This study evaluated patients with COPD participating the COSCONET cohort and investigated whether Pi10 on non-enhanced low-dose chest CT could be associated with exacerbations, mortality, and use of triple therapy. As pointed out by the authors, routine CT scans are becoming part of routine assessment in COPD. And the topic in this study is relevant for physicians and radiologists. To improve the manuscript, I have following comments.

1. Based on the method “study population”, this study analyzed CT obtained at visit 4 (V4), and functional and clinical data were obtained at visit 4. How did you categorize patients into GOLD A-D? More specifically, how did you evaluate a history of exacerbation in the previous year?

2. Please specify the definition of exacerbation in the methods section.

3. In the methods section, why did the authors calculate the decline in lung function using data at visit 1 and visit 5? As mentioned above, main clinical and functional data were obtained at V4.
   Thus, the decline in lung function between visit 1 and 4 should be used for the previous longitudinal lung function decline before CT. Or the decline between visit 4 and visit 5 would be used for subsequent longitudinal decline after CT. Please reconsider the way of calculating the decline.

4. The authors evaluated mortality up to 6 years after inclusion. Does this mean that the authors evaluated mortality up to 6 years after visit 4 (chest CT)? Please clarify it in the method.

5. For CT measurement, what generation branches were used for calculation of Pi10? As previously reported (Thorax 201;69(11):987-96. PMID: 24928812), using the airway dimensions of spatially-matched airways is critical for robust calculation of Pi10. I checked the reference [29] which described that the software evaluated up to the 8th generation airways. However, the number of airways visible on CT considerably varies among patients, so spatially-matched evaluation cannot be performed when the software uses the 8th generation airways. Please add more explanation of the Pi10 calculation and discuss this point in the discussion section.

6. The finding that Pi10 was lower in GOLD D with triple therapy than GOLD D without is interesting. But I wonder why these patients are categorized into GOLD D despite lower Pi10? Did they experience exacerbations and then started triple therapy? Or did they use triple therapy, but develop exacerbations?

7. In Table 1, what is the definition of airway predominance (CT)?
8. In table 3, how did the authors categorize patients into emphysema and airway types?

All of this reviewer's comments had been adequately responded.