Low Vitamin K Status and Risk of Chronic Obstructive Pulmonary Disease

<b>Background:</b> Vitamin K is a cofactor necessary for the biological activity of proteins like Matrix Gla Protein (MGP), which reduce calcification and help preserve lung function. This study aims to determine, first, whether low vitamin K status is associated with chronic obstructive pulmonary disease (COPD), and secondary, whether the level of vitamin K is associated with COPD severity, smoking exposure, or mortality. <b>Methods:</b> The plasma concentration of dephosphorylated uncarboxylated (dp-uc) MGP was used as an inverse biomarker for vitamin K in 98 COPD patients from the CODEX-P COPD study and 986 controls from the DanFunD study. Low vitamin K status was defined as the upper quartile of dp-ucMGP (>589 pmol/L). Using a logistic regression model, we examined whether low vs. high/moderate vitamin K status increased the odds ratio (OR) of having COPD. Secondary analyses, in the COPD cohort only, examined the association between low vitamin K status and COPD severity, smoking exposure in packyears and all-cause mortality, using a Welch's <i>t</i>-test and log-rank test, respectively. <b>Results:</b> Low vitamin K status was associated with increased odds of having COPD, OR 9.7 (95% CI [5.5 to 17.5], <i>p</i> < 0.001). We found no associations between low vitamin K and COPD severity (est. -0.03, <i>p</i> = 0.7; 95% CI [-0.2 to 0.1]), smoking exposure (<i>p</i> = 0.7), or all-cause mortality (<i>p</i> = 0.5). <b>Conclusions:</b> Low vitamin K status was associated with substantially higher odds of having COPD compared to high/moderate vitamin K status. No association was found between low vitamin K status and COPD severity, smoking exposure, or all-cause mortality. Further studies are needed to determine if vitamin K plays a role in the pathophysiology of COPD and whether supplement therapy is indicated.