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

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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

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Tenofovir
Fumarates
Point-of-Care Systems
Pharmaceutical Preparations
Confidence Intervals
Lost to Follow-Up
Point-of-Care Testing
Pre-Exposure Prophylaxis
Immunoassay
Proportional Hazards Models
Clinical Trials
Emtricitabine

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)

Cite this

Brief Report : Short-Term Adherence Marker to PrEP Predicts Future Nonretention in a Large PrEP Demo Project: Implications for Point-of-Care Adherence Testing. / Spinelli, Matthew A.; Glidden, David V.; Anderson, Peter L.; Gandhi, Monica; Cohen, Stephanie; Vittinghoff, Eric; Coleman, Megan E.; Scott, Hyman; Bacon, Oliver; Elion, Richard; Kolber, Michael A; Buchbinder, Susan P.; Liu, Albert Y.

In: Journal of acquired immune deficiency syndromes (1999), Vol. 81, No. 2, 01.06.2019, p. 158-162.

Research output: Contribution to journalArticle

Spinelli, MA, Glidden, DV, Anderson, PL, Gandhi, M, Cohen, S, Vittinghoff, E, Coleman, ME, Scott, H, Bacon, O, Elion, R, Kolber, MA, Buchbinder, SP & Liu, AY 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), vol. 81, no. 2, pp. 158-162. https://doi.org/10.1097/QAI.0000000000002005
Spinelli, Matthew A. ; Glidden, David V. ; Anderson, Peter L. ; Gandhi, Monica ; Cohen, Stephanie ; Vittinghoff, Eric ; Coleman, Megan E. ; Scott, Hyman ; Bacon, Oliver ; Elion, Richard ; Kolber, Michael A ; Buchbinder, Susan P. ; Liu, Albert Y. / Brief Report : Short-Term Adherence Marker to PrEP Predicts Future Nonretention in a Large PrEP Demo Project: Implications for Point-of-Care Adherence Testing. In: Journal of acquired immune deficiency syndromes (1999). 2019 ; Vol. 81, No. 2. pp. 158-162.
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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.",
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AU - Glidden, David V.

AU - Anderson, Peter L.

AU - Gandhi, Monica

AU - Cohen, Stephanie

AU - Vittinghoff, Eric

AU - Coleman, Megan E.

AU - Scott, Hyman

AU - Bacon, Oliver

AU - Elion, Richard

AU - Kolber, Michael A

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AU - Liu, Albert Y.

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N2 - 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.

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