Counts Of Hospital Admissions Research Articles

THE SHORT-TERM EFFECTS OF AIR POLLUTION ON CARDIOVASCULAR ADMISSIONS

This poster complements the paper in this area (A description of the SPIRT study for Brisbane, Melbourne, Perth and Sydney: Simpson et al) and details all the results referred in summary in the paper on the short-term health effects of air pollution on cardiovascular admissions in four Australian cities-Brisbane, Melbourne, Perth and Sydney. The study used a protocol similar to that used in Europe (Air Pollution and Health: A European Approach-APHEA) to examine the associations between health outcomes, such as daily mortality and daily hospital admissions counts, and air pollutants. This poster details all the results for the period 1996-1999 of a meta-analysis for the four cities for the acute health impacts of the pollutants-fine particles, nitrogen dioxide, and ozone. The meta-analyses often show statistically significant differences between the cities indicating the results can be quite different in different cities. Fine particles (as measured by nephelometery) and nitrogen dioxide both have a significant impact on cardiac admissions (14-65 years, greater than 65 years) and IHD admissions (all ages, > 65 years), while ozone has a significant impact on cardiac admissions (14-65 years, greater than 65 years). The sensitivity of the results to different statistical methods used in the meta-analyses have been carried out using a combination of three approaches: generalised additive models (GAM) using the S Plus statistical package and loess smoothing, generalised additive models using the S Plus package and natural splines, and penalised splines using the R statistical package.

THE SHORT-TERM EFFECTS OF AIR POLLUTION ON RESPIRATORY ADMISSIONS

This poster complements the paper in this area (A description of the SPIRT study for Brisbane, Melbourne, Perth and Sydney: Simpson et al) and details all the results referred in summary in the paper on the short-term health effects of air pollution on respiratory admissions in four Australian cities-Brisbane, Melbourne, Perth and Sydney. The study used a protocol similar to that used in Europe (Air Pollution and Health: A European Approach-APHEA) to examine the associations between health outcomes, such as daily mortality and daily hospital admissions counts, and air pollutants. This poster details all the results for the period 1996-1999 of a meta-analysis for the four cities for the acute health impacts of the pollutants-fine particles, nitrogen dioxide, and ozone. The meta-analyses often show statistically significant differences between the cities indicating the results can be quite different in different cities. Fine particles (as measured by nephelometery) and nitrogen dioxide both have a significant impact on cardiac admissions (14-65 years, greater than 65 years) and IHD admissions (all ages, > 65 years), while ozone has a significant impact on cardiac admissions (14-65 years, greater than 65 years) (although the results are sensitive to how temperature is used in the models). The sensitivity of the results to different statistical methods used in the meta-analyses have been carried out using a combination of three approaches: generalised additive models (GAM) using the S Plus statistical package and loess smoothing, generalised additive models using the S Plus package and natural spiines, and penalised splines using the R statistical package. The results for all methods are presented and for periods of lags of days 0-3 for all pollutants.

Impacts of federal ephedrine and pseudoephedrine regulations on methamphetamine-related hospital admissions.

To determine whether the federal regulation of ephedrine and pseudoephedrine, precursors used in illicit methamphetamine production, reduced methamphetamine-related acute care hospital admissions. ARIMA-intervention time-series analysis. California (1983-2000), Arizona and Nevada (1991-2000), USA. Monthly counts of methamphetamine-related acute care hospital admissions. Bulk powder ephedrine and pseudoephedrine: regulated November 1989. Products containing ephedrine as the single active medicinal ingredient: regulated August 1995. Products containing pseudoephedrine: regulated October 1997. Large-scale producers used ephedrine and pseudoephedrine in these forms. Ephedrine combined with other active medicinal ingredients (e.g. various cold medicines), used mainly by small-scale producers: regulated October 1996. In California, the bulk powder regulation stopped a 7-year rise in admissions (1983-89) and reduced them by 35% (P < 0.01). The single ingredient ephedrine regulation stopped a 4-year rise (1992-95) in California, Arizona and Nevada, with 48% (P < 0.01), 71% (P < 0.01) and 52% (P < 0.01) reductions, respectively. The pseudoephedrine products regulation stopped a 2-year rise (1996-97) in California, Arizona and Nevada, with 38% (P < 0.01), 41% (P < 0.05) and 61% (P < 0.01) reductions, respectively. Admissions rose at the end of the study period but were still well below peak 1990s levels. The regulation of ephedrine combined with other active medicinal ingredients had no significant impact in any of the three states. Regulations targeting precursors used by large-scale producers reduced admissions substantially during the study period. However, the regulation of precursors used primarily by small-scale producers had little, if any, effect.

The association of daily sulfur dioxide air pollution levels with hospital admissions for cardiovascular diseases in Europe (The Aphea-II study).

The objective of this study is to assess the short-term effect of sulfur dioxide (SO(2)) air pollution levels on hospital admissions for cardiovascular diseases. Daily mean hospital admissions for cardiovascular diseases, ischemic heart diseases (IHDs), and stroke in seven European areas (the cities of Birmingham, London, Milan, Paris, Rome, and Stockholm, and in The Netherlands) participating in the multicenter European study of air pollution (Aphea-II), were measured. Time series analysis of daily hospital admission counts was performed using poison autoregressive models. A summary regression coefficient for all cities was provided. Daily numbers of all cardiovascular admissions except stroke, and particularly IHDs, rose significantly with an increase of daily SO(2)levels of the same day and day before. After adjusting for PM(10)(i.e. particles with size <10 microm), the association of SO(2)with IHD admissions remained significant (i.e. an increase of 0.7%; 95% confidence interval=0.1-1.3, per each 10 microg/m(3)increase of SO(2)) among subjects younger than 65 years, but not among subjects older than 65. In the older group the increase was only significant for particles (1.3%; CI 0.7-1.8, per each increase in 10 microg/m(3)of PM(10)). This study provides new evidence for the effects of urban air pollution on cardiac diseases in Europe, and suggests that SO(2)pollution may play an independent role in triggering ischemic cardiac events. From a Public Health perspective these results suggest that reduction in SO(2)levels in European cities could imply a reduction of admissions for IHDs.

Acute effects of particulate air pollution on respiratory admissions: results from APHEA 2 project. Air Pollution and Health: a European Approach.

The APHEA 2 project investigated short-term health effects of particles in eight European cities. In each city associations between particles with an aerodynamic diameter of less than 10 microm (PM(10)) and black smoke and daily counts of emergency hospital admissions for asthma (0-14 and 15-64 yr), chronic obstructive pulmonary disease (COPD), and all-respiratory disease (65+ yr) controlling for environmental factors and temporal patterns were investigated. Summary PM(10) effect estimates (percentage change in mean number of daily admissions per 10 microg/m(3) increase) were asthma (0-14 yr) 1.2% (95% CI: 0.2, 2.3), asthma (15-64 yr) 1.1% (0.3, 1.8), and COPD plus asthma and all-respiratory (65+ yr) 1.0% (0.4, 1.5) and 0.9% (0.6, 1.3). The combined estimates for Black Smoke tended to be smaller and less precisely estimated than for PM(10). Variability in the sizes of the PM(10) effect estimates between cities was also investigated. In the 65+ groups PM(10) estimates were positively associated with annual mean concentrations of ozone in the cities. For asthma admissions (0-14 yr) a number of city-specific factors, including smoking prevalence, explained some of their variability. This study confirms that particle concentrations in European cities are positively associated with increased numbers of admissions for respiratory diseases and that some of the variation in PM(10) effect estimates between cities can be explained by city characteristics.

Data visualisation for time series in environmental epidemiology.

Data visualisation has become an integral part of statistical modelling. We present visualisation methods for preliminary exploration of time-series data, and graphical diagnostic methods for modelling relationships between time-series data in medicine. We use exploratory graphical methods to better understand the relationship between a time-series reponse and a number of potential covariates. Graphical methods are also used to examine any remaining information in the residuals from these models. We applied exploratory graphical methods to a time-series data set consisting of daily counts of hospital admissions for asthma, and pollution and climatic variables. We provide an overview of the most recent and widely applicable data-visualisation methods for portraying and analysing epidemiological time series. Exploratory graphical analysis allows insight into the underlying structure of observations in a data set, and graphical methods for diagnostic purposes after model-fitting provide insight into the fitted model and its inadequacies.

Air pollution and hospital admissions for respiratory conditions in Rome, Italy.

Most of the evidence regarding the association between particulate air pollution and emergency room visits or hospital admissions for respiratory conditions and asthma comes from the USA. European time-series analyses have suggested that gaseous air pollutants are important determinants of acute hospitalization for respiratory conditions, at least as important as particulate mass. The association between daily mean levels of suspended particles and gaseous pollutants (sulphur dioxide, nitrogen dioxide, carbon monoxide, ozone) was examined. The daily emergency hospital admissions for respiratory conditions in the metropolitan area of Rome during 1995-1997 were also recorded. Daily counts of hospital admissions for total respiratory conditions (43 admissions day(-1)), acute respiratory infections including pneumonia (18 day(-1)), chronic obstructive pulmonary disease (COPD) (13 day(-1)), and asthma (4.5 day(-1)) among residents of all ages and among children (0-14 yrs) were analysed. The generalized additive models included spline smooth functions of the day of study, mean temperature, mean humidity, influenza epidemics, and indicator variables for day of the week and holidays. Total respiratory admissions were significantly associated with same-day level of NO2 (2.5% increase per interquartile range (IQR) change, 22.3 microg x m(-3)) and CO (2.8% increase per IQR, 1.5 mg x m(-3)). No effect was found for particulate matter and SO2, whereas O3 was associated with admissions only among children (lag 1, 5.5% increase per IQR, 23.9 microg x m3). The effect of NO2 was stronger on acute respiratory infections (lag 0, 4.0% increase) and on asthma among children (lag 1, 10.7% increase). The admissions for all ages for asthma and COPD were associated only with same-day level of CO (5.5% and 4.3% increase, respectively). Multipollutant models confirmed the role of CO on all respiratory admissions, including asthma and COPD, and that of NO2 on acute respiratory infections. Among children, O3 remained a strong indicator of acute respiratory infections. Carbon monoxide and photochemical pollutants (nitrogen dioxide, ozone) appear to be determinants of acute respiratory conditions in Rome. Since carbon monoxide and nitrogen dioxide are good indicators of combustion products from traffic related sources, the detected effect may be due to unmeasured fine and ultrafine particles.

Respiratory diseases in children and outdoor air pollution in São Paulo, Brazil: a time series analysis

OBJECTIVESTo investigate the short term effects of air pollution on the respiratory morbidity of children living in São Paulo, Brazil, one of the largest cities in the developing world.METHODSDaily counts...

Air pollution and hospital admissions for respiratory and cardiovascular diseases in Hong Kong.

OBJECTIVE: To investigate short term effects of concentrations of pollutants in ambient air on hospital admissions for cardiovascular and respiratory diseases in Hong Kong. METHODS: Retrospective ecological study. A Poisson...

Air pollution and hospital admissions in Sydney, Australia, 1990 to 1994.

This study examined the effects of outdoor air pollutants on daily hospital admissions in Sydney, Australia. A time-series analysis of counts of daily hospital admissions and outdoor air pollutants (1990 to 1994) was performed, by means of Poisson regression that allowed for overdispersion and autocorrelation. An increase in daily maximum 1-hour concentration of nitrogen dioxide from the 10th to the 90th percentile was associated with an increase of 5.29% (95% confidence interval = 1.07, 9.68) in childhood asthma admissions and 4.60%(-0.17,9.61) in chronic obstructive pulmonary disease (COPD) admissions. A similar increase in daily maximum 1-hour particulate concentration was associated with an increase of 3.01% (-0.38, 6.52) in COPD admissions. An increase from the 10th to the 90th percentile in daily maximum 1-hour nitrogen dioxide, daily maximum 1-hour ozone, and daily mean particulate was associated with an increase in heart disease admissions among those 65 years and older of 6.71% (4.25, 9.23), 2.45% (-0.37, 5.35), and 2.82% (0.90, 4.77), respectively. Heart disease and childhood asthma were primarily associated with nitrogen dioxide; COPD was associated with both nitrogen dioxide and particulates. Current levels of air pollution in Sydney are associated with increased hospitalization for respiratory and heart disease.

A synoptic evaluation of asthma hospital admissions in New York City.

An evaluation of weather/asthma relationships in the New York City Standard Metropolitan Statistical Area (SMSA) is developed using a synoptic climatological methodology. This procedure isolates "air masses," or bodies of air that are homogeneous in meteorological character, and relates them to daily counts of overnight asthma hospital admissions. The synoptic procedure used here, known as the temporal synoptic index (TSI), can identify air masses in automated fashion for every day over many years. It is apparent that certain air masses are related to statistically significant increases in asthma hospital admissions. The impact varies seasonally, with weather having a particularly important impact on asthma admissions during fall and winter. It appears that air pollution has little impact on asthma during these two seasons, and the air masses associated with the highest admissions are not distinguished by high concentrations of pollutants. However, during spring and summer, the air masses associated with highest admissions are among those with high pollution concentrations. There is a strong interseasonal differential response to weather and air pollution by asthmatics in New York City. If these results can be replicated at other locations in future studies, it may be possible to develop an asthma/weather watch-warning system, based on the expected arrival of high-admissions air masses.

Methodological issues in studies of air pollution and daily counts of deaths or hospital admissions.

To review the issues and methodologies in epidemiologic time series studies of daily counts of mortality and hospital admissions and illustrate some of the methodologies. This is a review paper with an example drawn from hospital admissions of the elderly in Cleveland, Ohio, USA. The central issue is control for seasonality. Both over and under control are possible, and the use of diagnostics, including plots, is necessary. Weather dependence is probably non-linear, and adequate methods are necessary to adjust for this. In Cleveland, the use of categorical variables for weather and sinusoidal terms for filtering season are illustrated. After control for season, weather, and day of the week effects, hospital admission of persons aged 65 and older in Cleveland for respiratory illness was associated with ozone (RR = 1.09, 95% CI 1.02, 1.16) and particulates (PM10 (RR = 1.12, 95% CI 1.01, 1.24), and marginally associated with sulphur dioxide (SO2) (RR = 1.03, 95% CI = 0.99, 1.06). All of the relative risks are for a 100 micrograms/m3 increase in the pollutant. Several adequate methods exist to control for weather and seasonality while examining the associations between air pollution and daily counts of mortality and morbidity. In each case, care and judgement are required.

Effects of air pollution on daily hospital admissions for respiratory disease in London between 1987-88 and 1991-92.

To investigate whether air pollution levels in London have short term effects on hospital admissions for respiratory disease. Poisson regression analysis of daily counts of hospital admissions, adjusting for effects of trend, seasonal and other cyclical factors, day of the week, holidays, influenza epidemic, temperature, humidity, and autocorrelation. Pollution variables were particulates (black smoke: BS), sulphur dioxide (SO2), ozone (O3), and nitrogen dioxide (NO2), lagged 0-3 days. All immediate admissions for respiratory disease (ICD 460-519) to hospitals in London health districts in the five years April 1987 to February 1992 for all ages and the 0-14, 15-64, and 65+ age groups. O3 (lagged one day) was significantly associated with an increase in daily admissions among all age groups, except the 0-14 group, and this effect was stronger in the "warm" season (April-September). In this season, the relative risks of admission associated with an increase in 8 hour O3 levels of 29 ppb (10th to 90th centile) were 1.0483 (95% CI 1.0246, 1.0726), 1.0294 (0.9930,1.0672), 1.0751 (1.0354,1.1163), and 1.0616 (1.0243,1.1003) for all ages and age groups 0-14, 15-64, and 65+ respectively. Very few significant associations were observed with the other pollutants, though these tended to be positive. Controlling for other pollutants made little difference to the O3 coefficients. There was evidence of a threshold at about 40-60 ppb O3 (maximum hourly or maximum 8 hour). O3 levels in London have a small but significant effect on hospital admissions for respiratory disease at all ages. The possible role of aerollergen as a confounding factor needs to be examined. Unlike other cities where similar effects have been reported, little or no effect of particulates was observed in London.

Air pollution and hospital admissions for the elderly in Birmingham, Alabama.

Several studies have reported associations between airborne particles and/or ozone and hospital admissions for respiratory disease. This study examined whether such an association could be seen in Birmingham, Alabama, one of the few cities in the United States with daily monitoring of inhalable particles. Daily counts of hospital admissions were computed by date of admission from Medicare records for pneumonia and chronic obstructive pulmonary disease for the years 1986-1989. Classification was by discharge diagnosis. The daily average of ozone and particulate matter with an aerodiameter of < or = 10 microns (PM10) from all monitoring stations in Birmingham was computed. Approximately six admissions for pneumonia and two for chronic obstructive pulmonary disease were observed each day. In Poisson regression analysis controlling for time trends, seasonal fluctuations, and weather, inhalable particles were a risk factor for admission for pneumonia (for an increase of 100 micrograms/m3 in daily concentration, relative risk (RR) = 1.19, 95% confidence interval (CI) 1.07-1.32) and chronic obstructive pulmonary disease (RR = 1.27, 95% CI 1.08-1.50). The results were not sensitive to alternative methods for controlling for seasonal patterns and weather, nor to the exclusion of very hot or cold days. Ozone was more weakly associated with admissions for pneumonia, with a 2-day lag (RR = 1.14, 95% CI 0.94-1.38), and for chronic obstructive pulmonary disease, with a 1-day lag (RR = 1.17, 95% CI 0.86-1.60). The risks are for an increase in ozone exposure of 50 parts per billion. Tests for nonlinearity in the relation between inhalable particles and admissions were not significant, and nonparametric smoothing found no evidence of a threshold in the relation.