Figures & data
Figure 1. A theoretical model of disease activity and severity with time. If disease activity is stable with a similar age of onset, there will be a proportional relationship between disease severity and activity and age which will reflect preceding activity. The presence of more severe disease at a younger age therefore implies either a younger age of disease onset or more likely (based on the current understanding of the pathogenesis of COPD) this indicates a more active disease process.
Figure 2. The variability of disease activity in COPD is currently unknown, although current data suggest it is relatively stable (line A) with a small contribution from exacerbations (minor peaks). Alternatively, activity may be exacerbation predominant (line C) with exacerbations contributing significantly to disease progression (although this degree of contribution is not compatible with more recent data) or disease activity may decline with time/increasing severity (line B).
