A new taxonomy for describing and defining adherence to medications

Abstract

Interest in patient adherence has increased in recent years, with a growing literature that shows the pervasiveness of poor adherence to appropriately prescribed medications. However, four decades of adherence research has not resulted in uniformity in the terminology used to describe deviations from prescribed therapies. The aim of this review was to propose a new taxonomy, in which adherence to medications is conceptualized, based on behavioural and pharmacological science, and which will support quantifiable parameters. A systematic literature review was performed using MEDLINE, EMBASE, CINAHL, the Cochrane Library and PsycINFO from database inception to 1 April 2009. The objective was to identify the different conceptual approaches to adherence research. Definitions were analyzed according to time and methodological perspectives. A taxonomic approach was subsequently derived, evaluated and discussed with international experts. More than 10 different terms describing medication-taking behaviour were identified through the literature review, often with differing meanings. The conceptual foundation for a new, transparent taxonomy relies on three elements, which make a clear distinction between processes that describe actions through established routines ('Adherence to medications' , 'Management of adherence') and the discipline that studies those processes ('Adherence-related sciences'). 'Adherence to medications' is the process by which patients take their medication as prescribed, further divided into three quantifiable phases: 'Initiation' , 'Implementation' and 'Discontinuation' . In response to the proliferation of ambiguous or unquantifiable terms in the literature on medication adherence, this research has resulted in a new conceptual foundation for a transparent taxonomy. The terms and definitions are focused on promoting consistency and quantification in terminology and methods to aid in the conduct, analysis and interpretation of scientific studies of medication adherence.

Multilevel factors are associated with immunosuppressant nonadherence in heart transplant recipients: The international BRIGHT study

“…Following the ABC taxonomy for medication adherence,3 this measures implementation phase immunosuppressant nonadherence via 4 items, querying taking adherence, drug holidays, timing adherence, and self‐initiated dose reductions. Patients scored their adherence over the past 4 weeks.…”

“…Based on the ABC taxonomy, medication adherence has 3 phases: initiation, implementation, and discontinuation, and is defined as “the extent to which a patient's actual dosing corresponds to the prescribed dosing regimen.”3 Nonadherence is linked to poor posttransplant outcomes including late acute rejection and graft loss 2, 4, 5…”

Digitizing Medicines for Remote Capture of Oral Medication Adherence Using Co‐encapsulation

“…Poor adherence may also account for the development of resistance to therapy in an individual 3, 4, 6. Medication nonadherence is highly prevalent, common to all therapeutic fields, and until recently lacked taxonomy for describing and defining adherence to medications 7. Approximately 50% of patients do not adhere to prescribed medications over time8 and the economic burden is estimated to result in a total direct and indirect cost of $290 billion annually in the US 9, 10…”

Important Design Features of Personal Health Records to Improve Medication Adherence for Patients with Long-Term Conditions: Protocol for a Systematic Literature Review (Preprint)

“…Medication adherence can be defined as "the extent to which a person's behaviour towards their medication intake, corresponds with agreed recommendations from a health care provider" [19,20]. Medication adherence is the preferred terminology, but some sources still use the word "compliance" which many consider dated as a more restrictive term and less patient centred [21].…”

“…Furthermore, some studies consider additional aspects of medication adherence such as persistence, compliance and concordance. Medication adherence and persistence are closely related and often persistence is incorporated in the notion of adherence [20,22]. Medication persistence can be defined as the extent to which patients adhere over time [21].…”