Predictors of PrEP Adherence Over a Two-Year Period Among a National Sample of Patients in the United States, 2015-2017 Open Access

Coy, Kelsey (Spring 2018)

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Introduction: Despite the efficacy of pre-exposure prophylaxis for HIV prevention (PrEP), there have been few quantitative studies to date studying PrEP adherence over a long period of time in real world settings. Using pharmacy refill data as a validated approach, the objective of this study was to use a sample of patients from a large national chain pharmacy to describe adherence to PrEP care over a two-year period, and to explore correlates with PrEP care adherence.

Methods: We analyzed the pharmacy fill records of 7,148 eligible individuals who initiated PrEP in 2015 at a large national chain pharmacy, considering a modified Proportion of Days Covered (PDC) in three time periods as the adherence outcome of interest. Individuals were followed for 24-months post-initiation to explore correlates with PrEP care adherence from initiation to 1 year, 1 to 2 years, and initiation to 2 years of follow up.

Results: Adherence rates were 63% from initiation to 1 year and 56% from 1 to 2 years, with 35% retained from initiation to year 2. The age category with the lowest adherence was 18-24, with 43% adherent from initiation to 1 year and 54% adherent from 1 to 2 years. Males had higher adherence than females with 34% of females retained from initiation to 1 year and 49% retained from 1 to 2 years. Individuals with commercial insurance and individuals who attended a local specialty pharmacy also had higher retention over time. All three models had the same predictors; being male, being older than 18-24 years, having an average monthly copay of $20 or less, having commercial insurance, and attending a local specialty pharmacy were significantly associated with adherence from initiation to 1 year, 1 to 2 years, and initiation to 2 years of follow up.

Conclusions: PrEP adherence was suboptimal from initiation to 1 year, 1 to 2 years, and initiation to 2 years of follow up due to a combination of demographic, financial, and pharmacy factors. Further research is needed to explore how social, structural, or individual factors may undermine or enhance adherence to PrEP and retention in PrEP care.


Table of Contents

Background       1

Methods             4

Results  6

Demographics   6

Adherence Characteristics           8

Predictors of Refill Adherence   11

Discussion         14

Limitations        16

Conclusions       17

References         18

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