Figure 2. Age-Adjusted Absolute Incidence Density Rates by Lung Function Category.

Data were stratified by smoking status for all-cause mortality, respiratory-related mortality, coronary heart disease (CHD)-related mortality, respiratory-related events (hospitalizations and mortality), and CHD-related events (hospitalizations and mortality). Lung function category definitions: preserved ratio impaired spirometry (PRISm) (ratio of forced expired volume in the first second to forced vital capacity [FEV₁:FVC] ≥0.7 and FEV₁<80%), obstructive spirometry (FEV₁:FVC ratio <0.7), and normal spirometry (FEV₁:FVC ratio ≥0.7 and FEV₁ ≥80%). Using the direct method and the observed age distribution across all 9 cohorts, age-adjusted absolute incidence density rates and their differences were calculated per 1000 person-years for each combination of baseline smoking status and lung function category.