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Activity Number: 405 - Statistical Issues Specific to Therapeutic Areas
Type: Contributed
Date/Time: Tuesday, July 30, 2019 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract #302995 Presentation
Title: Statistical Modeling Strategies for Medication Adherence Research
Author(s): Josh DeClercq* and Leena Choi
Companies: Vanderbilt University Medical Center and Vanderbilt University Medical Center
Keywords: Medication adherence; Simulation study; Methods comparison; Proportion of Days Covered

Medication non-adherence is a widespread problem that is associated with worse health outcomes and increased healthcare costs. Although many measures of adherence have been developed, their usage is not consistent across studies and statistical methods for analyzing these measures have not been rigorously evaluated. Using Proportion of Days Covered (PDC), a commonly used adherence measure, we illustrated the importance of defining the PDC calculation method and study cohort by sensitivity analyses. We also performed simulation studies to investigate properties of three statistical models. Our sensitivity analysis showed that parameter estimates can vary greatly depending on the rules for determining the study end date in calculating PDC, or the minimum number of fills in defining the cohort. In simulation studies, logistic regression had lower power than ordinal logistic and negative binomial regression models. Ordinal logistic regression is robust to distributional assumptions with greater power, but covariates affecting the observation window should be adjusted to reserve type I error rate. We also provided a recommendation for defining the observation window in calculating PDC.

Authors who are presenting talks have a * after their name.

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