OBJECTIVES: To conduct a literature review investigating how adherence and persistence are measured using secondary data.

METHODS: Full text articles (n=1,505) were identified in PubMed, EMBASE, and Web of Science databases using these keywords: compliance, adherence, administrative claims, real-world, observational. Articles were excluded for these reasons: abstract review(n=18), cost/economic analyses (n=36), duplicates (n=136), not healthcare-related (n=23), non-human subjects (n=4), did not discuss adherence (n=488), physiology or pharmacology (n=23), randomized control trials (n=5), reviews/commentary (n=9), protocol only (n=36), technology management (n=2), vaccine adherence (n=13), not secondary data (n=8), focused on predictive models (n=3). Our full text review included 665 articles. For each article, we gathered information on the country where the study took place, drug(s) of interest, disease(s) of interest, which adherence methods were used and how measured, and the data source.

RESULTS: Adherence was measured using the Medication Possession Ratio (MPR) (n=156), defined as the sum of the days’ supply for a drug divided by number of days in a specified period. A cutoff of 80% was applied for categorizing patients as adherent vs. non-adherent. Other methods for assessing adherence included self-reported measures, e.g., the Morisky Green Levine Scale, MARS patient survey, and Kemp’s seven-point scale Persistence was measured through the Proportion of Days Covered (PDC) (n=192), defined as the number of days of use over the total days in a specified period. A cutoff of 80% was used for categorizing patients as persistent vs. non-persistent. Persistence was also measured in relation to drug discontinuation, defined as a gap of more than 30, 60, or 90 days in the utilization of the index drug.

CONCLUSIONS: Across products spanning therapeutic areas and recommended usage patterns, we found consistency with adherence and persistence measurement. We will apply these algorithms to large data sources to explore adherence and persistence for various biologics products.