Dosing guidelines, not protocols, for managing warfarin therapy

Assessment of warfarin algorithms for hospitalized adults: searching for a safe dosing strategy

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 overshoot 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 significant difference 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 significantly 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.

The Marginal Costs of Adverse Drug Events Associated With Exposures to Anticoagulants and Hypoglycemic Agents During Hospitalization

BACKGROUND

Anticoagulants and hypoglycemic agents are 2 of the most challenging drug classes for medical management in the hospital resulting in many adverse drug events (ADEs).

OBJECTIVE

Estimating the marginal cost (MC) of ADEs associated with anticoagulants and hypoglycemic agents for adults in 5 patient groups during their hospital stay and the total annual ADE costs for all patients exposed to these drugs during their stay.

RESEARCH DESIGN AND SUBJECT

Data are from 2010 to 2013 Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases and Medicare Patient Safety Monitoring System (MPSMS). Deidentified patients were linked using probabilistic matching in the same hospital and year for 5 patient groups. ADE information was obtained from the MPSMS using retrospective structured record review. Costs were derived using HCUP cost-to-charge ratios. MC estimates were made using Extended Estimating Equations controlling for patient characteristics, comorbidities, hospital procedures, and hospital characteristics. MC estimates were applied to the 2013 HCUP National Inpatient Sample to estimate annual ADE costs.

RESULTS

Adjusted MC estimates were smaller than unadjusted measures with most groups showing estimates that were at least 50% less. Adjusted anticoagulant ADE costs added >45% and Hypoglycemic ADE costs added >20% to inpatient costs. The 2013 hospital cost estimates for ADEs associated with anticoagulants and hypoglycemic agents were >$2.5 billion for each drug class.

CONCLUSIONS

This study demonstrates the importance of accounting for confounders in the estimation of ADEs, and the importance of separate estimates of ADE costs by drug class.

Dabigatran versus warfarin after bioprosthesis valve replacement for the management of atrial fibrillation postoperatively: protocol

Background

Warfarin and similar vitamin K antagonists have been the standard therapy for patients with mechanical or biological valve prosthesis and atrial fibrillation (AF). Even with the appropriate use of therapy, some studies have reported that there is a high incidence of thromboembolic events, 1%-4% per year. Furthermore, a bleeding risk is significant, ranging from 2% to 9% per year, according to some studies.

Objective

The objective of our study was to examine the effect of dabigatran etexilate versus dose-adjusted warfarin for the prevention of intracardiac thrombus in persistent or permanent AF at least 3 months after aortic and/or mitral bioprosthesis replacement.

Methods

Dabigatran versus warfarin after bioprosthesis valve replacement for the management of atrial fibrillation postoperatively (DAWA) is a phase 2, prospective, open label, randomized exploratory pilot study. The main variable to be observed in this study is intracardiac thrombus. From August 2013 to April 2015, 100 patients, at least 3 months after aortic and/or mitral bioprosthesis replacement and permanent or persistent AF postoperatively, who match eligibility criteria will be selected from Ana Nery Hospital in Salvador-Bahia with a follow-up of three months. Patients were randomly assigned in a 1:1 ratio to receive either dabigatran etexilate or warfarin.

Results

Although the present study has no statistic power to proof non-inferiority, it is expected that the dabigatran etexilate group will be protected as well as the warfarin group from intracardiac thrombus, without increasing the bleeding rates, since we are using safer doses (110 mg bid). The lack of necessity of monitoring INR is also another factor that contributes to a better adherence to the new drug and it can make all the difference in the manner of doing anticoagulation for patients with similar clinical characteristics.

Conclusions

The study is in the recruitment phase. It is possible that dabigatran etexilate is as effective as warfarin in preventing the emergence of intracardiac thrombus in patients with AF and mitral and/or aortic bioprosthesis.

Trial Registration

Clinicaltrials.gov NCT01868243; http://clinicaltrials.gov/ct2/show/NCT01868243 (Archived by WebCite at http://www.webcitation/6OABiuasd).

Interventions to improve anticoagulation with warfarin

INTRODUCTION

This study aimed to investigate potential drug-drug interactions (pDDIs) with warfarin to minimize them, assess the acceptability of pharmaceutical interventions by the medical team and the impact on the international normalized ratio (INR) results.

METHODS

This pertains to a prospective study involving inpatients who started warfarin therapy in a university hospital located in southern Brazil. The pDDIs with warfarin were identified using the interaction screening program Drug-Reax, Micromedex Healthcare Series 1.0.

RESULTS

Two hundred and two inpatients were monitored. The mean of 10 different drugs was prescribed for each patient (SD = 3.6). At least 1 major or moderate pDDIs with warfarin per patient was observed, the mean was 3.6 (SD = 1.6). The most common pDDIs with warfarin involved in the increase of anticoagulation effect were enoxaparin (32.2%), simvastatin (27.6%), omeprazole (22.5%), and tramadol (21.5%). For 32 patients (15.8%), interventions were rejected, and they had a higher risk (relative risk= 2.17; 95% confidence interval 1.10-4.27) for abnormal test results (INR > 5). Multivariate analysis showed that age, length of hospital stay, exposure to ≥4 major or moderate pDDIs, and refusal of pharmacist recommendations contribute significantly to the patient's INR result >5. Consequently, the risk of bleeding is increased.

CONCLUSIONS

Major and moderate pDDIs with warfarin are very common in inpatients and are associated with INR results outside the therapeutic range. Pharmaceutical interventions concerning the management of interactions by providing information to physicians can improve the patient safety.

Challenges and benefits of an inpatient anticoagulation service: one hospital's experience

While outpatient anticoagulation services (AMS) have existed extensively for a number of years, inpatient AMS have only recently begun to be implemented on a widespread basis. This is in direct response to anticoagulation regulations set forth by entities such as the Joint Commission (TJC) and the Centers for Medicare and Medicaid services (CMS). Hospitals not complying with these regulations are at risk for either financial or accreditation punition. Inpatient AMS have reported positive impacts on patient outcomes in the literature, which gives hospitals an additional impetus to provide this type of service. Inpatient AMS pose many challenges, including identification of resources for development and implementation of the service, means to make changes to the service as it evolves and effectively tracking performance of the service. Using a well-planned, methodical approach for implementation has helped our institution capitalize on the numerous potential benefits of an inpatient AMS, including improved inpatient anticoagulation therapy, improved transitions of care and enhanced interdisciplinary practices.