Warfarin management in the Era of Direct- Acting Oral anticoagulants (DOACs): An Observational Study in Patients Admitted to the Internal Medicine Ward

Amichai Perlman, Medicine, Hadassah Hospital, Mt Scopus, Jerusalem, Israel (amichp@gmail.com)
Sarit Hochberg- Klein, Medicine, Hadassah Hospital, Mt Scopus, Jerusalem, Israel
Lotan Choshen Cohen, Medicine, Hadassah Hospital, Mt Scopus, Jerusalem, Israel
Mordechai Muszkat, Medicine, Hadassah Hospital, Mt Scopus, Jerusalem, Israel

Background:  In the last decade DOACs have emerged as a safe and effective alternative to warfarin in the treatment of AF and VTE, and have eliminated the need for INR monitoring and warfarin dosage adjustment in these patients. Thus, many physicians may now be less adept in the art of warfarin management. However, for patients with mechanical heart valve, warfarin is still the only therapeutic option.

Aim: To describe the characteristics of patients using warfarin compared to those using DOACs, and evaluate the quality of warfarin management using the proportion of time spent in the target INR range (%TTR) prior to hospitalization.

Methods: Consecutive patients treated with anticoagulants admitted to the Department of Medicine at the Hadassah University Hospital, Mt. Scopus were included. Patient's TTR (time in therapeutic range) was calculated for the six-month prior admission, using the Rosendaal method.

Results: 146 patients were included. Compared to those using DOACs, patients using warfarin were more likely to have indications for anticoagulation other than AF (VTE - 36% vs 4%, p<0.001; Mechanical valve - 30% vs 0%, p<0.001). Warfarin users also had a higher mean serum creatinine level (132 µmol/L vs 181 µmol/L, p=0.046), and were more likely to suffer from severe renal failure (37% vs 17%, p=0.015). Median INR on admission was 2.59 (IQR 1.86-3.64). Among patients treated with warfarin for mechanical heart valves, INR on admission was statistically significant higher as compared to patients with AF and VTE (median 3.53, IQR 2.8-5.1; median 2.59 IQR 1.84-3.16, p=0.0085)

Patients with warfarin had median number of INR tests 11.5 (IQR 11.5-17.75), thus facilitating TTR evaluation. TTR in the 6 months prior to admission was lower than 30% in 41.5% of the patients studied. Among patients treated with warfarin for mechanical heart valves percent of deviation above the therapeutic range was larger as compared to patients with AF and VTE.

Conclusions: The level of INR control in the population studied was low compared to the data reported in the literature, including in patients with mechanical heart valves.

As TTR determines clinical outcomes with warfarin, and as DOACs are not a viable alternative for many patients, most notably patients with mechanical valves, these findings are reason for concern. Achieving safe and effective anticoagulation with warfarin remains a clinically important and relevant challenge in the era of DOACs.

 

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Abstract Reference & Short Personal Biography of Presenting Author

Prof Mordechai Muszkat is the Head of the Department of Medicine at the Hadassah University Hospital, Mt Scopus campus, Jerusalem.

Prof Muszkat is an Internist and Clinical Pharmacologist. He was trained in Clinical Pharmacology at the Hadassah University Hospital and Vanderbilt University Nashville, TN, USA.

His Main fields of interest include: DOACs safety in hospitalized patients, DOACs- drug interactions, prevention of medications errors, Beta1 adrenergic receptors pharmacogenomics