Key result
Oral vitamin K supplementation favored time in INR therapeutic range (pooled effect size 0.31; 95% CI 0.03-0.59), but wide variability among studies precludes recommending routine use.
Why the study?
Does oral vitamin K supplementation improve time in INR therapeutic range in patients on chronic anticoagulation therapy?
Meta-Analysis (n=678)
Does oral vitamin K supplementation improve time in INR therapeutic range in patients on chronic anticoagulation therapy?
Effect estimate: Effect size 0.31 (95% CI 0.03-0.59)
While oral vitamin K supplementation may improve time in therapeutic range for select patients with INR instability, there is insufficient evidence to support its routine use.
PURPOSE: Systematically review and quantitatively synthesize evidence on use of oral vitamin K supplementation in reducing international normalized ratio (INR) variability. DATA SOURCES: PubMed, The Cochrane Library, PsycINFO, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Turning Research Into Practice (TRIP), Web of Science were searched for studies meeting predetermined inclusion/exclusion criteria. Five studies meeting criteria (three randomized trials, one quasi-experimental pre-post study, one retrospective case series) were appraised for quality and data synthesized by two reviewers. Pooled effect size of time in INR therapeutic range (TTR) was estimated using random effects meta-analysis. CONCLUSIONS: Pooled effect size representing data from four studies (678 subjects) was 0.31, 95% confidence interval 0.03-0.59 (Cochran Q = 7.1; p = .07; I(2) = 57.8) and favored vitamin K supplementation. Given wide variability among individual studies, there is not enough evidence to advise for or against the routine use of vitamin K supplementation to achieve INR stability. However, evidence does suggest that it may be of some benefit for some patients with INR instability. IMPLICATIONS FOR PRACTICE: There is insufficient evidence to support routine supplementation with vitamin K in patients on chronic anticoagulation therapy but select patients, particularly those with persistent INR instability despite known adherence to regimen and no dietary or drug-drug interactions, may benefit from the intervention. Future research is warranted.
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Kramps et al. (2013) conducted a meta-analysis in INR instability in patients on chronic anticoagulation therapy (n=678). Oral vitamin K supplementation was evaluated on Time in INR therapeutic range (TTR) (Effect size 0.31, 95% CI 0.03-0.59). Oral vitamin K supplementation favored time in INR therapeutic range (pooled effect size 0.31; 95% CI 0.03-0.59), but wide variability among studies precludes recommending routine use.
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