PURPOSE: Medication adherence is crucial for achieving clinical goals. Medication adherence drivers and behaviors were explored across multiple conditions, countries, and medication schedules/modalities to develop a conceptual model of medication adherence, which could later be used to support development of a patient-reported outcome (PRO) measure of adherence. PATIENTS AND METHODS: Targeted review of qualitative literature identified important medication adherence concepts. Fifty-seven qualitative concept elicitation interviews were conducted (USA n=21, Spain n=18, Germany n=18). Participants were prescribed medication for: hypertension (n=9), asthma (n=8), multiple myeloma (n=8), psoriasis (n=8), diabetes (n=7), depression (n=7), multiple sclerosis (n=7), and/or schizophrenia (n=6). Thematic analysis of verbatim transcripts was performed. Expert clinicians (n=3) provided input throughout. RESULTS: Nine qualitative articles were selected for review from 2168 screened abstracts. Forty-two medication adherence concepts were reported and grouped into 10 domains. Eight forms of medication adherence were reported during interviews, along with 27 drivers of non-adherence, all of which were incorporated into a conceptual model. Participants reported skipping medication doses (n=36/57; 63.2%) or taking medication later in the day than prescribed (n=29/57; 50.9%). Common drivers of non-adherence included forgetfulness (n=35/57; 61.4%), being out of the usual routine (n=31/57; 54.4%) and being busy (n=22/57; 38.6%). US participants were more likely to report non-adherence due to low perceived efficacy (n=6/21, 28.6%) and cost (n=5/21, 23.8%) than German (n=1/18, 5.6%; n=0/18, 0.0%) or Spanish (n=2/18, 11.1%; n=1/18, 5.6%) participants. CONCLUSION: Findings highlight the diverse forms and drivers of medication non-adherence, informing the development of a comprehensive conceptual model of medication adherence. The conceptual model builds on and advances previous models of medication adherence and can be used by healthcare professionals to understand and interpret barriers to medication adherence and how best to support patients in taking their medication as intended.
Medication adherence is the extent to which a patient takes their medication as prescribed. This paper describes a literature review and concept elicitation interviews to identify forms and drivers of medication adherence across a diverse sample of participants. Forms of non-adherence identified included: deviating from the prescription, skipping a dose, taking a different amount, and taking medication at a different time. Behaviours and drivers can vary by condition, treatment modality, and dosing schedule.This research highlights the variation in the prevalence of medication non-adherence, and the different forms and drivers of non-adherence, based on individuals’ demographic and clinical characteristics. The conceptual model developed advances previous models of medication adherence and may support healthcare professionals in the management of patients and how they can be supported to take medication as intended. The research ultimately informed the development of the Adelphi Adherence Questionnaire (ADAQ(©)), a novel generic patient-reported outcome measure.