Accuracy of a portable international normalized ratio monitor for patients receiving a low molecular weight heparin as a bridge pending full oral anticoagulant efficacy.
BACKGROUND
Point of care (POC) devices measuring the international normalized ratio (INR) are accurate for patients with stable disease, but their efficiency has not been prospectively assessed during the "bridging period" when patients are receiving a low molecular weight heparin (LMWH) on top of a vitamin K antagonist (VKA) until the target INR is reached.


METHODS
188 dual INR measurement using the POC (INR(POC)) and the laboratory (INR(lab)) at the same time were consecutively determined : 69 in patients receiving LMWH+VKA (bridging group) and 119 in patients receiving only a VKA (control group). INRpoc was compared to INR(lab).


RESULTS
Test strip failure rate was higher in the bridging group than in the control group (29% vs 4%; p<0,001). In successful tests, POC accuracy was not modified by LMWH administration: the correlation coefficients between POC and lab INR values for the bridging group and the control group were 0,81 and 0,87 respectively, and the relative measure of divergence (RMD=INR(lab) - INR(poc)/INR(lab)) was lower in the bridging group than in the control group (4+/-7% vs 10+/-14%; p=0,02). Finally, clinically relevant agreement between POC and laboratory was of 90% in the bridging group and 92.1% in the control group (p=0.6).


CONCLUSIONS
With the POC used (INRatio), in patients receiving LMWH when the POC gives a result, it is as accurate as in patients not receiving a LMWH.
Meurin
Ph
P
Les Grands Prés - Centre de réadaptation Cardiaque de la Brie 27 rue Sainte Christine 77174 Villeneuve-Saint-Denis, France. philippe.meurin@hotmail.com
Tabet
J Y
JY
Monchi
M
M
Weber
H
H
Fabre
C
C
Gibier
B
B
Renaud
N
N
Driss
A Ben
AB
D000284:Administration, Oral; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D000933:Antifibrinolytic Agents / Q000037:antagonists & inhibitors / Q000627:therapeutic use; D016022:Case-Control Studies; D016903:Drug Monitoring / Q000295:instrumentation*; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D007297:Inpatients; D019934:International Normalized Ratio / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D019990:Perioperative Care / Q000295:instrumentation*; D019095:Point-of-Care Systems; D011446:Prospective Studies; D014812:Vitamin K / Q000037:antagonists & inhibitors / Q000627:therapeutic use
D000925:Anticoagulants; D000933:Antifibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight; D014812:Vitamin K