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.
Forastiere
Francesco
F
Department of Epidemiology, Rome E Health Authority, Rome, Italy. forastiere@asplazio.it
Stafoggia
Massimo
M
Berti
Giovanna
G
Bisanti
Luigi
L
Cernigliaro
Achille
A
Chiusolo
Monica
M
Mallone
Sandra
S
Miglio
Rossella
R
Pandolfi
Paolo
P
Rognoni
Magda
M
Serinelli
Maria
M
Tessari
Roberta
R
Vigotti
Mariangela
M
Perucci
Carlo A
CA
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis*; D002908:Chronic Disease / Q000453:epidemiology; D018592:Cross-Over Studies; D019992:Databases as Topic; D003710:Demography; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D010316:Particle Size; D018570:Risk Assessment; D014505:Urban Population; D014887:Weather
D000393:Air Pollutants