INR Testing at the Point of Dental Care Delivery

Objectives: INR testing helps determine whether patients taking warfarin can safely undergo dental treatment. The purpose of this pilot study was twofold: to compare the reliability of INR values obtained at chairside using a portable INR device with values obtained from standardized laboratory testing; and to assess patient satisfaction with point of care INR testing.

Methods: Adult patients (n=48) treated in a university dental clinic who had a cardiac diagnosis and were scheduled for a dental procedure requiring a 24 hour laboratory INR participated in the study. Subjects reported taking warfarin for at least 6 months. A drop of blood was taken from each subject’s finger using a portable hand-held device (CoaguChek® XS System, Roche Diagnostics) prior to initiating dental treatment. Both INR values were recorded. Subjects then completed a brief 10 item validated survey scored with a 4 point Likert scale to gain feedback about their experience with chair side INR testing. Data were analyzed using SPSS 23 (IBM Corp. Armonk, NY).
Results: Mean lab INR was 2.47, and mean chairside INR was 2.54. Intraclass correlation between values was 0.866, 95% CI: 0.773 to 0.933, (P < 0.001). Mean difference in values was 0.075±0.405, P = 0.205. For 41.7% of patients, the lab test exceeded the chairside test; for 45.8%, the chairside test exceeded the lab test. All (n=48, 100%) subjects agreed (A) or strongly agreed (SA) that they preferred the finger prick method for obtaining the blood draw, and reported confidence in the chair side INR result and the dentist’s ability to interpret the result. All (n=48, 100%) A or SA that having immediate feedback from their chair side INR test encouraged discussion about disease management and facilitated timely dental treatment.
Conclusions: Point of care INR testing provided reliable data and was preferred by dental patients taking warfarin.