Background

To date, no study has used quantitative CT to study whether radiological abnormalities seen in established COPD occur in younger smokers with a normal FEV1, at risk of subsequently developing COPD.

Methods

Participants in the BLF Early COPD multi-centre cohort (smokers, aged 30-45 yrs, with >10 pack-yrs tobacco history and normal (>80% predicted) FEV1) (NCT03480347) were compared to aged-matched healthy never smoking controls. Quantitative CT was performed to assess radiological COPD features: emphysema, functional small airways dysfunction, and airway wall thickness.

Results

Disease Probability Measure (DPM) of the thoracic CTs demonstrated that, compared to never smoking controls, the Early COPD cohort participants had a higher percentage of fSAD (DPM Airtrap) (7.3% (IQR 5.3 ? 12.5) for Early COPD cohort vs. 4.7% (IQR 4.2 ? 5.5); Mann-Whitney, P<0.001), emphysema (0.05% (IQR 0.01 ? 0.20) vs. 0.03% (IQR 0.01 ? 0.07)); P=0.049), and a greater Pi10 (3.87 (IQR 3.82 ? 3.94) vs. 3.78 (IQR 3.73 ? 3.83), P=0.002)(figure 1A-C). There were no differences in age, gender, BMI and spirometry between 421 BLF cohort participants and 67 never-smoking healthy controls. We found that the extent of air trapping on CT related weakly to lower FEV1/FVC and higher RV/TLC ratios (figure 1E-F) whilst quantifiable emphysema also related positively to an increase in RV/TLC.

Conclusion

For the first time we show the presence of functional small airways disease, emphysema and increased bronchial wall thickness is detectable in early disease and is increased compared to non-smoking controls with similar clinical characteristics. Radiological abnormalities relate to lung function abnormalities.