30 resultados para Mixed-effect models


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To compare the effects of three screen-based sedentary behaviours on acute energy intake (EI) in children. Normal-weight males aged 9-13 years participated in a randomised crossover trial conducted in a laboratory setting between November 2012 and February 2013 in Auckland, New Zealand. EI during an ad libitum meal was compared for three 1-hour conditions: (1) television (TV) watching, (2) sedentary video game (VG) play, and (3) recreational computer use. The primary endpoint was total EI from food and drink. Mixed regression models were used to evaluate the treatment conditions adjusting for age, BMI, and appetite at baseline. A total of 20 participants were randomised and all completed the three conditions. Total EI from food and drink in the TV, computer, and VG conditions was estimated at 820 (SE 73.15), 685 (SE 73.33), and 696 (SE 73.16) kcal, respectively, with EI being significantly greater in the TV versus computer condition (+135; P = 0.04), a trend towards greater intake in the TV versus VG condition (+124; P = 0.06), but not significantly different between the computer and VG conditions (-10; P = 0.87). TV watching was associated with greater EI compared with computer use, and a trend towards greater EI compared with VG play.

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Risk variants of fat mass and obesity-associated (FTO) gene have been associated with increased obesity. However, the evidence for associations between FTO genotype and macronutrient intake has not been reviewed systematically. Our aim was to evaluate the potential associations between FTO genotype and intakes of total energy, fat, carbohydrate and protein. We undertook a systematic literature search in OVID MEDLINE, Scopus, EMBASE and Cochrane of associations between macronutrient intake and FTO genotype in adults. Beta coefficients and confidence intervals (CIs) were used for per allele comparisons. Random-effect models assessed the pooled effect sizes. We identified 56 eligible studies reporting on 213,173 adults. For each copy of the FTO risk allele, individuals reported 6.46 kcal day(-1) (95% CI: 10.76, 2.16) lower total energy intake (P = 0.003). Total fat (P = 0.028) and protein (P = 0.006), but not carbohydrate intakes, were higher in those carrying the FTO risk allele. After adjustment for body weight, total energy intakes remained significantly lower in individuals with the FTO risk genotype (P = 0.028). The FTO risk allele is associated with a lower reported total energy intake and with altered patterns of macronutrient intake. Although significant, these differences are small and further research is needed to determine whether the associations are independent of dietary misreporting.

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CONTEXT: Modifiable factors of health-related quality of life (HRQOL) are poorly described among children with advanced cancer. Symptom distress may be an important factor for intervention. OBJECTIVES: We aimed to describe patient-reported HRQOL and its relationship to symptom distress. METHODS: Prospective, longitudinal data from the multicenter Pediatric Quality of Life and Symptoms Technology study included primarily patient-reported symptom distress and HRQOL, measured at most weekly with the Memorial Symptoms Assessment Scale and Pediatric Quality of Life inventory, respectively. Associations were evaluated using linear mixed-effects models adjusting for sex, age, cancer type, intervention arm, treatment intensity, and time since disease progression. RESULTS: Of 104 enrolled patients, 49% were female, 89% were white, and median age was 12.6 years. Nine hundred and twenty surveys were completed over nine months of follow-up (84% by patients). The median total Pediatric Quality of Life score was 74 (interquartile range 63-87) and was "poor/fair" (e.g., <70) 38% of the time. "Poor/fair" categories were highest in physical (53%) and school (48%) compared to emotional (24%) and social (16%) subscores. Thirteen of 24 symptoms were independently associated with reductions in overall or domain-specific HRQOL. Patients commonly reported distress from two or more symptoms, corresponding to larger HRQOL score reductions. Neither cancer type, time since progression, treatment intensity, sex, nor age was associated with HRQOL scores in multivariable models. Among 25 children completing surveys during the last 12 weeks of life, 11 distressing symptoms were associated with reductions in HRQOL. CONCLUSION: Symptom distress is strongly associated with HRQOL. Future research should determine whether alleviating distressing symptoms improves HRQOL in children with advanced cancer.

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PURPOSE: There is ongoing controversy on the effectiveness of psychotherapy in inflammatory bowel disease (IBD). In the few small studies, cognitive-behavioural therapy (CBT) has been shown to alleviate symptoms of anxiety or depression. However, there is little research on the impact of CBT on physical outcomes in IBD and no studies on long-term effectiveness of CBT.

METHODS: The present two-arm pragmatic randomised controlled trial aimed to establish the impact of CBT on disease course after 24 months of observation. The study compared standard care plus CBT (+CBT) with standard care alone (SC). CBT was delivered over 10 weeks, face-to-face (F2F) or online (cCBT). The data were analysed using linear mixed-effects models.

RESULTS: CBT did not significantly influence disease activity as measured by disease activity indices at 24 months (Crohn's Disease Activity Index (CDAI), p = 0.92; Simple Clinical Colitis Activity Index (SCCAI), p = 0.88) or blood parameters (C-reactive protein (CRP), p < 0.62; haemoglobin (Hb), p = 0.77; platelet, p = 0.64; white cell count (WCC), p = 0.59) nor did CBT significantly affect mental health, coping or quality of life (all p > 0.05).

CONCLUSIONS: Therefore, we conclude that CBT does not influence the course of IBD over 24 months. Given the high rate of attrition, particularly in the CBT group, future trials should consider a personalised approach to psychotherapy, perhaps combining online and one-to-one therapist time.

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As marine management measures increasingly protect static areas of the oceans, it is important to make sure protected areas capture and protect persistent populations. Rocky reefs in many temperate areas worldwide serve as habitat for canopy-forming macroalgae and these structure-forming species of kelps (order Laminariales) often serve as important habitat for a great diversity of species. Macrocystis pyrifera is the most common canopy-forming kelp species found along the coast of California, but the distribution and abundance of M. pyrifera varies in space and time. The purpose of this study is to determine what environmental parameters are correlated with and their relative contribution to the spatial and temporal persistence of M. pyrifera along the central coast of California and how well those environmental parameters can be used to predict areas where this species is more likely to persist. Nine environmental variables considered in this study included depth of the seafloor, structure of the rocky reef, proportion of rocky reef, size of kelp patch, biomass of kelp within a patch, distance from the edge of a kelp patch, sea surface temperature, wave orbital velocities, and population connectivity of individual kelp patches. Using a generalized linear mixed effects model (GLMM), the persistence of M. pyrifera was significantly associated with seven of the nine variables considered: depth, complexity of the rocky reef, proportion of rock, patch biomass, distance from the edge of a patch, population connectivity, and wave orbital velocities. These seven environmental variables were then used to predict the persistence of kelp across the central coast, and these predictions were compared to a reserved dataset of M. pyrifera persistence, which was not used in the creation of the GLMM. The environmental variables were shown to accurately predict the persistence of M. pyrifera within the central coast of California (r = 0.71, P < 0.001). Because persistence of giant kelp is important to the community structure of kelp forests, understanding those factors that support persistent populations of M. pyrifera will enable more effective management of these ecosystems.

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BACKGROUND: Inflammatory processes and neural-immune interactions have been implicated in the pathogenesis of psychiatric conditions, but studies in bipolar disorder are inconclusive so far. We aimed to investigate whether peripheral concentrations of C-reactive protein (CRP), an acute-phase response protein of inflammatory activity, are increased in bipolar disorder across the mood spectrum. METHODS: In this systematic review and meta-analysis, we searched MEDLINE, the Cochrane Library, Scopus, and Web of Knowledge from database inception to Aug 14, 2016, for studies that measured serum and plasma CRP concentrations in adult patients with bipolar disorder (as defined by DSM-IV-TR) and healthy controls. We extracted data from published reports. We did three between-group meta-analyses comparing CRP concentrations in patients in mania, depression, or euthymia, with those in healthy controls (cross-sectional studies), and two within-group meta-analyses comparing changes in CRP concentrations before and after treatment of an index manic or depressive episode (longitudinal studies). We used Hedges' adjusted g to calculate effect sizes and pooled results using random-effect models. We also did meta-regression analyses by mood state to investigate possible moderators of CRP concentrations. FINDINGS: We identified 27 studies representing 2161 patients with bipolar disorder and 81 932 healthy controls. Compared with healthy individuals, CRP concentrations were moderately increased in people with bipolar disorder during depression (g 0·67, 95% CI 0·23 to 1·11; p=0·003) and euthymia (0·65, 0·40 to 0·90; p<0·0001) and more substantially increased during mania (0·87, 0·58 to 1·15; p<0·0001). The extent of the increases in CRP concentrations in mania and depression was not related to symptom severity (p=0·256 for mania and p=0·626 for depression). CRP concentrations were moderately decreased after resolution of an index manic episode (-0·36, -0·66 to -0·05; p=0·022) and slightly decreased after resolution of an index depressive episode (-0·18, -0·30 to -0·07; p=0·002). INTERPRETATION: CRP concentrations are increased in bipolar disorder regardless of mood state, but are higher during mania than in depression and euthymia, suggesting an increased inflammatory burden in mania.

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OBJECTIVE:  To assess the effect of the FTO genotype on weight loss after dietary, physical activity, or drug based interventions in randomised controlled trials.

DESIGN:  Systematic review and random effects meta-analysis of individual participant data from randomised controlled trials.

DATA SOURCES:  Ovid Medline, Scopus, Embase, and Cochrane from inception to November 2015.

ELIGIBILITY CRITERIA FOR STUDY SELECTION:  Randomised controlled trials in overweight or obese adults reporting reduction in body mass index, body weight, or waist circumference by FTO genotype (rs9939609 or a proxy) after dietary, physical activity, or drug based interventions. Gene by treatment interaction models were fitted to individual participant data from all studies included in this review, using allele dose coding for genetic effects and a common set of covariates. Study level interactions were combined using random effect models. Metaregression and subgroup analysis were used to assess sources of study heterogeneity.

RESULTS:  We identified eight eligible randomised controlled trials for the systematic review and meta-analysis (n=9563). Overall, differential changes in body mass index, body weight, and waist circumference in response to weight loss intervention were not significantly different between FTO genotypes. Sensitivity analyses indicated that differential changes in body mass index, body weight, and waist circumference by FTO genotype did not differ by intervention type, intervention length, ethnicity, sample size, sex, and baseline body mass index and age category.

CONCLUSIONS:  We have observed that carriage of the FTO minor allele was not associated with differential change in adiposity after weight loss interventions. These findings show that individuals carrying the minor allele respond equally well to dietary, physical activity, or drug based weight loss interventions and thus genetic predisposition to obesity associated with the FTO minor allele can be at least partly counteracted through such interventions.

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One major difficulty frustrating the application of linear causal models is that they are not easily adapted to cope with discrete data. This is unfortunate since most real problems involve both continuous and discrete variables. In this paper, we consider a class of graphical models which allow both continuous and discrete variables, and propose the parameter estimation method and a structure discovery algorithm based on Minimum Message Length and parameter estimation. Experimental results are given to demonstrate the potential for the application of this method.

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Background:
To describe the frequency of mixed specifier as proposed in DSM-5 in bipolar I patients with manic episodes, and to evaluate the effect of mixed specifier on symptom severity and treatment outcome.

Methods:
This post-hoc analysis used proxies for DSM-5 mixed features specifier by using MADRS or PANSS items.

Results:
Of the 960 patients analysed, 34%, 18% and 4.3% of patients, respectively, had ≥3 depressive features with mild (score ≥1 for MADRS items and ≥2 for PANSS item), moderate (score ≥2 MADRS, ≥3 PANSS) and severe (score ≥3 MADRS, ≥4 PANSS) symptoms. In patients with ≥3 depressive features and independent of treatment: MADRS remission (score ≤12) rate decreased with increasing severity (61–43%) and YMRS remission (score ≤12) was similar for mild and moderate patients (36–37%), but higher for severe (54%). In asenapine-treated patients, the MADRS remission rate was stable regardless of baseline depressive symptom severity (range 64–67%), whereas remission decreased with increasing severity with olanzapine (63–38%) and placebo (49–25%). Reduction in YMRS was significantly greater for asenapine compared with placebo at day 2 across the 3 severity cut-offs and continued to decrease throughout the treatment period. The difference between olanzapine and placebo was statistically significant in mild and moderate patients.

Limitations:
Results are from post-hoc analyses.

Conclusions:
These analyses support the validity of proposed DSM-5 criteria. They confirm that depressive features are frequent in bipolar patients with manic episodes. With increasing baseline severity of depressive features, treatment outcome was poorer with olanzapine and placebo, but remained stable with asenapine.

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Childhood cardiovascular risk factors affect vascular function long before overt cardiovascular disease. Twin studies provide a unique opportunity to examine the influence of shared genetic and environmental influences on childhood cardiovascular function. We examined the relationship between birth parameters, markers of adiposity, insulin resistance, lipid profile and blood pressure and carotid-femoral pulse wave velocity (PWV), a validated non-invasive measure of arterial stiffness in a healthy cohort of school-aged twin children. PWV was performed on a population-based birth cohort of 147 twin pairs aged 7-11 years. Fasting blood samples, blood pressure and adiposity measures were collected concurrently. Mixed linear regression models were used to account for twin clustering, within- and between-twin pair associations. There were positive associations between both markers of higher adiposity, insulin resistance, elevated triglycerides and PWV, which remained significant after accounting for twin birth-set clustering. There was a positive association between both diastolic and mean arterial blood pressure and PWV in within-pair analysis in dizygotic, but not monozygotic twins, indicating genetic differences evident in dizygotic not monozygotic twins may affect these associations. Increased blood pressure, triglycerides and other metabolic markers are associated with increased PWV in school-aged twins. These results support both the genetic and environmental contribution to higher PWV, as a marker of arterial stiffness, and reiterate the importance of preventing metabolic syndrome from childhood.

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In this paper, we study the effect that different serial correlation adjustment methods can have on panel cointegration testing. As an example, we consider the very popular tests developed by Pedroni [Pedroni, P. (1999). Critical values for cointegration tests in heterogeneous panels with multiple regressors. Oxford Bulletin of Economics and Statistics 61, 653670., Pedroni, P. (2004). Panel cointegration: asymptotic and finite sample properties of pooled time series tests with an application to the PPP hypothesis. Econometric Theory 20, 597-625.]. Results based on both simulated and real data suggest that different adjustment methods can lead to significant variations in test outcome, and thus also in the conclusions. © 2007 Elsevier B.V. All rights reserved.

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Plantings of mixed native species (termed 'environmental plantings') are increasingly being established for carbon sequestration whilst providing additional environmental benefits such as biodiversity and water quality. In Australia, they are currently one of the most common forms of reforestation. Investment in establishing and maintaining such plantings relies on having a cost-effective modelling approach to providing unbiased estimates of biomass production and carbon sequestration rates. In Australia, the Full Carbon Accounting Model (FullCAM) is used for both national greenhouse gas accounting and project-scale sequestration activities. Prior to undertaking the work presented here, the FullCAM tree growth curve was not calibrated specifically for environmental plantings and generally under-estimated their biomass. Here we collected and analysed above-ground biomass data from 605 mixed-species environmental plantings, and tested the effects of several planting characteristics on growth rates. Plantings were then categorised based on significant differences in growth rates. Growth of plantings differed between temperate and tropical regions. Tropical plantings were relatively uniform in terms of planting methods and their growth was largely related to stand age, consistent with the un-calibrated growth curve. However, in temperate regions where plantings were more variable, key factors influencing growth were planting width, stand density and species-mix (proportion of individuals that were trees). These categories provided the basis for FullCAM calibration. Although the overall model efficiency was only 39-46%, there was nonetheless no significant bias when the model was applied to the various planting categories. Thus, modelled estimates of biomass accumulation will be reliable on average, but estimates at any particular location will be uncertain, with either under- or over-prediction possible. When compared with the un-calibrated yield curves, predictions using the new calibrations show that early growth is likely to be more rapid and total above-ground biomass may be higher for many plantings at maturity. This study has considerably improved understanding of the patterns of growth in different types of environmental plantings, and in modelling biomass accumulation in young (<25 years old) plantings. However, significant challenges remain to understand longer-term stand dynamics, particularly with temporal changes in stand density and species composition.

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Mixed monolayers of 1-octadecanol (C18OH) and ethylene glycol monooctadecyl ether (C18E1) were studied to assess their evaporation suppressing performance. An unexpected increase in performance and stability was found around the 0.5:0.5 bicomponent mixture and has been ascribed to a synergistic effect of the monolayers. Molecular dynamics simulations have attributed this to an additional hydrogen bonding interaction between the monolayer and water, due to the exposed ether oxygen of C18E1 in the mixed system compared to the same ether oxygen in the pure C18E1 system. This interaction is maximized around the 0.5:0.5 ratio due to the particular interfacial geometry associated with this mixture.