Choice of Renal Function Estimator Influences Adverse Outcomes with Dabigatran Etexilate in Patients with Atrial Fibrillation

Kidney function estimators for drug dose adjustment of direct oral anticoagulants in older adults with atrial fibrillation

Background

The Cockcroft-Gault equation (CrClC-G) is recommended for dose adjustment of direct oral anticoagulant drugs (DOACs) to kidney function. We aimed to assess whether defining DOAC dose appropriateness according to various kidney function estimators changed the associations between dose appropriateness and adverse events in older adults with atrial fibrillation (AF).

Methods

Participants of the Berlin Initiative Study with AF and treated with DOACs were included. We investigated CrClC-G and estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration and European Kidney Function Consortium equations based on creatinine and/or cystatin C. Marginal structural Cox models yielded confounder-adjusted hazard ratios for the risk of mortality, thromboembolism and bleeding associated with dose status.

Results

A total of 224 patients were included in the analysis (median age 87 years). Using CrClC-G, 154 (69%) had an appropriate dose of DOACs, 52 (23%) were underdosed and 18 (8%) were overdosed. During a 39-month median follow-up period, 109 (14.9/100 person-years) participants died, 25 (3.6/100 person-years) experienced thromboembolism and 60 (9.8/100 person-years) experienced bleeding. Dose status was not associated with mortality and thromboembolism, independent of the equation. Underdose status was associated with a lower risk of bleeding with all the equations compared with the appropriate dose group. In participants with discrepancies in dose status using CrClC-G and eGFR equations, the occurrence of endpoints did not differ between participants having an appropriate dose using CrClC-G or eGFR.

Conclusion

In older adults with AF, the association of DOAC dose status with adverse events did not differ when using CrClC-G or eGFR. Our results suggest that eGFR equations are not inferior to CrClC-G within this context.

Acute Stroke and Atrial Fibrillation: Risk of Incorrect NOAC Dosage When Estimating Renal Function From Plasma Creatinine Only

Background

Cardioembolic stroke (CS) due to atrial fibrillation (AF) bears a high risk of unfavorable outcome. Treatment with a non-vitamin K antagonist oral anticoagulant (NOAC) reduces this risk. NOAC dosage occurs on a thin line during the acute phase of the stroke unit when the patient is threatened by both recurrent CS and a hemorrhagic stroke. It is often adapted to renal function—usually glomerular filtration rate (GFR)—to prevent both under- and overdosing. This study investigates the hypothetical risk of incorrect NOAC dosage after acute stroke when relying on plasma creatinine alone in comparison to a more exact renal function assessment including urine collection.

Methods

In a cohort study on consecutive 481 patients treated in a stroke unit with acute stroke and AF, the GFR estimated from plasma creatinine (eGFR) was compared to concurrent creatinine clearance measurement (CrCl) from urine collection regarding the hypothetically derived NOAC dosage.

Results

The risk of incorrect dosage (mean, 95% confidence interval) was 6.9% (4.8–9.5), 26% (23–31), 38% (33–42), and 20% (16–23) for apixaban, dabigatran, edoxaban, and rivaroxaban, respectively. The overall risk for incorrect dosage of any NOAC was 23% (21–25). Thresholds for age and admission eGFR were optimized to achieve an overall risk below 5% by additional CrCl measurements in selected patients (apixaban <36 ml/min and any age, dabigatran <75 ml/min and >70 y, edoxaban >36 ml/min and >58 y, rivaroxaban <76 ml/min and >75 y, any NOAC <81 ml/min and >54 y). The resulting portion of patients requiring an additional CrCl measurement was 10, 60, 80, 55, and 65% for apixaban, dabigatran, edoxaban, rivaroxaban, and any NOAC, respectively.

Conclusions

There is a considerable risk of incorrect NOAC dosage in patients with acute CS treated in a stroke unit that can be lowered by targeted CrCl measurements in selected patients.

Dabigatran in patients with atrial fibrillation after COVID-19 hospitalization: an update of the ANIBAL protocol

COVID-19 increases the risk of atrial fibrillation (AF) and thrombotic complications, particularly in severe cases, leading to higher mortality rates. Anticoagulation is the cornerstone to reduce thromboembolic risk in patients with AF. Considering the risk of hepatotoxicity in patients with severe COVID-19 as well as the risk of drug-drug interactions, drug-induced hepatotoxicity and bleeding, the ANIBAL protocol was developed to facilitate the anticoagulation approach at discharge after COVID-19 hospitalization. However, since the publication of the original algorithm, relevant changes have occurred. First, treatment of COVID-19 pneumonia has been modified with the use of dexamethasone or remdesivir during the first week in patients that require oxygen therapy, and of dexamethasone and/or tocilizumab or baricitinib during the second week in patients that necessitate supplementary oxygen or with a high inflammation state, respectively. On the other hand, metabolic syndrome is common in patients with AF as well as metabolic-associated fatty liver disease, and this could negatively impact the prognosis of patients with COVID-19, including high transaminase levels in patients treated with immunomodulators. The EHRA guidelines update also introduce some interesting changes in drug-drug interaction patterns with the reduction of the level of the interaction with dexamethasone, which is of paramount importance in this clinical context. Considering the new information, the protocol, named ANIBAL II, has been updated. In this new protocol, the anticoagulant of choice in patients with AF after COVID-19 hospitalization is provided according to three scenarios: with/without dexamethasone treatment at discharge and normal hepatic function, transaminases ≤2 times the upper limit of normal, or transaminases >2 times the upper limit of normal.

Impact of different renal function equations on direct oral anticoagulant concentrations

The purpose of this study is to investigate the correlation between glomerular filtration rate (GFR) estimated by different renal function equations and non-vitamin K antagonist oral anticoagulant concentration. Atrial fibrillation patients who aged ≥ 20 years and used dabigatran, rivaroxaban, or apixaban for thromboembolism prevention were enrolled to collect blood samples and measure drug concentrations using ultra-high-performance liquid chromatography with tandem mass spectrometry. The GFR was estimated using the Cockroft–Gault formula (abbreviated as creatinine clearance, CrCL), Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI) featuring both creatinine and cystatin C, and the Modification of Diet in Renal Disease Study equation (MDRD). Multivariate regression was used to investigate the associations of different renal function estimates with drug concentrations. A total of 511 participants were enrolled, including 146 dabigatran users, 164 rivaroxaban users and 201 apixaban users. Compared to clinical trials, 35.4% of dabigatran, 4.9% of rivaroxaban, and 5.5% of apixaban concentrations were higher than the expected range (p < 0.001). CKD-EPI and MDRD estimates classified fewer patients as having GFR < 50 mL/min than CrCL in all 3 groups. Both CrCL and CKD-EPI were associated with higher-than-expected ranges of dabigatran or rivaroxaban concentrations. Nevertheless, none of the renal function equations was associated with higher-than-expected apixaban concentrations. For participants aged ≥ 75 years, CKD-EPI may be associated with higher-than-expected trough concentration of dabigatran. In conclusion, CrCL and CKD-EPI both can be used to identify patients with high trough concentrations of dabigatran or rivaroxaban. Among elderly patients who used dabigatran, CKD-EPI may be associated with increased drug concentration.

Clearance Confusion: An Exploratory Analysis of Inpatient Dosing Discordances Between Renal Estimating Equations

Background:

Numerous equations exist for estimating renal clearance for drug dosing, and discordance rates may be as high as 40% in certain populations. However, the populations and types of equations used in these studies may not be generalizable to broader pharmacy practice.

Objectives:

To determine the dosing discordance rate between Cockcroft-Gault (C-G), Chronic Kidney Disease Epidemiology (CKD-EPI), and Modification of Diet in Renal Disease (MDRD) equations in a community hospital population.

Methods:

This was a cross-sectional analysis of inpatients who had documented renal function assessment over a 6-month period. Renal estimation was calculated using 5 equations (MDRD, CKD-EPI, and 3 C-G variants). Differences between equations were assessed using mean bias, dosing discordance, and agreement (κ statistic). Patients with acute kidney injury and those requiring renal replacement therapy were excluded.

Results:

A total of 466 patients were eligible for inclusion. Dosing discordance was evident between C-G variants and both MDRD and CKD-EPI equations in greater than 20% of patients. Agreement was highest between MDRD and CKD-EPI (κ = 0.93) and lowest between MDRD and C-G calculated using ideal body weight (κ = 0.33). The majority of discordant instances led to higher dosing recommendations when using MDRD and CKD-EPI equations compared with C-G variants. Dosing discordance exceeded 18% between the different C-G variants, with the highest discordance (36%) observed between total body weight and ideal body weight variants.

Conclusion and Relevance:

Dosing discordance between renal estimating equations is widespread. Practitioners and institutions should be aware of these differences when dosing medications and implementing renal dosing policies.

Monitoring the use of dabigatran etexilate for stroke prevention: compliance with renal function guidelines

ABSTRACT INTRODUCTIONDabigatran etexilate has become widely used in New Zealand, but information relating to when renal function monitoring is being undertaken is lacking. AIMTo investigate if clinically appropriate renal function monitoring is being undertaken in New Zealand primary care for stroke prevention in non-valvular atrial fibrillation patients prescribed dabigatran etexilate. METHODSNew Zealand non-valvular atrial fibrillation patients’ prescription and primary care health data were extracted from national administrative databases for the period 1 July 2011 to 31 December 2015. The proportion of patients who had serum creatinine measurements at close proximity to treatment initiation and 12-months post initiation were assessed with 95% confidence intervals (CIs) and compared with Fisher’s exact test. Log-rank tests for univariate analysis (gender, age, ethnicity and deprivation) effects on serum creatinine testing at dabigatran etexilate treatment initiation and 12-months post initiation were performed. RESULTSOverall, 1,948 patients who had been dispensed dabigatran etexilate with available primary care health data were identified. A total of 1,752 (89.9% [CI: 88.5–91.2]) patients had a renal function test at dabigatran etexilate initiation. There were 929 (72.8% [CI: 70.2–75.2]) patients who received ≥1 year supply of dabigatran etexilate and of these 207 (22.3% [CI: 19.6.6–25.1]) had a serum creatinine test 1 year after initiation. Demographic univariate analysis yielded insignificant log-rank tests for association with having serum creatinine measurements, except for Pacific Peoples. DISCUSSIONThere appears to be sub-optimal adherence to renal function monitoring for non-valvular atrial fibrillation patients who receive more than 12-months’ treatment with dabigatran etexilate in New Zealand primary care.