Background
Vitamin K has been hypothesized as being lung protective through Matrix Gla Protein-vitamin K-dependent activation. To our knowledge no prior study has assessed a potential negative effect of vitamin K antagonists (VKA) compared to Non-vitamin K oral anticoagulants (NOAC) on exacerbations and mortality in patients with COPD.

Objective
To assess the 1-year risk of hospitalization due to an acute exacerbation of COPD(AECOPD) and all-cause mortality in COPD-patients treated with either VKA or NOAC.

Methods
We conducted a nationwide Danish register-based cohort study of VKA- or NOAC-treated COPD-patients. We applied a cox proportional hazard regression model adjusting for known and suspected confounders. As a sensitivity analysis, we matched every NOAC-treated with two VKA-treated patients by propensity matching scores.

Results
We identified 3385 COPD-patients, where 1045 were treated with NOAC (31%) and 2340 were treated with VKA (69%). We found an adjusted hazard ratio of 0.80 (95% confidence interval (CI): 0.66 ? 0.96, p=0.017) favoring VKA treatment. After propensity matching, we found an identical hazard ratio of 0.79 (95% CI: 0.66 ? 0.96, p=0.018.)

Conclusion
The use of vitamin-K antagonists was associated with a reduced risk of severe exacerbation and death in COPD-patients. Further studies are needed to confirm this association.