Pharmacologic Drug Detection and Self-Reported Adherence in the HPTN069/ACTG5305 Phase II PrEP Trial

Area of Science:

• Clinical Pharmacology
• Infectious Diseases
• Public Health

Background:

• Adherence to pre-exposure prophylaxis (PrEP) is essential for its effectiveness in preventing HIV.
• Clinical trials require accurate assessment of adherence to interpret efficacy data.

Purpose of the Study:

• To compare self-reported adherence with measured plasma drug concentrations in a PrEP trial.
• To identify factors associated with discrepancies between self-reported and measured adherence.

Main Methods:

• The HPTN069/ACTG5305 trial assessed safety and tolerability of candidate PrEP regimens.
• Plasma drug concentrations and computer-assisted self-interview (CASI) adherence data were collected at weeks 24 and 48.
• A generalized linear model analyzed associations between demographics, self-reported adherence, and drug concentrations.

Main Results:

• 65% of observations had drug concentrations consistent with daily adherence, while only 43% reported daily adherence via CASI.
• 11% reported daily adherence but had drug concentrations indicating less-than-daily use.
• Factors like being assigned male at birth, older age, White race, advanced education, employment, and being partnered/married were associated with higher adherence.
• Not being employed or being single/unpartnered were linked to lower adherence.

Conclusions:

• Discrepancies between self-reported and measured adherence are common in PrEP trials.
• Demographic and socioeconomic factors influence adherence.
• Ongoing adherence counseling is vital for the success of PrEP clinical trials.