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Updated: Jan 24, 2026
09:20
In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells
Published on: July 23, 2010
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Brief Report: Short-Term Adherence Marker to PrEP Predicts Future Nonretention in a Large PrEP Demo Project:
Matthew A Spinelli1, David V Glidden2, Peter L Anderson3
1Division of HIV, ID, and Global Medicine, University of California, San Francisco, CA.
Summary
Poor adherence to pre-exposure prophylaxis (PrEP), both short-term and long-term, significantly predicts future loss to follow-up. Point-of-care adherence testing could enable timely interventions to improve PrEP retention.
Area of Science:
- Pharmacology and Infectious Diseases
- Public Health and Epidemiology
- Clinical Trial Methodology
Background:
- Objective adherence metrics are crucial for interpreting pre-exposure prophylaxis (PrEP) efficacy.
- Drug levels can inform interventions for PrEP reengagement and adherence.
- The predictive value of short- and long-term adherence for future PrEP nonretention is not well understood.
Purpose of the Study:
- To investigate the association between short-term and long-term adherence metrics and future study nonretention in a U.S. PrEP demonstration project.
- To evaluate the utility of drug levels as predictors of loss to follow-up in PrEP users.
Main Methods:
- Secondary data analysis of a prospective, multi-site U.S. PrEP demonstration project.
- Utilized an adjusted Cox-proportional hazards model.
- Assessed dried blood spot (DBS) levels of emtricitabine-triphosphate (FTC-TP) for short-term adherence and tenofovir-diphosphate (TFV-DP) for long-term adherence.
Main Results:
- Among 294 participants, 27% were lost to follow-up.
- Poor short-term adherence (undetectable FTC-TP) was strongly associated with future nonretention (aHR=6.3).
- Suboptimal long-term adherence (low TFV-DP) was also associated with nonretention (aHR=4.3).
Conclusions:
- Both short- and long-term PrEP adherence metrics are significant predictors of future loss to follow-up.
- Point-of-care short-term adherence measures could facilitate real-time, tailored interventions for PrEP retention.
- These findings highlight the importance of monitoring adherence to optimize PrEP effectiveness.
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