Demographic characteristics of participants included in the analysis
| N | Severe COPD (%)** | Moderate COPD (%) | Mild COPD (%) | Symptoms only (%) | Restrictive disease (%) | Death | |
|---|---|---|---|---|---|---|---|
| Participants included in the analysis were stratified by age, race, sex, education level, and smoking status at the baseline evaluation; the age adjusted* proportion within each subgroup with class of COPD, respiratory symptoms, or restrictive lung disease; and the age adjusted proportion who died during the follow up period. | |||||||
| *Age adjusted to the analytical population sample. Proportions by age are age specific. | |||||||
| **Severe COPD = forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) <0.70 and FEV1 <50% predicted; moderate COPD=FEV1/FVC <0.70 and FEV1 ⩾50–<80% predicted; mild COPD=FEV1/FVC <0.70 and FEV1 ⩾80%; symptoms only=presence of respiratory symptoms in the absence of any lung function abnormality; restrictive lung disease=FEV1/FVC ⩾0.70 and FVC <80% predicted. | |||||||
| From the First National Health and Nutrition Examination Survey 1971–5 and follow up to 1992. | |||||||
| Age | |||||||
| 25–39 | 1903 | 0.2 | 2.8 | 4.0 | 19.2 | 6.5 | 3.8 |
| 40–49 | 1171 | 0.8 | 5.9 | 7.0 | 18.7 | 7.9 | 11.8 |
| 50–59 | 1168 | 2.6 | 10.4 | 9.5 | 12.8 | 11.6 | 26.4 |
| 60–69 | 967 | 3.7 | 10.7 | 12.7 | 12.5 | 11.4 | 53.6 |
| 70–74 | 333 | 4.2 | 13.5 | 14.1 | 11.4 | 14.4 | 79.6 |
| Race | |||||||
| White | 4896 | 1.6 | 6.9 | 7.5 | 16.4 | 8.5 | 22.7 |
| Non-white | 646 | 1.8 | 8.4 | 10.5 | 14.0 | 14.6 | 28.6 |
| Sex | |||||||
| Male | 2508 | 2.2 | 10.0 | 9.8 | 16.1 | 8.8 | 28.3 |
| Female | 3034 | 1.2 | 4.6 | 6.2 | 16.1 | 9.6 | 19.2 |
| Education | |||||||
| ⩽12 years | 4044 | 1.9 | 7.6 | 8.3 | 16.6 | 9.0 | 24.2 |
| ⩾13 years | 1498 | 0.9 | 5.2 | 6.8 | 14.8 | 10.1 | 21.0 |
| Smoking status | |||||||
| Current smoker | 2323 | 2.5 | 11.8 | 10.3 | 20.2 | 10.0 | 30.2 |
| Former smoker | 1110 | 1.8 | 6.6 | 7.9 | 15.9 | 6.9 | 22.0 |
| Never smoker | 2109 | 0.9 | 2.8 | 5.9 | 10.5 | 9.4 | 17.9 |
| Pack years | |||||||
| ⩾60 | 524 | 2.7 | 16.4 | 12.8 | 19.0 | 11.8 | 33.0 |
| 30–<60 | 961 | 2.9 | 12.8 | 11.0 | 24.1 | 9.6 | 29.5 |
| <30 | 1948 | 1.4 | 5.5 | 7.6 | 16.8 | 8.8 | 23.7 |
| Never smoker | 2109 | 0.9 | 2.8 | 5.9 | 10.5 | 9.4 | 17.9 |
| Years since regularly smoked | |||||||
| 0 | 2432 | 2.5 | 11.5 | 9.9 | 19.6 | 9.8 | 29.8 |
| >0–<10 | 629 | 2.3 | 8.4 | 9.1 | 16.6 | 8.0 | 22.6 |
| ⩾10 | 372 | 0.8 | 4.9 | 6.1 | 16.1 | 5.7 | 20.1 |
| Never smoker | 2109 | 0.9 | 2.8 | 5.9 | 10.5 | 9.4 | 17.9 |
| Body mass index (kg/m2) | |||||||
| <18.5 | 180 | 6.9 | 10.2 | 9.2 | 17.8 | 13.4 | 31.4 |
| ⩾18–24 | 2604 | 1.8 | 7.7 | 9.1 | 14.8 | 7.4 | 22.1 |
| 25–29 | 1885 | 1.1 | 6.7 | 8.0 | 16.1 | 9.3 | 23.1 |
| ⩾30 | 873 | 1.6 | 5.7 | 4.6 | 19.1 | 13.4 | 27.0 |
| Total | 5542 | 1.7 | 7.1 | 7.9 | 16.1 | 9.2 | 23.4 |