Takeaway
- Blood neutrophil counts (BNCs) were strongly related to long-term mortality and frequency of exacerbations in stable chronic obstructive pulmonary disease (COPD).
- Patients with elevated BNCs (defined as 6000-150,00 cells/μL) had poorer outcomes regardless of the time point in their COPD disease course that the BNC was measured.
Why this matters
- The neutrophil remains central to the pathophysiology of COPD, and therapeutic development targeting neutrophilic inflammation is urgently needed in appropriate patients.
Study design
- 178,120 stable and 15,826 exacerbation-associated BNCs were obtained from 7220 patients with COPD (mean follow-up: 9 years) in a large population-based COPD registry in the East of Scotland (TARDIS: Tayside Allergic and Respiratory Disease Information System).
- Funding: Glaxosmithkline.
Key results
- Median BNC was 5200 cells/μL (interquartile range, 4000-7000 cells/μL).
- Patients with elevated BNCs (n=2462) vs those with BNC in the normal range (2000-6000 cells/Μl; n=4465) had higher mortality rates at the study start (14.0 vs 7.9/100 person-years; P<.001).
- People with elevated BNCs were more likely to be classified as GOLD D (46% vs 33%), had more exacerbations (mean, 2.3 vs 1.3/year) and were more likely to have severe exacerbations (13% vs 5%; P<.001 for all) in the following year.
- Eosinophil counts were much less predictive of mortality and exacerbation rates.
- In a subcohort (n=276), patients with elevated BNC had a higher relative abundance of Proteobacteria and reduced microbiome diversity.
Limitations
- Retrospective design.
