PrEP use and sexually transmitted infections are not associated longitudinally in a cohort study of young men who have sex with men and transgender women in Chicago

Abstract

Our goal was to understand whether PrEP users are at increased risk for STIs, a key target in prevention efforts aimed at disrupting the spread of STIs and likely downstream HIV infection risk.

Data were collected as part of RADAR, a cohort study of young men who have sex with men and transgender women (YMSM/TW) (aged 16-29) in Chicago. Longitudinal lagged regression models were utilized to assess the relationship between PrEP use and odds of rectal STI acquisition. Mediation models were also utilized to consider the potential pathway between PrEP use, condomless anal sex (CAS), and rectal STI.

One hundred eighty-seven (16.2%) participants had a rectal STI at baseline. In both crosssectional and longitudinal models, no significant association was observed between PrEP use and STI. In mediation models, PrEP use was significantly associated with increased CAS, however, CAS was not associated with STI status.

We demonstrated that, overall, PrEP use was not associated with STIs among YMSM/TW but did observe that PrEP users were more likely to report increased participation in CAS at the subsequent study visit.

Introduction

In the United States, the rate of sexually transmitted infections (STIs) has risen steadily in recent years¹. Compared to 2014, the rate of gonorrhea infections increased 12.8% in 2015 (from 109.8 to 123.9 cases per 100,000) and has risen a total of 26.3% since 2009 (from 98.1 to 123.9 per 100,000)². Chlamydia has similarly increased, up 5.9% in 2015 compared to 2014 (452.2 to 478.8 per 100,000), after declining in the period 2011-2013 (453.4 to 443.5 per 100,00)³. Recent work has suggested that this rise in STI incidence may be attributable to several factors, including increased extragenital testing for STIs, greater participation in sexual risk behaviors, or risk compensation by users of pre-exposure prophylaxis (PrEP).⁴ The goal of this analysis is to address the last of these hypotheses by testing the prospective association between PrEP use and STIs and mediation by engagement in sexual risk behaviors.

PrEP has been shown to be highly effective at preventing the acquisition of HIV with up to a 92% reduction in HIV risk.⁵ PrEP, however, does not protect against other STIs. One of the more controversial topics in the literature today, with several past studies demonstrating mixed findings,^6-8 is whether the recent rise in STI incidence can be attributed to the use of PrEP. One key argument against this association is that trends of increasing STI incidence,⁹ as well as associated risk behaviors,¹⁰ pre-date the use of PrEP.⁷ On the other hand, other research has found that among those who expressed an interest in starting PrEP, many indicated they would also decrease their subsequent condom use, potentially driving an increase in STI incidence among PrEP users.¹¹ In fact, recent work among young men who have sex with men (YMSM) observed that PrEP users reported higher rates of receptive condomless anal sex (CAS) at times when they were on PrEP compared to when they were not.¹² This study also found that YMSM with poorer PrEP adherence were also those most likely to decrease their condom use while on PrEP.¹² One limiting factor of these past studies is the sole comparison of STI rates before and after PrEP uptake. Among the few studies using longitudinal data, an increase in STI rates has been observed,¹³ particularly among those staring PrEP for the first time.¹⁴ It is therefore important to expand on these past studies using longitudinal mediation analyses to examine whether the association between PrEP and STIs is mediated through a change in participation in condomless sex.

The rate of STIs varies not only among PrEP users but also varies by demographic characteristics, particularly race, ethnicity, and sexual orientation,⁹ as well as substance use patterns.¹⁵ The CDC has reported that, compared to the white community, the black community experiences a much higher rate of infection of both gonorrhea² and chlamydia³ (i.e., 9.6 and 5.9 times higher, respectively). Further, marijuana use has been associated with a reduction in use of condoms and an increase in STI incidence.¹⁵ Disparity has also been observed among men who have sex with men (MSM), who have higher STI rates compared to their heterosexual counterparts.^16,17 Within-group differences by race and ethnicity also exist among MSM themselves with black MSM (BMSM) experiencing the highest rates of both chlamydia and gonorrhea.^18,19 This is important given that BMSM have previously been demonstrated to engage in fewer risk behaviors than other MSM.^20,21 While seemingly contradictory, these findings may be explained by past work which observed high racial homophily in sexual networks of BMSM,²¹ potentially facilitating greater movement of STIs only through this population. This area of research is particularly important as STIs have been associated with increased risk of subsequent HIV infection and may be a contributor to extant racial disparities in HIV among MSM.^22,23 Understanding how risk of STIs among PrEP users varies by race and ethnicity will help guide prevention efforts aimed at preventing STIs and may aid in reducing the risk of downstream HIV infection as well.

In this paper we aim to: 1) use longitudinal analyses to determine the risk of STI acquisition among those who have used PrEP in the past six months; 2) whether a relationship between risk of STI acquisition and PrEP use is mediated through condomless sex; and 3) assess whether this association differs by race and ethnicity. Sexually transmitted infections will be assessed using gold-standard laboratory testing²⁴ as opposed to self-reported data. In light of past findings, we hypothesize that the rate of STIs will be higher among those individuals on PrEP due to more engagement in condomless sex. We also anticipate that, given differences in racial homophily of sexual networks²¹ and existing disparities in STI incidence,¹⁸ BMSM on PrEP will have the highest rates of STIs compared to other MSM. Developing a better understanding of this relationship is key in order to counter the spread of STIs and, potentially, HIV.

Methods

Study Design & Recruitment

Data are from the baseline visit and 6, 12, 18, 24, 30, and 36-month follow-up visits of the ongoing RADAR cohort study of YMSM and transgender women (YMSM/TW) living in the Chicago metropolitan area. The primary objective of this cohort study is to apply a multilevel perspective to a syndemic of health issues associated with HIV among diverse YMSM/TW. First, a subset of participants from two cohorts of YMSM, Project Q2 and Crew 450, who were first recruited in 2007 and 2010, respectively, enrolled in the cohort. In 2015, a third cohort of YMSM/TW was recruited. At the time of enrollment into their original respective cohorts, all participants were between 16 and 20 years of age, assigned male at birth, spoke English, and had a sexual encounter with a man in the previous year or identified as gay, bisexual or transgender. Data were collected using a health survey administered via a computer-assisted self-interview (CASI) and rectal swabs were collected and tested for chlamydia and gonorrhea. The study was reviewed and approved by the Northwestern University Institutional Review Board (IRB STU00087614).

The total sample at the time of analysis included 1,155 participants and 5,305 visits. Each lagged observation included data from visit t-2 on PrEP, rectal STI testing results, condomless sex with a male partner, and covariates; from visit t-1 on condomless sex; and from visit t on rectal STI testing results. 296 individuals were dropped form the analytic sample as they did not provide data at two observations one year apart (i.e., t-2 and t). Participants who were HIV-positive did not answer questions about PrEP use, so observations when a participant was HIV-positive were excluded (329 observations). The analytic sample included 744 individuals and 1431 lagged observations.

Measures

Demographics.

Participants self-reported demographic information including age, race and ethnicity, assigned sex at birth, current gender identity, and sexual orientation. Participants reporting a Hispanic ethnicity were coded as such, regardless of their racial identity. Participants were also asked to self-report information on their current level of education. No demographic information was missing.

Sexually Transmitted Infections.

Regardless of participants’ sexual history or history of condom use, we tested for both rectal gonorrhea and chlamydia via collection of rectal swabs. These tests were administered at baseline, 12-, 24-, and 36-month follow-ups.

PrEP, HIV Risk, and Substance Use Behaviors.

Past six-month PrEP usage was assessed using the following item, “In the past six months, have you taken any PrEP medication such as Truvada to reduce your risk of HIV transmission?”, and was operationalized as those who had or had not used PrEP in the past six months. Discontinuation of PrEP use was defined as those individuals who had used PrEP in the past six months but were no longer using PrEP at the time of the interview.

Condomless anal sex with male partners was assessed using the HIV Risk Assessment of Sexual Partnerships Survey (HRASP) and was reported by participants on a partner-by-partner basis as the number of instances of condomless anal sex in the past six months.^25,26 It was operationalized as having either no instances of condomless sex or having at least one instance of condomless sex. Number of male sexual partners in the past six months was reported and utilized as a count variable. We also examined differences in condomless sex based on sexual positioning by stratifying analyses according to insertive versus receptive condomless anal sex.

Marijuana use was assessed using an eight-item screener for problematic use:, the Cannabis Use Disorder Identification Test (CUDIT, alpha=0.91).²⁷ CUDIT scores ranged from 0-32 and were operationalized as a continuous variable with higher scores indicating more hazardous cannabis use. Alcohol use among participants was assessed using the Alcohol Use Disorders Identification Test (AUDIT, alpha=0.86)²⁸ and was utilized as a continuous variable with higher scores indicating high levels of problematic alcohol use.

Statistical Analyses

Analyses were conducted in Mplus Version 8 using robust maximum likelihood estimation and missing data was handled using full information maximum likelihood. Multilevel modeling was used to account for the non-independence of longitudinal data. Bivariate multilevel logistic regressions were used to examine unlagged associations between demographic characteristics, sexual risk behaviors, and STIs. Multivariable multilevel logistic regression models were used to examine whether sexual risk behaviors at time t-2 predicted an increased likelihood of having a rectal STI at time t, controlling for the presence of a rectal STI at time t-2 and demographic characteristics. Analyses were conducted examining risk for any rectal STI, gonorrhea only, and chlamydia only. All covariates identified as statistically significant in bivariate analyses and known confounders were included in the multivariable regression model. We also examined whether the associations between sexual risk behaviors and STIs varied by race or ethnicity using a series of cross-level interactions. Within-level indirect effects analyses were also conducted, in which the indirect effect of PrEP use at t-2 on rectal STI at t via condomless sex with a male partner at t-1 were examined. In addition to the covariates included in the multivariable logistic regressions described above, we also controlled for condomless sex with a male partner at t. Finally, sensitivity analyses were conducted among the analytic sample excluding those individuals whose PrEP use status changed from t-2 to t (242 observations excluded).

Results

Demographic characteristics

This analytic sample (Table 1) had an average age of 20.9 years at baseline (SD = 2.9). Most participants were cisgender men, but 54 (7.3%) were gender minorities assigned male at birth. Most of the sample identified as gay (n = 512, 68.8%), followed by bisexual (n = 164, 22.0%), and other identities (n = 68, 9.1%). The racial/ethnic composition of the sample was 30.1% (n = 224) black, 28.0% (n = 208) white, 31.3% (n = 233) Latinx, and 10.6% (n = 79) identified with other racial/ethnic identities. Highest level of education at baseline included less than high school (21.1%, n = 157), high school (20.7%, n = 154), some college (48.7%, n = 362), and a Bachelor’s degree or higher (9.5%, n = 71). At any point during the study, 245 (32.9%) participants reported PrEP use, 125 (16.8%) tested positive for rectal gonorrhea, and 171 (23.0%) tested positive for rectal chlamydia.

Table 1.

Demographic and health characteristics of participants in the analytic sample, RADAR, Chicago

	N	%/SD
Age	20.9	2.9
Race/Ethnicity
White	208	28.0
Black	224	30.1
Hispanic	233	31.3
Other	79	10.6
Education
< High school	157	21.1
High school/GED	154	20.7
Some college/Assoc.	362	48.7
≥ Bachelor	71	9.5
Gender Identity
Cis-male	690	92.7
Gender Minority	54	7.3
Sexual Orientation
Gay	512	68.8
Bisexual	164	22.0
Other	68	9.1
PrEP Use1	245	32.9
Rectal gonorrhea1	125	16.8
Rectal chlamydia1	171	23.0
Number of sexual partners2	1.74	3.31
Condomless sex2	551	74.1

¹Across all time points

²At least once in the past six months

Bivariate associations

Figure 1 presents STI data across multiple time points comparing the proportion of participants testing positive for STIs before and after PrEP uptake to consistent non-PrEP users. Among those who began PrEP use, the rates of STIs before PrEP uptake were higher than after uptake, although this difference was not significant at any time point. The rates among non-PrEP users, meanwhile, remained relatively consistent over time. Table 2 presents unlagged bivariate multilevel associations between demographic and risk behavior characteristics of the analytic sample. We did not observe significant associations between the likelihood of having a rectal STI and PrEP use, although the within-person association between condomless sex and the likelihood of having a rectal STI approached significance (p = .07).

Figure 1.

Proportion of participants testing positive for any rectal sexually transmitted infection comparing those pre and post PrEP uptake to those consistent non-PrEP users. No significant differences existed between proportions at any time point.

Table 2.

Unlagged bivariate multilevel associations between demographic and risk behavior characteristics of analytic sample (N = 744)

	Rectal STI
	Within	Between
	OR	OR
Age	-	.94
Race/Ethnicity
White	-	Reference
Black	-	4.36**
Hispanic	-	1.73
Other	-	1.63
Education
< High school	-	Reference
High school/GED	-	1.12
Some college/Assoc.	-	.54
≥ Bachelor	-	.71
Gender Identity
Cis-male	-	Reference
Gender Minority	-	3.16*
Sexual Orientation
Gay	-	Reference
Bisexual	-	.87
Other	-	1.09
PrEP Use1
No	Reference	Reference
Yes	.75	1.76
Number of sexual partners1	1.04	1.05
Condomless sex1
Never	Reference	Reference
≥Once	1.72	1.15
Substance Use1
Marijuana Use Problems2	1.09*	1.07**
Alcohol Use Problems3	1.11*	1.01

¹In the past six months

²Assessed using the CUDIT test and scoring method; higher score indicates higher risk marijuana use

³Based on the Alcohol Use Disorders Identification Test (AUDIT) and scoring methods; higher score indicates higher risk alcohol use

^*p < .05;

^**p < .01

Regression analyses

Table 3 presents multivariate models examining whether a participant had any rectal STI (gonorrhea and/or chlamydia), rectal gonorrhea, or rectal chlamydia. No prospective associations between PrEP use and rectal STIs was observed. Participants who reported having had any rectal STI or rectal chlamydia 12 months earlier were more likely to have any rectal STI (Adjusted Odds Ratio [AOR] = 3.04; 95% Confidence Interval [CI]: 1.94, 4.76) or chlamydia (AOR = 3.62; 95% CI: 2.03, 6.47), but not gonorrhea. Engagement in condomless sex was prospectively associated with significantly higher risk of having any rectal STI (AOR = 1.70; 95% CI: 1.09, 2.65) or gonorrhea (AOR = 2.07; 95% CI: 1.13, 3.80), but not chlamydia, compared to those who consistently used condoms or were abstinent. Compared to white participants, black and other race participants were, respectively, 3.08 and 2.70 times more likely to have had gonorrhea, but there were no differences in the overall likelihood of having any rectal STI or having rectal chlamydia. Gender minorities were 1.92 times more likely to have chlamydia than cisgender men, but no differences in risk were observed for any rectal STI or gonorrhea. No significant difference in odds of rectal STIs were observed when considering number of male sexual partners in the past six months, alcohol or cannabis use problems, age at baseline, or education level.

Table 3.

Adjusted lagged multilevel associations between demographic and risk behavior characteristics of analytic sarrmle. RADAR (N = 744)

	Either STI				Chlamydia Only				Gonorrhea Only
	Within1		Between		Within1		Between		Within1		Between
Characteristic	AOR	95% CI	AOR	95% CI	AOR	95% CI	AOR	95% CI	AOR	95% CI	AOR	95% CI
Age	-	-	0.93	0.86, 1.01	-	-	0.95	0.87, 1.04	-	-	0.88	0.79, 0.98
Race
White	-	-	Ref	-	-	-	Ref	-	-	-	Ref	-
Black	-	-	1.47	0.89, 2.44	-	-	1.18	0.65, 2.16	-	-	3.08*	1.27, 7.45
Hispanic	-	-	1.16	0.71, 1.82	-	-	1.12	0.66, 1.90	-	-	1.80	0.82, 3.99
Other	-	-	1.51	0.81, 2.82	-	-	0.94	0.42, 2.07	-	-	2.70*	1.07, 6.87
Education
<High school	-	-	Ref	-	-	-	Ref	-	-	-	Ref	-
High school/GED	-	-	0.92	0.57, 1.50	-	-	0.85	0.48, 1.48	-	-	1.02	0.48, 2.18
Some college/Assoc.	-	-	0.75	0.48, 1.16	-	-	0.74	0.43, 1.25	-	-	0.92	0.47, 1.81
≥ Bachelor	-	-	0.91	0.41, 2.03	-	-	0.78	0.29, 2.12	-	-	2.24	0.72, 7.01
Gender
Cisgender Man	-	-	Ref	-	-	-	Ref	-	-	-	Ref	-
Gender Minority	-	-	1.55	0.85, 2.83	-	-	1.92	1.04, 3.56	-	-	0.81	0.26, 2.52
PrEP use2
No	Ref	-	-	-	Ref	-	-	-	Ref	-	-	-
Yes	1.07	0.63, 1.82	-	-	1.13	0.59, 2.15	-	-	1.40	.65, 3.02	-	-
STI
Negative	Ref	-	-	-	Ref	-	-	-	Ref	-	-	-
Positive	3.04*	1.94, 4.76	-	-	3.62*	2.03, 6.47	-	-	2.74	.94, 8.00	-	-
Number of sexual partners2	0.98	0.93, 1.03	0.97	0.92, 1.02	1.01	0.94, 1.07	0.97	0.91, 1.04	.99	.92, 1.07	0.95	0.88, 1.02
Condomless sex2
None	Ref	-	Ref	-	Ref	-	Ref	-	Ref	-	Ref	-
≥ Once	1.70*	1.09, 2.65	0.86	0.54, 1.38	1.55	0.88, 2.71	0.86	0.49, 1.50	2.07*	1.13, 3.80	0.73	0.38, 1.40
Substance Use2
Marijuana Use3	0.95	0.89, 1.02	1.00	0.97, 1.03	0.95	0.88, 2.71	0.99	0.96, 1.03	.92	.84, 1.01	1.03	0.99, 1.07
Alcohol Use4	0.98	0.89, 1.07	0.99	0.94, 1.03	0.91	0.88, 1.00	0.97	0.91, 1.03	1.10	.98, 1.23	0.99	0.94, 1.05

¹All within-person predictors assessed at visit t-2; outcome assessed at visit t.

²In the past six months

³Assessed using the CUDIT test and scoring method; higher score indicates higher risk marijuana use

⁴Based on the Alcohol Use Disorders Identification Test (AUDIT) and scoring methods; higher score indicates higher risk alcohol use

^*p < .05;

^**p < .01

In sensitivity analyses, we examined whether the associations between PrEP use and STI risk were affected by the inclusion of lagged observations in which a participant varied in their PrEP use (e.g., used PrEP at time t-2 and t-1 but did not use PrEP at t). These analyses displayed the same pattern as those presented above. Additionally, no significant association was observed between PrEP and rectal STIs when comparing consistent PrEP users (e.g. used PrEP at time t-2, t-1, and t) to those who varied their PrEP use across visits nor compared to those who never used PrEP (data not shown). Finally, in cross-sectional analyses no significant difference in rate of rectal STIs was observed between those who had or had not taken PrEP in the six-month period preceding interview.

Moderation by race/ethnicity

We examined whether the association between PrEP use and any rectal STIs differed by race/ethnicity using cross-level interactions (data not shown). Due to the relatively small number of individuals who identified with races/ethnicities other than white, black, and Latinx, the inclusion of individuals of other races produced difficulties with estimation and unreliable coefficients. Therefore, these individuals were excluded from these analyses. Results indicated that the association between PrEP and having any rectal STI, chlamydia, or gonorrhea, was not moderated by race/ethnicity.

Indirect effects

Indirect effects analyses were conducted to determine if PrEP use indirectly affected the likelihood of having a rectal STI via condomless sex with a male partner (Table 4). PrEP use at one visit (t-2) did prospectively predict an increased likelihood of condomless sex in the subsequent six months (t-1). However, condomless sex at t-1 did not predict a higher likelihood of having a rectal STI (any, chlamydia, or gonorrhea) at the subsequent visit (t) when controlling for having a rectal STI and condomless sex at visit t-2. These findings held in sensitivity analyses separately considering receptive or insertive condomless anal sex. Indirect effect parameters were non-significant and thus were not examined. Together, these results suggest there was no significant relationship between PrEP and STIs, mediated by condomless anal sex.

Table 4.

Indirect effects results from adjusted mediation models examining the pathway between PrEP use, condomless anal sex, and STI diagnosis, RADAR (N = 744)

Association	Either STI		Chlamydia Only		Gonorrhea Only
	AOR	95% CI	AOR	95% CI	AOR	95% CI
PrEP Use → Condomless Sex	1.61*	1.10, 2.36	1.63*	1.11, 2.38	1.64*	1.12, 2.40
Condomless Sex → STI	0.95	.58, 1.57	1.10	.69, 1.74	0.61	.29, 1.26
PrEP Use → STI	1.04	.58, 1.84	1.16	.62, 2.17	1.40	.62, 3.18
Prior STI → STI	2.65*	1.65, 4.23	3.74*	2.11, 6.59	2.57*	1.24, 5.34

Discussion

Among a diverse sample of young MSM in Chicago, 16.2% had either rectal gonorrhea, rectal chlamydia, or both at baseline. Overall, no significant relationship was observed between PrEP use and risk of STI in either longitudinal lagged or mediation models. We did find that, in lagged models, black individuals, those with a prior STI diagnosis, and those who participated in condomless anal sex were more likely to be diagnosed with either gonorrhea or chlamydia, supporting one of our hypotheses. In mediating models, we also found that PrEP users reported an increase in condomless anal sex but that this increase was not associated with an increase in STI diagnoses in the context of the mediation model. Further, we observed that those with a prior diagnosis of either gonorrhea or chlamydia were significantly more likely to be diagnosed a second time. No significant difference in STI risk was observed among those who consistently or inconsistently used PrEP.

Much debate exists in the literature today as to whether the use of PrEP directly increases the incidence of STIs through risk compensation.^6-8 In this study, contrary to our original hypothesis, we observed no significant increase in risk of STIs between those who had or had not used PrEP in the past six months. In fact, in crude analyses, the rate of STIs decreased following PrEP uptake. In contrast, two recent papers, one large meta-analysis²⁹ and one cohort study,¹³ have each reported higher STI incidence rates among PrEP users, raising concerns about how its use may affect HIV incidence in the future. Although our findings contrast those of past work, it is possible that, due to increased STI testing among PrEP users, we are observing the early stages of a decline or plateau in STI incidence. Frequency of STI testing was similar and comparable across studies. Specifically, in RADAR, all participants receive STI testing, not only those on PrEP allowing us to examine the association between annual STI testing results and the uptake of PrEP. To illustrate this possibility, one past modeling study found that, given a high rate of PrEP coverage, the rate of STIs would initially increase in the first year but would then be followed by a subsequent decrease due to increased STI testing.³⁰ Importantly, while a strong association between STIs and HIV has long been established,³¹ little is currently known about how STIs may increase risk for HIV acquisition under conditions of less than perfect PrEP adherence. This point is particularly salient as black MSM have been shown to have greater risk compensation among PrEP users, particularly among those less adherent to medication,¹² findings which may influence the risk of HIV acquisition among this population. Given the contrast between past research and the findings presented here, further research should be dedicated towards better understanding the context in which PrEP increases risk of STIs, particularly surrounding less than perfect adherence and discussion of STI status with sexual partners.

In addition to observing no longitudinal association between PrEP and STI, we also did not find an indirect effect of PrEP on STIs through condomless anal sex, either in combined analyses or separated by sexual positioning. Here, PrEP use at one study visit (time t-2) was significantly associated with an increase in condomless sex at the subsequent visit (time t-1). Although condomless sex was prospectively associated with an increased risk of gonorrhea or any STI in multivariable analyses, changes in condomless sex were not associated with an increased risk of any STI in the context of the mediation model (time t). We also observed that having a prior STI did significantly predict future diagnosis of an STI. Although we cannot be sure whether this was a new infection or an untreated infection, participants are linked to providers for treatment making it less likely it is the same infection a year later. Taken together, these results suggest that individuals who increase participation in condomless sex following uptake of PrEP may be compensating for their additional STI risk in other ways, such as discussing STI status with sexual partners or increasing testing and treatment frequency. While it is encouraging to observed no mediated relationship, more research is needed in this area to better understand why some individuals continue to be at risk while others’ risk of STIs does not increase.

While we observed several important associations between risk behaviors and risk of STIs, our findings should be viewed in the context of their limitations. First, many of the variables relied on self-report measures and as such may be subject to recall biases. We benefited from the use of longitudinal data, however, we were lacking a history of STI treatment. Additionally, this sample was a community sample, as opposed to a probability sample, therefore findings may not generalize to the larger population of young MSM. Finally, while the RADAR study tested participants for both urethral and rectal STIs, few urethral STIs were found; thus, we limited this analysis to only rectal STIs, limiting the generalizability of our findings.

Even in the context of our limitations, we have demonstrated that no significant relationship between PrEP and STIs exists among this population of YMSM/TW, even when stratifying these results by race and ethnicity. Additionally, we observed an increase in condomless anal sex among PrEP users but not a subsequent increase in risk of acquiring an STI. Finally, we noted several risk behaviors and demographic characteristics associated with acquisition of either gonorrhea or chlamydia. These findings warrant further exploration, particularly in light of contrasting findings by other research groups. Future research should continue to assess longitudinal trends in risk of STI acquisition, particularly in the context of PrEP use and risk compensation as PrEP continues to become more widely adopted.