BACKGROUND: In Latin America, HIV incidence continues to grow, while some countries are slowly scaling-up daily oral PrEP (d-PrEP); event-driven PrEP (ED-PrEP) is not being promoted yet; and other PrEP modalities such as long-acting injectable PrEP (inj-PrEP) remain under development. This study aimed to assess preferences across those three PrEP modalities and associated factors among MSM from Brazil, Mexico and Peru.
METHODS: During March-May/2018, MSM were recruited to complete a web-based survey through advertisements on dating apps (Grindr and Hornet) and Facebook. Subjects were: cisgender MSM, '¥18 years, and HIV-negative (self-report). Preferences for PrEP modalities were assessed through the question: 'If all these forms of PrEP were available, please rank from 1 (most preferred) to 3 (least preferred)' (i.e. d-PrEP, ED-PrEP and inj-PrEP).' Multivariable logistic regression models assessed factors associated with each modality.
RESULTS: A total of 19,457 MSM completed the questionnaire (58%, 31% and 11% from Brazil, Mexico and Peru; respectively); median age was 28 years (IQR:24-34) (Table). Overall, inj-PrEP was the first option for 42%[95%CI:41-43] of the respondents, followed by d-PrEP (35%,95%CI:34-35), and ED-PrEP (23%,95%CI:23-24). In multivariable logistic regression, preference for d-PrEP was associated with age '¤25 years (aOR 1.18, 95%CI1.09-1.27), lower income (aOR1.18,95%CI:1.10-1.26), lower education (aOR1.10,95%CI:1.02-1.19) and never testing for HIV (aOR1.18,95%CI:1.08-1.29). Preference for inj-PrEP was associated with age >25 (aOR 1.12,95%CI:1.04-1.21), higher income (aOR1.21,95%CI:1.13-1.29), HIV ever testing (aOR 1.32,95%CI:1.22-1.44), PrEP awareness (aOR1.23,95%CI:1.15-1.32), having >5 male sexual partners (aOR1.05,95%CI:0.99-1.12) and binge drinking (aOR1.15,95%CI:1.07-1.23). Preference for ED-PrEP was associated with lower sexual risk behavior ('¤5 male sexual partners: aOR1.15,95%CI:1.06-1.24; binge drinking: aOR1.10,95%CI:1.02-1.19) and being unaware of PrEP (aOR1.25,95%CI:1.15-1.34).

		d-PrEP 6771 (34.8%)	ED-PrEP 4538 (23.3%)	Inj-PrEP 8148 (41.9%)	Total 19457	p-value
Age (years)	<25 '¥25	2310 (39.3) 4460 (32.8)	1385 (23.6) 3153 (23.2)	2182 (37.1) 5966 (43.9)	5877 (100) 13579 (100)	< 0.001
Family montly income	Low (<250USD) Middle or High	2801 (37.9) 3691 (32.8)	1765 (23.9) 2559 (22.7)	2824 (38.2) 5020 (44.5)	7390 (100) 11270 (100)	< 0.001
Education	'¤secondary school >secondary school	2367 (38) 4353 (33.3)	1455 (23.3) 3053 (23.3)	2412 (38.7) 5684 (43.4)	6234 (100) 13090 (100)	< 0.001
Ever tested for HIV (lifetime)	No Yes	1544 (40.1) 5178 (33.5)	1025 (26.6) 3470 (22.4)	1281 (33.3) 6817 (44.1)	3850 (100) 15465 (100)	< 0.001
Condomless receptive anal sex (past 6 months)	No Yes	4024 (34.8) 2700 (34.8)	2763 (23.9) 1740 (22.4)	4784 (41.3) 3315 (42.7)	11571 (100) 7755 (100)	0.042
Number of male sexual partners (past 6 months)	'¤5 >5	4447 (35.1) 2296 (34.2	3124 (24.7) 1387 (20.7)	5101 (40.3) 3021 (45.1)	12672 (100) 6704 (100)	< 0.001
Binge drinking (past 6 months)	No Yes	2172 (36.2) 4574 (34.2)	1486 (24.8) 3035 (22.7)	2346 (39.1) 5777 (43.2)	6004 (100) 13386 (100)	< 0.001
PrEP awareness	No Yes	2504 (36.8) 4243 (33.7)	1814 (26.7) 2703 (21.5)	2486 (36.5) 5646 (44.8)	6804 (100) 12592 (100)	< 0.001

CONCLUSIONS: Long-acting injectable PrEP was preferred by MSM at high HIV risk in Latin America, while individuals with fewer sexual partners and unaware of PrEP preferred ED-PrEP. Interventions to increase literacy about PrEP modalities in the region are necessary especially among young, lower income and less educated MSM.