Table 1.
Descriptive statistics for the study population.
| Variables | Full cohort |
|
|---|---|---|
| Number | % | |
| Years of clean period | 1 | |
| Total population | 17,443,900 | 100 |
| Total Stroke cases | 2,240,586 | 12.8 |
| Total person-years | 144,611,520 | |
| Median follow-up year | 8 | |
| Age at entry (years) | ||
| 65–74 | 15,378,824 | 88.2 |
| 75–115 | 2,065,076 | 11.8 |
| Mean (SD) | 69.1 (4.8) | |
| Sex | ||
| Male | 7,291,664 | 41.8 |
| Female | 10,152,236 | 58.2 |
| Race | ||
| White | 15,405,416 | 88.3 |
| Black | 1,039,110 | 6.0 |
| Othera | 999,374 | 5.7 |
| Medicaid eligibility | ||
| Dual-eligible | 1,177,587 | 6.8 |
| Non-dual eligible | 16,266,313 | 93.2 |
| Region | ||
| Northeast | 3,672,246 | 21.1 |
| Southeast | 4,781,586 | 27.4 |
| Midwest | 4,130,490 | 23.7 |
| West | 2,934,175 | 16.8 |
| Southwest | 1,921,509 | 11.0 |
| Body-mass index (kg/m2) | 27.5 (1.0) | |
| Ever smoked (%) | 46.2 (7.4) | |
| Below poverty level (%) | 12.4 (7.3) | |
| Not graduated from high school (%) | 13.8 (8.2) | |
| Median household income (US$1000) | 57.1 (23.7) | |
| Air pollutantsb | ||
| Annual PM2.5 (μg/m3) | 9.4 (3.7) | |
| Annual NO2 (ppb) | 17.5 (12.4) | |
| Warm-season O3 (ppb) | 42.8 (6.5) | |
Note: Data are n (%) or mean (SD), except otherwise specified.
a
Other included Asian, Hispanic, American Indian or Alaskan Native, and unknown.
b
Presented as mean concentration (interquartile range) over the study period.