Pulmonary function testing was not obtained on 3355 of the original 20,050 subjects. The significant predictors of not having testing done were the presence of cardiovascular disease (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.2-1.7) and age (OR, 1.9; 95% CI, 1.4-2.5 for those aged 65-74 years; OR, 2.9; 95% CI, 2.3-3.8 for those aged 75-84 years; and OR, 5.3; 95% CI, 3.8-7.3 for those aged 85 years and older, compared with those aged 17-24 years). Overall, 6.8% of the population, or an estimated 11.5 million people had low lung function (Table 2). An additional 7.2% of the population had an FEV1-FVC ratio of less than 0.7 but an FEV1 greater than 80% of the predicted value. Significant predictors of low lung function included current smoking (OR, 4.3; 95% CI, 3.2-5.7), former smoking (OR, 2.0; 95% CI, 1.5-2.5), pipe or cigar smoking (OR, 2.7; 95% CI, 1.4-5.0), current OLD (OR, 5.4; 95% CI, 4.1-7.0), prior OLD (OR, 1.8; 95% CI, 1.0-3.0), and age (ORs increased from 2.1 for those aged 25 to 44 years to 21.0 for those aged 85 years and older, compared with 17- to 24-year-olds, all CIs significant). Moderate to severe lung obstruction (FEV1 less than 50% of the predicted value and an FEV1-FVC ratio of less than 0.7) was more common among current and former smokers and among people aged 45 years and older (Figure 2 and Figure 3). Overall, 1.5% of the population, or an estimated 2.6 million people, had an FEV1 of less than 50% of the predicted value, including an estimated 900,000 people with an FEV1 of less than 35% of the predicted value. Lower levels of lung function were associated with higher levels of reported symptoms (Table 3).