Demetris Lamnisos

Predicting cardiometabolic risk: waist-to-height ratio or BMI. A meta-analysis.

Background and objectives The identification of increased cardiometabolic risk among asymptomatic individuals remains a huge challenge. The aim of this meta-analysis was to compare the association of body mass index (BMI), which is an index of general obesity, and waist-to-height ratio (WHtR), an index of abdominal obesity, with cardiometabolic risk in cross-sectional and prospective studies. Methods PubMed and Embase databases were searched for cross-sectional or prospective studies that evaluated the association of both BMI and WHtR with several cardiometabolic outcomes. The strength of relative risk (RR) with 95% confidence interval (CI) was calculated using the optimal cutoffs of BMI and WHtR in cross-sectional studies, while any available cutoff was used in prospective studies. The pooled estimate of the ratio of RRs (rRR [=RRBMI/RRWHtR]) with 95% CIs was used to compare the association of WHtR and BMI with cardiometabolic risk. Meta-regression was used to identify possible sources of heterogeneity between the studies. Results Twenty-four cross-sectional studies and ten prospective studies with a total number of 512,809 participants were identified as suitable for the purpose of this meta-analysis. WHtR was found to have a stronger association than BMI with diabetes mellitus (rRR: 0.71, 95% CI: 0.59–0.84) and metabolic syndrome (rRR: 0.92, 95% CI: 0.89–0.96) in cross-sectional studies. Also in prospective studies, WHtR appears to be superior to BMI in detecting several outcomes, including incident cardiovascular disease, cardiovascular disease mortality, and all-cause mortality. The usefulness of WHtR appears to be better in Asian than in non-Asian populations. BMI was not superior to WHtR in any of the outcomes that were evaluated. However, the results of the utilized approach should be interpreted cautiously because of a substantial heterogeneity between the results of the studies. Meta-regression analysis was performed to explain this heterogeneity, but none of the evaluated factors, ie, sex, origin (Asians, non-Asians), and optimal BMI or WHtR cutoffs were significantly related with rRR. Conclusion The results of this meta-analysis support the use of WHtR in identifying adults at increased cardiometabolic risk. However, further evidence is warranted because of a substantial heterogeneity between the studies.

Effectiveness of heart failure management programmes with nurse-led discharge planning in reducing re-admissions: A systematic review and meta-analysis

BACKGROUND Heart failure (HF) is a clinical condition with major socioeconomic burden. Scientists are trying to find effective solutions to eliminate the effects of the disease and the current innovations in research address the introduction of HF management programmes (HF-MPs). OBJECTIVES A meta-analysis was undertaken to estimate the effect of HF-MP with a nurse-driven pre-discharge phase on the outcomes of HF and all-cause re-admission. DATA SOURCES A systematic search of PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Cochrane Library (reviews and clinical trials) was performed to locate randomised controlled trials (RCTs), published in English language, which implemented any HF-MP with discharge planning carried out by a nurse. Identified articles were further screened for additional studies. STUDY SELECTION Two reviewers independently screened relevant abstracts or titles using a standardised predefined check list. Pilot studies, studies additionally assessing other conditions and studies that evolved technology utilities or included medication management beyond optimisation of therapy, were excluded. DATA EXTRACTION Selected articles were thoroughly screened and data of interest (characteristics and outcomes) were obtained. Quality assessment was done by two reviewers separately. DATA SYNTHESIS Nineteen RCTs were selected for the meta-analysis. The overall pooled effect (relative risk, RR) of the intervention group compared with the control group was estimated by using a random effects analysis (95% confidence interval (CI)) for the outcomes of HF-related re-admission and all-cause re-admission. The overall RR of HF re-admissions was 0.68, 95% CI (0.53, 0.86), p<0.05 and of all-cause re-admission was 0.85, 95% CI (0.76, 0.94), p<0.05 favouring the intervention. Metaregression analysis was performed while trying to explain the observed heterogeneity but none of the factors (environment, duration of follow-up, origin and complexity) were significantly related with the RR. No significant publication bias was observed regarding both HF and all-cause re-admission. CONCLUSIONS The results of the current meta-analysis highlight the potential of HF-MPs with nurse-driven pre-discharge interventions to reduce hospital re-admissions. Essential characteristics or components of a successful HF-MP are still to be determined; thus more studies are required to solve this issue.

Asthma and atopy in children born by caesarean section: effect modification by family history of allergies – a population based cross-sectional study

BackgroundStudies on the association of birth by caesarean section (C/S) and allergies have produced conflicting findings. Furthermore, evidence on whether this association may differ in those at risk of atopy is limited. This study aims to investigate the association of mode of delivery with asthma and atopic sensitization and the extent to which any effect is modified by family history of allergies.MethodsAsthma outcomes were assessed cross-sectionally in 2216 children at age 8 on the basis of parents’ responses to the ISAAC questionnaire whilst skin prick tests to eleven aeroallergens were also performed in a subgroup of 746 children. Adjusted odds ratios of asthma and atopy by mode of delivery were estimated in multivariable logistic models while evidence of effect modification was examined by introducing interaction terms in the models.ResultsAfter adjusting for potential confounders, children born by C/S appeared significantly more likely than those born vaginally to report ever wheezing (OR 1.36, 95% CI 1.07-1.71), asthma diagnosis (OR 1.41, 95% CI 1.09-1.83) and be atopic (OR 1.67, 95% CI 1.08-2.60). There was modest evidence that family history of allergies may modify the effect of C/S delivery on atopy (p for effect modification=0.06) but this was not the case for the asthma outcomes. Specifically, while more than a two-fold increase in the odds of being a topic was observed in children with a family history of allergies if born by C/S (OR 2.62, 95% CI 1.38-5.00), no association was observed in children without a family history of allergies (OR 1.16, 95% CI 0.64-2.11).ConclusionsBirth by C/S is associated with asthma and atopic sensitization in childhood. The association of C/S and atopy appears more pronounced in children with family history of allergies.

Transdimensional Sampling Algorithms for Bayesian Variable Selection in Classification Problems With Many More Variables Than Observations

Model search in probit regression is often conducted by simultaneously exploring the model and parameter space, using a reversible jump MCMC sampler. Standard samplers often have low model acceptance probabilities when there are many more regressors than observations. Implementing recent suggestions in the literature leads to much higher acceptance rates. However, high acceptance rates are often associated with poor mixing of chains. Thus, we design a more general model proposal that allows us to propose models “further” from our current model. This proposal can be tuned to achieve a suitable acceptance rate for good mixing. The effectiveness of this proposal is linked to the form of the marginalization scheme when updating the model and we propose a new efficient implementation of the automatic generic transdimensional algorithm of Green (2003). We also implement other previously proposed samplers and compare the efficiency of all methods on some gene expression datasets. Finally, the results of these applications lead us to propose guidelines for choosing between samplers. Relevant code and datasets are posted as an online supplement.

Low serum high-density lipoprotein cholesterol in childhood is associated with adolescent asthma.

Whilst emerging evidence from animal and cell experiments has shown high‐density lipoprotein cholesterol to have anti‐inflammatory effects consistent with a protective role in asthma, human studies investigating the relationship of high‐density lipoprotein cholesterol with asthma have produced conflicting results.

Adaptive Monte Carlo for Bayesian Variable Selection in Regression Models

This article describes methods for efficient posterior simulation for Bayesian variable selection in generalized linear models with many regressors but few observations. The algorithms use a proposal on model space that contains a tuneable parameter. An adaptive approach to choosing this tuning parameter is described that allows automatic, efficient computation in these models. The method is applied to examples from normal linear and probit regression. Relevant code and datasets are posted online as supplementary materials.

Association of vitamin D with adiposity measures and other determinants in a cross-sectional study of Cypriot adolescents

OBJECTIVE To assess vitamin D status among Cypriot adolescents and investigate potential determinants including BMI and body fat percentage (BF%). DESIGN Participants had cross-sectional assessments of serum vitamin D, physical activity, dietary vitamin D intake and sun exposure. Linear and logistic regression models were used to explore the associations of vitamin D with potential predictors. SETTING Hospitals, Cyprus, November 2007-May 2008. SUBJECTS Adolescents (n 671) aged 16-18 years. RESULTS Mean serum vitamin D was 22·90 (sd 6·41) ng/ml. Only one in ten children had sufficient levels of vitamin D (≥30 ng/ml), while the prevalence of vitamin D deficiency (12-20 ng/ml) and severe deficiency (<12 ng/ml) was 31·7 % and 4·0 %, respectively. Lower vitamin D was associated with winter and spring season, female gender, reduced sun exposure in winter and darker skin. Participants with highest BMI and BF% when compared with a middle reference group had increased adjusted odds of vitamin D insufficiency (OR = 3·00; 95 % CI 1·21, 7·45 and OR = 5·02; 95 % CI 1·80, 13·97, respectively). A similar pattern, although not as strong, was shown for vitamin D deficiency with BF% (OR = 1·81; 95 % CI 1·04, 3·16) and BMI (OR = 1·51; 95 % CI 0·85, 2·67). Participants in the lowest BMI and BF% groups also displayed compromised vitamin D status, suggesting a U-shaped association. CONCLUSIONS Vitamin D deficiency in adolescence is very prevalent in sunny Cyprus, particularly among females, those with darker skin and those with reduced sun exposure in winter. Furthermore, vitamin D status appears to have a U-shaped association with adiposity measures.

Cross-validation prior choice in Bayesian probit regression with many covariates

This paper examines prior choice in probit regression through a predictive cross-validation criterion. In particular, we focus on situations where the number of potential covariates is far larger than the number of observations, such as in gene expression data. Cross-validation avoids the tendency of such models to fit perfectly. We choose the scale parameter c in the standard variable selection prior as the minimizer of the log predictive score. Naive evaluation of the log predictive score requires substantial computational effort, and we investigate computationally cheaper methods using importance sampling. We find that K-fold importance densities perform best, in combination with either mixing over different values of c or with integrating over c through an auxiliary distribution.

Associations of body fat percent and body mass index with childhood asthma by age and gender

High body mass index (BMI) has been shown to be associated with asthma, but the pattern of this association is still unclear and may differ by gender or stage of puberty. BMI is only a proxy of adiposity, whereas estimation of body fat percent (BF%) by the bioimpedance technique is considered an accurate measure of adiposity. We investigated whether BMI and BF% behave differently in their association with asthma between genders, before and during adolescence.

Evaluation of the psychometric properties of the Greek version of the Minnesota living with heart failure questionnaire

PURPOSE: One of the major challenges for health care professionals in heart failure (HF) management is to maintain and/or improve HF patient health-related quality of life. The Minnesota Living With Heart Failure Questionnaire (MLHFQ) is one of the most comprehensive and widely used tools for measuring health-related quality of life among patients with HF. The aim of the study was to assess the psychometric properties of the Greek version of the tool. METHODS: The MLHFQ was administered among 128 Greek-Cypriot HF patients to assess the internal consistency, content validity, and contrast validity of its Greek version. Exploratory factor analysis was undertaken to establish its construct validity. RESULTS: The factor analysis in this study provided support for a 3-factor solution explaining 64.15% of the variance (physical, emotional, and social subscales). The internal consistency for the Greek version of the MLHFQ total scale (0.95) and subscales (0.80–0.94) were found to be high. The contrast validity of the Greek version of the MLHFQ was explored through cumulative MLHFQ scores and comparisons that were able to distinguish among all different levels of HF severity, as defined by the New York Heart Association functional class grouping. CONCLUSION: This study provides support for the reliability and validity of the Greek version of the MLHFQ.