Table 1. Baseline characteristics of NHANES III participants, according to age group.
| Characteristic | Age 40-80 N=7,115 | Age 40-64 N=4,632 | Age 65-80 N=2,483 | P Value f |
|---|---|---|---|---|
| Age (years), mean (SD) | 58.3 (11.9) | 51.1 (7.7) | 71.7 (4.5) | <.001 |
| Females, No. (%) | 3,645 (51.2) | 2,391 (51.6) | 1,254 (50.5) | .370 |
| Ethnicity, No. (%) | ||||
| White | 3,506 (49.3) | 2,007 (43.3) | 1,499 (60.4) | <.001 |
| African-American | 1,860 (26.1) | 1,343 (29.0) | 517 (20.8) | |
| Mexican-American | 1,749 (24.6) | 1,282 (27.7) | 467 (18.8) | |
| BMI (kg/m2), mean (SD) | 27.9 (5.6) | 28.2 (5.8) | 27.3 (5.2) | <.001 |
| Smoking history, No. (%) a | 2,627 (37.4) | 1,677 (36.6) | 950 (38.9) | .054 |
| Chronic conditions, No. (%) b | ||||
| Hypertension | 2,668 (37.6) | 1,472 (31.9) | 1,196 (48.3) | <.001 |
| Diabetes mellitus | 857 (12.1) | 449 (9.7) | 408 (16.4) | <.001 |
| COPD c | 478 (6.7) | 264 (5.7) | 214 (8.6) | <.001 |
| Myocardial infarction | 440 (6.3) | 168 (3.7) | 272 (11.1) | <.001 |
| Heart Failure | 321 (4.5) | 116 (2.5) | 205 (8.3) | <.001 |
| Stroke | 258 (3.6) | 84 (1.8) | 174 (7.0) | <.001 |
| High CV risk, No. (%) d | 4,139 (58.2) | 2,470 (53.3) | 1,669 (67.2) | <.001 |
| Fair-to-poor health status, No. (%) | 2,012 (28.3) | 1,186 (25.6) | 826 (33.3) | <.001 |
| Spirometry, No. (%) e | ||||
| Normal | 5,764 (81.0) | 3,828 (82.6) | 1,936 (78.0) | <.001 |
| Airflow-obstruction | 905 (12.7) | 523 (11.3) | 382 (15.4) | |
| Restrictive-pattern | 444 (6.2) | 281 (6.1) | 163 (6.6) | |
| Respiratory symptoms, No. (%) | ||||
| Dyspnea on exertion (DOE) | 2,033 (28.6) | 1,187 (25.7) | 846 (34.2) | <.001 |
| Chronic bronchitis (CB) | 895 (12.6) | 520 (11.2) | 375 (15.1) | <.001 |
| Wheezing | 916 (12.9) | 608 (13.1) | 308 (12.4) | .390 |
Abbreviations: ATS, American Thoracic Society; NHANES III, Third National Health and Nutrition Examination Survey; COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1-second; FVC, forced vital capacity; GLI, Global Lung Function Initiative; SD, standard deviation.
≥ 10 pack-years.
Self-reported, physician-diagnosed.
Included chronic bronchitis or emphysema.
Includes the presence of any of the following: BMI ≥ 30, hypertension, diabetes, heart failure, stroke, or myocardial infarction.
Normal pulmonary function was defined by FEV1/FVC and FVC, both ≥GLI-LLN5; airflow-obstruction by FEV1/FVC<GLI-LLN5; and restrictive-pattern by FEV1/FVC≥GLI-LLN5 and FVC<GLI-LLN5.
Comparisons were made between the age groups of 40-64 and 65-80, using chi-square tests for categorical variables and t-tests for continuous variables.