Anticoagulation: iv vitamin K lowered INR faster than sc vitamin K

Clinical bottom line (level 1b)

  1. Patients on anticoagulation with supratherapeutic INRs who received vitamin K iv compared with vitamin K sc were more likely to have an INR < 5.0 after 8 hours (NNT = 1 at 8 hours) , but there was no clear difference after 24 hours.
Raj et al: Archives of Internal Medicine 1999; 159 : 2721-2724
Expires October 2003

The study

Single-blinded ?concealed randomised trial with intention-to-treat
Setting: 3 acute hospitals, USA

22 patients (aged , % male) on stable doses of warfarin and INR > 6.0

Excluded if
  • evidence of active bleeding (includnig, excessive bruising, epistaxis, haematuria)
  • on a stable dose of warfarin for less than 6 weeks
  • on oral anticoagulation for less than 3 months
Control Group: (n = 11, 11 analysed): vitamin K 1 mg iv
Experimental Group: (n = 11, 11 analysed): vitamin K 1 mg sc
Warfarin was withheld for at least 24 hours and longer if the INR > 6.0 at 24 hours.
100% followed for 24 hours

The evidence

Outcome Time to outcome CER EER RRR
(95% CI)		 ARR
(95% CI)		 NN T
(95% CI)
INR < 5.0 8 hours 9
(81.8%)		 1
(9.09%)		 89%
(26% to 98%)		 72.7%
(44.3% to 100%)		 1
(1 to 2)
INR < 5.0 24 hours 9
(81.8%)		 7
(63.6%)		 22%
(-32% to 54%)		 18.2%
(-18.3% to 54.6%)		 6
(NNT = 2 to infinity;
NNH = 5 to infinity)

Comments

  1. The study was too small to show any difference at 24 hours between the two groups.

  • Citation

    1. Raj G, Kumar R, McKinney P: time course of reversal of anticoagulant effect of warfarin by intravenous and subcutaneous phytonadione. Archives of Internal Medicine 1999; 159 : 2721-2724
    Search Terms:
    Contributor: , October 2001
    Reviewer:

    Clinical Question.
    Patient supratherapeutic INR
    Intervention or Exposure subcutaneous (sc) vitamin K
    Comparison intravenous (iv) vitamin K
    Outcome INR < 5.0
    		•