Epistaxis associated with dabigatran in an elderly patient with reduced creatinine clearance

Appropriateness of Dabigatran and Rivaroxaban Prescribing for Hospital Inpatients

BACKGROUND

Recent approval of the new oral anticoagulants dabigatran and rivaroxaban has led to rapid changes in anticoagulant prescribing practices. Postmarketing reports have highlighted safety concerns with these agents, and their use outside of evidence-based recommendations was noted at the authors' centre.

OBJECTIVES

To determine the incidence of and risk factors associated with inappropriate prescribing of dabigatran and rivaroxaban.

METHODS

This retrospective cohort study investigated randomly selected dabigatran or rivaroxaban prescriptions for patients admitted to a tertiary teaching hospital between January 2010 and December 2012. Appropriateness of prescribing was determined from the documented indication, drug dosage, patient's renal function, and presence of drug interactions, if applicable.

RESULTS

Among a total of 321 medication orders reviewed, the incidence of inappropriate use was 31.2% (34/109) for dabigatran and 26.9% (57/212) for rivaroxaban. Of the 97 reasons for inappropriate use that were identified, the most common were prescribing for an unapproved indication (49/97 [50.5%]), concomitant prescribing of another anticoagulant (22/97 [22.7%]), and high prescribed dose (9/97 [9.3%]). The prescribing service was found to be an independent risk factor for inappropriate prescribing (p = 0.041). Corrections were made to 23.1% (21/91) of the incorrect regimens before hospital discharge. In a sensitivity analysis using calculated ideal body weight to estimate renal function, the overall incidence of inappropriate prescribing increased to 31.5% (101/321).

CONCLUSIONS

The proportion of patients with inappropriate prescribing of dabigatran or rivaroxaban in clinical practice was higher than expected. Educational interventions and pharmacy-led initiatives with a focus on appropriate indications, concomitant anticoagulant prescribing, and review of dosage regimens are recommended to improve patient safety.

Assessment of novel oral anticoagulant use within a community teaching hospital

Background: Novel oral anticoagulants (NOACs) are considered to be at least as effective and safe as warfarin with several advantages such as predictable pharmacokinetics, allowing for standardized dosing without monitoring, a lack of food interactions and fewer drug interactions; however, their misuse could potentially result in patient harm. Objective: To evaluate the appropriate use of the NOACs within a community teaching hospital. Setting: A community teaching hospital in the United States. Method: A retrospective chart review of patients that were prescribed dabigatran, rivaroxaban, or apixaban at our institution from October 2012 through November 2014 was conducted. Main outcome measure: The primary objective was to determine the percentage of patients that were appropriately prescribed NOACs. Secondary objectives were to determine the number of patients who were inappropriately transitioned from warfarin or parenteral anticoagulants to a NOAC or vice versa, the number of incidents when a NOAC was held or discontinued inappropriately before a procedure and the number of bleeding or thrombotic events while taking a NOAC. Results: Of the 113 patients receiving therapy with an NOAC, appropriate prescribing was observed in 79.7%. Dabigatran, rivaroxaban, and apixaban were appropriately prescribed in 73.8%, 88.3%, and 85.8% of patients respectively. Lack of renal dose-adjustment in patients with reduced renal function was the most common reason for inappropriate use (8.8%). Ten out of 38 patients (26%) were inappropriately transitioned from/to other anticoagulants. Two out of six patients underwent a procedure without holding NOACs as recommended prior to surgery. Of all patients receiving NOACs, a total of 3 bleeding incidents were observed, one with each NOAC. Conclusion: The NOACs were appropriately prescribed for the majority of patients within our institution. Future efforts however should focus on ensuring appropriate dose adjustments for renal impairment, procedures for transitioning between NOACs and parenteral anticoagulants, and adequate withholding times for NOACs prior to surgery in order to optimize the management of NOACs usage within our institution.

Estimated glomerular filtration rate leads to higher drug dose recommendations in the elderly compared with creatinine clearance

PURPOSE

The elderly are at risk for adverse drug events because of inappropriate dosing of renally eliminated medications. The purpose of this study was to evaluate differences in estimates of kidney function and recommended doses of select medications in the elderly using the Modification of Diet in Renal Disease (MDRD) or the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations compared with the Cockcroft-Gault (CG) equation.

METHODS

Patients 65 years of age and older were included in this retrospective, observational analysis. Kidney function was estimated by CG, MDRD and CKD-EPI equations for all patients and by age category (65-69, 70-79, 80-89 and 90-100 years). Differences in estimates and dosing of allopurinol, enoxaparin, gabapentin, piperacillin/tazobactam and sulfamethoxazole/trimethoprim using the MDRD and CKD-EPI compared with the CG were assessed.

RESULTS

In the 4160 patients (98% male, mean age 74 ± 7 years), the MDRD and CKD-EPI estimates were significantly higher than CG estimates for all patients and by age category (p < 0.001). Dosing discordance was predominantly because of a higher dose recommended by MDRD and CKD-EPI estimates compared with CG. Discordance was highest with gabapentin (27%), the medication with the greatest number of dosing stratifications by estimated kidney function, and increased by 66% from the youngest to the oldest age category.

CONCLUSIONS

Until newer equations are used uniformly to develop dosing nomograms, it is prudent to adopt a process for drug dosing in the elderly that is more conservative than eGFR based dosing, but that considers the potential for underestimating kidney function with the CG equation.

Comparison of estimated glomerular filtration rate equations for dosing new oral anticoagulants in patients with atrial fibrillation

INTRODUCTION AND OBJECTIVES

New oral anticoagulants require dosing adjustment according to renal function. We aimed to determine discordance in hypothetical recommended dosing of these drugs using different estimated glomerular filtration rate equations in patients with atrial fibrillation.

METHODS

Cross-sectional analysis of 910 patients with atrial fibrillation and an indication for oral anticoagulation. The glomerular filtration rate was estimated using the Cockcroft-Gault, Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration equations. For dabigatran, rivaroxaban, and apixaban we identified dose discordance when there was disagreement in the recommended dose based on different equations.

RESULTS

Among the overall population, relative to Cockcroft-Gault, discordance in dabigatran dosage was 11.4% for Modification of Diet in Renal Disease and 10% for Chronic Kidney Disease Epidemiology Collaboration, discordance in rivaroxaban dosage was 10% for Modification of Diet in Renal Disease and 8.5% for the Chronic Kidney Disease Epidemiology Collaboration. The lowest discordance was observed for apixaban: 1.4% for Modification of Diet in Renal Disease and 1.5% for the Chronic Kidney Disease Epidemiology Collaboration. In patients with Cockcroft-Gault<60mL/min or elderly patients, discordances in dabigatran and rivaroxaban dosages were higher, ranging from 13.2% to 30.4%. Discordance in apixaban dosage remained<5% in these patients.

CONCLUSIONS

Discordance in new oral anticoagulation dosages using different equations is frequent, especially among elderly patients with renal impairment. This discordance was higher in dabigatran and rivaroxaban dosages than in apixaban dosages. Further studies are needed to clarify the clinical importance of these discordances and the optimal anticoagulant dosages depending on the use of different equations to estimate renal function.

Concerns about the use of new oral anticoagulants for stroke prevention in elderly patients with atrial fibrillation

The prevalence of atrial fibrillation (AF) and the embolic risk increase with age. Elderly AF patients are undertreated with vitamin K antagonists (VKA). The new oral anticoagulants (NOAC) dabigatran, rivaroxaban and apixaban have been shown to be non-inferior to VKA for stroke prevention in AF. We summarize the knowledge about primary and secondary stroke prevention by NOAC in AF patients >75 years of age. A literature search was carried out using the terms 'dabigatran', 'rivaroxaban', 'apixaban', 'elderly', 'octogenarians', 'atrial fibrillation' and 'anticoagulation' from 1998 to 2013. Randomized clinical trials, longitudinal studies, case series and case reports were included. Whereas studies investigating the use of VKA for stroke prevention in the 1990s were carried out by industry-independent institutions, all NOAC-investigating trials were sponsored by the manufacturers of the respective drugs. Frail elderly people were not represented in NOAC-investigating trials because of various exclusion criteria, and only one-third of patients were aged >75 years. A subgroup analysis from the dabigatran-investigating trial indicated that elderly patients might have a higher risk for extracranial bleeding complications with NOAC than with VKA. Further concerns about the use of NOAC in the elderly are the high prevalence of renal insufficiency in AF patients >75 years of age, the largely unknown risk of drug-drug and drug-food interactions, the lack of easily available laboratory monitoring tests of anticoagulant activity and the lack of an antidote. There is a need for independent studies comparing the efficacy and risk of side effects of NOAC with that of VKA in elderly AF patients.

Life-threatening epistaxis and red blood cell polyagglutination under dabigatran

Dabigatran is an oral thrombin inhibitor which has been approved for prevention of stroke or embolism in atrial fibrillation patients as an alternative to vitamin K antagonists. Dabigatran has been introduced into clinical practice, although issues like laboratory monitoring, its use in elderly patients, drug and food interactions, and an antidote have not been completely clarified. Severe epistaxis leading to haemorrhagic shock occurred in an 89-year-old woman with atrial fibrillation and moderate renal insufficiency after 10 months of dabigatran 110 mg/b.i.d. Correction of the anaemia with blood transfusions became difficult because it was impossible to assess her blood group due to polyagglutination. The indirect Coombs test was very highly +++ positive for IgG. Investigations about previous hospital admissions disclosed that in 2011, her blood group was 0 positive. The course was complicated by an erysipela of the right upper extremity, most probably induced by an infection through a venous catheter. An increase in the knowledge about potential side effects of dabigatran-concerning infections and polyagglutination is urgently needed.

Glomerular filtration rate equations overestimate creatinine clearance in older individuals enrolled in the Baltimore Longitudinal Study on Aging: impact on renal drug dosing

OBJECTIVES

To evaluate the performance of kidney function estimation equations and to determine the frequency of drug dose discordance in an older population.

DESIGN

Cross-sectional analysis of data from community-dwelling volunteers randomly selected from the Baltimore Longitudinal Study of Aging from January 1, 2005, to December 31, 2010.

SUBJECTS

A total of 269 men and women with a mean ± SD age of 81 ± 6 years, mean serum creatinine concentration (Scr ) of 1.1 ± 0.4 mg/dl, and mean 24-hour measured creatinine clearance (mClcr ) of 53 ± 13 ml/minute.

MEASUREMENTS AND MAIN RESULTS

Kidney function was estimated by using the following equations: Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). The performance of each equation was assessed by measuring bias and precision relative to mClcr . Dose calculation errors (discordance) were determined for 10 drugs requiring renal dosage adjustments to avoid toxicity when compared with the dosages approved by the Food and Drug Administration. The CG equation was the least biased estimate of mClcr . The MDRD and CKD-EPI equations were significantly positively biased compared with CG (mean ± SD 34 ± 20% and 22 ± 15%, respectively, p<0.001) and mClcr (29 ± 47% and 18 ± 40%, respectively, p<0.001). Rounding low Scr values (less than 1.0 mg/dl) up to an arbitrary value of 1.0 mg/dl resulted in CG values (44 ± 10 ml/minute) that were significantly lower than mClcr (56 ± 12 ml/minute, p<0.001) and CG (56 ± 15 ml/minute, p<0.001). The MDRD and CKD-EPI equations had median dose discordance rates of 28.6% and 22.9%, respectively.

CONCLUSION

The MDRD and CKD-EPI equations significantly overestimated creatinine clearance (mClcr and CG) in elderly individuals. This leads to dose calculation errors for many drugs, particularly in individuals with severe renal impairment. Thus equations estimating glomerular filtration rate should not be substituted in place of the CG equation in older adults for the purpose of renal dosage adjustments. In addition, the common practice of rounding or replacing low Scr values with an arbitrary value of 1.0 mg/dl for use in the CG equation should be avoided. Additional studies that evaluate alternative eGFR equations in the older populations that incorporate pharmacokinetic and pharmacodynamic outcomes measures are needed.