Developing a Core Outcome Set for Evaluating Medication Adherence Interventions for Adults Prescribed Long-Term Medication in Primary Care

BackgroundApproximately half of people prescribed medications do not take them as prescribed. There is a significant unmet need regarding the barriers to medication adherence not being addressed in primary care. There is no agreement on which outcomes should be measured and reported in trials of medication adherence interventions.ObjectiveTo develop a core outcome set (COS) for trials of medication adherence interventions in primary care for adults prescribed medications for long-term health conditions.MethodsA list of potentially relevant outcomes from the literature was developed. Using a two-round Delphi survey of stakeholder groups representing patients and their carers; primary care staff; and academic researchers with an interest in medication adherence; each outcome was scored in terms of importance for determining the effectiveness of medication adherence interventions in primary care. This was followed by two consensus workshops, where importance, as well as feasibility and acceptability of measurement, were considered in order to finalise the COS.ResultsOne hundred and fifty people took part in Delphi Round 1 and 101 took part in Round 2. Eight people attended the workshops (four attendees per workshop). Seven outcomes were identified as most important, feasible and acceptable to collect in medication adherence trials: Health-related quality of life, number of doses taken, persistence with medicines, starting (initiating) a medicine, relevance of the medication adherence intervention for an individual, mortality, and adverse medicine events.ConclusionsThis COS represents the minimum outcomes that should be collected and reported in all medication adherence trials undertaken in primary care. When developing and finalizing the COS, feasibility and acceptability of collection of outcomes has been considered. In addition to the COS, medication adherence trials can choose to include outcomes to suit their specific context such as the health condition associated with their medication adherence intervention.