Brief Report: Short-Term Adherence Marker to PrEP Predicts Future Nonretention in a Large PrEP Demo Project: Implications for Point-of-Care Adherence Testing

Matthew A. Spinelli, David V. Glidden, Peter L. Anderson, Monica Gandhi, Stephanie Cohen, Eric Vittinghoff, Megan E. Coleman, Hyman Scott, Oliver Bacon, Richard Elion, Michael A Kolber, Susan P. Buchbinder, Albert Y. Liu

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

BACKGROUND: Objective adherence metrics for tenofovir (TFV) disoproxil fumarate/emtricitabine (FTC)-based pre-exposure prophylaxis (PrEP) were critical for interpretation of efficacy in PrEP clinical trials, and there is increasing interest in using drug levels to tailor interventions for reengagement and adherence. Point-of-care immunoassays for TFV, which examine short-term adherence, are in development. However, the ability of poor short-term and long-term adherence to predict future PrEP nonretention is unknown. SETTING: Secondary data analysis of a large, prospective multi-site U.S. PrEP demonstration project. METHODS: An adjusted Cox-proportional hazards model examined the relationship of dried blood spot (DBS) levels of FTC-triphosphate (FTC-TP) or TFV-diphosphate (TFV-DP), measures of short-term and long-term PrEP adherence, respectively, with future study nonretention. RESULTS: Overall, 294 individuals (median age 33 years) contributed drug levels within the U.S. PrEP demonstration project. By the end of study, 27% were lost to follow-up, 25% had at least one undetectable FTC-TP level indicating poor short-term adherence, and 29% had a drug level indicating suboptimal long-term adherence (TFV-DP <700 fmol/punch). The strongest factor associated with future study nonretention using a binary drug-level cut-off was an undetectable DBS FTC-TP level (adjusted hazard ratio 6.3; 95% confidence interval 3.8 to 10.2). The suboptimal long-term adherence based on low DBS TFV-DP levels was also associated with nonretention (adjusted hazard ratio 4.3; 95% confidence interval: 2.4 to 7.6). CONCLUSIONS: Both short- and long-term metrics of PrEP adherence are strongly associated with future loss to follow-up in a U.S. demonstration project study. Short-term metrics of adherence, once available at the point-of-care, could be used to direct real-time tailored retention and adherence interventions.

Original languageEnglish (US)
Pages (from-to)158-162
Number of pages5
JournalJournal of acquired immune deficiency syndromes (1999)
Volume81
Issue number2
DOIs
StatePublished - Jun 1 2019

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)

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    Spinelli, M. A., Glidden, D. V., Anderson, P. L., Gandhi, M., Cohen, S., Vittinghoff, E., Coleman, M. E., Scott, H., Bacon, O., Elion, R., Kolber, M. A., Buchbinder, S. P., & Liu, A. Y. (2019). Brief Report: Short-Term Adherence Marker to PrEP Predicts Future Nonretention in a Large PrEP Demo Project: Implications for Point-of-Care Adherence Testing. Journal of acquired immune deficiency syndromes (1999), 81(2), 158-162. https://doi.org/10.1097/QAI.0000000000002005