Trends in antithrombotic drug use and adherence to non-vitamin K oral anticoagulants in the Netherlands

Abstract

Background Non-vitamin K oral anticoagulants (NOACs) became available in the Netherlands in 2008, providing another antithrombotic treatment besides vitamin K antagonists (VKAs) and antiplatelet agents (APAs). Objective To describe the patterns of antithrombotic drug use between 2008 and 2013 by examination of dispensing data form community pharmacies in the Netherlands; to determine the concomitant use of NOACs with VKAs and APAs and switching between the drug classes; and to compare adherence to NOACs with adherence to APAs. Setting An observational retrospective study was conducted using routinely collected dispensing data from Dutch community pharmacies. Methods For each calendar year, the numbers of NOAC, VKA, and APA users were calculated. Adherence was determined for NOACs and APAs by the percentage of days covered by medication (PDC). Information on the prescribed daily dose of VKAs was unavailable. Main outcome measures Comparison of age, sex, and co-medications of users of the three drug classes; concomitant use of different antithrombotic drug classes and switching between these in each year; and mean PDC and percentages of all users with a PDC above 80 %. Results NOAC use increased during the study period to 29,687 users in 2013. In that year there were 484,024 VKA users and 1313,032 APA users. Compared with users of VKAs, NOAC users were slightly younger and more frequently used antiarrhythmic drugs and beta blockers as co-medications. Substantial numbers of patients were dispensed potentially harmful combinations in 2013: 820 subjects were dispensed NOACs together with VKAs, and 684 subjects were dispensed NOACs, VKAs, and APAs concomitantly. Mean adherence to NOACs was 84.2 % compared with 87.3 % to APA. One in four NOAC users had a PDC lower than 80 % compared with one in five APA users. Conclusion Our findings show increasing use of NOACs by outpatients. The number of patients taking potentially harmful combinations of antithrombotic drugs was substantial. Adherence to NOACs in daily practice may be suboptimal to prevent thrombotic events.

Frequency and Determinants of Adherence to Oral Anticoagulants in Stroke Patients with Atrial Fibrillation in Clinical Practice

“…(iii) Prior stroke, as a dramatic life event, may in itself be an adherence-enhancing factor, as previously suggested [13] . This may explain the lower adherence rates in observational studies in mixed populations [4,[9][10][11][12]16] compared to our study, which included only stroke patients.…”

“…This is surprising, as adherence in RCTs is criticized as not reflecting real-world situations [1] . In contrast, the vast majority of observational studies have reported lower ≥ 80% adherence rates to NOACs, ranging from 57 to 88% [4,[9][10][11][12] . In turn, there are a few observational studies that reported similarly high rates [8,13] ; the rate of ≥ 80% and full adherence to NOACs was >70 and >90% respectively in one of them [8] .…”

“…Due to patient selection and intensive follow-up in RCTs, these high rates may not reflect clinical practice [1] . Observational studies using prescription claims data [4,[8][9][10] and smaller cohort studies [11][12][13][14][15][16][17] have sought to provide 'real-world' data on adherence to OACs. They yielded adherence rates ranging from as low as 57% to as high as 96%.…”

Drug Adherence in Patients With Nonvalvular Atrial Fibrillation Taking Non-Vitamin K Antagonist Oral Anticoagulants in Turkey: NOAC-TR

“…In real-world data, medication adherence level evaluated with proportion of days covered (PDC) method was reported to be in a wide range between 47.7% and 95%. [18][19][20] This discrepancy is thought to result from the difference and number of the population in which medication adherence is assessed, follow-up duration, divergence of indications for NOAC, and diversity of the methods used to evaluate adherence. The studies with self-report method had also controversial results.…”

Evaluation of drug adherence in patients with non-valvular atrial fibrillation according to geographic regions of Turkey: an analysis from NOAC-TR study

“…It is a striking finding that data from randomized studies do not align with the real-world data. The studies reflecting the real-world data report a wide range of drug adherence from 47.7% to 95% [19][20][21][22]. The real-world studies have reported different rates of drug adherence due to differences in the study population and study samples, duration of follow-up, different indications for the use of NOAC therapy, and differences in methods to evaluate drug adherence.…”