Air pollution effects on myocardial infarction.
OBJECTIVE
Myocardial infarction is an acute and severe cardiovascular disease that generally leads to patient admissions to intensive care units and few cases are initially admitted to infirmaries. The objective of the study was to assess whether estimates of air pollution effects on myocardial infarction morbidity are modified by the source of health information.


METHODS
The study was carried out in hospitals of the Brazilian Health System in the city of São Paulo, Southern Brazil. A time series study (1998-1999) was performed using two outcomes: infarction admissions to infirmaries and to intensive care units, both for people older than 64 years of age. Generalized linear models controlling for seasonality (long and short-term trends) and weather were used. The eight-day cumulative effects of air pollutants were assessed using third degree polynomial distributed lag models.


RESULTS
Almost 70% of daily hospital admissions due to myocardial infarction were to infirmaries. Despite that, the effects of air pollutants on infarction were higher for intensive care units admissions. All pollutants were positively associated with the study outcomes but SO2 presented the strongest statistically significant association. An interquartile range increase on SO2 concentration was associated with increases of 13% (95% CI: 6-19) and 8% (95% CI: 2-13) of intensive care units and infirmary infarction admissions, respectively.


CONCLUSIONS
It may be assumed there is a misclassification of myocardial infarction admissions to infirmaries leading to overestimation. Also, despite the absolute number of events, admissions to intensive care units data provides a more adequate estimate of the magnitude of air pollution effects on infarction admissions.
Cendon
Sônia
S
Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil. cendon.barral@uol.com.br
Pereira
Luiz A A
LA
Braga
Alfésio L F
AL
Conceição
Gleice M S
GM
Cury Junior
Abraão
A
Romaldini
Hélio
H
Lopes
Antônio C
AC
Saldiva
Paulo H N
PH
D000368:Aged; D000393:Air Pollutants / Q000009:adverse effects*; D001938:Brazil / Q000453:epidemiology; D006779:Hospitals, Public; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000209:etiology; D010343:Patient Admission / Q000706:statistics & numerical data*; D010362:Patients' Rooms / Q000706:statistics & numerical data*; D012621:Seasons; D014505:Urban Population
D000393:Air Pollutants