Demographic factors associated with continuation of oral anti-retroviral HIV pre-exposure prophylaxis at one and three months in Nairobi, Kenya

BACKGROUND: The effectiveness of oral anti-retroviral HIV pre-exposure prophylaxis (PrEP) depends on continued adherence over the users' risk period. We sought to determine one and three months PrEP continuation rates, as proxy of adherence, and examine demographic characteristics associated with the continuation.
METHODS: Retrospective cohort analysis was conducted using data from thirty University of Maryland, Baltimore (UMB) supported facilities in Nairobi, Kenya. Individuals newly initiated on PrEP, beginning July 2019 through June 2020, were included in these analyses. Continuation rates (prescription refill) at one and three months were computed and logistic regression model was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for the association of demographics (age, gender and population type) with PrEP continuation.
RESULTS: Of 1607 individuals who initiated PrEP within the reviewed period, 1192 (74%) were 25 years or older, 1161 (72%) were female and 874 (54%) were female sex workers (FSWs). Overall, continuation rate was 38% and 17% at one and three months respectively. Younger individuals (15-24 years) had continuation rates of 27% and 10%, while key populations (FSW and MSM) had 23% and 9% at one and three months respectively. Compared to younger individuals, those '¥ 25 years were more likely to continue with PrEP, [OR 1.97 (95% CI 1.54' 2.52)] and [OR 2.03 (95% CI 1.44' 2.86)] at one and three months respectively. Males had higher odds of continuing with PrEP at month 1, [OR 1.41 (95% CI 1.13'1.76)]. Key population were less likely to continue with PrEP at both one and three months compared to general population individuals in HIV sero-discordant relationships (Table 1).

Table 1: Predictors of HIV pre-exposure prophylaxis continuation at month one and three in Nairobi, Kenya, 2019 - 2020.

Demographic characteristics	Month 1 prescription refill		Month 3 prescription refill
	OR (95 % CI)	P-value	OR (95 % CI)	P-value
Age 15'24 > 24	Ref 1.97 (1.54'2.52)	<.0001	Ref 2.03 (1.44' 2.86)	<.0001
Gender Female Male	Ref 1.41 (1.13'1.76)	0.0023	Ref 1.28 (0.97' 1.69)	0.0846
Population type Discordant couples* FSW MSM/MSW General population**	Ref 0.17 (0.14'0.22) 0.04 (0.02' 0.08) 0.58 (0.33' 1.00)	<.0001 <.0001 0.0514	Ref 0.20 (0.15'0.27) 0.05 (0.02'0.13) 0.30 (0.14'0.66)	<.0001 <.0001 0.0024
Abbreviations: FSW, Female sex worker; MSM, Men who have sex with men; MSW, Men who have sex with men as sex workers (transactional) * Excluding key population ** Excluding key population and individuals in HIV sero-discordant relationships

CONCLUSIONS: These results show sub-optimal PrEP continuation among younger and key population individuals. Targeted interventions for these two groups are necessary to optimize PrEP continuation in light of national scale-up of PrEP uptake.