Multidimensional adaptive P-splines with application to neurons' activity studies.

The receptive field (RF) of a visual neuron is the region of the space that elicits neuronal responses. It can be mapped using different techniques that allow inferring its spatial and temporal properties. Raw RF maps (RFmaps) are usually noisy, making it difficult to obtain and study important features of the RF. A possible solution is to smooth them using P-splines. Yet, raw RFmaps are characterized by sharp transitions in both space and time. Their analysis thus asks for spatiotemporal adaptive P-spline models, where smoothness can be locally adapted to the data. However, the literature lacks proposals for adaptive P-splines in more than two dimensions. Furthermore, the extra flexibility afforded by adaptive P-spline models is obtained at the cost of a high computational burden, especially in a multidimensional setting. To fill these gaps, this work presents a novel anisotropic locally adaptive P-spline model in two (e.g., space) and three (space and time) dimensions. Estimation is based on the recently proposed SOP (Separation of Overlapping Precision matrices) method, which provides the speed we look for. Besides the spatiotemporal analysis of the neuronal activity data that motivated this work, the practical performance of the proposal is evaluated through simulations, and comparisons with alternative methods are reported.

Analysis of Prior Aspirin Treatment on in-Hospital Outcome of Geriatric COVID-19 Infected Patients.

Background and Objectives: Aspirin (ASA) is a commonly used antithrombotic drug that has been demonstrated to reduce venous thromboembolism. The aim was to analyze if geriatric COVID-19 patients undergoing a 100 mg/day Aspirin (ASA) treatment prior to hospitalization differ in hospital outcome compared to patients without previous ASA therapy. Materials and Methods: An observational retrospective study was carried out using an anonymized database including geriatric COVID-19 patients (March to April 2020) admitted to Madrid Hospitals Group. A group of COVID-19 patients were treated with low ASA (100 mg/day) prior to COVID-19 infection. Results: Geriatric ASA-treated patients were older (mean age over 70 years; n = 41), had higher frequency of hypertension and hyperlipidemia, and upon admission had higher D-dimer levels than non-ASA-treated patients (mean age over 73 years; n = 160). However, patients under ASA treatment did not show more frequent pulmonary thromboembolism (PE) than non-ASA-treated patients. ASA-treated geriatric COVID-19-infected patients in-hospital < 30 days all-cause mortality was more frequent than in non-ASA-treated COVID-19 patients. In ASA-treated COVID-19-infected geriatric patients, anticoagulant therapy with low molecular weight heparin (LMWH) significantly reduced need of ICU care, but tended to increase in-hospital < 30 days all-cause mortality. Conclusions: Prior treatment with a low dose of ASA in COVID-19-infected geriatric patients increased frequency of in-hospital < 30 days all-cause mortality, although it seemed to not increase PE frequency despite D-dimer levels upon admission being higher than in non-ASA users. In ASA-treated geriatric COVID-19-infected patients, addition of LMWH therapy reduced frequency of ICU care, but tended to increase in-hospital < 30 days all-cause mortality.

Modeling latent spatio-temporal disease incidence using penalized composite link models.

Epidemiological data are frequently recorded at coarse spatio-temporal resolutions to protect confidential information or to summarize it in a compact manner. However, the detailed patterns followed by the source data, which may be of interest to researchers and public health officials, are overlooked. We propose to use the penalized composite link model (Eilers PCH (2007)), combined with spatio-temporal P-splines methodology (Lee D.-J., Durban M (2011)) to estimate the underlying trend within data that have been aggregated not only in space, but also in time. Model estimation is carried out within a generalized linear mixed model framework, and sophisticated algorithms are used to speed up computations that otherwise would be unfeasible. The model is then used to analyze data obtained during the largest outbreak of Q-fever in the Netherlands.

Early, Non-Invasive Sensing of Sustained Hyperglycemia in Mice Using Millimeter-Wave Spectroscopy.

Diabetes is a very complex condition affecting millions of people around the world. Its occurrence, always accompanied by sustained hyperglycemia, leads to many medical complications that can be greatly mitigated when the disease is treated in its earliest stage. In this paper, a novel sensing approach for the early non-invasive detection and monitoring of sustained hyperglycemia is presented. The sensing principle is based on millimeter-wave transmission spectroscopy through the skin and subsequent statistical analysis of the amplitude data. A classifier based on functional principal components for sustained hyperglycemia prediction was validated on a sample of twelve mice, correctly classifying the condition in diabetic mice. Using the same classifier, sixteen mice with drug-induced diabetes were studied for two weeks. The proposed sensing approach was capable of assessing the glycemic states at different stages of induced diabetes, providing a clear transition from normoglycemia to hyperglycemia typically associated with diabetes. This is believed to be the first presentation of such evolution studies using non-invasive sensing. The results obtained indicate that gradual glycemic changes associated with diabetes can be accurately detected by non-invasively sensing the metabolism using a millimeter-wave spectral sensor, with an observed temporal resolution of around four days. This unprecedented detection speed and its non-invasive character could open new opportunities for the continuous control and monitoring of diabetics and the evaluation of response to treatments (including new therapies), enabling a much more appropriate control of the condition.

Derivative estimation for longitudinal data analysis: Examining features of blood pressure measured repeatedly during pregnancy.

Estimating velocity and acceleration trajectories allows novel inferences in the field of longitudinal data analysis, such as estimating change regions rather than change points, and testing group effects on nonlinear change in an outcome (ie, a nonlinear interaction). In this article, we develop derivative estimation for 2 standard approaches-polynomial mixed models and spline mixed models. We compare their performance with an established method-principal component analysis through conditional expectation through a simulation study. We then apply the methods to repeated blood pressure (BP) measurements in a UK cohort of pregnant women, where the goals of analysis are to (i) identify and estimate regions of BP change for each individual and (ii) investigate the association between parity and BP change at the population level. The penalized spline mixed model had the lowest bias in our simulation study, and we identified evidence for BP change regions in over 75% of pregnant women. Using mean velocity difference revealed differences in BP change between women in their first pregnancy compared with those who had at least 1 previous pregnancy. We recommend the use of penalized spline mixed models for derivative estimation in longitudinal data analysis.

Effect of a smoking ban and school-based prevention and control policies on adolescent smoking in Spain: a multilevel analysis.

We evaluated the impact of a smoking ban in schools and of school-based smoking prevention and control policies on adolescent smoking. Annual surveys carried out between 2001 and 2005 that were representative of students in the 4th year of secondary education in the Madrid region, with 203 schools and 9127 students participating. The student questionnaire gathered information about personal and family variables. The contextual factors were: the periods before (years 2001-2002) and after the law; and through a survey of school management boards: compliance with the law, policy reflected in the school regulations, existence of complaints against smoking, and undertaking of educational activities regarding smoking. Multilevel logistic regression models were constructed with two dependent variables: current smoking and the proportion giving up smoking. Smoking declined in 2003, the first year after the law came into force (Odds ratio: 0.80; CI 95%: 0.66-0.96), and this decline was maintained in 2005. By contrast, smoking increased in those schools that did not undertake educational programmes regarding smoking (Odds ratio: 1.34; CI 95%: 1.13-1.59), and in those that received complaints about smoking (Odds ratio: 1.12; CI 95%: 0.96-1.29). This association is partly due to the effect of the increase in giving up smoking. The inclusion of contextual variables into the model with the individual factors reduces the variability of smoking between schools by 32.6%. In summary, the coming into force of a law banning smoking in schools, and the implementing of educational policies for the prevention and control of smoking are related to a lower risk of adolescent smoking.

Confirmatory factor analysis of the General Health Questionnaire (GHQ-12) in Spanish adolescents.

PURPOSE: To evaluate the factor structure of the 12-item General Health Questionnaire (GHQ-12) in a population of Spanish adolescents. METHODS: Cross-sectional study among 4,146 individuals (mean age 16.3 years). The students completed a health questionnaire that included the GHQ-12. A confirmatory factor analysis (CFA) was conducted with four factor structure models. Three of the models were theory-driven: unidimensional, two-dimensional (positive and negative questions), model proposed by Graetz (anxiety and depression, social dysfunction, loss of confidence); and the fourth model was based on our exploratory factor analysis (EFA). RESULTS: The Cronbach's alpha for internal consistency was 0.82. A three-dimensional structure was identified in the EFA. The first factor included items 1, 2, 5, 6, 7, and 9 of the GHQ-12; the second, items 3, 10, and 11; and the third, items 4, 8, and 12. The three factors together explained 53.7% of the variance. The model with the best fit in the CFA was the three-dimensional model proposed by Graetz, followed by the three-dimensional model derived from the EFA. These two models had acceptable goodness-of-fit indices. CONCLUSIONS: In an adolescent population from Southern Europe, the GHQ-12 showed high internal consistency. The factor structure that best fitted the data was the Graetz three-dimensional model. However, the high correlations observed between factors suggest that the GHQ-12 should be used as a unidimensional scale, as currently done.

Individual and contextual factors associated to smoking on school premises.

INTRODUCTION: Despite regulations, tobacco consumption in schools is still very common. The objective was to evaluate the relationship of personal, family, and school-level contextual factors with smoking on school premises. METHODS: A representative survey was undertaken of students in the 4th year of secondary education in the Madrid region (Spain), including 79 schools and 3,622 individuals. The student questionnaire gathered information about personal and family variables. The contextual factors were type of school, perception of compliance with the law, smoking policy, existence of complaints against smoking, and undertaking of educational activities regarding smoking. Analysis was carried out in the smoking population (n = 1,179) using multilevel logistic regression models. RESULTS: During the last 30 days, 50.6% of smokers had smoked on school premises. Having a father with a university education (in comparison with fathers who have not attained any educational level) reduces this probability (odds ratio [OR]: 0.43; 95% CI: 0.19-0.96), whereas smoking a larger number of cigarettes (p < .001), illicit drug consumption (p < .001), and low academic achievement (p = .052) increases it. The probability is reduced when there is no parental permission to smoke (OR: 0.66; 95% CI: 0.43-1.01) and is lower both in nonsubsidized private schools (OR: 0.29; 95% CI: 0.12-0.67) and in state subsidized private schools (OR: 0.17; 95% CI: 0.09-0.34) than in public schools. CONCLUSIONS: A very low level of educational attainment by the father, smoking a higher number of cigarettes, as well as illicit drug consumption, low academic achievement, having parental permission to smoke, and attending public schools are all related to a higher probability of smoking on school premises.

Intimate partner violence: last year prevalence and association with socio-economic factors among women in Madrid, Spain.

BACKGROUND: Intimate partner violence (IPV) is a public health problem with significant consequences on women's health. This study estimates the prevalence of intimate partner violence by type among Madrid's female population and assesses the association with socio-economic variables. METHODS: We conducted a cross-sectional study in 2004, 2136 women aged 18-70 years, living in the Madrid region with a partner or who had been in contact with an ex-partner in the previous year, were interviewed by telephone. The questionnaire used to measure past-year intimate partner violence, consisted of a Spanish translation of the psychological and sexual violence module of the French National Survey on Violence against Women, and the physical violence module of the Conflict Tactics Scale-1. To assess the association with socio-economic factors, logistic regression models were fitted. RESULTS: About 10.1% [confidence interval (CI) 8.9-11.5] of the women had suffered some type of IPV in the previous year. 8.6% (CI 7.4-9.8) experienced psychological violence, 2.4% (CI 1.8-3.1) physical violence and 1.1% (CI 0.68-1.6) sexual violence; the prevalence of psychological-only violence (non-physical/non-sexual) was 6.9% (CI 5.8-8.0). Factors associated with psychological-only violence were divorced or separated status and Group III (clerical workers; supervisors of manual workers) or V (unskilled manual workers) occupation. Unemployment and divorced or separated status were associated with physical violence. CONCLUSIONS: Spanish women in our study, experienced past year partner violence at a similar level as in other industrialized countries. Unemployment and low occupational status are associated with physical and psychological-only violence, respectively.

Decreasing prevalence of disability in activities of daily living, functional limitations and poor self-rated health: a 6-year follow-up study in Spain.

BACKGROUND AND AIMS: Forecasting functional status in elderly populations is uncertain. Our aim is to provide evidence of population trends of Activities of Daily Living (ADL) disability, functional limitations and self-rated health. METHODS: Data come from a longitudinal study of aging in Leganés (Spain), collected in 1993, 1995, 1997 and 1999, on a representative sample of 1560 community dwelling people over 65. Response rate at baseline was 82%. ADL disability was defined as needing help in at least one of the following: walking across a small room, taking a shower, toileting, getting out of bed, getting up from a chair, using the toilet, dressing and eating. Functional limitations were based on questions of difficulty with upper and lower limbs. Self-rated health was assessed with a single question. ADL disability, functional limitations and self-rated health were regressed on age, survey year, sex and education. RESULTS: There are significant declines in ADL disability, functional limitations and poor self-rated health at every age and up to very advanced ages. Over 90, the ADL disability trend may be reversed, with the emergence of a very old and disabled population. Women and people with little education have a higher prevalence of disability, functional limitations and poor health, when compared with men and those with higher education. CONCLUSIONS: Results suggest the postponement of severe disability onset in this Spanish population, leading to longer healthy life expectancy, and support the emergence of a very disabled population over 90 years of age.