Design: Prospective multicentre cohort (SPIROMICS) with serial quantitative CT
Population: 880 participants: smokers with and without COPD and non-smoking controls
Primary outcome: FEV1 decline from visit 2 to visit 5 by 1-year CT change
Effect: Per SD increase: combined bronchitic-apical emphysema −4.2 mL/yr (95% CI −8.3 to −0.2); diffuse −6.2 mL/yr (−10.7 to −1.8)

SPIROMICS followed 880 participants (smokers with and without COPD, plus non-smoking controls) with annual visits and CT scans. This analysis asked whether change over one year in quantitative CT measures predicted later FEV1 decline.

Average FEV1 fell by 30.4 mL/year. A one-standard-deviation increase over one year in machine-learned emphysema subtypes predicted faster later decline: combined bronchitic-apical emphysema by an extra 4.2 mL/year (95% CI 0.2 to 8.3) and diffuse emphysema by 6.2 mL/year (1.8 to 10.7). Standard CT emphysema measures also predicted decline, but only the two subtypes remained independent predictors when all were combined.

This is mainly important for research: CT changes over a year could shorten COPD trials that now need years of spirometry. For patients, it is another reason why smoking cessation remains the single most important intervention for lung function.

CT emphysema progression over one year predicted later FEV1 decline.
Quantitative CT subtyping is a research tool, not yet a routine clinical test.
Smoking cessation remains the most effective proven way to slow FEV1 decline.
Emphysema seen on CT done for other reasons deserves spirometry and smoking review.

Why it matters

Faster endpoints could bring disease-modifying COPD drugs to trial, and to patients, sooner.

The statistics, in plain English

An extra 4 to 6 mL/year of FEV1 loss per standard deviation of change is modest for an individual but meaningful across a trial population. The lower confidence limit for one subtype (0.2 mL/year) is close to zero.