V itamin K intake and risk of all-cause and cardiovascular m ortality in p eople with c hronic k idney disease : Implication in coagulation treatment and management

Ching-Lung Cheung1, Shivani Sahni2, Ian Wong1, Bernard Cheung1. 1The University of Hong Kong, Hong Kong, Hong Kong, 2Hebrew SeniorLife, Harvard Medical School, Boston, MA, USA

Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD), partly due to increased vascular calcification. Emerging evidence suggests that vitamin K plays a key role in preventing vascular calcification in CKD. It is known that vitamin K intake plays a key role in the effectiveness of the warfarin treatment. However, the relationship between vitamin K intake and all-cause and CVD mortality in people with CKD remains unknown. The objective was to examine the association of vitamin K intake with all cause and CVD mortality in a nationally representative sample aged 20 or above.

3,401 participants with CKD from the Third National Health and Nutrition Examination Survey. Dietary intake was assessed during nutritional examination based on 24–h dietary recall. Participants provided at least one reliable 24-h dietary recall (as defined by the variable “Dietary Recall Status”) were included. Vitamin K intake was used in multivariate Cox regression analysis to predict all-cause and CVD mortality.

During a median follow-up of 13.3 years (37,408 person-years), 1,815 and 876 participants died from all cause and CVD causes, respectively. The majority of participants had vitamin K intake lower than the recommended intake levels. In multivariable Cox-regression analysis, participants in higher quintiles (quintile 4-5) of vitamin K intake had significantly lower risk of all-cause (HR: 0.86 (95% CI: 0.75-1; P=0.046) and CVD mortality (HR: 0.79 (95% CI: 0.64-96; P=0.021) when compared with quintiles 1 through 3. Participants with vitamin K intake higher than recommended adequate intake value for vitamin K (90μg/day for women; 120μg/day for men) were associated with lower risk of all-cause and CVD mortality.

These findings suggest that adequate-to-high level of vitamin K intake reduces CVD and all-cause mortality in people with CKD. However, the findings may be affected by confounded by co-mediations at baseline and during follow up period. Nevertheless, our findings may have implication in coagulation treatment and management, especially in people with CKD.