Rationale: Emphysema is characterized by increased lung elastin degradation. The vitamin K dependent protein matrix Gla-protein (MGP) is an endogenous inhibitor of elastin breakdown and calcification. Vitamin K status is reduced in COPD patients and an inverse association between vitamin K intake and emphysema risk has been reported.

Aim: To assess the association of vitamin K status with CT-quantified emphysema severity and lung function in a COPD cohort.

Methods: In this study, participants from the COSYCONET cohort with available CT-scans were included, consisting of 391 patients with GOLD grade 1-4 and 74 patients at risk for COPD. Emphysema severity was assessed by CT and defined as % low attenuation area <-950 HU (%LAA). Plasma dephosphorylated uncarboxylated MGP (dp-ucMGP) levels are inversely associated with vitamin K status and were used as surrogate marker. Analyses were adjusted for age, gender, vitamin K antagonist use, serum creatinine and BMI.

Results: Subjects in the highest dp-ucMGP tertile (>610pmol/L, i.e. lowest vitamin K status), had significantly higher %LAA values (mean±SD: 16.7±13.2%) compared to subjects in the lowest tertile (dp-ucMGP <442pmol/L; %LAA 12.9±13.3%, P<0.001), but not compared to those in the middle tertile. Dp-ucMGP as continuous variable was positively associated with %LAA and inversely associated with FEV1 and DLCO (P<0.001, for all analyses).

Conclusions: Vitamin K status is inversely associated with emphysema severity and positively correlated with FEV1 and DLCO. Clinical trials are warranted to confirm our data and to assess if vitamin K supplementation could attenuate emphysema progression and lung function decline in COPD.