Vol.:(0123456789) 1 3 Journal of Thrombosis and Thrombolysis https://doi.org/10.1007/s11239-019-01902-0 Assessment of warfarin algorithms for hospitalized adults: searching for a safe dosing strategy Jessica L. Cohen 1,2  · Elena Thompson 2  · Liron Sinvani 1,2  · Andrzej Kozikowski 2,3  · Guang Qiu 1  · Renee Pekmezaris 2,3  · Alex C. Spyropoulos 2,4  · Jason J. Wang 2,3 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract This study evaluates three warfarin dosing algorithms (Kimmel, Dawson, High Dose ≥ 2.5 mg) for hospitalized older adults. A random selection of 250 patients with overshoots (INR ≥ 5 after 48 h of hospitalization) and 250 patients without overshoots were accessed from a database of 12,107 inpatients ≥ 65 years treated with chronic warfarin during hospitalization between January 1, 2014 and June 30, 2016. Algorithms were retrospectively applied to patients 2 days prior to overshoots in the over- shoot group, and 2 days prior to the maximum INR reached after 48 h of hospitalization in the non-overshoot group. Patients were categorized as overdosed or not overdosed and compared using descriptive statistics. Logistic regression modeling determined predictors for overshoots. There was no signifcant diference between overdose and non-overdose groups for progressing to overshoots by the Kimmel (51.0% vs. 48.7%, p = 0.67) or Dawson (48.5 vs. 57.9%, p = 0.19) algorithms. The Low Dose Group (≤ 2.5 mg) was signifcantly more likely to experience an overshoot than the High Dose Group (56.6% vs. 45.5%, p = 0.04). The Low Dose Group was more likely to be older (81.4% vs. 71.1%, p = 0.02), female (63.5% vs. 49.8%, p = 0.02), weigh less (71.3 ± 21.9 vs. 79 ± 23.1, p = 0.002), and be prescribed amiodarone (16.6% vs. 8.1%, p = 0.01). While none of the algorithms predicted overshoots in logistic regression modeling, weight over 70 kg and black race remained protective. The High Dose Algorithm revealed that providers appropriately gave lower doses to patients at highest risk for warfarin sensitivity. Future studies are needed to investigate tools for inpatient warfarin dosing in older adults. Keywords Warfarin · Inpatients · International normalized ratio · Dose algorithm Highlights • The purpose of this study was to evaluate whether over- dosing as defined by three separate algorithms (the Dawson algorithm, Kimmel algorithm, and High Dose Algorithm) 2 days prior to INR overshoots or maximums predicted INR overshoot occurrences and would prove to be of greater beneft in inpatient warfarin dosing than relying on provider-dependent gestalt alone. • Kimmel and Dawson algorithms do not appear to add value or improve safety in inpatient warfarin manage- ment for patients on chronic warfarin. • Findings suggest that while providers appropriately gave doses under 2.5 mg warfarin to the group of patients that would be at highest risk for warfarin sensitivity (i.e. older, female, low weight, on amiodarone), these patients were more likely to experience overshoots than the group who received higher doses. * Jessica L. Cohen jcohen11@northwell.edu 1 Division of Hospital Medicine, Department of Medicine, Northwell Health, 300 Community Drive, Manhasset, NY 11030, USA 2 Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Northwell Health, Manhasset, NY 11030, USA 3 Division of Health Services Research, Center for Heath Innovations and Outcomes Research, Department of Medicine, Northwell Health, Manhasset, NY 11030, USA 4 Department of Medicine, Anticoagulation and Clinical Thrombosis Services, Northwell Health System, Lenox Hill Hospital, New York, NY 10075, USA