Table 1.
Baseline Characteristics—Baltimore Longitudinal Study on Aging
| Characteristic | Analytical Sample N = 501 |
Excluded Participants§
N = 871 |
p Value║ |
|---|---|---|---|
| Mean ± SD or No. (%) | |||
| Age (years) | 56.4±11.4 | 64.6±13.9 | <.001 |
| Females | 142 (28.3%) | 312 (35.8%) | .005 |
| Height (cm) | 172.7±9.2 | 170.7±9.4 | <.001 |
| BMI (kg/m2) | 25.3±3.4 | 25.6±4.0 | .237 |
| Obesity (BMI ≥30kg/m2) | 43 (8.6%) | 103 (11.8%) | .061 |
| Never-smoker | 171 (34.1%) | 334 (38.3%) | .119 |
| Hypertension* | 120 (24.0%) | 289 (33.2%) | <.001 |
| Chronic bronchitis | 58 (11.6%) | 101 (11.6%) | .992 |
| Diabetes mellitus† | 42 (8.4%) | 106 (12.2%) | .030 |
| Myocardial infarction | 6 (1.2%) | 49 (5.6%) | <.001 |
| FEV1 Liters | 3.240±0.846 | Not applicable | |
| FEV1/Height3 (L/m3) | 0.621±0.199 | ||
| FEV1 %Pred | 96.4±14.8 | ||
| FEV1 Z-score‡ | −0.239±1.012 | ||
Notes: BMI = body mass index; FEV1 = forced expiratory volume in 1 second; %Pred = percent predicted ([measured/predicted] × 100).
*Systolic blood pressure ≥140 or diastolic ≥90mm Hg.
†Based on fasting hyperglycemia, abnormal glucose tolerance test, or use of hypoglycemic drugs (see text).
‡A Z-score of −0.239 corresponds to the 40.6th percentile, which is well above the lower limit of normal (defined by a Z-score of −1.645 as the 5th percentile of distribution in a reference population of asymptomatic lifelong nonsmokers).
§Were age-eligible but did not complete at least three longitudinal spirometric assessments, each of which had to achieve two or more acceptable and reproducible spirometric maneuvers (see text).
║Comparisons between the analytical and excluded sample were conducted using chi-square tests for categorical variables and t tests for continuous variables.