Table 3.

Frequency of pre-exposure prophylaxis (PrEP) composite adherence scores at study baseline and follow-up visits.

Composite scorea	Baseline (%)	Follow-up (%)
0	0 (0)	0 (0)
1	1 (10)	0 (0)
2	0 (0)	0 (0)
3	0 (0)	0 (0)
4	8 (80)	7 (70)
5	1 (10)	3 (30)

^aComposite scores were based on concentrations of tenofovir (TFV) in plasma and intracellular TFV-diphosphate (TFV-DP) in upper layer packed cells. Scores assess adherence in the past 4 weeks, ranging from 0 (low or no doses of drug identified) to 5 (good adherence). A score of 4 (ie, 4-5 doses per week) or 5 (approximately daily dosing) is typically considered as a good level of adherence in which PrEP is efficacious. Because 1 participant was on PrEP for only 2 weeks, the baseline visit adherence score for this participant could have been artificially lower as a result of taking PrEP for a shorter duration in comparison to other study participants (ie, all other participants reported being on it for at least 5 months). However, this participant yielded a baseline adherence score of 4, indicating an adequate level of protection since starting on PrEP and that his score was likely not artificially lower.