Supporting Adherence to Medicines for Long-Term Conditions: A Perceptions and Practicalities Approach Based on an Extended Common-Sense Model

Pharmaceutical prescriptions are core to the treatment of most chronic illnesses, yet only half are taken as prescribed. Despite the high costs of nonadherence to individuals and society, effective adherence-promoting interventions are elusive. This is partly due to the sheer complicity of the issue. There are numerous determinants of adherence, both internal to the patient (intrinsic) and external (extrinsic, e.g., environmental or health system-related factors). Also, the relative importance of these determinants varies between individuals and even within the same individual over time and across treatments, presenting a challenge for intervention design. One complication is that interventions can target several levels: (1) patient (e.g., enhancing motivation and/or ability to adhere), (2) patient-provider interactions (e.g., improving communication and the prescribing process), and (3) the healthcare system (e.g., providing the opportunity to access medication through regulatory approval and co-payment schemes). Here, we focus on level 1: the patient. Although environmental factors are important, the effect of an intervention designed to change them will depend on how they impact on the individual. We describe the Perceptions and Practicalities Approach (PAPA), a pragmatic framework positing that adherence/nonadherence is essentially a produce of individual motivation and ability. Adherence interventions, targeted at any level, will therefore be more effective if tailored to address the perceptions and practicalities underpinning individual motivation and ability. We discuss how PAPA can be operationalized, including the application of theoretical models of illness and treatment representation (Necessity-Concerns Framework and Leventhal's Common-Sense Model) to address salient adherence-related perceptions.