From monitoring to vigilance about patient adherence to new oral anticoagulants

Ambivalence envelops the European Heart Rhythm Association Practical Guide1 on the use of new oral anticoagulants (NOACs). The Guide recites the NOACs' marketing claim of ‘predictable effect without need for monitoring’, but proclaims that ‘therapy prescription with the new class of drugs requires vigilance’. ‘Monitoring’, thus renamed ‘vigilance’, draws prescribers into an array of partial measures of NOAC actions of limited value, e.g. interpretations where, to be viable, knowledge of the time since the last-taken dose is required but where approximately one-third of patient-reported data on dose-timing are substantially erroneous, even in controlled clinical trials settings. The Guide aptly emphasizes the need to minimize patient non-adherence, which is well-documented as the single, biggest source of variance in the effects of patient-administered drugs of all classes.2 However, the Guide adopts a ‘make it up as you go’ approach to minimizing non-adherence, failing to recognize the progress, summarized in2 that has occurred in the field of adherence research since the advent of highly reliable, electronic methods for quantifying patient adherence. The Guide calls for patient education to achieve and maintain good adherence, but two other essentials for sustained good adherence, often neglected, are patients' motivation and their awareness of deviations from dosing instructions.3 The Guide recommends that once-daily dosing is preferable to twice-daily dosing. This recommendation may not be the better choice, because continuity of drug action is more often the result of twice-daily than of once-daily dosing.4 It is true that patients prescribed once-daily dosing regimens take a somewhat higher percentage of prescribed doses than those prescribed twice-daily dosing, but it is the temporal sequence of doses taken that determines whether continuity of drug action prevails: percentages of doses prescribed do not activate receptors or other targets of drug actions. The Guide suggests that NOAC prescribers should ask patients to bring their drug packages to follow-up visits, so that untaken doses can be counted by the prescriber. Two factors can nullify value in this recommendation: (i) the count of returned tablets is not interpretable without knowledge of when the packaged drug was dispensed by the pharmacist, whose necessary role in providing dispensing information is completely neglected by the Guide; (ii) the pill-count method of measuring adherence was thoroughly discredited 25 years ago.5 That conclusion has been repeatedly confirmed. The need is indeed urgent to enable patients using NOAC's to monitor and manage their medication adherence. Calendared blister packages designed to help patients track medication adherence have previously proven to make a meaningful impact. More comprehensive understanding comes from electronic measurements of patient adherence, which will, if history is a reliable guide, reveal a wide array of delayed or omitted doses, and some extra doses taken by patients prescribed NOACs.2 Increasing patient awareness of dosing errors, through blister package design and electronic compilation of dosing history data, provides patients with individualized dosing histories. Such data are gaining recognition as a strong force in minimizing dosing errors by ambulatory patients.2,3 Conflict of interest: B.V. and J.U. are employees of MWV Healthcare.