Table. Descriptive Characteristics of Study Participants at Baseline in 2000 and Unadjusted Longitudinal Outcomes by Study Areas in the Analysis of Percent Emphysema.
| Baseline Characteristics | Winston-Salem, NC | New York, NY | Baltimore, MD | St. Paul, MN | Chicago, IL | Los Angeles, CA |
|---|---|---|---|---|---|---|
| No. of participants | ||||||
| Baseline (n = 6860) | 1037 | 1182 | 1054 | 1021 | 1142 | 1424 |
| Follow-up (n = 5780) | 928 | 1031 | 821 | 914 | 1016 | 1070 |
| Age, mean (SD), y | 62.6 (9.8) | 61.7 (10.3) | 63.2 (10) | 60.4 (10.5) | 62.4 (10.1) | 62.7 (10.5) |
| Sex, No. (%) | ||||||
| Female | 553 (53.3) | 662 (56.0) | 569 (54.0) | 516 (50.5) | 611 (53.5) | 725 (50.9) |
| Male | 484 (46.7) | 520 (44.0) | 485 (46.0) | 505 (49.5) | 531 (46.5) | 699 (49.1) |
| Race/ethnicity, No. (%) | ||||||
| White | 552 (53.2) | 236 (20.0) | 521 (49.4) | 596 (58.4) | 542 (47.5) | 148 (10.4) |
| Chinese | 0 | 2 (0.2) | 0 | 0 | 300 (26.4) | 521 (36.6) |
| Black | 482 (46.5) | 409 (34.6) | 533 (50.6) | 0 | 299 (26.2) | 171 (12.1) |
| Hispanic | 3 (0.3) | 534 (45.2) | 0 | 425 (41.6) | 0 | 584 (41.0) |
| Education, No. (%) | ||||||
| ≤High school | 304 (29.3) | 526 (44.5) | 339 (32.2) | 417 (40.8) | 175 (15.3) | 755 (53.0) |
| ≥Some college | 733 (70.7) | 656 (55.5) | 715 (67.8) | 604 (59.2) | 967 (84.7) | 669 (47.0) |
| Smoking status, No. (%) | ||||||
| Never | 403 (38.9) | 532 (45.0) | 436 (41.4) | 414 (40.5) | 545 (47.7) | 796 (55.9) |
| Former | 464 (44.7) | 472 (39.9) | 456 (43.3) | 438 (42.9) | 464 (40.6) | 474 (33.3) |
| Current | 170 (16.4) | 177 (15.0) | 161 (15.3) | 169 (16.6) | 134 (11.7) | 154 (10.8) |
| Pack-years of smoking in ever-smokers, median (25th percentile, 75th percentile) | 19 (5, 37) | 12 (3, 30) | 17 (5, 35) | 14 (3, 33) | 16 (4, 35) | 11 (2, 28) |
| Secondhand smoking, No. (%)a | 590 (56.9) | 518 (43.8) | 531 (50.4) | 627 (61.4) | 592 (51.8) | 410 (28.8) |
| Current employment at baseline, No. (%) | 661 (63.7) | 671 (56.8) | 628 (59.6) | 712 (69.7) | 762 (66.7) | 658 (46.2) |
| BMI <30, No. (%) | 658 (63.5) | 766 (64.8) | 637 (60.4) | 602 (59.0) | 762 (78.5) | 1081 (75.9) |
| Airflow obstruction, No. (%) | 256 (24.7) | 273 (23.1) | 278 (26.4) | 211 (20.7) | 274 (24.0) | 263 (18.5) |
| Air pollution at baseline, mean (SD)b | ||||||
| O3, ppb | 25.2 (1.6) | 14 (2.0) | 20.4 (1.3) | 23.2 (1.3) | 18.3 (1.6) | 16.6 (2.1) |
| PM2.5, μg/m3 | 17 (0.4) | 17.5 (1.8) | 16.2 (0.8) | 12 (0.6) | 16.2 (1.2) | 22.7 (2.6) |
| NOx, ppb | 24.2 (6.7) | 83.4 (21.6) | 42.7 (12.1) | 26.1 (5.6) | 47.5 (8.0) | 73.4 (18.7) |
| Black carbon, μg/m3 | 0.5 (0.1) | 1.4 (0.3) | 0.7 (0.2) | 0.5 (0.1) | 0.7 (0.1) | 1.1 (0.1) |
| Air pollution over follow-up, mean (SD)c | ||||||
| O3, ppb | 25.7 (2.4) | 15 (1.6) | 22.2 (2.2) | 22.5 (1.6) | 21.4 (2.3) | 18.3 (2.4) |
| PM2.5, μg/m3 | 13.5 (1.3) | 14.7 (1.8) | 13.2 (1.9) | 9.7 (0.6) | 13.6 (1.6) | 18.4 (3.9) |
| NOx, ppb | 16.5 (6.0) | 66.7 (17.2) | 30.2 (11.6) | 20.6 (4.8) | 35.5 (10.0) | 55.4 (14.9) |
| Percent emphysema, mean, (SD)d | ||||||
| Baseline | 3.26 (4.85) | 4.70 (4.29) | 4.04 (3.95) | 3.50 (4.09) | 5.37 (4.46) | 4.08 (4.07) |
| Progression/y | 0.07 (0.28) | 0.08 (0.55) | 0.09 (0.42) | 0.06 (0.23) | 0.11 (0.57) | 0.01 (0.45) |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); NOx, oxides of nitrogen; O3, ozone; PM2.5, fine particulate matter; ppb, parts per billion
Secondhand smoking was defined as participants, including never and ever smokers, who contacted other people smoking at home, in a car, or at work in the past year.
Baseline exposures were assessed as pollutant concentration for the year of the baseline examination in 2000 or for the years 2006 to 2008 (for black carbon) for a total of 18902 scans in 6860 participants.
Exposure over follow-up was the mean exposures for each participant aggregated from the year of the baseline examination to that of the follow-up clinic examination within the years 2000 to 2018 for a total of 18574 scans in 6860 participants.
The percentage of lung pixels below −950 Hounsfield units.