Validity of criteria used to evaluate fingerstick devices that assess international normalized ratio.
BACKGROUND
Investigators commonly rely on unvalidated, mainly arithmetic criteria to predict if point-of-care fingerstick devices that assess International Normalized Ratio (INR) lead to the same warfarin dosing decisions as a standard measure.


METHODS
Criteria that predict warfarin dosing agreement between 2 INR measurements were evaluated using clinicians' actual dosing decisions as the standard. Bayesian hierarchical modeling was used to rank the criteria by the proportion of correct dosing predictions and the magnitude of difference between actual and predicted dosing agreement.


RESULTS
The prediction criteria misclassified dosing agreement for between 19% and 38% of paired INR values (x: 27%). The magnitude of misclassification varied inconsistently throughout the INR scale.


CONCLUSIONS
The unvalidated criteria used to predict warfarin dosing agreement between 2 INR measurements are associated with large error. Warfarin dosing decisions should be measured directly in such assessments.
Shermock
Kenneth M
KM
Center for Pharmaceutical Outcomes and Policy, The Johns Hopkins Hospital, Baltimore, MD 21287-6180, and Department of Statistics, H. John Heinz III School of Public Policy and Management, Carnegie Mellon University, Pittsburgh, PA, USA. kshermo1@jhmi.edu
Connor
Jason T
JT
Smith
Nicole T
NT
Fink
Jodie M
JM
Bragg
Lee
L
D000925:Anticoagulants / Q000008:administration & dosage; D001499:Bayes Theorem; D006801:Humans; D019934:International Normalized Ratio; D009339:Needles; D019095:Point-of-Care Systems; D014859:Warfarin / Q000008:administration & dosage
D000925:Anticoagulants; D014859:Warfarin