Group-Based Trajectory Modelling (GBTM) To Assess the Effect of Medication Adherence on Health-Related Outcomes: A Protocol for A Systematic Review

Abstract

Background: The Group-based trajectory modelling (GBTM) method is increasingly used in pharmacoepidemiologic studies to describe medication adherence trajectories over time. However, assessing the effects of these medication adherence trajectories on health-related outcomes remains challenging. The purpose of this review is to describe studies assessing the effects of medication adherence trajectories estimated by the GBTM method on health-related outcomes. Methods: We will conduct a systematic review according to the recommendations of the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guidelines. We will search in the following databases: PubMed, Embase, PsycINFO, Web of Science, CINAHL, and Cochrane database up to April 1st, 2021. Two reviewers will independently select articles and extract data. Discrepancies at every step will be resolved through discussion, and consensus will be reached for all disagreed articles. A third reviewer will act as a referee if needed. We will use tables to synthesize the modalities used to estimate medication adherence trajectories and the effect of adherence trajectories on health-related outcomes. We will identify the types of health-related outcomes studied and how they are defined, the statistical models used, the effect measure yield, and how medication adherence trajectories have been incorporated in the model. We will also review the limitations and biases reported by the authors and their attempts to mitigate them. We will provide a narrative synthesis.Discussion: This review will provide a clear view of the strategies and methods used in medication adherence research to estimate the effects of adherence trajectories on different health-related outcomes. A thorough exploration of how GBTM is used for this specific purpose could represent the first crucial steps towards optimizing the utilization of this method in adherence studies. Systematic review registration: Prospero CRD42021213503.