Descriptive cohort characteristics for US Medicare beneficiaries from 2000 to 2016. Values are number (%) or mean (SD)
| Participants in full cohort (n=61 097 767) | Participants in low exposure cohort† (n=7 022 642) | Participants not in low exposure cohort‡ (n=54 075 125) | |
| Age at entry, years | |||
| 65-74 | 46 886 857 (76.7) | 5 399 807 (76.9) | 41 487 050 (76.7) |
| 75-84 | 10 434 150 (17.1) | 1 188 202 (16.9) | 9 245 948 (17.1) |
| >85 | 3 776 760 (6.2) | 434 633 (6.2) | 3 342 127 (6.2) |
| Sex | |||
| Men | 27 413 250 (44.9) | 3 258 875 (46.2) | 24 154 385 (44.7) |
| Women | 33 684 507 (55.1) | 3 763 767 (53.8) | 29 920 740 (55.3) |
| Race | |||
| White | 51 577 679 (84.4) | 6 610 683 (94.1) | 44 966 996 (83.2) |
| Black | 5 372 559 (8.8) | 122 114 (1.7) | 5 250 445 (9.7) |
| Other* | 3 480 763 (5.7) | 223 421 (3.2) | 3 257 342 (6.0) |
| Medicaid eligibility | |||
| Not eligible | 53 561 222 (87.7) | 6 355 624 (90.5) | 47 205 598 (87.3) |
| Eligible | 7 536 545 (12.3) | 667 018 (9.5) | 6 869 527 (12.7) |
| Air pollution concentration | |||
| PM2.5 (µg/m3) | 9.8 (3.1) | 7.2 (2.2) | 10.2 (3.0) |
| NO2 (ppb) | 19.0 (10.2) | 9.9 (3.6) | 20.3 (10.2) |
| Potential confounder (community level characteristics) | |||
| Below poverty level (%) | 10.5 (8.1) | 9.3 (7.0) | 10.7 (8.2) |
| Population density (people per km2) | 3300.5 (8590.2) | 266.3 (702.8) | 3744.6 (9109.1) |
| Median home value ($1000) | 203.8 (167.6) | 161.8 (127.2) | 209.3 (171.9) |
| Black (%) | 11.9 (18.4) | 2.8 (7.1) | 13.2 (19.1) |
| Hispanic (%) | 7.2 (8.7) | 4.6 (5.9) | 7.5 (9.0) |
| Median annual household income ($1000) | 52.6 (23.1) | 47.7 (16.0) | 53.3 (23.9) |
| Owner occupied housing (%) | 67.4 (17.8) | 75.2 (11.6) | 66.3 (18.2) |
| Below high school education (%) | 27.0 (16.1) | 23.5 (14.5) | 27.6 (16.3) |
| Ever smoked (%) | 46.0 (7.2) | 48.8 (8.0) | 45.6 (6.9) |
| Body mass index | 27.5 (1.0) | 27.6 (1.0) | 27.5 (1.0) |
$1.00=£0.76, €0.90. SD=standard deviation.
*Other included Asian, Hispanic, American Indian or Alaskan Native, and unknown. Data on race were obtained from Medicare beneficiary files.
†Fine particles (PM2.5)<12 µg/m3 and nitrogen dioxide (NO2)<20 ppb.
‡PM2.5≥12 µg/m3 and NO2≥20 ppb.