Abstract
To identify barriers to medication adherence in patients prescribed medicines for the prevention of cardiovascular disease and map these to the Theoretical Domains Framework (TDF), to produce a conceptual framework for developing a questionnaire-based medication adherence tool.
A scoping review of barriers to medication adherence in long-term conditions was conducted to generate an initial pool of barriers. After preliminary mapping to the TDF, these barriers were presented to two focus groups of patients prescribed medicines for the prevention of cardiovascular disease (n = 14) to stimulate discussion. The group discussions enabled the patients’ interpretations of the adherence barriers to be determined, provided validity from the patient perspective and identified additional barriers unrepresented in the scoping review.
The preliminary pool of adherence barriers was identified from 47 studies across a range of long-term conditions. The majority of TDF domains were represented by these literature-identified barriers except ‘social/professional role and identity’ and ‘behavioural regulation’. Barrier mapping was largely endorsed by focus group participants, who also contributed additional barriers, including those relating to not having a ‘system’ in place for managing their medicines and the negative emotions evoked by medicine taking.
The TDF enabled full exploration of adherence barriers including those relating to emotions which have received limited attention in the literature. This work has provided a conceptual framework for developing a questionnaire to identify an individual’s adherence barriers which may then be coupled with appropriate behaviour change techniques to deliver a theory-based intervention tailored for individual need.
Introduction
An estimated 30 to 50% of patients with long-term conditions (LTCs) are non-adherent to their prescribed medicines.[1] A large-scale meta-analysis estimated adherence to medicines for the prevention of cardiovascular disease (CVD) to be 57% (95% CI 50–64%).[2] These medicines are prescribed for a range of LTCs including hypertension, dyslipidaemia and angina and are amongst the most commonly prescribed medicines in the UK.[2]
Medication adherence is a complex health behaviour, influenced by a plethora of factors.[3] Non-adherence can diminish treatment effects leading to increased morbidity and mortality[4] plus wasted healthcare resources.[3] Evidence suggests that a greater understanding of the barriers to adherence is needed to improve the effectiveness of adherence interventions.[5] A plethora of theoretical models has been developed to explain the complexities of medication adherence, including those focused on the balance between patient perceived necessity and concerns about medicines[6] and those focused on the importance of practitioner consultation style.[7]Though these models highlight important considerations for medication adherence research, the most recent Cochrane review highlights that meaningful progress with adherence research is still sub-optimal.[5] Theoretical models such as social cognitive theory, the health belief model and self-regulation model have been applied to medication adherence interventions.[8] However, a systematic review of theory-based interventions to improve medication adherence identified that none have successfully guided the development of an effective adherence intervention applicable to all long-term medications.[8]
Psychology-based behaviour change techniques, such as motivational interviewing, show promise as effective adherence interventions.[9] However, core training of the existing healthcare workforce is not designed to equip practitioners in selecting the most appropriate behaviour change techniques (BCT) for improving adherence, according to identified individual adherence barriers.[10–12]
Developing an adherence tool which identifies a patient’s barriers to adherence and guides the practitioner to work with the patient to select the most appropriate BCTs may enable the healthcare workforce to respond to the call for theory and evidence guided, individualised interventions,[13,14] which identify potential barriers to behaviour change.[5,8,15]
The Theoretical Domains Framework (TDF)[16,17] is a composite of health psychology theory which offers a structured approach for exploring the determinants of individual behaviour.[18] The domains of the TDF have been linked to evidence-based BCTs,[19,20] leading to successful use of the TDF to guide the intervention development for behaviour change.[21] The TDF may therefore be suitable for mapping adherence barriers and creating a conceptual framework.
Literature describing application of the TDF to medication adherence[22–25] represents notable advancements in the field. However, each study focusses on medication adherence in a specific disease rather than multiple LTCs. Most patients have multiple diseases for which they are prescribed multiple medicines; routine practice consultations such as medication reviews are therefore not focused on medication adherence in one specific disease state. Intervention implementation is supported by compatibility with routine practice;[26] thus, an adherence support tool applicable across a range of LTCs is a stronger candidate for effective implementation into routine practice.[27] Exploration of barriers to adherence in medicines prescribed for the prevention of CVD (which covers multiple LTCs) is therefore an intuitive opportunity to broaden TDF-based adherence research towards multiple LTCs, whilst minimising the confounding factors that could be introduced by considering all LTCs collectively.
The current article presents the developmental work which underpinned the Identification of Medication Adherence Barriers Questionnaire (IMAB-Q),[28] a TDF-based questionnaire to support practitioners in identifying non-adherent patient’s and elucidating their individual reasons for non-adherence. It comprises a scoping review of barriers to adherence in LTCs, the initial mapping of these barriers to the TDF and the qualitative exploration of these barriers in patients prescribed medicines for the prevention of CVD, in order to develop a conceptual framework to inform questionnaire development.
Existing literature syntheses ([29,30]) report quantitative findings from intervention studies and non-modifiable adherence determinants such as age, gender and socioeconomic status. Modifiable determinants of adherence, relating to psychosocial and environmental barriers are often overlooked. These reviews also consider non-adherence in all conditions, yet important differences in adherence determinants exist between acute and LTCs.[3] A broader evidence synthesis, narratively combining both quantitative and qualitative studies, may therefore provide a better foundation for exploring adherence barriers. Scoping reviews are an appropriate method to ‘map’ relevant literature and address broad topics where differing study designs are available.[31]
Correct mapping of adherence barriers to a theoretical framework requires deep understanding which cannot always be elucidated from the literature. Qualitative exploration to supplement a literature review can provide this depth of understanding,[32] enhance the utility of a scoping review and ensure meaningful mapping.