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Sports analytics is defined as the process that identifies and acquires knowledge and insight about players and teams’ performances. To do so, analysts use a wide variety of data sources coming from matches and individual players’ performances (O'Donoghue & Holmes 2014; Jayal, McRobert, Oatley & O’Donoghue, 2018). Nowadays, detailed data from different nature including technical skills, individual physiological performances, team formations, or injuries are analysed on a daily basis by the analytics departments belonging to sports clubs and professional franchises. Even private companies like STATS or OPTA generate important revenues offering their movement tracking values and advanced metrics to media and fans. In the emerging field of Sports Analytics, as in many others, analysts must be aware of spurious correlations. These can come up due to the size (not nature) of data, a common-causal variable or just due to serendipity. For this reason, we always must keep in mind the lessons of the statistician Stephen John Senn and his sharp quote on the matter: “Statistics is not just about merely warning that correlation is not causation. Sometimes correlation isn’t even correlation”. Thus, we will explain an example of how climate change can be affecting, or not, on the FIFA World Cup performance statistics.

Objective. To describe and discuss the results of non-pharmacological interventions (NPI) adjuvants in the treatment of depressive symptoms among women with breast cancer (BC). Materials and methods. A systematic review on NPI was performed, which was applied to patients with cancer and depressive symptoms in seven databases. The review was limited from January 1, 2006 to December 31, 2017 and to English, Spanish and Portuguese languages. The medical descriptors used were “breast neoplasm” and “depression”. Results. There are several NPI that are able stimulate the physical or psychosocial dimensions. In this article we propose a classification based on nine identified therapeutic strategies, among which exercise, psychotherapy and yoga with meditation stand out. Conclusions. Based on the available evidence, we concluded that psychotherapy and yoga with meditation reduce depressive symptoms in patients with CaMa. More research is needed to determine the magnitude of the reduction of depressive symptoms, according to their severity, presence of comorbidities and diversity of INF.

Abstract Background Autism spectrum disorder (ASD) is a complex developmental disorder characterised by impaired social interaction and communication, and restrictive and repetitive behaviour. Previous systematic reviews have traditionally assessed the prevalence of ASD on global or regional context, with very few meta-analyses at the country level. The objective of this study will be to systematically evaluate published and unpublished observational studies that present prevalence and comorbidity of ASD among children, adolescent and adult population in Spain. Methods/design We designed and registered a study protocol for a systematic review and meta-analysis of descriptive epidemiology data. Observational studies (cohort, cross-sectional) reporting the prevalence of ASD and conducted in a wide range of people (e.g. general population, outpatient and/or school settings) will be included. The primary outcome will be the prevalence of ASD. Secondary outcomes will be the prevalence of any physical or mental comorbidity in association with ASD. No limitations will be imposed on publication status, study conduct period, and language of dissemination. Comprehensive literature searches will be conducted in seven electronic databases (from January 1980 onwards), including PubMed/MEDLINE, EMBASE, Scopus, Web of Science, PsycINFO, IME—Spanish Medical Index and IBECS—Spanish Bibliographic Index of Health Sciences. Grey literature will be identified through searching dissertation databases, Google Scholar and conference abstracts. Two team members will independently screen all citations, full-text articles, and abstract data. Potential conflicts will be resolved through discussion. The study methodological quality (or bias) will be appraised using an appropriate tool. If feasible, we will conduct random effects meta-analysis of observational data. Prevalence estimates will be stratified according to gender, age and geographical location. Additional analyses will be conducted to explore the potential sources of heterogeneity (e.g. methodological quality, sample size, diagnostic criteria). Discussion This systematic review and meta-analysis of observational data will identify, evaluate and integrate the epidemiological knowledge underlying the prevalence of ASD in Spain. The results of this study will be of interest to multiple audiences including patients, their families, caregivers, healthcare professional, scientists and policy makers. Results will be published in a peer-reviewed journal. Implications for future epidemiological research will be discussed. Systematic review registration PROSPERO CRD42018090372

Background Previous studies investigating the relationship of influenza with acute myocardial infarction (AMI) have not distinguished between AMI types 1 and 2. Influenza and cold temperature can explain the increased incidence of AMI during winter but, because they are closely related in temperate regions, their relative contribution is unknown. Methods and Results The temporal relationship between incidence rates of AMI with demonstrated culprit plaque (type 1 AMI) from the regional primary angioplasty network and influenza, adjusted for ambient temperature, was studied in Madrid region (Spain) during 5 influenza seasons (from June 2013 to June 2018). A time‐series analysis with quasi‐Poisson regression models and distributed lag‐nonlinear models was used. The incidence rate of type 1 AMI according to influenza vaccination status was also explored. A total of 8240 cases of confirmed type 1 AMI were recorded. The overall risk ratio (RR) of type 1 AMI during epidemic periods, adjusted for year, month, and temperature, was 1.23 (95% CI, 1.03–1.47). An increase of weekly influenza rate of 50 cases per 100 000 inhabitants resulted in an RR for type 1 AMI of 1.16 (95% CI, 1.09–1.23) during the same week, disappearing 1 week after. When adjusted for influenza, a decrease of 1ºC in the minimum temperature resulted in an increase of 2.5% type 1 AMI. Influenza vaccination was associated with a decreased risk of type 1 AMI in subjects aged 60 to 64 years (RR, 0.58; 95% CI, 0.47–0.71) and ≥65 years (RR, 0.53; 95% CI, 0.49–0.57). Conclusions Influenza and cold temperature were both independently associated with an increased risk of type 1 AMI, whereas vaccination was associated with a reduced risk among older patients.

ObjectiveReport maternal, fetal and neonatal complications associated with single intrauterine fetal death (sIUFD) in monochorionic twin pregnancies.DesignProspective observational study.SettingUK.Population81 monochorionic twin pregnancies with sIUFD after 14 weeks gestation, irrespective of cause.MethodsUKOSS reporters submitted data collection forms using data from hospital records.Main outcome measuresAetiology of sIUFD; surviving co-twin outcomes: perinatal mortality, central nervous system (CNS) imaging, gestation and mode of delivery, neonatal outcomes; post-mortem findings; maternal outcomes.ResultsThe commonest aetiology was twin-twin transfusion syndrome (38/81, 47%), "spontaneous" sIUFD (22/81, 27%) was second commonest. Death of the co-twin was common (10/70, 14%). Preterm birth (ConclusionsMonochorionic twin pregnancies with single IUD are complex and require specialist care. Further research is required regarding optimal gestation at delivery of the surviving co-twin, preterm birth prevention, and classifying the cause of death in twin pregnancies. Awareness of the importance of CNS imaging, and follow-up, needs improvement.

Background: Increased atmospheric particulate matter (PM) concentrations are commonly observed during desert dust days in Iran, but there is still no evidence of their effects on human health. We aimed to evaluate the association between daily mortality and exposure to PM10 and PM2.5 during dust and non-dust days in Tehran and Ahvaz, two major Middle Eastern cities with different sources, intensity, and frequency of desert dust days. Methods: We identified desert dust days based on exceeding a daily PM10 concentration threshold of 150 µg/m3 between 2014 and 2017, checking for low PM2.5/PM10 ratio typical of dust days. We used a time-stratified case-crossover design to estimate the short-term effects of PM10 and PM2.5 concentrations on daily mortality during dust and non-dust days. Data was analyzed using conditional Poisson regression models. Results: Higher concentrations of PM and frequency of desert dust days were observed in Ahvaz rather than Tehran. In Ahvaz, the effect of PM10 at lag 0 was much higher during dust days, an increment of 10 μg/m3 was associated with 3.28% (95%CI = [2.42, 4.15]) increase of daily mortality, than non-dust days, 1.03% (95%CI = [−0.02, 2.08]), while in Tehran, was slightly higher during non-dust days, 0.72% (95%CI = [0.23, 1.23]), than in dust days, 0.49% (95%CI = [−0.22, 1.20]). No statistically significant associations were observed between PM2.5 and daily mortality in Ahvaz, while in Teheran the effect of PM2.5 increased significantly during non-dust days at lag 2, 1.89% (95%CI = [0.83, 1.2.95] and lag 3, 1.88% (95%CI = [0.83, 1.2.95]). Conclusion: The study provides evidence that exposure to PM during Middle East dust days is an important risk factor to human health in arid regions and areas affected by desert dust events. Keywords: Air pollution, Desert dust, Particulate matter, PM10, PM2.5, Mortality, Tehran, Ahvaz

Background: Evidence on the short-term effects of ultrafine particles (with diameter

Abstract Background Meta-analysis is very useful to summarize the effect of a treatment or a risk factor for a given disease. Often studies report results based on log-transformed variables in order to achieve the principal assumptions of a linear regression model. If this is the case for some, but not all studies, the effects need to be homogenized. Methods We derived a set of formulae to transform absolute changes into relative ones, and vice versa, to allow including all results in a meta-analysis. We applied our procedure to all possible combinations of log-transformed independent or dependent variables. We also evaluated it in a simulation based on two variables either normally or asymmetrically distributed. Results In all the scenarios, and based on different change criteria, the effect size estimated by the derived set of formulae was equivalent to the real effect size. To avoid biased estimates of the effect, this procedure should be used with caution in the case of independent variables with asymmetric distributions that significantly differ from the normal distribution. We illustrate an application of this procedure by an application to a meta-analysis on the potential effects on neurodevelopment in children exposed to arsenic and manganese. Conclusions The procedure proposed has been shown to be valid and capable of expressing the effect size of a linear regression model based on different change criteria in the variables. Homogenizing the results from different studies beforehand allows them to be combined in a meta-analysis, independently of whether the transformations had been performed on the dependent and/or independent variables.

This review describes essential concepts of network meta-analysis and indirect comparisons and their application to clinical science. There are an increasing number of systematic reviews and meta-analyses providing direct comparisons between different interventions, although this is often not feasible when there is a lack of evidence related to all possible comparisons. Thus, important statistical tools that help make indirect comparisons based on previously existing comparisons have been developed. Network meta-analyses are an innovative tool that could assist doctors, researchers, and governmental organizations when making clinical and public health decisions.

Las revisiones sistemáticas y los metaanálisis se han consolidado como una herramienta fundamental para la práctica clínica basada en la evidencia. Inicialmente, el metaanálisis fue propuesto como una técnica que podría mejorar la precisión y la potencia estadística de la investigación procedente de estudios individuales con pequeño tamaño muestral. Sin embargo, uno de sus principales inconvenientes es que suelen comparar no más de 2 intervenciones alternativas a la vez. Los «metaanálisis en red» utilizan técnicas novedosas de análisis que permiten incorporar la información procedente de comparaciones directas e indirectas a partir de una red de estudios que examina los efectos de diversos tratamientos de una manera más completa. Pese a sus potenciales limitaciones, su aplicación en epidemiología clínica podría ser potencialmente útil en situaciones en las que existen varios tratamientos que se han comparado frente a un comparador común. Además, estas técnicas pueden ser relevantes ante una pregunta clínica o de investigación cuando existen múltiples tratamientos que deben ser considerados, o cuando se dispone tanto de información directa como indirecta en el cuerpo de la evidencia.

En investigación clínica, el meta análisis ha servido generalmente para evaluar la eficacia y la seguridad de un tratamiento a través de la comparación con un único comparador. Las comparaciones indirectas, a través del método de Bucher, permiten combinar datos procedentes de estudios primarios de una forma sencilla cuando la información para las comparaciones directas es limitada o inexistente. Las comparaciones mixtas permiten combinar las estimaciones procedentes de comparaciones directas e indirectas, aumentando el poder estadístico. En la actualidad, es necesario el desarrollo de aplicaciones informáticas para el cálculo de meta análisis de comparaciones indirectas y mixtas. Por este motivo, se ha desarrollado una hoja de cálculo con Microsoft Office Excel para el cálculo de comparaciones indirectas y mixtas, de uso sencillo para investigadores clínicos interesados en revisiones sistemáticas con meta análisis, pero no familiarizados con el uso de paquetes estadísticos más avanzados. La utilización de esta hoja de cálculo para las comparaciones indirectas y mixtas puede ser de gran utilidad en epidemiología clínica, con el fin de extender el conocimiento proporcionado por el metaanálisis tradicional cuando la evidencia de las comparaciones directas es limitada o inexistente.

The relationship between photochemical air pollutants (nitrogen dioxide and ozone) and emergency room admissions for asthma in Madrid (Spain) for the period 1995-1998 was analysed using the statistical models commonly used to studying the short-term effects of air pollution on health: linear and Cochrane-Orcutt regression, standard Poisson and Poisson corrected by overdispersion, Poisson autoregressive models, and generalised additive models. Linear regression models presented residual autocorrelation, Poisson regression models also showed overdispersion, and generalised additive models did not show residual autocorrelation and overdispersion was substantially reduced. Linear models provided biased estimates because our health outcome is non-normally distributed. Estimates from Poisson regression allowing for overdispersion and autocorrelation did not differ substantially from those reported by generalised additive models, which present the best model fit in terms of the absence of autocorrelation and reduction of overdispersion. [ABSTRACT FROM AUTHOR]

BackgroundMedications aimed at inhibiting the renin-angiotensin system (RAS) have been used extensively for preventing cardiovascular and renal complications in patients with diabetes, but data that compare their clinical effectiveness are limited. We aimed to compare the effects of classes of RAS blockers on cardiovascular and renal outcomes in adults with diabetes.Methods and findingsEligible trials were identified by electronic searches in PubMed/MEDLINE and the Cochrane Database of Systematic Reviews (1 January 2004 to 17 July 2014). Interventions of interest were angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and direct renin (DR) inhibitors. The primary endpoints were cardiovascular mortality, myocardial infarction, and stroke-singly and as a composite endpoint, major cardiovascular outcome-and end-stage renal disease [ESRD], doubling of serum creatinine, and all-cause mortality-singly and as a composite endpoint, progression of renal disease. Secondary endpoints were angina pectoris and hospitalization for heart failure. In all, 71 trials (103,120 participants), with a total of 14 different regimens, were pooled using network meta-analyses. When compared with ACE inhibitor, no other RAS blocker used in monotherapy and/or combination was associated with a significant reduction in major cardiovascular outcomes: ARB (odds ratio [OR] 1.02; 95% credible interval [CrI] 0.90-1.18), ACE inhibitor plus ARB (0.97; 95% CrI 0.79-1.19), DR inhibitor plus ACE inhibitor (1.32; 95% CrI 0.96-1.81), and DR inhibitor plus ARB (1.00; 95% CrI 0.73-1.38). For the risk of progression of renal disease, no significant differences were detected between ACE inhibitor and each of the remaining therapies: ARB (OR 1.10; 95% CrI 0.90-1.40), ACE inhibitor plus ARB (0.97; 95% CrI 0.72-1.29), DR inhibitor plus ACE inhibitor (0.99; 95% CrI 0.65-1.57), and DR inhibitor plus ARB (1.18; 95% CrI 0.78-1.84). No significant differences were showed between ACE inhibitors and ARBs with respect to all-cause mortality, cardiovascular mortality, myocardial infarction, stroke, angina pectoris, hospitalization for heart failure, ESRD, or doubling serum creatinine. Findings were limited by the clinical and methodological heterogeneity of the included studies. Potential inconsistency was identified in network meta-analyses of stroke and angina pectoris, limiting the conclusiveness of findings for these single endpoints.ConclusionsIn adults with diabetes, comparisons of different RAS blockers showed similar effects of ACE inhibitors and ARBs on major cardiovascular and renal outcomes. Compared with monotherapies, the combination of an ACE inhibitor and an ARB failed to provide significant benefits on major outcomes. Clinicians should discuss the balance between benefits, costs, and potential harms with individual diabetes patients before starting treatment.Review registrationPROSPERO CRD42014014404.

Fundamentos: La gripe estacional es una causa frecuente de episodios de incapacidad temporal por contingencia común (ITcc). En este estudio se valora el impacto laboral de la gripe pandémica (H1N1) 2009 en Andalucía y Cataluña durante el periodo 20072009. Métodos: Estudio de series temporales de los casos de ITcc por gripe, según edad y sexo. Se compararon los nuevos casos de ITcc por gripe en un primer periodo epidémico (de 01/01/2007 hasta 30/09/2009) y un segundo periodo pandémico (tres últimos meses de 2009). Se calculó el número semanal de nuevos casos de ITcc por gripe, representándose gráficamente los valores mínimo, mediano y máximo de los casos notificados durante el periodo epidémico y el pandémico. Resultados: Al contrario de lo esperado, las mujeres presentaron 52,2% en Cataluña y 49,7% en Andalucía de nuevos casos de ITcc por gripe durante el periodo pandémico. Durante ambos periodos, el grupo de edad de 25 a 34 años presentó mayor número de casos tanto en Cataluña (37.439 en el periodo epidémico y 15.379 en el pandémico) como en Andalucía (periodo epidémico 20.465 y periodo pandémico 9.630). La llegada de la pandemia se situó alrededor del mes de noviembre (aproximadamente 10.000 casos en Cataluña y 5.000 casos en Andalucía), produciéndose un importante aumento de casos respecto a la mediana del periodo epidémico. Conclusiones: La aparición de la pandemia de gripe produjo un incremento importante de casos de ITcc, algo superior en Cataluña que en Andalucía, adelantándose su acmé a noviembre, especialmente en las mujeres de las dos Comunidades Autónomas.

El diseño de casos cruzados es un diseño epidemiológico observacional propuesto por Maclure en 1991 para valorar si alguna exposición intermitente o inusual ha desencadenado un evento agudo a muy corto plazo. En este trabajo se presentan los fundamentos de los diseños de casos cruzados, con sus aplicaciones y limitaciones. El diseño de casos cruzados se basa en seleccionar sólo sujetos caso. Para calcular el riesgo relativo se compara la exposición durante el periodo de tiempo previo al evento (periodo caso) con la exposición del mismo sujeto en uno o varios periodos control. Este método únicamente es adecuado cuando las exposiciones son cambiantes en el tiempo, con efectos a corto plazo, y el efecto es agudo. Para exposiciones en que no existe tendencia, el planteamiento unidireccional es el más frecuente, y consiste en seleccionar uno o varios periodos control previos al momento caso. Cuando la exposición tiene una tendencia temporal (por ejemplo las de contaminación atmosférica), el planteamiento unidireccional proporciona estimaciones sesgadas, por lo que se utilizan diseños de casos cruzados bidireccionales, que seleccionan periodos de tiempo control anteriores y posteriores al del evento. Es un método que cuenta con una creciente utilización en amplios campos: desencadenantes de accidentes de tráfico, laborales y domésticos, o de infarto agudo de miocardio, contaminación atmosférica y salud, farmacoepidemiología, etc. Para el análisis de datos, generalmente se pueden considerar los diseños de casos cruzados como estudios de casos y controles emparejados, por lo que se aplica regresión logística condicional. Finalmente, en este trabajo se analizan ejemplos prácticos de diferentes aplicaciones del diseño de casos cruzados.Case-crossover analysis is an observational epidemiological design that was proposed by Maclure in 1991 to assess whether a given intermittent or unusual exposure may have triggered an immediate short-term, acute event. The present article outlines the basics of case-crossover designs, as well as their applications and limitations. The case-crossover design is based on exclusively selecting case subjects. To calculate relative risk, exposure during the period of time prior to the event (case period) is compared against the same subject's exposure during one or more control periods. This method is only appropriate when the exposures are transient in time and have acute short-term effects. For exposures in which there is no trend, a unidirectional approach is the most frequent and consists of selecting one or more control periods prior to the case period. When the exposure displays a time trend (e.g., air pollution), a unidirectional approach will yield biased estimates, and therefore bidirectional case-crossover designs are used, which select control time intervals preceding and subsequent to that of the event. The case-crossover design is being increasingly used across a wide range of fields, including factors triggering traffic, occupational and domestic accidents and acute myocardial infarction, and those involved in air pollution and health and pharmacoepidemiology, among others. Insofar as data-analysis is concerned, case-crossover designs can generally be regarded as matched case-control studies and consequently conditional logistic regression can be applied. Lastly, this study analyzes practical examples of distinct applications of the case-crossover design.

Fundamento: el efecto de las temperaturas sobre la mortalidad ha sido estudiado más en profundidad que el efecto sobre la morbilidad. En Murcia se monitorizan el número de urgencias diarias y los casos de golpes de calor atendidos en los hospitales de la Región. Objetivo: valorar el efecto de la temperatura sobre el número de urgencias hospitalarias y la utilidad de estos indicadores para vigilar la morbilidad por calor. Métodos: se ha estudiado el efecto de la temperatura sobre el número de urgencias en verano (periodo 2000-2005), estimando el incremento porcentual de urgencias cuando se superan los umbrales establecidos por el Ministerio de Sanidad y Consumo (Tª máxima 38ºC y Tª mínima 22,4ºC) y por cada grado de aumento de temperatura, expresado en Riesgo Relativo (RR) con un IC95%. Se han cotejado los golpes de calor comunicados con los ingresos registrados en el Conjunto Mínimo Básico de Datos al Alta Hospitalaria (CMBD). Resultados: En 2000-2005 las urgencias se incrementaron un 1,6% en los días con más de 22,4ºC de mínima (RR 1,016; IC95% 1,0076-1,0244), y un 0,21% por cada grado de aumento de la mínima (RR 1,0021; IC95% 1,0000-1,0044). El 38% de los golpes de calor ingresados no se notificaron, y el 40% de los notificados tenían exposición laboral. Conclusiones: La temperatura mínima podría tener un mayor efecto en Murcia que la máxima. Con los actuales umbrales, el número de urgencias diarias no parece un indicador adecuado para monitorizar el efecto de la temperatura, necesitándose información sobre el diagnóstico y la edad. Los golpes de calor aportan información parcial del impacto, pero resaltan grupos de población en riesgo menos considerados.

Fundamento:Diversos países han realizado estudios de compa-rabilidad entre las revisiones 10ª y 9ª de la Clasificación Internacio-nal de Enfermedades para listas agregadas de causas de muerte. EnEspaña el proyecto COMPARA pretende evaluar el impacto delcambio de revisión.Métodos:Estudio epidemiológico transversal descriptivo de88.048 defunciones inscritas en 1999 en España con la causa demuerte doblemente codificada en CIE-9 y 10. Se establecen lascorrespondencias teóricas entre CIE en las listas INE y Murcia. Secalculan las razones de comparabilidad e intervalos de confianza y elíndice kappa global.Resultados:Descienden las enfermedades infecciosas (-1,7%),las hepatitis víricas (-12,3%), mientras que aumenta el Sida (5,7%).Las neoplasias aumentan el 0,3% por la incorporación del síndromemielodisplásico (55,2%). Se incrementa la diabetes mellitus (2,1%).Se reducen los trastornos mentales al salir las demencias hacia laenfermedad de Alzheimer (28,6%). Las enfermedades cardiovascu-lares descienden ligeramente (-1,4%), sin impacto sobre las cerebro-vasculares, aunque el infarto agudo de miocardio decrece (-0,6%)con aumento de la enfermedad isquémica cardiaca (0,3%). La neu-monía decrece (-12,5%) y la cirrosis hepática se aumenta (4,3%).Las entidades mal definidas aumentan por la cesión de las insufi-ciencias cardiorrespiratorias. Las causas externas no varían sin querecojan la precisión de la CIE-9. La lista INE - 102 grupos obtiene uníndice kappa del 95,4%, similar a las variantes de Murcia. Conclusiones: Aunque el impacto global de la CIE-10 es menor,se deberían tener en cuenta las razones de comparabilidad significa-tivas de los grupos de causas de muerte con diferencias absolutasimportantes entre las revisiones.

Objectives: To describe the clustering of behavioural risk factors in the adult population of the Autonomous Community of Madrid (Spain), and to evaluate the association between the level of aggregation of such factors and suboptimal subjective health. Methods: Data were drawn from the Non-communicable Disease Risk-Factor Surveillance System (Sistema de Vigilancia de Factores de Riesgo asociados a Enfermedades No Transmisibles - SIVFRENT). We studied the relationships between tobacco use, high-risk alcohol consumption, leisure-time inactivity and unbalanced diet in 16,043 people aged 18-64, comparing observed against expected proportions. Logistic regression was used to estimate the association between aggregation of risk factors and suboptimal health (fair, poor and very poor health). Results: Almost 20% of subjects had 3 or 4 risk factors. Most combinations of three risk factors exceeded expectations and, in particular, 4-factor clustering yielded observed/expected quotients of 2.15 (95% confidence interval [CI], 1.93-2.38) in men and 2.96 (95% CI, 2.46-3.46) in women. In both sexes, smoking was the individual factor most frequently associated with the remaining risk factors. Aggregation of risk factors was more frequent among men, in younger age groups and among subjects with low educational level. Compared to people with none of the 4 risk factors, those with 3 or four reported suboptimal subjective health more frequently (OR = 2.49; 95% CI, 1.59-3.90 for men and OR = 1.96; 95% CI, 1.29-2.97 for women). Conclusions: Behavioural risk factors tend to aggregate, and this clustering is higher among men, in younger age groups and among subjects with a low educational level. A greater level of clustering is associated with a higher frequency of suboptimal self-rated health.Objetivos: Describir la agregación de factores de riesgo relacionados con el comportamiento en la población adulta de la Comunidad de Madrid y evaluar la asociación del grado de agregación de dichos factores con la salud subjetiva subóptima. Métodos: Los datos proceden del Sistema de Vigilancia de Factores de Riesgo asociados a Enfermedades No Transmisibles (SIVFRENT). Las relaciones entre el consumo de tabaco, el consumo de alcohol de riesgo, el sedentarismo en tiempo libre y la dieta desequilibrada fueron estudiadas en 16.043 personas de 18 a 64 años, y se compararon las proporciones observadas respecto a las esperadas. Mediante un análisis de regresión logística se estimó la asociación entre la agregación de factores de riesgo y la salud percibida subóptima (regular, mala y muy mala). Resultados: Cerca del 20% de los sujetos presentan 3 o 4 factores de riesgo simultáneamente. La mayoría de combinaciones de 3 factores de riesgo son superiores a las esperadas, destacando la agregación de los 4 factores con un cociente observado/esperado de 2,15 (IC del 95%, 1,93-2,38) en varones y de 2,96 (IC del 95%, 2,46-3,46) en mujeres. En ambos sexos, el factor individual que más se asocia al resto de factores de riesgo es el tabaco. La agregación de factores de riesgo es más frecuente en varones, en edades jóvenes y en el nivel educativo bajo. En comparación con los que carecen de los 4 factores de riesgo, los que presentan simultáneamente 3 o 4 de ellos tienen con mayor frecuencia una salud percibida subóptima (OR = 2,49; IC del 95%, 1,59-3,90 en varones y OR = 1,96; IC del 95%, 1,29-2,97 en mujeres). Conclusiones: Los factores de riesgo ligados al comportamiento se agregan, y esta acumulación es superior en varones, en personas jóvenes y con bajo nivel de estudios. Un mayor grado de agregación se asocia a mayor frecuencia de salud percibida subóptima.

Objetivo: Ilustrar por primera vez con datos españoles la utilidad de la vigilancia por encuesta telefónica de los factores de riesgo de enfermedades no transmisibles para orientar las políticas de salud pública. Métodos: Se analiza la información del Sistema de Vigilancia de Factores de Riesgo asociados con Enfermedades No Transmisibles (SIVFRENT) entre 1995 y 2003, basada en encuestas telefónicas mensuales y dirigida a la población de 18-64 años de la Comunidad de Madrid. Se realizaron 18.049 entrevistas durante todo el período. Se calculan los indicadores de sobrepeso y obesidad, sedentarismo, dieta, consumo de tabaco y alcohol, prácticas preventivas, accidentabilidad y seguridad vial. La tendencia se estima a través del promedio anual de las razones de prevalencia obtenidas mediante modelos lineales generalizados con vínculo logarítmico y familia binomial. Resultados: Los mayores cambios en los varones corresponden al incremento del sobrepeso y la obesidad, con un aumento relativo del 3,7% anual, y al descenso de la realización de dietas (-3%), del consumo elevado de alcohol (-6,1%) y de la no utilización del cinturón de seguridad (-4%). En las mujeres se incrementan el sobrepeso y la obesidad (3,3%), el abandono del consumo de tabaco (3,1%) y la realización de mamografías (6,4%), y disminuye la realización de dietas (-4,1%) y la no utilización del cinturón de seguridad (-4,5%). Conclusiones: Se observan importantes progresos en numerosos indicadores, como el consumo de tabaco y alcohol, la seguridad vial y la realización de prácticas preventivas, mientras que en otros la situación empeora, fundamentalmente el incremento del sobrepeso y la obesidad.Objective: To illustrate -for the first time with Spanish data- the usefulness of telephone-interview-based surveillance of non-communicable diseases risk factors for the purpose of drawing up public health policies. Methods: We analysed information from the Non-Communicable Disease Risk Factor Surveillance System (Sistema de Vigilancia de Factores de Riesgo asociados a Enfermedades No Transmisibles- SIVFRENT) for the period 1995-2003. This system is based on monthly telephone interviews covering a representative population sample, aged 18-64 years. 18,049 interviews were conducted for the whole period. Indicators of overweight and obesity, sedentary lifestyle, diet, tobacco and alcohol consumption, preventive practices, accidents and injuries, and road safety were calculated. The time trend was estimated using average annual prevalence ratios, obtained from generalised linear models with binomial family and logarithmic link. Results: Among men, the changes of greatest magnitude corresponded to an increase in overweight and obesity, which registered a relative annual rise of 3.7%, and a decrease in dieting (-3%), high alcohol consumption (-6.1%) and non-use of safety belts (-4%). Among women, there was a marked increase in overweight and obesity (3.3%), cessation of smoking (3.1%) and recourse to mammograms (6.4%), and a decrease in dieting (-4.1%) and non-use of safety belts (-4.5%). Conclusions: Although important progress was observed in a number of indicators, such as tobacco and alcohol consumption, road safety and the undertaking of preventive practices, the situation worsened in others, i.e., fundamentally the increase in overweight and obesity.

El presente ensayo trata de aclarar algunos conceptos utilizados habitualmente en el campo de investigación de la salud pública, que en numerosas situaciones son interpretados de manera incorrecta. Entre ellos encontramos la estimación puntual, los intervalos de confianza, y los contrastes de hipótesis. Estableciendo un paralelismo entre estos tres conceptos, podemos observar cuáles son sus diferencias más importantes a la hora de ser interpretados, tanto desde el punto de vista del enfoque clásico como desde la óptica bayesiana.This essay reviews some statistical concepts frequently used in public health research that are commonly misinterpreted. These include point estimates, confidence intervals, and hypothesis tests. By comparing them using the classical and the Bayesian perspectives, their interpretation becomes clearer.