Richert, Mary

Abstract Rationale: Individuals with chronic obstructive pulmonary disease (COPD) have different clinical trajectories, some with minimal symptom burden, others experiencing recurrent exacerbations, the most severe of which require hospitalization. Existing diagnostics, including spirometry and symptom assessments, lack the precision to identify high-risk patients who may benefit from timely preventive therapies. Nuclear cell-free DNA (ncfDNA) is a well-established marker of systemic tissue injury, implicated in amplifying inflammation by triggering type 1 interferon release by activating DNA-sensing pathways. Because COPD is accompanied by inflammation and tissue injury systemically, we hypothesized that ncfDNA is associated with increased risk of severe exacerbations requiring hospitalization. Methods: Design: We utilized baseline plasma samples randomly selected from 672 individuals with COPD from the Subpopulations and Intermediate Outcomes Measures in COPD Study (SPIROMICS) cohort, which prospectively collected exacerbation numbers and type. The primary endpoint was exacerbation requiring hospitalization. Secondary endpoints included total number of exacerbations (defined as use of oral steroids, antibiotics, or healthcare utilization) and severe exacerbations (defined as requiring emergency room care or hospitalization). Measure: We measured plasma ncfDNA using digital droplet PCR. Analysis: We assessed the association of ncfDNA with exacerbation outcomes using negative binomial regression or Cox regression, adjusting for age, percent post-bronchodilator forced expiratory volume in one second (FEV1), supplemental oxygen use, and smoking status. Results: In total, 57% (n=383) of COPD participants experienced exacerbations, 29% (n=197) at least one severe, and 22% (n=145) requiring hospitalization, the latter at a median of 622 days from enrollment (IQR=287-997). Higher ncfDNA levels at enrollment correlated with measures of COPD severity, including baseline FEV1 (beta = -0.12, 95% CI -0.18 to -0.049, p <0.001). Higher ncfDNA associated with increased risk of COPD exacerbation requiring hospitalization (incidence rate ratio (IRR) 1.40, 95% CI 1.12-1.75, p =0.003) and severe exacerbations (IRR 1.36, 95% CI 1.11-1.67, p=0.002) and a trend towards total exacerbations (IRR 1.11, 95% CI 0.98-1.26, p= 0.09). The primary outcome, risk of time-to-first hospitalization, correlated significantly with higher ncfDNA with hazard ratio (HR) 1.23, 95% CI 1.01-1.49, p=0.037. Conclusion: These results suggest that ncfDNA may serve as a predictor for severe and hospitalization-associated COPD exacerbations. To better understand the relationship between ncfDNA and COPD pathophysiology, follow-up studies should explore longitudinal trends and cfDNA tissue sources, and their link to COPD exacerbations.