Santiago Pérez-Hoyos

Air pollution and cardiovascular admissions association in Spain: results within the EMECAS project

Objective: To evaluate the short term effect of air pollution on cardiovascular admissions in 14 Spanish cities Methods: The period under study was from 1995 to 1999. Daily emergency admissions for all cardiovascular diseases (CVD) and heart diseases (HD) were obtained from hospital records, and the corresponding daily levels of particulates, SO2, NO2, CO, and ozone were recorded. The magnitude of association was estimated using Poisson generalised additive models controlling for confounding and overdispersion. For each cause, lagged effects, up to three days, of each pollutant were examined and combined estimates were obtained. For ozone the analyses were restricted to the warm period. One and two pollutant models were performed. Results: Associations were more consistent in lag 0 (concurrent day) and 1 (lag 0–1), except in the case of ozone where there was a more delayed relation (lag 2–3). For combined estimates an increase of 10 μg/m3 in the PM10 levels in lag 0–1 was associated with an increase of 0.9% (95% CI: 0.4 to 1.5%) in the number of hospital admissions for CVD, and 1.6% (0.8 to 2.3%) for HD. For ozone the corresponding estimates for lag 2–3 were 0.7% (0.3 to 1.0) for CVD, and 0.7% (0.1 to 1.2) for HD. An increase of 1 mg/m3 in CO levels was associated with an increase of 2.1% (0.7 to 3.5%) in CVD admissions, and 4.2% (1.3 to 7.1%) in HD admissions. SO2 and NO2 estimates were more sensitive in two pollutant models Conclusions: A short term association between increases in daily levels of air pollutants and the number of daily admissions for cardiovascular diseases, with specificity for heart diseases, has been described in Spanish cities.

Air pollution and emergency hospital admissions for cardiovascular diseases in Valencia, Spain

STUDY OBJECTIVE To estimate the short-term association between air pollution levels and emergency hospital admissions for cardiovascular diseases in Valencia, within 1994–1996 period. DESIGN Daily levels of air pollution and emergency admissions for cardiovascular diseases were related to using an ecological time series design. The number of admissions was obtained from the hospital records database. Selected groups of causes were all cardiovascular diseases, heart admissions, and admissions for cerebrovascular diseases. The number of admissions for digestive diseases was used as control. Pollutants were black smoke, sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3). Magnitude of association was estimated by Poisson autoregresive regression. Estimations were calculated according the hottest (May to October) and the coldest (November to April) periods. SETTING City of Valencia, Spain, about 750u2009000 inhabitants. PARTICIPANTS People being admitted to the two major hospitals in the city, with a catchment area of nearly 400u2009000 inhabitants. MAIN RESULTS For the whole period, a significant association for SO2-24 h was found so a rise in its levels of 10 μg/m3 was associated with an increment of 3% (95%CI 0.4 to 5.7%) in the expected number of cardiovascular admissions. A significant association for black smoke, SO2-24 h, SO2-1 h, and CO-1 h was found in the hottest semester. All these associations were verified with a lag of two days. The estimates of the associations for particles, SO2, and CO were affected by the inclusion of the other pollutants in their models. NO2 was independently associated with cerebrovascular admissions. There were no significant associations between air pollution and admissions for digestive diseases. CONCLUSIONS Current levels of air pollution and emergency cardiovascular admissions are significantly related in Valencia.

Air pollution and mortality in Valencia, Spain: a study using the APHEA methodology.

STUDY OBJECTIVE: To assess the short term relationship between daily air pollution indicators (black smoke and sulphur dioxide (SO2)) and mortality in Valencia. DESIGN: This was an ecological study using time series data with application of Poisson regression. Daily variations in four selected outcome variables (total mortality, mortality in those over 70 years of age, and cardiovascular and respiratory mortality) were considered in relation to daily variations in air pollution levels for the period 1991-93. SETTING: The city of Valencia, Spain. MAIN RESULTS: The mean daily mortality was 17.5, and the average daily levels of air pollutants from the three monitoring stations included in the study were, 67.7 micrograms/m3 for black smoke, and 39.9 micrograms/ m3 for SO2. A significant positive association between black smoke and three of the four outcomes in the study was found. The estimated relative risk (RR) of dying corresponding to a 10 micrograms/m3 increase in mean daily black smoke over the whole period was 1.009 (95% confidence interval (95% CI): 1.003, 1.015). For mortality in the group aged more than 70 years and for cardiovascular mortality, the RRs were 1.008 (95% CI: 1.001, 1.016) and 1.012 (95% CI: 1.003, 1.022) respectively. The association with SO2 was less clear: it was only evident during the warm season. The estimated RRs in this case were 1.007 (95% CI: 0.999, 1.015) for total mortality, 1.009 (95% CI: 1.00, 1.21) for total mortality in those older than 70, and 1.012 (95% CI: 0.995, 1.026) for cardiovascular deaths. No significant association was found between mortality from respiratory diseases and either of the two pollutants. CONCLUSIONS: A positive relationship between air pollution and mortality was found in the short term, as has been shown in an important number of studies carried out elsewhere. Although the current levels of particulate air pollution in Valencia are not very high, they could have an effect on the number of premature deaths. Despite the fact that the association is weak, it is important at the public health level both because of the numbers of population exposed and the possibility of establishing control measures.

Relation between Temperature and Mortality in Thirteen Spanish Cities

In this study we examined the shape of the association between temperature and mortality in 13 Spanish cities representing a wide range of climatic and socio-demographic conditions. The temperature value linked with minimum mortality (MMT) and the slopes before and after the turning point (MMT) were calculated. Most cities showed a V-shaped temperature-mortality relationship. MMTs were generally higher in cities with warmer climates. Cold and heat effects also depended on climate: effects were greater in hotter cities but lesser in cities with higher variability. The effect of heat was greater than the effect of cold. The effect of cold and MMT was, in general, greater for cardio-respiratory mortality than for total mortality, while the effect of heat was, in general, greater among the elderly.

Changes in the incidence of tuberculosis in a cohort of HIV-seroconverters before and after the introduction of HAART.

Objective:To analyse incidence and determinants of tuberculosis in HIV-seroconverters before and after the introduction of HAART. Methods:Data from a multicenter cohort study of 2238 HIV-seroconverters between the 1980s and 2004 were analysed and censored by December 2004. Calendar year at risk intervals were pre-1992, 1992–1996 and 1997–2004. Incident tuberculosis was calculated as cases per 1000 person-years (p-y). Survival analyses using Kaplan–Meier and multivariate Cox regression allowing for late-entry were used. Proportional hazards assumptions were checked with tests based on Schoenfeld residuals. Results:Overall, 173 (7.7%) patients developed tuberculosis over 23 698 p-y at a rate of 7.3 cases per 1000 p-y [95% confidence interval (CI), 6.3–8.5]. Incident tuberculosis was higher in intravenous drug-users (IDUs), 12.3 per 1000 p-y compared with persons infected sexually, 3.8 per 1000 p-y (P < 0.001), and persons with clotting disorders (PCD), 2.7 per 1000 p-y (P < 0.001). A decreasing tuberculosis incidence trend was observed from 1995 in all categories. Highest tuberculosis rates, 44 per 1000 p-y, were observed prior to 1997 in IDUs infected with HIV for 11 years. In multivariable analyses women were less likely to develop tuberculosis [relative hazard (RH), 0.62; 95% CI, 0.41–0.96; P < 0.05) and IDUs were more likely to develop tuberculosis (RH, 3.0; 95% CI, 1.72–5.26, P < 0.001). In the HAART era, the hazard of developing tuberculosis was 70% lower (RH, 0.31; 95% CI, 0.17–0.54; P < 0.001). Before 1997, the risk of tuberculosis increased with time since HIV seroconversion, whereas it remained nearly constant in the HAART era. Conclusions:Since the mid-1990s important decreases in tuberculosis have been observed in HIV-seroconverters that probably reflect the impact of both HAART and tuberculosis control programmes.

Air pollution and hospital emergency room admissions for chronic obstructive pulmonary disease in Valencia, Spain.

Abstract The short-term relationship between levels of air pollution and emergency room admissions for chronic obstructive pulmonary disease was assessed in Valencia, Spain. The design was an ecological time-series study in which daily variation in air pollution was related to emergency chronic obstructive pulmonary disease visits to one of the citys hospitals. The pollutants under investigation were Black Smoke, sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone. The degree of association was analyzed with Poisson autoregressive regression, for which trend, seasonal patterns, temperature, humidity, days of the week, and incidence of influenza were controlled. Increases of 10 μg/m3 in ozone levels (lag 5) and of 1 mg/m3 in carbon monoxide (lag 1) were associated with increases of 6.1 % (95% confidence interval [CI] = 2.2%, 10.1%) and of 3.9% (95% CI = 1.4%, 6.6%), respectively, in the expected chronic obstructive pulmonary disease cases. There was no significant association for the remainder of the pollutants. The described effects persisted even when the authors used models of differing specifications and when generalized additive models were used. The authors concluded that the results of this investigation, together with results of earlier research, demonstrate the significant effect of pollution on various health indicators within Valencia.

Shiftwork: its impact on the length and quality of sleep among nurses of the Valencian region in Spain

SummaryPrevious research has shown the repercussions of Shiftwork for workers sleep. The objective of the present work is to evaluate the impact of shiftwork on the length and quality of sleep among nurses and on the intake of psychotropic drugs. A cross-sectional epidemiological study was carried out in 606 female nurses and 367 male nurses selected at random from the public hospitals in the Valencian region. Information was collected by means of a questionnaire. Univariate and multivariate statistical analysis techniques were used. For both female and male nurses, Shiftwork led to a reduction in the length of sleep (by 2 h in those permanently on night shifts and by 30 min in those on a rotating night shift system) and an alteration in the quality of sleep (difficulty in sleeping, intermittent sleep, early waking, etc. occurred 10% more frequently), but it did not lead to an increase in the consumption of psychotropic drugs.

Spatial Analysis of the Relationship between Mortality from Cardiovascular and Cerebrovascular Disease and Drinking Water Hardness

Previously published scientific papers have reported a negative correlation between drinking water hardness and cardiovascular mortality. Some ecologic and case–control studies suggest the protective effect of calcium and magnesium concentration in drinking water. In this article we present an analysis of this protective relationship in 538 municipalities of Comunidad Valenciana (Spain) from 1991–1998. We used the Spanish version of the Rapid Inquiry Facility (RIF) developed under the European Environment and Health Information System (EUROHEIS) research project. The strategy of analysis used in our study conforms to the exploratory nature of the RIF that is used as a tool to obtain quick and flexible insight into epidemiologic surveillance problems. This article describes the use of the RIF to explore possible associations between disease indicators and environmental factors. We used exposure analysis to assess the effect of both protective factors—calcium and magnesium—on mortality from cerebrovascular (ICD-9 430–438) and ischemic heart (ICD-9 410–414) diseases. This study provides statistical evidence of the relationship between mortality from cardiovascular diseases and hardness of drinking water. This relationship is stronger in cerebrovascular disease than in ischemic heart disease, is more pronounced for women than for men, and is more apparent with magnesium than with calcium concentration levels. Nevertheless, the protective nature of these two factors is not clearly established. Our results suggest the possibility of protectiveness but cannot be claimed as conclusive. The weak effects of these covariates make it difficult to separate them from the influence of socioeconomic and environmental factors. We have also performed disease mapping of standardized mortality ratios to detect clusters of municipalities with high risk. Further standardization by levels of calcium and magnesium in drinking water shows changes in the maps when we remove the effect of these covariates.

Métodos de series temporales en los estudios epidemiológicos sobre contaminación atmosférica

Se revisan los metodos de series temporales en los estudios epidemiologicos sobre contaminacion atmosferica, ilustrandolo mediante una regresion de Poisson autoregresiva, la cual ha sido utilizada en los proyectos APHEA y EMECAM. Se relacionan las variaciones en el numero diario de muertos mayores de 70 anos (todas las causas, CIE-9:001-799) en Barcelona, 1991-1995, con las variaciones en los niveles diarios promedio de contaminacion por humos negros. Se utiliza una regresion de Poisson por cuanto la variable aleatoria dependiente sigue presumiblemente tal distribucion de probabilidad. Como confusores se consideran variables meteorologicas (promedios diarios de temperatura y de humedad), comportamientos tendenciales, estacionales y efectos de calendario presentes en la mortalidad (todos ellos aproximados de forma determinista) asi como cualquier otra variable que tenga un comportamiento que pueda relacionarse con la variable dependiente (ocurrencia de epidemias de gripe por ejemplo). La relacion entre la mortalidad y las variables confusoras se modeliza de forma no lineal y se tienen en cuenta ademas los previsibles periodos de latencia (utilizando retardos de variables explicativa por ejemplo). Sin embargo, y debido a que el control no es perfecto, se opta por estimar un modelo de Poisson autoregresivo (introduciendo como variables explicativas diversos retardos de la mortalidad) corrigiendo la autocorrelacion residual. La principal ventaja del metodo de analisis descrito es la de permitir un control de variables confusoras desde un punto determinista, con un software al alcance de todos los grupos que participan en el proyecto. Ademas, permite que el metodo se pueda aplicar de una formar protocolizada y estandarizada que facilite la comparacion de resultados y permita la realizacion de un meta-analisis.

Comparing meta-analysis and ecological-longitudinal analysis in time-series studies. A case study of the effects of air pollution on mortality in three Spanish cities

STUDY OBJECTIVE The objective of this paper is to introduce a different approach, called the ecological-longitudinal, to carrying out pooled analysis in time series ecological studies. Because it gives a larger number of data points and, hence, increases the statistical power of the analysis, this approach, unlike conventional ones, allows the complementation of aspects such as accommodation of random effect models, of lags, of interaction between pollutants and between pollutants and meteorological variables, that are hardly implemented in conventional approaches. DESIGN The approach is illustrated by providing quantitative estimates of the short-term effects of air pollution on mortality in three Spanish cities, Barcelona, Valencia and Vigo, for the period 1992–1994. Because the dependent variable was a count, a Poisson generalised linear model was first specified. Several modelling issues are worth mentioning. Firstly, because the relations between mortality and explanatory variables were non-linear, cubic splines were used for covariate control, leading to a generalised additive model, GAM. Secondly, the effects of the predictors on the response were allowed to occur with some lag. Thirdly, the residual autocorrelation, because of imperfect control, was controlled for by means of an autoregressive Poisson GAM. Finally, the longitudinal design demanded the consideration of the existence of individual heterogeneity, requiring the consideration of mixed models. MAIN RESULTS The estimates of the relative risks obtained from the individual analyses varied across cities, particularly those associated with sulphur dioxide. The highest relative risks corresponded to black smoke in Valencia. These estimates were higher than those obtained from the ecological-longitudinal analysis. Relative risks estimated from this latter analysis were practically identical across cities, 1.00638 (95% confidence intervals 1.0002, 1.0011) for a black smoke increase of 10 μg/m3 and 1.00415 (95% CI 1.0001, 1.0007) for a increase of 10u2009μg/m3 of sulphur dioxide. Because the statistical power is higher than in the individual analysis more interactions were statistically significant, especially those among air pollutants and meteorological variables. CONCLUSIONS Air pollutant levels were related to mortality in the three cities of the study, Barcelona, Valencia and Vigo. These results were consistent with similar studies in other cities, with other multicentric studies and coherent with both, previous individual, for each city, and multicentric studies for all three cities.