Photo Credit: Bowonpat Sakaew
Self-reported PrEP intake in a diary app was strongly associated with blood concentrations reflecting actual PrEP intake in the previous 6 weeks.
Self-reported oral PrEP intake reported in a diary app was strongly and positively associated with actual use as reflected in drug concentrations in blood, according to a study published in AIDS.
“Several studies have demonstrated considerable incongruencies between self-reported adherence in retrospective questionnaires and blood drug concentrations, although this finding has been inconsistent,” Elske Hoornenborg, PhD, and colleagues wrote.
The diary app in the study was designed for a prospective demonstration project that, between 2015 and 2020, provided daily and event-driven PrEP to MSM. Participants could report PrEP intake and sexual activity in the app and were encouraged to do so daily. They could also enter data retrospectively.
Dried blood spots taken at 6, 12, 24, and 48 months allowed investigators to measure drug metabolite concentrations. The analysis included 759 dried blood spots from 282 MSM.
Pill Diaries A Proxy for PrEP Intake
According to the study results, self-reported PrEP intake (eg, the number of pills) was strongly associated with blood concentrations that reflected actual PrEP intake in the preceding 6 weeks.
“Pill diaries thus offer an appropriate proxy for average PrEP intake when used in a study setting to compare PrEP adherence between groups,” Dr. Hoornenborg and colleagues wrote.
However, concordance between categories of self-reported PrEP intake (<2, 2–3, 4–6, or 7 pills per week) and categories of blood concentrations (<350, 350–699, 700–1249, or ≥1250 femtomole/punch) was just moderate, the study found. Half of the participants reported PrEP intake that corresponded to categorized blood drug concentrations, but one in three participants had lower blood drug concentrations than reflected in reports.
Concordance Seen Between Self-Report, Blood Levels
“We did not expect this based on our population’s demographic characteristics,” the researchers wrote. “The directionality of the observed discordance may thus indicate that individuals over-report PrEP intake, possibly owing to social desirability or recall bias.”
Meanwhile, the study found high concordance between self-reported PrEP intake in the past 2 days (yes/no) and quantifiable drug concentrations (yes/no).
“This high concordance may be explained by the straightforward cut-offs used to categorize adherence measures, or by the phenomenon of ’white coat dosing,’ whereby individuals are more conscious of their medication intake or reporting in the days leading up to a clinical visit,” Dr. Hoornenborg and colleagues wrote.
