Herramientas estadísticas para el estudio de perfiles de riesgo

En este documento se ilustra de un modo práctico, el empleo de tres instrumentos que permiten al actuario definir grupos arancelarios y estimar premios de riesgo en el proceso que tasa la clase para el seguro de no vida. El primero es el análisis de segmentación (CHAID y XAID) usado en primer lugar en 1997 por UNESPA en su cartera común de coches. El segundo es un proceso de selección gradual con el modelo de regresión a base de distancia. Y el tercero es un proceso con el modelo conocido y generalizado de regresión linear, que representa la técnica más moderna en la bibliografía actuarial. De estos últimos, si combinamos funciones de eslabón diferentes y distribuciones de error, podemos obtener el aditivo clásico y modelos multiplicativos

Pretreatment with statins improves early outcome in patients with first-ever ischaemic stroke: a pleiotropic effect of statins or a beneficial effect of hypercholesterolemia?

Background: Data from different studies suggest a favourable association between pretreatment with statins or hypercholesterolemia and outcome after ischaemic stroke. We examined whether there were differences in in-hospital mortality according to the presence or absence of statin therapy in a large population of first-ever ischaemic stroke patients and assessed the influence of statins upon early death and spontaneous neurological recovery. Methods: In 2,082 consecutive patients with first-ever ischaemic stroke collected from a prospective hospital-based stroke registry during a period of 19 years (1986-2004), statin use or hypercholesterolemia before stroke was documented in 381 patients. On the other hand, favourable outcome defined as grades 0-2 in the modified Rankin scale was recorded in 382 patients. Results: Early outcome was better in the presence of statin therapy or hypercholesterolemia (cholesterol levels were not measured) with significant differences between the groups with and without pretreatment with statins in in-hospital mortality (6% vs 13.3%, P = 0.001) and symptom-free (22% vs 17.5%, P = 0.025) and severe functional limitation (6.6% vs 11.5%, P = 0.002) at hospital discharge, as well as lower rates of infectious respiratory complications during hospitalization. In the logistic regression model, statin therapy was the only variable inversely associated with in-hospital death (odds ratio 0.57) and directly associated with favourable outcome (odds ratio 1.32).

Incidencia de la incapacidad temporal por contingencia común y profesional en la muestra continua de vidas laborales en 2009

Objetivo: Describir la incidencia de la incapacidad temporal por contingencia común (ITcc) y profesional (ITcp) iniciada en 2009 en afiliados a la Seguridad Social (SS) que forman parte de la Muestra Continua de Vida Laboral.Métodos: Cohorte formada por 873.008 afiliados a la SS en España que registraron 163.008 episodios de IT con un tiempo acumulado total en riesgo de 675.923,6 trabajadores-año. Se estimó la tasa de incidencia de todos los primeros episodios de IT y por trastornos musculo-esqueléticos (TME) según variables demográficas y laborales. Posteriormente se calcularon las razones de tasas crudas (RTc) y ajustadas (RTa) mediante un modelo de regresión Poisson.Resultados: La incidencia de la ITcc e ITcp fue de 23,1 y 1,0 casos por 100 trabajadores-año, respectivamente. La incidencia por ITcc fue superior en mujeres, en menores de 26 años y en Navarra (32,8 casos por 100 trabajadores-año), y por ITcp las mayores incidencias se observaron en hombres y en Galicia. Por diagnóstico, los TME presentaron 424,7 casos y 3,6 casos por 10.000 trabajadores-año según contingencia común y profesional respectivamente. Por otra parte, los trabajadores temporales tuvieron más riesgo de desarrollar ITcp (RTa=1,09;IC95%=1,04-1,15) e ITcc (RTa=1,02;IC95%=1,01-1,03) respecto a los permanentes.Conclusiones: La incidencia de la IT sigue un mismo patrón según edad, régimen de afiliación y relación laboral. Por tipo de contingencia se observaron diferencias en la ocupación, sexo, tamaño de empresa, comunidad autónoma y actividad económica. Es necesario estudiar con más detenimiento las diferencias observadas por actividad económica y tipo de relación contractual.

¿La incidencia de la pobreza discrimina por razones de género? : Análisis de los factores determinantes en el caso español

El presente trabajo traslada el debate académico alrededor del mayor riesgo de pobreza que afrontan las mujeres en relación a los hombres al contexto español. Tras una breve revisión bibliográfica de los datos disponibles sobre la pobreza femenina en países industrializados y sus posibles causantes, se ponen a prueba esos mismos factores potencialmente culpables en el caso español. Del EU-SILC de 2010 se ha sacado una muestra formada únicamente por mujeres y hombres que o bien viven solos o con hijos a su cargo y, partiendo de ella, el método de la regresión logística ha concluido que hay factores exclusivamente explicativos de la pobreza femenina. Ser madre soltera, ser joven (entre 16 y 25 años) y no haber nacido en España tienen una importante capacidad explicativa de la pobreza femenina mientras no son significativas como explicación de la pobreza masculina. Si a estos factores añadimos no tener un trabajo, un bajo logro educativo y no recibir ningún subsidio individual, obtenemos un conjunto de factores que explican un 26.8% de los casos de mujeres españolas pobres que viven solas o son madres solteras. Estos datos ponen de relieve la necesidad de más investigaciones al respecto que consigan un mayor poder explicativo.

¿Favorece la publicación en abierto el impacto de los artículos científicos? Un estudio empírico en el ámbito de la medicina intensiva

Peer-reviewed

La decisión de endeudamiento y los factores de mayor relevancia. Una aplicación empírica en la empresa industrial española

El presente trabajo aborda el estudio de los factores determinantes del endeudamiento empresarial para contrastar empíricamente la hipótesis del Pecking Order. El endeudamiento empresarial se mide junto a su madurez y para los diferentes tamaños empresariales dada la importancia de diferenciar sus posibles efectos contrapuestos o compensados. Los modelos utilizados para el contraste de hipótesis se han estimado con una muestra de 1.320 empresas manufactureras españolas proporcionada por la Encuesta sobre Estrategias Empresariales (ESEE), para el período 1993-2001. El análisis empírico aplica un modelo multivariante de regresión logística que permite concluir que la teoría del Pecking Order es la de mejor cumplimiento, además de constatarse que las empresas de menor tamaño tienen mayores dificultades de acceso a la financiación con deuda a largo plazo.

Prevalencia de la discapacidad en España por comunidades autónomas: el papel de los factores individuales y del entorno geográfico en su variabilidad

Fundamento: La prevalencia de discapacidad en la población general presenta una gran variabilidad geográfica, de manera que identificar aquellos factores que pudieran explicarla será importante para la planificación de políticas sociales. En este trabajo se analiza la variabilidad de la discapacidad por comunidades autónomas desde una doble vertiente, los factores individuales y del entorno. Métodos: Los datos proceden principalmente de la Encuesta de Discapacidad, Deficiencias y Estado de Salud de 1999 y del Inebase, ambas del Instituto Nacional de Estadística (INE). Se calculó la prevalencia de discapacidad simple y ajustada por edad de las CCAA. Se analizan los factores individuales asociados a la discapacidad mediante una regresión logística y los factores individuales y de la comunidad autónoma conjuntamente con una regresión logística de dos niveles. Resultados: La prevalencia de discapacidad muestra una diferencia máxima de 5,75 puntos entre las comunidades autónomas. En la regresión logística la comunidad de residencia fue estadísticamente significativa (OR: 3,35 en la de mayor prevalencia respecto a la de menor) junto con otras variables individuales: edad (OR de 40-64= 1,78 OR de 65-79= 1,87 y OR de >79= 3,34), sexo (OR mujer= 0,66), situación laboral (OR sin trabajo=2,25 OR amas casa/estudiante=1,39 y OR otros=2,03), estado de salud (OR regular= 1,69 OR malo/muy malo= 2,05) y enfermedades crónicas (OR 1-3=1,56 OR4-6=1,82 OR>6=2,59). En la regresión de dos niveles las variables individuales explican poca varianza (s=0,261) y ninguna de las variables relativas a las CCAA mejora el modelo. Conclusiones: Las características individuales no explican suficientemente la variabilidad de la discapacidad entre CCAA y no se han identificado variables del entorno que sean significativas.

Breast cancer incidence and overdiagnosis in Catalonia (Spain)

Introduction: Early detection of breast cancer (BC) with mammography may cause overdiagnosis and overtreatment, detecting tumors which would remain undiagnosed during a lifetime. The aims of this study were: first, to model invasive BC incidence trends in Catalonia (Spain) taking into account reproductive and screening data; and second, to quantify the extent of BC overdiagnosis. Methods: We modeled the incidence of invasive BC using a Poisson regression model. Explanatory variables were: age at diagnosis and cohort characteristics (completed fertility rate, percentage of women that use mammography at age 50, and year of birth). This model also was used to estimate the background incidence in the absence of screening. We used a probabilistic model to estimate the expected BC incidence if women in the population used mammography as reported in health surveys. The difference between the observed and expected cumulative incidences provided an estimate of overdiagnosis. Results: Incidence of invasive BC increased, especially in cohorts born from 1940 to 1955. The biggest increase was observed in these cohorts between the ages of 50 to 65 years, where the final BC incidence rates more than doubled the initial ones. Dissemination of mammography was significantly associated with BC incidence and overdiagnosis. Our estimates of overdiagnosis ranged from 0.4% to 46.6%, for women born around 1935 and 1950, respectively. Conclusions: Our results support the existence of overdiagnosis in Catalonia attributed to mammography usage, and the limited malignant potential of some tumors may play an important role. Women should be better informed about this risk. Research should be oriented towards personalized screening and risk assessment tools.

Positive Outcomes Influence the Rate and Time to Publication, but Not the Impact Factor of Publications of Clinical Trial Results

Objectives: Publication bias may affect the validity of evidence based medical decisions. The aim of this study is to assess whether research outcomes affect the dissemination of clinical trial findings, in terms of rate, time to publication, and impact factor of journal publications. Methods and Findings: All drug-evaluating clinical trials submitted to and approved by a general hospital ethics committee between 1997 and 2004 were prospectively followed to analyze their fate and publication. Published articles were identified by searching Pubmed and other electronic databases. Clinical study final reports submitted to the ethics committee, final reports synopses available online and meeting abstracts were also considered as sources of study results. Study outcomes were classified as positive (when statistical significance favoring experimental drug was achieved), negative (when no statistical significance was achieved or it favored control drug) and descriptive (for non-controlled studies). Time to publication was defined as time from study closure to publication. A survival analysis was performed using a Cox regression model to analyze time to publication. Journal impact factors of identified publications were recorded. Publication rate was 48·4% (380/785). Study results were identified for 68·9% of all completed clinical trials (541/785). Publication rate was 84·9% (180/212) for studies with results classified as positive and 68·9% (128/186) for studies with results classified as negative (p<0·001). Median time to publication was 2·09 years (IC95 1·61-2·56) for studies with results classified as positive and 3·21 years (IC95 2·69-3·70) for studies with results classified as negative (hazard ratio 1·99 (IC95 1·55-2·55). No differences were found in publication impact factor between positive (median 6·308, interquartile range: 3·141-28·409) and negative result studies (median 8·266, interquartile range: 4·135-17·157). Conclusions: Clinical trials with positive outcomes have significantly higher rates and shorter times to publication than those with negative results. However, no differences have been found in terms of impact factor.

Factors affecting hospital admission and recovery stay duration of in-patient motor victims in Spain

Hospital expenses are a major cost driver of healthcare systems in Europe, with motor injuries being the leading mechanism of hospitalizations. This paper investigates the injury characteristics which explain the hospitalization of victims of traffic accidents that took place in Spain. Using a motor insurance database with 16.081 observations a generalized Tobit regression model is applied to analyse the factors that influence both the likelihood of being admitted to hospital after a motor collision and the length of hospital stay in the event of admission. The consistency of Tobit estimates relies on the normality of perturbation terms. Here a semi-parametric regression model was fitted to test the consistency of estimates, concluding that a normal distribution of errors cannot be rejected. Among other results, it was found that older men with fractures and injuries located in the head and lower torso are more likely to be hospitalized after the collision, and that they also have a longer expected length of hospital recovery stay.

Modelling the disability severity score in motor insurance claims: an application to the Spanish case

Bodily injury claims have the greatest impact on the claim costs of motor insurance companies. The disability severity of motor claims is assessed in numerous European countries by means of score systems. In this paper a zero inflated generalized Poisson regression model is implemented to estimate the disability severity score of victims in-volved in motor accidents on Spanish roads. We show that the injury severity estimates may be automatically converted into financial terms by insurers at any point of the claim handling process. As such, the methodology described may be used by motor insurers operating in the Spanish market to monitor the size of bodily injury claims. By using insurance data, various applications are presented in which the score estimate of disability severity is of value to insurers, either for computing the claim compensation or for claim reserve purposes.

Fiscal Regime Shifts in Portugal

We estimate changes in fiscal policy regimes in Portugal with a Markov Switching regression of fiscal policy rules for the period 1978-2007, using a new dataset of fiscal quarterly series. We find evidence of a deficit bias, while repeated reversals of taxes making the budget procyclical. Economic booms have typically been used to relax tax pressure, especially during elections. One-off measures have been preferred over structural ones to contain the deficit during economic crises. The EU fiscal rules prompted temporary consolidation, but did not permanently change the budgeting process.

Association between Long-Term Exposure to Traffic-Related Air Pollution and Subclinical Atherosclerosis: The REGICOR Study

Background: Epidemiological evidence of the effects of long-term exposure to air pollu tion on the chronic processes of athero genesis is limited. Objective: We investigated the association of long-term exposure to traffic-related air pollu tion with subclinical atherosclerosis, measured by carotid intima media thickness (IMT) and ankle–brachial index (ABI). Methods: We performed a cross-sectional analysis using data collected during the reexamination (2007–2010) of 2,780 participants in the REGICOR (Registre Gironí del Cor: the Gerona Heart Register) study, a population-based prospective cohort in Girona, Spain. Long-term exposure across residences was calculated as the last 10 years’ time-weighted average of residential nitrogen dioxide (NO2) estimates (based on a local-scale land-use regression model), traffic intensity in the nearest street, and traffic intensity in a 100 m buffer. Associations with IMT and ABI were estimated using linear regression and multinomial logistic regression, respectively, controlling for sex, age, smoking status, education, marital status, and several other potential confounders or intermediates. Results: Exposure contrasts between the 5th and 95th percentiles for NO2 (25 μg/m), traffic intensity in the nearest street (15,000 vehicles/day), and traffic load within 100 m (7,200,000 vehicle-m/day) were associated with differences of 0.56% (95% CI: –1.5, 2.6%), 2.32% (95% CI: 0.48, 4.17%), and 1.91% (95% CI: –0.24, 4.06) percent difference in IMT, respectively. Exposures were positively associated with an ABI of > 1.3, but not an ABI of < 0.9. Stronger associations were observed among those with a high level of education and in men ≥ 60 years of age. Conclusions: Long-term traffic-related exposures were associated with subclinical markers of atherosclerosis. Prospective studies are needed to confirm associations and further examine differences among population subgroups.key words: ankle–brachial index, average daily traffic, cardiovascular disease, exposure assessment, exposure to tailpipe emissions, intima media thickness, land use regression model, Mediterranean diet, nitrogen dioxide