The relationship between ambient particulate matter and respiratory mortality: a multi-city study in Italy

The association of air pollutants with natural and respiratory mortality has been consistently reported. However, several aspects of the relationship between particulate matter with a 50% cut-off aerodynamic diameter of 10 μm (PM(10)) and respiratory mortality require further investigation. The aim of the present study was to assess the PM(10)-respiratory mortality association in Italy and examine potentially susceptible groups. All deaths from natural (n=276,205) and respiratory (n=19,629) causes among subjects aged ≥ 35 yrs in 10 northern, central and southern Italian cities in 2001-2005 were included in the study. Pollution data for PM(10), nitrogen dioxide and ozone were also obtained. A time-stratified case-crossover analysis was carried out. Different cumulative lags were selected to analyse immediate, delayed, prolonged and best-time effects of air pollution. The shape of the exposure-response curve was analysed. Age, sex, chronic conditions and death site were investigated as potential effect modifiers. We found a 2.29% (95% CI 1.03-3.58%) increase in respiratory mortality at 0-3 days lag. The increase in respiratory mortality was higher in summer (7.57%). The exposure-response curve had a linear shape without any threshold. Sex and chronic diseases modified the relationship between particular matter (PM) and respiratory mortality. The effect of PM on respiratory mortality was stronger and more persistent than that on natural mortality. Females and chronic disease sufferers were more likely to die of a respiratory disease caused by air pollution than males and healthy people.

[Air pollution and mortality in ten Italian cities. Results of the EpiAir Project]

OBJECTIVE

the relationship between air pollution and mortality has been well established in national and international scientific literature. This study reports the results of the EpiAir Project relative to the effect of air pollution on mortality in 10 Italian cities during 2001-2005. The association between particulate matter (PM10) and gases (nitrogen dioxide, NO2, and ozone, O3), and all natural mortality, as well as cardiac, cerebrovascular and respiratory mortality, is presented. Specific issues have been investigated, such as the latency of the air pollution-mortality effects and the identification of individual demographic characteristics and clinical conditions that result in greater susceptibility to the effects of particulate matter.

METHODS

the study population consisted of 276,205 subjects aged 35+ years old, resident in one of the 10 Italian cities studied, which died in the city between 2001-2005. For each subject, information was collected on cause of death, location of death, demographical variables and hospital discharge diagnoses in the previous 2-year period. The statistical analysis was adjusted for the relevant temporal and meteorological factors using the case-crossover approach. The results for ozone are limited to the warm semester (April through September). An analysis of the association between air pollution and mortality was conducted for each city, and the city-specific estimates were meta-analyzed on a second level to obtain a pooled result, and reported inter-city heterogeneity.

RESULTS

a short-term effect of PM10 on mortality has been detected for all the groups of causes considered, with latencies ranging from lag 0 for cerebrovascular mortality to lag 0-3 for respiratory mortality. The association between NO2 and mortality displays strong and similar effects for all death causes, with prolonged effects (lag 0-5) for all groups of causes. The results for O3 are similar to those found for NO2, with prolonged latency (lag 0-5) for all causes of death with the exception of cerebrovascular mortality, for which a delayed effect (lag 3-5) was identified. Individual susceptibility factors of the PM10-natural mortality association include age, as elderly subjects are especially vulnerable to the effects of particles.

CONCLUSIONS

the main results of the study suggest that the air pollution originated by vehicular traffic is the most relevant environmental problem in Italian cities from a public health viewpoint.

[EpiAir health data]

INTRODUCTION

the EpiAir (Air pollution and health: epidemiological surveillance and prevention) Project has been conducted in 10 Italian cities. In this paper we describe the health data used to detect adverse health effects associated with air pollution exposure (mortality and hospital discharge databases) and to identify comorbidities (based on hospital discharge databases) as susceptibility factors to the effects of air pollution.

MATERIAL AND METHODS

for each city, we performed descriptive analyses of mortality data included in the study.We considered subjects aged 35+ years old, resident and deceased within the cities in the study period (2001-2005) for non-accidental causes. For each deceased subject, information were collected on hospital discharge diagnoses in the previous 2-year period. Urgent hospital admissions of subjects resident in nine cities and hospitalized within the city for specific diseases (including cardiac, cerebrovascular and respiratory conditions) were also included as endpoints. Annual mean raw death and hospitalization rates were calculated for each city.

RESULTS

276,205 deaths and 701,902 urgent hospital admissions have been included in the study. Annual mean crude death rates for non accidental causes in the population aged +35 yrs resident and deceased in the municipalities ranged from 12.1 and 15.7 per 1,000 residents.The percentage of deceased subjects with at least one of the selected comorbidities ranged from 32 to 48%. Annual mean crude urgent hospitalization rates in the resident population ranged from 5.5 to 11.7 per 1,000 residents for cardiac diseases; 1.7 to 3.7 per 1,000 residents for cerebrovascular diseases and 3.3 to 10.7 per 1,000 residents for respiratory diseases. Several factors can explain the between-cities differences observed, especially in the hospitalization rates, including availability and variability in the health care services utilization.

CONCLUSION

an epidemiological surveillance system based on health databases has to take into account the observed differences.

[Air pollution and urgent hospital admissions in nine Italian cities. Results of the EpiAir Project]

INTRODUCTION

the relationship between air pollution and hospital admissions has been well studied. In this study, the results of the Italian EpiAir Project are reported on the effect of air pollution on hospital admissions in 9 Italian cities during 2001-2005. The association between particulate matter (PM10) and gases (NO2 and O3) and hospital admissions for cardiac, cerebrovascular, respiratory conditions, pulmonary embolism and diabetes has been evaluated.

MATERIAL AND METHODS

The study population consists of 701,902 hospital admissions of subjects residents in nine Italian cities and hospitalized in the city in the period 2001- 2005. We used a case-crossover approach and the statistical analysis considered the relevant temporal and meteorological factors for confounding adjustment. The results for ozone refer to the warm semester. The analysis of the association between air pollution and admissions was conducted for each city, and the city-specific estimates were meta-analyzed to obtain pooled results.

RESULTS

we found an immediate effect of PM10 and NO2 (lag 0) for cardiac diseases as a group and for specific conditions (coronary syndrome and heart failure). No effect of ozone was observed. For cerebrovascular diseases we did not observe a positive effect of the three pollutants. An effect of NO2 on pulmonary embolism was detected. The association between air pollutants and hospitalization for respiratory diseases (respiratory infections, COPD and asthma) showed different lags for the three pollutants: the effect of PM10 was immediate at lag 0-1 while the effects of NO2 and ozone were prolonged at lag 0-5. The strongest association was between NO2 and asthma admissions, especially in children. No effects on diabetes were found.

CONCLUSIONS

the main results of the present study confirm the deleterious short term impact of air pollution on cardiovascular and respiratory morbidity in Italian cities.

[Environmental indicators in ten Italian cities (2001-2005): the air quality data for epidemiological surveillance]

OBJECTIVE

to produce environmental indicators suitable for an epidemiological surveillance in 10 Italian cities part of the EpiAir Project (2001-2005).

METHODS

the environmental parameters that correlate to relevant health effects are the particles with diameters less than or equal to 10 micrometers (PM10), the nitrogen dioxide (NO2) and the ozone (O3). The necessary meteorological data are: temperature, relative humidity, barometric pressure and apparent temperature.We have identified some criteria to select monitoring stations and have taken standard methods of calculation to produce environmental indicators starting from the daily data available after closely evaluating the completeness of the existing data. Furthermore, we have checked the homogeneity of the selected data to ensure that it represents the population's exposure.

RESULTS

close examination of descriptive statistics shows a critical situation of the considered pollutants. The analysis of the yearly state underlines for PM10 values higher than 40 microg/m3 in the area of Mestre-Venice and in Milan, Turin, Bologna e Taranto. For NO2, values are consistently above 40 microg/m3 in Milan, Turin, Bologna, Florence, Rome and Palermo. For ozone, the concentrations were stable, with the exception of Summer 2003 when we recorded, on average, an increase of 13% compared to the mean value estimated for the ten cities during the study period, especially in Mestre-Venice, Turin and Palermo.

CONCLUSIONS

it is important to ensure the consistency of the methods and instruments in environmental monitoring. To evaluate health effects and perform interventions over the longterm, it is therefore fundamental that the data be homogenous, especially during the periodic reorganizations and rationalizations of air quality management. It is also necessary to include daily meteorological data that influence pollutant dispersion and population health status.

[Methods of statistical analysis to evaluate the short term effects of air pollution in the EpiAir Project]

The EpiAir Project, which is funded by the Italian Center for disease prevention and control, Ministry of Health, involves 10 Italian cities for the period 2001-2005, and has the following objectives: to monitor the environmental characteristics associated with relevant health effects; to systematically collect data on relevant health outcomes, such as mortality and hospitalizations, for which the impact of air pollution has been established; to report estimates of the health effects attributable to air pollution; to identify the subgroups of the population most vulnerable to the effects of air pollution. An important part of the project deals with estimating the association between several air pollutants (PM10, NO2, O3 ) and adverse health outcomes, such as mortality for a broad spectrum of causes and hospital admissions for single disease diagnoses or diseases groups. The analyses are implemented at the city level, and then pooled estimates are calculated with random-effects metaanalyses. The present paper provides details on the statistical methodology applied, focusing on: the definition of and control for the confounding factors in the city-specific analyses, estimating the association between health outcomes and air pollution at different temporal latencies (lags), identifying population subgroups most vulnerable to PM10, and analysing the heterogeneity of the city-specific results.

Particulate matter and daily mortality: a case-crossover analysis of individual effect modifiers

BACKGROUND

Several time-series studies have established the relationship between particulate matter (PM10) and mortality. We adopted a case-crossover design to evaluate whether individual socio-demographic characteristics and chronic or acute medical conditions modify the PM10-mortality association.

METHODS

We selected all natural deaths (321,024 subjects) occurring among adult (aged 35+ years) residents of 9 Italian cities between 1997 and 2004. We had access to individual information on socio-demographic variables, location of death, and chronic conditions (hospital admissions in the preceding 2-year period). For in-hospital deaths, we collected information on treatment wards at time of death and acute medical conditions. In a case-crossover analysis we adjusted for time, population changes, and meteorological conditions.

RESULTS

PM10 was associated with mortality among subjects age 65 years and older (0.75% increase per 10 microg/m3 [95% confidence interval = 0.42% to 1.09%]), with a more pronounced effect among people age 85 and older. A weaker effect was found among the most affluent people. The effect was present for both out-of-hospital and in-hospital deaths, especially among those treated in general medicine and other less specialized wards. PM10 effects were stronger among people with diabetes (1.03% [0.28% to 1.79%]) and chronic obstructive pulmonary disease (0.84% [0.17% to 1.52%]). The acute conditions with the largest effect estimates were acute impairment of pulmonary circulation (4.56% [0.75% to 8.51%]) and heart failure (1.67% [0.30% to 3.04%]).

CONCLUSIONS

Several factors, including advanced age, type of hospital ward, and chronic and acute health conditions, modify the PM10-related risk of death. Altered pulmonary circulation and heart failure are important effect modifiers, suggesting that cardiac decompensation is a possible mechanism of the fatal PM10 effect.

Does temperature modify the association between air pollution and mortality? A multicity case-crossover analysis in Italy

Adverse health effects of particulate matter <10 microm in aerodynamic diameter (PM(10)) and high temperatures are well known, but the extent of their interaction on mortality is less clear. This paper describes effect modification of temperature in the PM(10)-mortality association and tests the hypothesis that higher PM(10) effects in summer are due to enhanced exposure to particles. All deaths of residents of nine Italian cities between 1997 and 2004 were selected. The case-crossover approach was adopted to estimate the effect of PM(10) on mortality by season and temperature level. Three strata of temperature corresponding to low, medium, and high "ventilation" were identified, and the interaction between PM(10) and temperature within each stratum was examined. Season and temperature levels strongly modified the PM(10)-mortality association: for a 10-microg/m(3) variation in PM(10), a 2.54% increase in risk of death in summer (95% confidence interval: 1.31, 3.78) compared with 0.20% (95% confidence interval: -0.08, 0.49) in winter. Analysis of the interaction between PM(10) and temperature within temperature strata resulted in positive but, in most cases, nonstatistically significant coefficients. The authors found much higher PM(10) effects on mortality during warmer days. The hypothesis that such an effect is attributable to enhanced exposure to particles in summer could not be rejected.

Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis

BACKGROUND

Several studies have identified strong effects of high temperatures on mortality at population level; however, individual vulnerability factors associated with heat-related in-hospital mortality are largely unknown. The objective of the study was to evaluate heat-related in-hospital mortality using a multi-city case-crossover analysis.

METHODS

We studied residents of four Italian cities, aged 65+ years, who died during 1997-2004. For 94,944 individuals who died in hospital and were hospitalised two or more days before death, demographics, chronic conditions, primary diagnoses of last event and hospital wards were considered. A city-specific case-crossover analysis was performed to evaluate the association between apparent temperature and mortality. Pooled odds ratios (OR) of dying on a day with a temperature of 30 degrees C compared to a day with a temperature of 20 degrees C were estimated with a random-effects meta-analysis.

RESULTS

We estimated an overall OR of 1.32 (95% confidence interval: 1.25, 1.39). Age, marital status and hospital ward were important risk indicators. Patients in general medicine were at higher risk than those in high and intensive care units. A history of psychiatric disorders and cerebrovascular diseases gave a higher vulnerability. Mortality was greater among patients hospitalised for heart failure, stroke and chronic pulmonary diseases.

CONCLUSIONS

In-hospital mortality is strongly associated with high temperatures. A comfortable temperature in hospitals and increased attention to vulnerable patients during heatwaves, especially in general medicine, are necessary preventive measures.

Comparison of regression models with land-use and emissions data to predict the spatial distribution of traffic-related air pollution in Rome

Spatial modeling of traffic-related air pollution typically involves either regression modeling of land-use and traffic data or dispersion modeling of emissions data, but little is known to what extent land-use regression models might be improved by incorporating emissions data. The aim of this study was to develop a land-use regression model to predict nitrogen dioxide (NO2) concentrations and compare its performance with a model including emissions data. The association between each land-use variable and NO2 concentrations at 68 locations in Rome in 1995 and 1996 was assessed by univariate linear regression and a multiple linear regression model that was constructed based on the importance of each variable. Traffic emissions (particulate matter, carbon monoxide, nitrogen oxides, and benzene) were estimated for 164 areas of the city based on vehicle type, traffic counts and driving patterns. Mean NO2 concentration across the 68 sites was 46.8 microg/m3 (SD 9.8 microg/m3; inter-quartile range 11.5 microg/m3; min 24 microg/m3; max 73 microg/m3). The most important predicting variables were the circular traffic zones (main ring road, green strip, inner ring road, traffic-limited zone), distance from busy streets, size of the census block, the inverse population density, and altitude. A multiple regression model including these variables resulted in an R2 of 0.686. The best-fitting model adding an emission term of benzene resulted in an R2 of 0.690, but was not significantly different from the model without emissions (P=0.147). In conclusion, these results suggest that a land-use regression model explains the traffic-related air pollution levels with reasonable accuracy and that emissions data do not significantly improve the model.

Airport and city-centre temperatures in the evaluation of the association between heat and mortality

A variety of ambient exposure indicators have been used to evaluate the impact of high temperature on mortality and in the identification of susceptible population sub-groups, but no study has evaluated how airport and city centre temperatures differ in their association with mortality during summer. This study considers the differences in temperatures measured at the airport and in the city centre of three Italian cities (Milan, Rome and Turin) and investigates the impact of these measures on daily mortality. The case-crossover design was applied to evaluate the association between daily mean apparent temperature (MAT) and daily total mortality. The analysis was conducted for the entire population and for subgroups defined by demographic characteristics, socioeconomic status and chronic comorbidity (based on hospitalisation during the preceding 2 years). The percentage risk of dying, with 95% confidence intervals (95% CI), on a day with MAT at the 95th percentile with respect to the 25th percentile of the June-September daily distribution was estimated. Airport and city-centre temperature distributions, which vary among cities and between stations, have a heterogeneous impact on mortality. Milan was the city with the greatest differences in mean MAT between airport and city stations, and the overall risk of dying was greater when airport MAT (+47% increase, 95%CI 38-57) was considered in comparison to city MAT (+37% increase, 95%CI 30-45). In Rome and Turin, the results were very similar for both apparent temperature measures. In all cities, the elderly, women and subjects with previous psychiatric conditions, depression, heart and circulation disorders and cerebrovascular disease were at higher risk of dying during hot days, and the degree of effect modification was similar using airport or city-centre MAT. Studies on the impact of meteorological variables on mortality, or other health indicators, need to account for the possible differences between airport and city centre meteorological variables in order to give more accurate estimates of health effects.

Socioeconomic status, particulate air pollution, and daily mortality: differential exposure or differential susceptibility

BACKGROUND

Short-term increases in particulate air pollution are linked with increased daily mortality and morbidity. Socioeconomic status (SES) is a determinant of overall health. We investigated whether social class is an effect modifier of the PM(10) (particulate matter with diameter <10 micron)-daily mortality association, and possible mechanisms for this effect modification.

METHODS

Area-based traffic emissions, income, and SES were available for each resident in Rome. All natural deaths (83,253 subjects) occurring in Rome among city residents (aged 35+ years) during the period 1998-2001 were identified. For each deceased individual, all the previous hospitalizations within 2 years before death were available via a record linkage procedure. PM(10) daily data were available from two urban monitoring sites. A case-crossover analysis was utilized in which control days were selected according to the time stratified approach (same day of the week during the same month). Conditional logistic regression was used.

RESULTS

Due to the social class distribution in the city, exposure to traffic emissions was higher among those with higher area-based income and SES. Meanwhile, people of lower social class had suffered to a larger extent from chronic diseases before death than more affluent residents, especially diabetes mellitus, hypertension, heart failure, and chronic obstructive pulmonary diseases. Overall, PM(10) (lag 0-1) was strongly associated with mortality (1.1% increase, 95%CI = 0.7-1.6%, per 10 microg/m(3)). The effect was more pronounced among persons with lower income and SES (1.9% and 1.4% per 10 microg/m(3), respectively) compared to those in the upper income and SES levels (0.0% and 0.1%, respectively).

CONCLUSIONS

The results confirm previous suggestions of a stronger effect of particulate air pollution among people in low social class. Given the uneven geographical distributions of social deprivation and traffic emissions in Rome, the most likely explanation is a differential burden of chronic health conditions conferring a greater susceptibility to less advantaged people.

Socioeconomic status, particulate air pollution, and daily mortality: differential exposure or differential susceptibility

BACKGROUND

Short-term increases in particulate air pollution are linked with increased daily mortality and morbidity. Socioeconomic status (SES) is a determinant of overall health. We investigated whether social class is an effect modifier of the PM(10) (particulate matter with diameter <10 micron)-daily mortality association, and possible mechanisms for this effect modification.

METHODS

Area-based traffic emissions, income, and SES were available for each resident in Rome. All natural deaths (83,253 subjects) occurring in Rome among city residents (aged 35+ years) during the period 1998-2001 were identified. For each deceased individual, all the previous hospitalizations within 2 years before death were available via a record linkage procedure. PM(10) daily data were available from two urban monitoring sites. A case-crossover analysis was utilized in which control days were selected according to the time stratified approach (same day of the week during the same month). Conditional logistic regression was used.

RESULTS

Due to the social class distribution in the city, exposure to traffic emissions was higher among those with higher area-based income and SES. Meanwhile, people of lower social class had suffered to a larger extent from chronic diseases before death than more affluent residents, especially diabetes mellitus, hypertension, heart failure, and chronic obstructive pulmonary diseases. Overall, PM(10) (lag 0-1) was strongly associated with mortality (1.1% increase, 95%CI = 0.7-1.6%, per 10 microg/m(3)). The effect was more pronounced among persons with lower income and SES (1.9% and 1.4% per 10 microg/m(3), respectively) compared to those in the upper income and SES levels (0.0% and 0.1%, respectively).

CONCLUSIONS

The results confirm previous suggestions of a stronger effect of particulate air pollution among people in low social class. Given the uneven geographical distributions of social deprivation and traffic emissions in Rome, the most likely explanation is a differential burden of chronic health conditions conferring a greater susceptibility to less advantaged people.

Vulnerability to heat-related mortality: a multicity, population-based, case-crossover analysis

BACKGROUND

Although studies have documented increased mortality during heat waves, little information is available on the subgroups most susceptible to these effects. We evaluated the effects of summertime high temperature on daily mortality among population subgroups defined by demographic characteristics, socioeconomic status, and episodes of hospitalization for various conditions during the preceding 2 years.

METHODS

We studied a total of 205,019 residents of 4 Italian cities (Bologna, Milan, Rome, and Turin) age 35 or older who died during 1997-2003. The case-crossover design was applied to evaluate the association between mean apparent temperature (same and previous day) and all-cause mortality. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) of dying at 30 degrees C (apparent temperature) relative to 20 degrees C were estimated accounting for time, population changes, and air pollution.

RESULTS

We found an overall OR of 1.34 (CI = 1.27-1.42) at 30 degrees C relative to 20 degrees C. The odds ratio increased with age and was higher among women (OR = 1.45; 1.37-1.52) and among widows and widowers (1.50; 1.33-1.69). Low area-based income modestly increased the effect. Among the preexisting medical conditions investigated, effect modification was detected for previous psychiatric disorders (1.69; 1.39-2.07), depression (1.72; 1.24-2.39), heart conduction disorders (1.77; 1.38-2.27), and circulatory disorders of the brain (1.47; 1.34-1.62). Temperature-related mortality was higher among people residing in nursing homes, and a large effect was also detected for hospitalized subjects.

CONCLUSIONS

Subsets of the population that are particularly vulnerable to high summer temperatures include the elderly, women, widows and widowers, those with selected medical conditions, and those staying in nursing homes and healthcare facilities.

Comparison of different methods in analyzing short-term air pollution effects in a cohort study of susceptible individuals

BACKGROUND

Short-term fluctuations of ambient air pollution have been associated with exacerbation of cardiovascular disease. A multi-city study was designed to assess the probability of recurrent hospitalization in a cohort of incident myocardial infarction survivors in five European cities. The objective of this paper is to discuss the methods for analyzing short-term health effects in a cohort study based on a case-series.

METHODS

Three methods were considered for the analyses of the cohort data: Poisson regression approach, case-crossover analyses and extended Cox regression analyses. The major challenge of these analyses is to appropriately consider changes within the cohort over time due to changes in the underlying risk following a myocardial infarction, slow time trends in risk factors within the population, dynamic cohort size and seasonal variation.

RESULTS

Poisson regression analyses, case-crossover analyses and Extended Cox regression analyses gave similar results. Application of smoothing methods showed the capability to adequately model the complex time trends.

CONCLUSION

From a practical point of view, Poisson regression analyses are less time-consuming, and therefore might be used for confounder selection and most of the analyses. However, replication of the results with Cox models is desirable to assure that the results are independent of the analytical approach used. In addition, extended Cox regression analyses would allow a joint estimation of long-term and short-term health effects of time-varying exposures.

[PM 10 exposure and asthma exacerbations in pediatric age: a meta-analysis of panel and time-series studies]

OBJECTIVE

review of the time series and panel studies on the short term effects of PM10 on the increases of the illness in childhood.

DESIGN

meta-analysis of panel and time-series studies.

METHODS

all studies cited in PubMed that were published between 1990 and 2003 were selected. The results of individual studies were combined to provide an overall estimate of the effect of PMl0 exposure on hospital admissions or emergency room visits for asthma, the frequency of asthmatic symptoms (wheezing and cough), the use of anti-asthma medications (in addition to regular therapy) and lung functioning (peak expiratory flow PEE 1/min) using fixed effects models. Random effects models were used (ORRE or betaRE, 95% CI) when heterogeneity (p <0.10) was present. The presence of publication bias was tested using Egger's test and the bias was corrected with the "trim and fill" method

RESULTS

ten time series studies and 23 panel studies fit the search criteria. Exposure to PM10 was associated with an increase in hospitalizations for asthma (ORRE= 1.017, 95% CI 1.008;1.025), with episodes of wheezing (ORRE= 1.063, 95% CI 1.038;1.087) and coughing (ORRE= 1.026, 95% CI 1.013;1.039), in the use of medications for asthma (ORRE= 1.033, 95% CI 1.008;1.059) and to a decrease in lung function (PRE=-0.269, 95% CI -0.451;-0. 087). We observed heterogeneity and publication bias. The correction for publication bias mitigated the estimates of risk but the most important impact on the results was due to a single, multicenter european study (PEACE) that was very influential

CONCLUSION

exposure to PM10 was associated with an increase in hospitalizations for asthma and, in asthmatic children, with the frequency of asthmatic symptoms (wheezing and cough), the use of anti-asthma medications (in addition to regular therapy) and a decrease in lung functioning. Additional research is necessary to explain the causes of the heterogeneity in the estimates.

Associations of area based deprivation status and individual educational attainment with incidence, treatment, and prognosis of first coronary event in Rome, Italy

BACKGROUND

Socioeconomic gradients in the occurrence of myocardial infarction are well known, but few studies have examined socioeconomic disparities in post-infarction outcomes. The objective of this study was to explore relations of socioeconomic status with the incidence, treatment, and outcome of first coronary event in Rome, Italy, during the period 1998-2000, examining effect modification by gender.

METHODS

Subjects were Rome residents aged 35-84 years who died from first acute coronary event before reaching the hospital (n=3470) or were hospitalised for first acute myocardial infarction (n=8467). Area based deprivation status and patients' educational attainment were the exposure variables. The outcomes were: incidence of coronary event; recanalisation at the index hospitalisation and fatality within 28 days of hospitalisation; cardiac readmissions and fatality between 28 days and one year of index hospitalisation.

RESULTS

Incidence rates increased as area based deprivation status increased; the effect was stronger among women than among men (men RR=1.40, 95%CI:1.30, 1.50, women RR=1.78, 95%CI:1.60, 1.98, most compared with least deprived). Rates of recanalisation were significantly lower in the most deprived patients than in the least deprived (OR=0.77, 95%CI:0.59, 0.99) and in the less educated than in the highly educated (OR=0.73, 95%CI:0.58, 0.90). Associations of short term fatality with area based deprivation status and educational attainment were weak and inconsistent. However, neither deprivation status nor education was associated with one year outcomes.

CONCLUSIONS

Area based deprivation status is strongly related to incidence of coronary events, and more so among women than among men. Deprivation status and educational attainment are weakly and inconsistently associated with short term fatality but seem not to influence one year prognosis of acute myocardial infarction. Deprived and less educated patients experience limited access to recanalisation procedures.

A case-crossover analysis of out-of-hospital coronary deaths and air pollution in Rome, Italy

RATIONALE

Out-of-hospital coronary heart disease death is a major public health problem, but the association with air pollution is not well understood.

OBJECTIVES

We evaluated the association between daily ambient air pollution levels (particle number concentration [PNC]--a proxy for ultrafine particles [diameter < 0.1 microm], mass of particles with diameter less than 10 microm [PM10]; CO, NO2, and O3) and the occurrence of fatal, nonhospitalized coronary events.

METHODS

Subjects were 5,144 out-of-hospital fatalities (410-414, International Classification of Diseases-9; 1998-2000) who had been residents of Rome. Hospitalizations during the 3 yr before death were considered to identify comorbidities (e.g., diabetes, hypertension, heart failure, dysrhythmia, chronic obstructive pulmonary disease). Statistical analyses were performed using a case-crossover design.

MEASUREMENTS AND MAIN RESULTS

The association with out-of-hospital coronary deaths was statistically significant for PNC, PM10, and CO. Air pollution on the day of death had the strongest effect (e.g., 7.6% increase [95% confidence interval, 2.0-13.6%]) for an interquartile range of PNC, 27,790 particles/cm3. The 65-74- and 75+-yr age groups were at higher risk than the 35-64-yr age group, and there was a suggestion of effect modification for people with hypertension and chronic obstructive pulmonary disease.

CONCLUSIONS

Air pollutants originating from combustion processes, including ultrafine particles, are related to fatal, nonhospitalized coronary events. The effect is stronger among people over 65 years of age, but is not limited to a group with a specific comorbidity.

[Air pollution and fatal and non fatal coronary events in Rome]

OBJECTIVE

To examine the relationship between air pollution and coronary events in Rome in the period 1998-2000, considering both out-of-hospital deaths and hospitalisations.

DESIGN

Time-series of daily counts of out-of-hospital deaths and hospitalised events, implementation of Generalised Additive Models.

SETTING

The air pollutants taken into account were PNC (Particle Number Concentration--a measure of ultrafine particles), PM10, CO, NO2, SO2 and O3. The association was studied with respect to either single days or the cumulative effect on more consecutive days; furthermore, effect modification by age was tested (for the age groups 0-64, 65-74 and 75+).

PARTICIPANTS

People resident of Rome and died/hospitalised for coronary causes into the city in the period 1998-2000.

MAIN OUTCOME MEASURE

Association between pollutants and out-of-hospital deaths/hospitalised events. Distinction between fatal events (out-of-hospital deaths + hospitalisations with death within 28 days of admission) and non fatal events (hospitalisations with survival longer than 28 days).

RESULTS

Significant association between PNC, PM10, and CO with out-of-hospital deaths, smaller effect on hospitalised events. For a variation of PNC of 28000 particles per cm3 (interquartile range of the distribution) the increase in the risk of out-of-hospital coronary death at lag 0 was 8.1%; for hospital admissions, the risk increased by 4%. The association was stronger in subjects older than 65, and was more evident for total fatal events than for non-fatal hospitalisations.

CONCLUSION

The study showed increased risks of coronary events associated with air pollution in Rome: ultrafine particles, directly generated by vehicular traffic, are the environmental indicator which best characterizes the health risk.