Results
- Enrollment is complete for the ongoing FOOTPRINTS® study
- Baseline data from 443 participants are shown in Table 1 and patient disposition in Figure 2
Table 1. Baseline demographics and clinical characteristics
aData were missing for 3 patients with COPD GOLD 1–3. bNumber of patients who had exacerbations at any time point prior to entering the FOOTPRINTS® study. cSubjects with any air trapping >0%. dMild-to-severe paraseptal emphysema.
Ex-smokers without airflow limitation:
- >50% had expiratory air trapping
- Non-emphysematous air trapping was less common in those with airflow limitation, probably because a higher proportion of them had emphysema
- Almost 35% of this population had centrilobular emphysema, slightly higher than the 22% seen in COPDGene®1
Figure 2. Subject disposition after 1 year
Distribution of subjects by GOLD status
- In the COPDGene® study, two main disease axes (emphysema- and airway-predominant axis) characterized different pathophysiologic disease processes in COPD patients.2 Using the correlation structure of this analysis, the disease axes were created in FOOTPRINTS. Individuals were later stratified to risk groups based on the highest 2 deciles of the disease axes3
Figure 3. Distribution of high-/low-risk disease subjects by GOLD status in (a) the FOOTPRINTS® and (b) the COPDGene® study3
COPDGene® 5-year mortality risk: 26% APD, 21% EPD; 54% APD-EPD, 10% not high risk
- The distribution of disease phenotypes by GOLD status showed a similar pattern in the FOOTPRINTS® study compared with COPDGene® data
Abbreviations: A1ATD, alpha1-antitrypsin deficiency; APD, airway-predominant disease; CAT, COPD Assessment Test; COPD, chronic obstructive pulmonary disease; CT, computed tomography; EPD, emphysema-predominant disease; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; mMRC, modified Medical Research Council; pred, predicted; SD, standard deviation; SGRQ, St. George’s Respiratory Questionnaire.