Background and importance Phytonadione is widely used in patients with an elevated international normalised ratio (INR) in whom the goal is rapid reversal of INR to a safe range, whether in preparation for an invasive procedure or in supratherapeutic INR due to vitamin K antagonist (VKA) treatment. Vitamin K promotes liver synthesis of clotting factors (II, VII, IX, X) by an unknown mechanism; nonetheless, it has not been clearly demonstrated that phytonadione lowers the risk of major haemorrhage. Moreover, intravenous phytonadione administration is not free of side effects such as anaphylactoid reaction, overcorrection of INR or resistance to VKAs. Lack of compliance between published guidelines is probably because of the limited data available.
Aim and objectives The aim of the study was to analyse the reversal effect of INR caused to 2 mg intravenous phytonadione treatment depending on the initial INR and to evaluate if lowering INR is directly related to the number of doses administered.
Material and methods A retrospective observational study was carried out based on data obtained from the hospital database that included all hospitalised adults treated with 2 mg intravenous phytonadione in 2019. The analysis was developed by Stata/IC-V.15 and commandos cir means, cir, ttest and twoway scatter. The collected parameters were date of birth, sex, frequency, number of doses administered, INR values, date and hour INR values were collected and vitamin K administrations.
Results The study included 47 adults: 24 (51.1%) men and 23 (48.9%) women. Four frequencies were registered: unique dose (29.8%), 24 hours (29.8%), 12 hours (12.8%) and 8 hours (27.7%). Average age was 74.3 years (95% CI 70.4 to 78.3). No mean difference in age was found between men and women (p=0.32). There were significant differences between those adults not anticoagulated and those anticoagulated (p=0.001; 12.1 (95% CI 5.1 to 19.2)) and between VKA treated and not treated (p=0.0001;14.4 (95% CI 7.4 to 21.4)). Pearson correlation of INR reversal was significantly related to the original INR value (r=−0.99 (95% CI −0.99476 to −0.98301); p=0.000) and VKAs/no VKAs (r=−0.52 (95% CI −0.70 to −0.27); p=0.000) but was not related to the number of doses administered (0.14 (95% CI −0.18 to 0.42); p=0.39) or age (p=0.12 (95% CI −0.39 to 0.18); p=0.44).
Conclusion and relevance Even though the INR is not universally accepted as a parameter for evaluating haemorrhage risk, it demonstrates that phytonadione reversal of an elevated INR depends on the VKA treatment status of the patient and the initial INR value but not the number of doses administered or age.
References and/or acknowledgements No conflict of interest.
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