Use of Anticoagulants Has Increased for Patients With Atrial Fibrillation, CKD

A study published in Open Heart found that use of direct oral anticoagulants (DOACs) had increased in patients with atrial fibrillation (AF) and all stages of chronic kidney disease (CKD) except for severe and end-stage CKD. Patients with AF were also found to have a gradual decline in renal function.

DOACs are recommended over warfarin for patients with AF to prevent strokes. However, these medicines come with a risk of excessive drug exposure and associated bleeding in patients with CKD. The aim of the study was to illustrate the treatment patterns of warfarin and DOACs in patients with AF and CKD and to evaluate the time in therapeutic range (TTR) among such patients taking warfarin.

The study population came from the Swedish national quality register for AF and oral anticoagulation, AuriculA, which is estimated to include about 50% of all patients with AF in Sweden. All patients living in the region of Uppsala who had a diagnosis of AF that was registered between January 1, 2013, and December 31, 2018, were included. Patients who were 17 years or younger or who had mechanical heart valves or mitral stenosis were excluded. All information on medical treatment with warfarin or DOAC and dosages was obtained from AuriculA.

There were 6567 patients included in the study with a median age of 77.2 years; 42.3% were women. Those whose CKD worsened over time tended to be older, more often male, and had more comorbidities.

From 2013 to 2018, use of warfarin in the study population decreased from 90.8% to 10.7%, whereas the proportion treated with DOACs increased from 9.2% to 89.3%. The same trend was found in patients with normal (glomerular filtration rate [eGFR] ≥ 90), mildly decreased (eGFR 60-89), and moderately decreased (eGFR 30-59) renal function.

However, there was a slower uptake of DOACs among patients with severely decreased (eGFR 15-29) renal function, and patients with end-stage CKD (eGFR < 15) were more likely to receive warfarin than a DOAC.

During a median follow-up time of 1.7 years, the median TTR was 77.1% in patients using warfarin; poorer TTR was found in patients with worsening stages of CKD. Over half of patients with normal renal function (58.1%) had a good TTR (defined as ≥ 70%), and even more patients with mild (72.4%) and moderately (68.5%) decreased renal function had a good TTR. Less than half of patients with severe (49.6%) or end-stage (42.9%) CKD had a good TTR, however.

Patients with serial measurements of eGFR had a median (IQR) annual decline in eGFR of –1.1 (–4.4 to 1.3) mL/min/1.73 m². There were 1415 patients (34.9%) who had a decline in eGFR of at least 20% compared with baseline.

There were some limitations to this study. This study only included patients from 1 region of Sweden with renal function data, which means it may not be applicable to the entire nation. Comorbidities and medications at baseline were the only factors accounted for when assessing associations among renal function, TTR, and decline in renal function over time, which means residual confounders may be present.

The researchers concluded that DOAC usage has increased over the past few years for patients with AF and normal and moderate CKD. However, this increase in DOAC usage was not seen among patients with severe and end-stage CKD.

“A close follow-up of patients at risk might be crucial to timely adjust DOAC treatment in terms of drug of choice and correct dosage,” the authors wrote.

Reference

Batra G, Modica A, Renlund H, Larsson A, Christersson C, Held C. Oral anticoagulants, time in therapeutic range and renal function over time in real-life patients with atrial fibrillation and chronic kidney disease. Open Heart. 2022;9:e002043. doi:10.1136/openhrt-2022-002043