TEOS framework improves operational definitions of medication adherence in research

When designing a medication adherence research and reporting on these components, measurement quality can be improved with the use of the Timelines-Events-Objectives-Sources (TEOS) framework, suggests a study.

“Its application to different medication regimens and clinical settings would advance our understanding of adherence to medications and the role of adherence management in improving population health,” the authors said.

In this study, a structured approach to formulate operational definitions of adherence was developed to support researchers in their measurement decisions. A team of adherence and research methodology experts examined the process of applying adherence definitions to various research settings, questions, and data sources using theoretical, methodological, and practical considerations. They reached consensus through an iterative review of discussion summaries and framework versions.

TEOS, a four-component framework, was established to guide the operationalization of adherence concepts. [Br J Clin Pharmacol 2021;87:2521-2533]

These components were as follows: (1) describe treatment as four simultaneous interdependent timelines (recommended and actual use, conditional on prescribing and dispensing); (2) locate four key events along these timelines to delimit the three ABC phases (first and last recommended use, first and last actual use); (3) revisit study objectives and design to adjust research questions and evaluate measurement validity and reliability needs; (4) and select data sources (eg, electronic monitoring, self-report, electronic healthcare databases) that best address measurement needs.

“By using TEOS, we hope to encourage researchers to explore more options for study design and identify more accurate ways to measure adherence, formulate hypotheses, and analyse data,” the authors said. “Although full replication and cross-study comparability will always be difficult to achieve as rarely will two studies share the same specifics, we believe that reporting operational definitions using TEOS will improve transparency and reproducibility of adherence studies and thus facilitate comparisons.”

TEOS underscored how many important research questions about medication adherence were not being asked accurately enough. In previous reviews, researchers found that initiation and persistence were less examined than implementation, while adherence was evaluated more at patient levels than at the provider or healthcare site levels. [Eur Respir J 2015;45:994-1018; West J Nurs Res 2012;34:635-653]

TEOS also revealed certain limitations in earlier studies on the temporal properties of adherence and its multilevel variation. A common practice was the nonseparation of adherence phases, which usually led to errors in measurement and confusion in interpreting results. [AIDS 2019;33:2081-2089; BMJ 2008;336:1114-1117]

Moreover, current interventions that target changes in within-person adherence largely depend on evidence at the between-person level, which is predisposed to various influences. Identifying between- and within-person variation in adherence may help improve these interventions, according to the authors. [Eur Respir J 2019;54:1900901]

“We hope that the explicit use of TEOS will stimulate new research in these less explored areas, and result in the formulation of more precise hypotheses which can generate more actionable evidence for adherence management,” they added.