioactivity and ftuorescence quantitation. Alinear dose-response relationship was found over the range of 0.05-50 p.glkg of body weight/day. Two humans dosed with 1.0 µ.g of pure AFB 1 excreted 6-7% of the dose asurinary AFM 1 over 5-7 days. Pooled urine samples from 30 men from each of 69 rural counties in mainland China and 16 survey areas in Taiwan, with two villages per county or area, were analyzed with this improved method (170 villages total). The correlationcoefficient of urinary excretion of AFM 1 compared between villages within all 85 survey areas was 0.50 (P <0.001). Sixty-five % of the samples contained detectable concentrations of AFM 1 with an average excretion of 3.1 ng/12 h. Assuming an excretion rate of 2-6%, this AFM 1 excretion corresponds to a very low average daily AF consumption of 0.1-0.3 p.g/day (possible range, 0-11 p.g/day). Patterns of urinary excretion of AFM 1 were similar in mainland China and Taiwa

Flavonol Intake and Cognitive Decline in Middle-Aged Adults

Cognitive decline occurs with age and may be slowed by dietary measures, including increased intake of dietary phytochemicals. However, evidence from large and long-term studies of flavonol intake is limited. Dietary intakes of flavonols were assessed from a large biracial study of 10,041 subjects, aged 45–64, by analysis of a food frequency ques tionnaire administered at visit 1 of triennial visits.Cognitive function was assessed at visits 2 and 4 with the following three cognitive performance tests: the delayed word recall test, the revised Wechsler Adult Intelligence Scale digit symbol subtest, and the word fluency test of the Multilingual Aphasia Examination. The change in each score over 6 years was calculated, and a combined standardized change score was calculated. Generalized linear models controlled for age, ethnicity, gender, education level, energy intake, current smoking, physical activity,body mass index, diabetes, and vitamin C intake. Total flavonols across quintiles of intake were positively associated with preserved combined cognitive function (P < .001). This pattern with preserved combined cognitive function was consistent for the three major individual flavonols in the diet, myricetin, kaempferol, and quercetin (each P < .001). The positive association with total flavonols was strongest for the digit symbol subtest (P < .001). In this cohort, flavonol intake was correlated with protected cognitive function over tim

Breast cancer and dietary and plasma concentrations of carotenoids and vitamin A

A case-control study of breast cancer was conducted inBuffalo. Participants completed a food frequency questionnaire and donateda fasting blood sample before definitiveworkup for breast masses. Dietaryand plasma concentrationsof carotenoids and retinol for 83 women foundto have breast cancer were compared with those of 1 13 women found to befree of breast cancer (control subjects). There were no case-controldifferences in dietary estimates of vitamin A intakeor in plasma a-caroteneand lycopene. However, subjects with breast cancer had lower concentrationsof plasma fj-carotene than did control subjects (P = 0.02). There was nooverall association between plasma retinol and breast cancer but a positiverelationship was observed between retinol and breast cancerin thesubgroup with low fj-carotene values. These results suggest that low plasmafj-carotene is associated with increased risk of breast cancer. Other studieswill need to determine whether low carotene concentrations are a subtleeffect of the disease or might be causally related to breast cance