Table 1.
Number of hospitalizations for acute myocardial infarction in Alberta subgroups (1999–2009).
Fig 1.
Seasonal trends of monthly average frequency of AMI hospitalizations and monthly average concentrations of air pollutants (April 1999 –March 2010).
Monthly frequency of AMI hospitalizations (1 unit = 100) were the average number of events by month. Monthly average concentration levels of CO (1 unit = 1 mg/m3), NO (1 unit = 10 μg/m3), NO2 (1 unit = 10 μg/m3), O3 (1 unit = 10 μg/m3), or PM2.5 (1 unit = 10 μg /m3) were averaged by month in which the daily mean concentrations linked to the event days.
Table 2.
Step 2 multivariate analysis with full adjustment results (p-value ≤0.05).
Table 3.
Step 3 Bootstrap model averaging results.
Fig 2.
Adverse associations between air pollutants and AMI hospitalizations with frequency over 700 of 1,000 bootstrap replications.
AGECAT2 = age ≥65; NSTEMI = Non-ST Segment Elevation Myocardial Infarction; HTN = Hypertension. OR estimates calculated by bootstrap model averaging of 1,000 replications for an inter-quintile range increase of NO2_AVE (28.2 μg/m3), NO2_AVE12 (30.1 μg/m3), NO2_AVE6 (34.2 μg/m3). Freq represents frequency that a variable had p-value ≤0.05 from 1,000 model replications.
Fig 3.
Comparison of 1-day lag NO2 concentration effects in subgroups defined by age and type of AMI.
AGECAT1 = age <65; AGECAT2 = age ≥65; STEMI = ST Segment Elevation Myocardial Infarction; NSTEMI = Non-ST Segment Elevation Myocardial Infarction. OR estimates calculated by bootstrap model averaging of 1000 replications for an inter-quintile range increase of NO2_AVE (28.2 μg/m3), NO2_AVE12 (30.1 μg/m3), NO2_AVE6 (34.2 μg/m3), NO2_MIN (16.9 μg/m3), NO2_MAX (39.5 μg/m3). Freq represents frequency that a variable had p-value ≤0.05 from 1,000 model replications.
Fig 4.
Comparison of 1-day lag NO2 concentration effects in subgroups defined by age and hypertension condition.
AGECAT1 = age <65; AGECAT2 = age ≥65; HTN = Hypertension. NO-HTN = No Hypertension. OR estimates calculated by bootstrap model averaging of 1,000 replications for an inter-quintile range increase of NO2_AVE (28.2 μg/m3), NO2_AVE12 (30.1 μg/m3), NO2_AVE6 (34.2 μg/m3), NO2_MIN (16.9 μg/m3), NO2_MAX (39.5 μg/m3). Freq represents frequency that a variable had p-value ≤0.05 from 1,000 model replications.