Hair levels of preexposure prophylaxis drugs measure adherence and are associated with renal decline among men/transwomen

Monica Gandhi, Pamela M. Murnane, Peter Bacchetti, Richard Elion, Michael A. Kolber, Stephanie E. Cohen, Howard Horng, Alexander Louie, Karen Kuncze, Catherine A. Koss, Peter L. Anderson, Susan Buchbinder, Albert Liu

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Objective: The US preexposure prophylaxis (PrEP) Demonstration Project (U.S. Demo) evaluated MSM on PrEP postmarketing and found low seroconversion rates. The objective of this study is to examine hair levels as an adherence measure to PrEP. Design: Using an 'opt-in' design, participants of PrEP Demo were invited to enroll into a substudy where hair was collected quarterly. Methods: Tenofovir concentrations were measured in hair by liquid chromatography/tandem mass spectrometry. Hair levels consistent with ≥4 doses/week (protective in other studies) defined adequate adherence. Mixed effects multivariate logistic regression models examined factors associated with ≥4 doses/week. Separate mixed effects models evaluated the relationship between hair PrEP levels and changes in creatinine clearance (CrCl) over time. Results: Overall, 58% of U.S. Demo participants enrolled into this opt-in study; reasons for nonparticipation included insufficient hair (61%) and concerns about hairstyle (27%). Hair and dried blood spots levels consistent with ≥4 doses/week were highly concordant (84%). Hair levels showed adequate adherence in 87% of 875 person-visits (among 280 participants). Factors associated with adequate adherence in multivariate models were amphetamine use [adjusted odds ratio (aOR) 2.59 (0.97-6.9, P 0.06)], condomless receptive anal sex [aOR 2.28 (1.19-4.40, P 0.01)], and stable housing [aOR 2.63 (1.03-6.67), P 0.04]. Hair levels of tenofovir showed a monotonic relationship with decline in CrCl (P 0.01 for trend). Conclusion: In this substudy of the U.S. PrEP demonstration project, hair and dried blood spots levels were highly concordant and hair concentrations demonstrated adequate adherence 87% of the time, with stable housing and high-risk behavior associated with higher adherence. Daily PrEP drug taking is associated with modest declines in CrCl.

Original languageEnglish (US)
Pages (from-to)2245-2251
Number of pages7
Issue number16
StatePublished - Oct 23 2017


  • HIV prevention
  • creatinine clearance
  • enhancing preexposure prophylaxis in community
  • hair concentrations
  • pharmacologic measures
  • preexposure prophylaxis
  • preexposure prophylaxis US Demo project
  • tenofovir/emtricitabine

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Infectious Diseases


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