Daily INR Measurement Best for Hospitalized Patients on Warfarin

Increased odds of warfarin-associated adverse events in patients for whom INR not measured daily

hand of elderly patient

WEDNESDAY, Dec. 23, 2015 (HealthDay News) -- For hospitalized patients, international normalized ratio (INR) monitoring less frequently than daily is associated with increased odds of warfarin-associated adverse events, according to a study published online Dec. 14 in the Journal of Hospital Medicine.

Mark L. Metersky, M.D., from the University of Connecticut School of Medicine in Farmington, and colleagues examined the correlation between daily versus less frequent INR monitoring and overanticoagulation and warfarin-related adverse events in a retrospective cohort study. Data were included for 8,529 patients hospitalized from 2009 to 2013 for pneumonia, acute cardiac disease, or surgery who received warfarin for three or more days.

The researchers found that the INR was not measured on two or more days in 18.2 percent of patients. The propensity-adjusted odds ratios of having warfarin-associated adverse events were higher for these patients (odds ratio [OR], 1.48 for cardiac patients; 1.73 for surgical patients; no significant association for pneumonia patients). The propensity-adjusted odds ratios of having an INR ≥6.0 were higher for cardiac and pneumonia patients with one day or more without an INR measurement (ORs, 1.61 and 1.92, respectively). Overall, 12.5 percent of patients had a one-day increase in the INR of ≥0.9, which predicted a subsequent INR of ≥6.0 (positive likelihood ratio, 4.2).

"Daily INR measurement and recognition of a rapidly rising INR might decrease the frequency of warfarin-associated adverse events in hospitalized patients," the authors write.

One author disclosed financial ties to Medtronic.

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