Descriptive results: variables used in the analysis*
| Unweighted (SD)† | Weighted (95% CI) | |
| Age, first analytic observation, mean | 30.8 (10.7) | 31.8 (31.5 to 32.1) |
| Age, last analytic observation, mean | 45.4 (13.6) | 45.5 (45.1 to 45.8) |
| Female, % | 53.4 | 49.1 (47.1 to 51.2) |
| Race or ethnicity, % | ||
| African–American or black | 32.0 | 10.5 (8.0 to 12.9) |
| Hispanic | 6.1 | 4.8 (3.5 to 6.1) |
| Non-Hispanic white | 58.7 | 80.9 (77.5 to 84.3) |
| Other race or ethnicity | 3.2 | 3.8 (2.6 to 5.0) |
| Educational attainment, mean years | 13.6 (2.6) | 13.8 (13.7 to 13.9) |
| Smoking status, % | ||
| Current smoker | 17.3 | 13.1 (9.4 to 16.7) |
| Past smoker | 31.9 | 32.1 (26.7 to 37.4) |
| Never smoker | 57.8 | 60.2 (54.9 to 65.5) |
| Atopy, % | ||
| Childhood (ages 0 through 18) | 5.5 | 4.9 (4.0 to 5.8) |
| Adult | 3.0 | 2.9 (1.5 to 4.3) |
*Data source: Panel Study of Income Dynamics, 1968–2015; weighted results account for the survey design.
†SD shown for continuous variables.