The science of being a study participant: FEM-PrEP participants' explanations for overreporting adherence to the study pills and for the whereabouts of unused pills

J Acquir Immune Defic Syndr. 2015 Apr 15;68(5):578-84. doi: 10.1097/QAI.0000000000000525.


Background: FEM-PrEP was unable to determine whether once-daily, oral emtricitabine/tenofovir disoproxil fumarate reduces the risk of HIV acquisition among women because of low adherence. Self-reported adherence was high, and pill-count data suggested good adherence. Yet, drug concentrations revealed limited pill use. We conducted a follow-up study with former participants in Bondo, Kenya, and Pretoria, South Africa, to understand factors that had influenced overreporting of adherence and to learn the whereabouts of unused pills.

Methods: Qualitative, semistructured interviews were conducted with 88 participants, and quantitative, audio computer-assisted self-interviews were conducted with 224 participants. We used thematic analysis and descriptive statistics to analyze the qualitative and quantitative data, respectively.

Results: In audio computer-assisted self-interviews, 31% (n = 70) said they had overreported adherence; the main reason was the belief that nonadherence would result in trial termination (69%, n = 48). A considerable percentage (35%, n = 78) acknowledged discarding unused pills. Few acknowledged giving their pills to someone else (4%, n = 10), and even fewer acknowledged giving them to someone with HIV (2%, n = 5). Many participants in the semistructured interviews said other participants had counted and removed pills from their bottles to appear adherent.

Conclusions: Despite repeated messages that nonadherence would not upset staff, participants acknowledged several perceived negative consequences of reporting nonadherence, which made it difficult to report accurately. Uneasiness continued in the follow-up study, as many said they had not overreported during the trial. Efforts to improve self-reported measures should include identifying alternative methods for creating supportive environments that allow participants to feel comfortable reporting actual adherence.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenine / administration & dosage
  • Adenine / analogs & derivatives*
  • Adult
  • Clinical Trials as Topic*
  • Deoxycytidine / administration & dosage
  • Deoxycytidine / analogs & derivatives*
  • Emtricitabine
  • Female
  • HIV Infections / prevention & control*
  • Humans
  • Interviews as Topic
  • Kenya
  • Medication Adherence*
  • Organophosphonates / administration & dosage*
  • South Africa
  • Tenofovir
  • Treatment Outcome


  • Organophosphonates
  • Deoxycytidine
  • Tenofovir
  • Emtricitabine
  • Adenine