David Moriña

A statistical model for hospital admissions caused by seasonal diseases

We present a model based on two-order integer-valued autoregressive time series to analyze the number of hospital emergency service arrivals caused by diseases that present seasonal behavior. We also introduce a method to describe this seasonality, on the basis of Poisson innovations with monthly means. We show parameter estimation by maximum likelihood and model validation and show several methods for forecasting, on the basis of long-time means and short-time and long-time prediction regions. We analyze an application to model the number of hospital admissions per week caused by influenza.

Effects of poly-bioactive compounds on lipid profile and body weight in a moderately hypercholesterolemic population with low cardiovascular disease risk: a multicenter randomized trial.

A dietary supplement (AP, Armolipid Plus) that combines red yeast rice extract, policosanol, berberine, folic acid, coenzyme Q10 and asthaxantine can have beneficial effects on cardiovascular disease (CVD) biomarkers. The aim of this study was to assess whether the intake of AP, in combination with dietary recommendations, reduces serum low density lipoprotein cholesterol (LDL-c) concentrations and other CVD biomarkers in patients with hypercholesterolemia. Eligible patients were recruited from the outpatient clinics of six Spanish hospitals Hospital Virgen del Rocío (Sevilla); Hospital San Jorge (Huesca); Hospital San Pedro (Logroño); Hospital Gregorio Marañón (Madrid), Hospital la Fe (Valencia) and Hospital Universitari Sant Joan (Reus) as recruiting and coordinating center. 102 participants (mean age ± SD; 50.91±11.61; 32 men) with low CVD, with mild-to-moderately elevated LDL-c (between 3.35 mmol/L and 4.88 mmol/L) without hypolipemic therapy were randomized in a double-blind, parallel, controlled, multicenter trial commencing January 2012 and ending December 2012. Among the exclusion criteria were any concomitant chronic disease, triglycerides (TG) >3.97 mmol/L, pregnant or lactating, and history of CVD. At 12 weeks, compared to placebo, AP reduced LDL-c by −6.9%, apolipoprotein (Apo) B-100 by −6.6% and total cholesterol/HDL-c ratio by −5.5%, the ApoB/ApoA1 ratio by −8.6%, while increasing ApoA1 by +2.5% (p<0.05). AP consumption was associated with modest mean weight loss of −0.93 kg (95%CI: -1.74 to -0.12; P = 0.02) compared with control group while dietary composition remained unchanged in the AP group. The AP product was well tolerated. In conclusion, AP, combined with dietary recommendations, reduced LDL-c levels as well as total cholesterol/HDL-c and ApoB/ApoA1 ratios, while increasing Apo A1, all of which are improvements in CVD risk indicators. AP is a product which could benefit patients having moderate hyperlipidemia and excess body weight. Trial Registration ClinicalTrials.gov NCT01562080

A primary-school-based study to reduce the prevalence of childhood obesity – the EdAl (Educació en Alimentació) study: a randomized controlled trial

BackgroundObesity is one of the main determinants of avoidable disease burden.To implement a program by university students acting as “health promoting agents” (HPAs) and to evaluate the effects on obesity prevalence of the primary-school-based program that promotes healthy lifestyle, including dietary and physical activity recommendations over 28 months.MethodsTwo school clusters were randomly assigned to intervention (24 schools, 1,222 pupils) or control (14 schools, 717 pupils); 78% of pupils were Western European. Mean age (±SD) was 8.4 ± 0.6 years (49.9% females) at baseline. Generalized linear mixed models were used to analyze differences in primary outcome between both groups. Data collected included body mass index (BMI) every year. Dietary habits and lifestyle questionnaires were filled in by the parents at baseline and at the end of the study. The interventions focused on eight lifestyle topics covered in 12 activities (1 hour/activity/session) implemented by HPAs over 3 school academic years.ResultsAt 28 months, obesity prevalence in boys was decreased −2.36% in the intervention group (from 9.59% to 7.23%) and increased 2.03% (from 7.40% to 9.43%) in the control group; the difference was 4.39% (95% CI 3.48 to 5.30; P = 0.01). The boys in the intervention group had an effective reduction of −0.24 units in the change of BMI z-score (from 0.01 to −0.04), compared to control (from −0.10 to 0.09); 5.1% more intervention pupils undertook physical activity >5 hours/week than control pupils (P = 0.02).Fish consumption was a protector (odds ratio 0.39; 95% CI 0.23 to 0.67) while “fast-food” consumption was a risk factor for childhood obesity (odds ratio: 2.27; 95% CI 1.08 to 4.77).ConclusionsOur school-based program, conducted by HPA students, successfully reduced childhood obesity prevalence in boys.Trial registrationInternational Standard Randomized Controlled Trial Number: ISRCTN29247645.

A primary-school-based study to reduce prevalence of childhood obesity in Catalunya (Spain) - EDAL-Educació en alimentació: study protocol for a randomised controlled trial

BackgroundThe EdAL (Educació enAlimentació) study is a long-term, nutrition educational, primary-school-based program designed to prevent obesity by promoting a healthy lifestyle that includes dietary recommendations and physical activity.The aims are: 1) to evaluate the effects of a 3-year school-based life-style improvement program on the prevalence of obesity in an area of north-west Mediterranean 2) To design a health-promotion program to be implemented by health-promoter agents (university students) in primary schools.Methods/Design1) The intervention study is a randomised, controlled, school-based program performed by university-student health-promoter agents. Initial pupil enrolment was in 2006 and continued for 3 years. We considered two clusters (designated as cluster A and cluster B) as the units for randomisation. The first cluster involved 24 schools from Reus and the second involved 14 schools from surrounding towns Cambrils, Salou and Vilaseca combined in order to obtain comparable groups. There are very good communications between schools in each town, and to avoid cross influence of the programs resulting from inter-school dialogue, the towns themselves were the unit for randomisation. Data collected included name, gender, date and place of birth at the start of the program and, subsequently, weight, height, body mass index (BMI) and waist circumference every year for 3 years. Questionnaires on eating and physical activity habits are filled-in by the parents at the start and end of the study and, providing that informed consent is given, the data are analysed on the intention-to-treat basis.The interventions are based on 8 nutritional and physical activity objectives. They are implemented by university students as part of the university curriculum in training health-promoter agents. These 8 objectives are developed in 4 educational activities/year for 3 years (a total of 12 activities; 1 h/activity) performed by the health-promoter agents in primary schools. Control pupils follow their usual activities.2) Courses on education and promotion of health, within in the curriculum of medicine and health sciences for university students, are designed to train health-promoter agents to administer these activities in primary schools.DiscussionThis controlled school-based intervention will test the possibility of preventing childhood obesity.Trial registration numberISRCTN: ISRCTN29247645

Follow-up of a healthy lifestyle education program (the Educació en Alimentació Study): 2 years after cessation of intervention

PURPOSE The Educació en Alimentació (EdAl) program conducted over 28 months in primary school children reduced obesity (OB) prevalence in boys and increased voluntary physical activity (PA). The continued benefit after cessation of EdAl is unknown. We assessed the changes in OB prevalence and healthy lifestyle in 11- to 13-year-old adolescents, the age group that had complete inclusion data available 2 years after the EdAl programs conclusion. METHODS Adolescents (n = 421 intervention; n = 198 control) with data at baseline and 2-year follow-up were recruited. Analyses included body mass index (BMI), BMI z-score, and lifestyle data (from questionnaires). RESULTS Between baseline and 2-year follow-up, OB prevalence was reduced (-5.5%; p < .01) and BMI z-score (-.29; p < .001) in intervention compared with control group. BMI z-score was effectively reduced in intervention in both genders: -.26 units in boys and -.32 units in girls, compared with control group. The ≥4 hours/week after-school PA was increased significantly by 13.1% in adolescents of intervention group compared with control group (p = .023); a tendency toward increased PA in intervention girls was observed (p = .062). At 2-year follow-up, participating in ≥4 hours/week after-school PA (odds ratio, .240; p = .002) and daily fruit consumption (odds ratio, .447; p = .025) were protective factors against OB, whereas ≤2 hours/week after-school PA was a risk factor for OB. CONCLUSIONS At 2-year follow-up, the EdAl program induced a lowering of BMI z-score and OB prevalence, compared with control group. After-school PA practice can be stimulated in primary school as part of a healthy lifestyle and maintained subsequently despite cessation of the intervention program.

Under-reported data analysis with INAR-hidden Markov chains.

In this work, we deal with correlated under-reported data through INAR(1)-hidden Markov chain models. These models are very flexible and can be identified through its autocorrelation function, which has a very simple form. A naïve method of parameter estimation is proposed, jointly with the maximum likelihood method based on a revised version of the forward algorithm. The most-probable unobserved time series is reconstructed by means of the Viterbi algorithm. Several examples of application in the field of public health are discussed illustrating the utility of the models. Copyright

Hazard Functions to Describe Patterns of New and Recurrent Sick Leave Episodes for Different Diagnoses

OBJECTIVES This study aims to identify the hazard functions that describe the occurrence patterns of new and recurrent sick leave (SL) episodes for mental, respiratory, and musculoskeletal diagnoses. METHODS The data come from a cohort of workers in the Hospital das Clínicas da Universidade Federal de Minas Gerais, Brazil, including all employees working ≥ 20 hours per week, whose first employment relation with the hospital started between 1 January 2000 and 31 December 2007 (N=1579). We created 15 samples corresponding to combinations of diagnoses causing SL and the number of previous episodes already suffered. We fitted Weibull, log-normal, and log-logistic models by resampling and selected the model having the lowest Akaike information criterion in the greatest number of resamples. RESULTS Differences were observed in the probability distributions associated with the process generating a SL. Diagnosis showed important differences in terms of risk intensity: mental episodes were the least frequent. There were differences in risk intensity and shape of the function over time depending on the episode number, particularly between the first episode and recurrences. In addition, these differences varied by diagnosis. CONCLUSIONS In most of the samples analyzed, we identified a mixture of distributions, implying a need to revise the statistical methods of analysis for SL occurrence with the aim of obtaining consistent estimates of the risk and the associated factors.

Development of a source-exposure matrix for occupational exposure assessment of electromagnetic fields in the INTEROCC study.

To estimate occupational exposures to electromagnetic fields (EMF) for the INTEROCC study, a database of source-based measurements extracted from published and unpublished literature resources had been previously constructed. The aim of the current work was to summarize these measurements into a source-exposure matrix (SEM), accounting for their quality and relevance. A novel methodology for combining available measurements was developed, based on order statistics and log-normal distribution characteristics. Arithmetic and geometric means, and estimates of variability and maximum exposure were calculated by EMF source, frequency band and dosimetry type. The mean estimates were weighted by our confidence in the pooled measurements. The SEM contains confidence-weighted mean and maximum estimates for 312 EMF exposure sources (from 0 Hz to 300 GHz). Operator position geometric mean electric field levels for radiofrequency (RF) sources ranged between 0.8 V/m (plasma etcher) and 320 V/m (RF sealer), while magnetic fields ranged from 0.02 A/m (speed radar) to 0.6 A/m (microwave heating). For extremely low frequency sources, electric fields ranged between 0.2 V/m (electric forklift) and 11,700 V/m (high-voltage transmission line-hotsticks), whereas magnetic fields ranged between 0.14 μT (visual display terminals) and 17 μT (tungsten inert gas welding). The methodology developed allowed the construction of the first EMF–SEM and may be used to summarize similar exposure data for other physical or chemical agents.

Competing risks simulation with the survsim R package

ABSTRACT The goal of this work is to describe how the last version available of the survsim R package can be used to simulate a cohort in a competing risks context by means of a cause-specific hazards model following the ideas introduced by Beyersmann in 2009, and also allowing for individual heterogeneity through a random effect. An example of its application based on a real cohort will be discussed.

Hepatic accumulation of S-Adenosylmethionine in hamsters with non-alcoholic-fatty liver disease associated to metabolic syndrome under selenium and vitamin E deficiency.

Progression of non-alcoholic fatty liver disease (NAFLD) in the context of metabolic syndrome (MetS) is only partially explored due to the lack of preclinical models. In order to study the alterations in hepatic metabolism that accompany this condition, we developed a model of MetS accompanied by the onset of steatohepatitis (NASH) by challenging golden hamsters with a high-fat diet low in vitamin E and selenium (HFD), since combined deficiency results in hepatic necroinflammation in rodents. Metabolomics and transcriptomics integrated analyses of livers revealed an unexpected accumulation of hepatic S-Adenosylmethionine (SAM) when compared with healthy livers likely due to diminished methylation reactions and repression of GNMT. SAM plays a key role in the maintenance of cellular homeostasis and cell cycle control. In agreement, analysis of over-represented transcription factors revealed a central role of c-myc and c-Jun pathways accompanied by negative correlations between SAM concentration, MYC expression and AMPK phosphorylation. These findings point to a drift of cell cycle control toward senescence in livers of HFD animals, which could explain the onset of NASH in this model. In contrast, hamsters with NAFLD induced by a conventional high-fat diet did not show SAM accumulation, suggesting a key role of selenium and vitamin E in SAM homeostasis. In conclusion, our results suggest that progression of NAFLD in the context of MetS can take place even in a situation of hepatic SAM excess and that selenium and vitamin E status might be considered in current therapies against NASH based on SAM supplementation.