Whole blood international normalization ratio measurements in children using near-patient monitors.
OBJECTIVE
To report a comparison of international normalization ratio (INR) measurements on four near-patient (point-of-care or bedside) whole blood INR monitors in children.


METHODS
The INR results from 19 ambulatory pediatric subjects (30 hospital visits) receiving warfarin sodium were analyzed on four near-patient monitors and compared with plasma INR measurements on the laboratory CA-1000 Analyze. The instruments evaluated were CoaguChek, Hemochron Jr. Signature, ProTime Microcoagulation System, and RapidpointCoag.


RESULTS
The INR measurements ranged from 1.05 to 5.25. Over the entire INR range, the near-patient instrument with the least bias relative to the CA-1000 was the RapidpointCoag (r(2) = 0.923). The correlations (r(2)) of the CoaguCheck, Hemochron Jr., and ProTime were 0.877, 0.834, and 0.885, respectively. Precision studies involved repeated analysis of one nonmedicated adult (mean CA-1000 INR = 0.908) and one adult receiving oral anticoagulation therapy (mean CA-1000 INR = 2.42). The coefficient of variation on the near-patient monitors for both adult volunteers ranged from 4.9% to 22.3%. Bilirubin levels up to 20 mg/dL did not interfere in any of the methods.


CONCLUSIONS
Near-patient testing whole blood INR monitors offer acceptably accurate and precise measurements. Values obtained on near-patient monitors may vary considerably from the reference method, and data obtained should serve as a supplement to, but not a replacement for, routine clinical laboratory measurements.
Nowatzke
William L
WL
Department of Pathology, Washington University School of Medicine, St. Louis, MO, USA.
Landt
Michael
M
Smith
Carl
C
Wilhite
Timothy
T
Canter
Charles
C
Luchtman-Jones
Lori
L
D000284:Administration, Oral; D000293:Adolescent; D000925:Anticoagulants / Q000627:therapeutic use; D001663:Bilirubin / Q000032:analysis; D001778:Blood Coagulation Disorders / Q000188:drug therapy*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006470:Hemorrhage / Q000517:prevention & control; D006801:Humans; D007223:Infant; D019934:International Normalized Ratio / Q000295:instrumentation*; D008297:Male; D019095:Point-of-Care Systems / Q000592:standards*; D011517:Prothrombin Time; D012015:Reference Standards; D013927:Thrombosis / Q000097:blood / Q000188:drug therapy; D014859:Warfarin / Q000627:therapeutic use
D000925:Anticoagulants; D014859:Warfarin; D001663:Bilirubin