The Centers for Disease Control and Prevention (CDC; 2021b) recommends that sexually active men who have sex with men (MSM) test for STIs such as HIV, Syphilis, and Gonorrhea at least annually, regardless of condom usage every 3 to 6 months if they are at an increased risk (e.g., on pre-exposure prophylaxis [PrEP], having multiple sexual partners). Despite the elevated risk, MSM have suboptimal adherence to this recommended STI testing guidance (CDC, 2021b). For example, less than half (42%) of MSM who participated in the American Men’s Internet Survey reported receiving any STI test in 2017 (de Voux et al., 2019). Previous studies on STI testing adherence have mostly focused on the general MSM population or MSM who identify as single (i.e., not in a relationship), while sometimes overlooking the distinct and important subgroup of MSM: the non-single MSM (Hoff et al., 2012). Non-single MSM could be particularly vulnerable to STIs (Mitchell et al., 2012) since these individuals may engage in non-traditional relationships (e.g., non-monogamous, open relationships) and have multiple sex partners outside their primary relationship(s) (Purcell et al., 2014). While non-single MSM may be vulnerable to STIs, they also report lower testing rates than the general MSM population (Chakravarty et al., 2012). Specifically, nearly half of non-single HIV-negative MSM reported either not being tested for HIV since the relationship began or only testing when they felt at risk (Mitchell & Petroll, 2012). One possible explanation of this risk-behavior gap among non-single MSM could be that STI testing is often communicated and recommended to single MSM by healthcare providers, through public information, and by public health professionals rather than prioritizing MSM who are in a relationship. The current study seeks to examine how behavioral risk and demographic factors are associated with adherence to CDC’s STI testing recommendations among non-single MSM. We hope to contribute to the current literature by examining this often-overlooked subgroup of MSM and potential risk predictors to inform more tailored practice guidelines.

Risk factors

Following the CDC’s (2021b) STI testing guidelines, the current study examines three factors that are associated with greater STI risks. These factors, including taking PrEP, having had extra-relational sex, or having had condomless sex, are all associated with greater STI risks (Bavinton et al., 2021; Calabrese et al., 2018; Stupiansky et al., 2010). Non-single MSM who report these risk factors theoretically would adhere to CDC’s (2021b) guidelines, but the actual adherence associated with each risk factor either remains untested or yields mixed results among non-single MSM in the current literature.

PrEP uptake

PrEP is a prevention method – often in the form of a daily, oral medication – that reduces one’s risk of contracting HIV. Research emphasizes the importance for MSM PrEP users to follow STI testing adherence, given that overall MSM PrEP users may have lower risk perceptions of STI transmission (Ramchandani & Golden, 2019) and engage in more risky sexual behaviors (e.g., condomless sex with casual sex partners; Hevey et al., 2018; Werner et al., 2018). Routine STI testing is particularly important among non-single MSM who are on PrEP, as they may have lower risk perceptions of having condomless sex with an HIV-positive partner(s) in a serodiscordant relationship (Quinn et al., 2020) or causal sex outside the relationship (Bavinton et al., 2021). When providing PrEP, healthcare providers, per the CDC’s recommendations (2021a), usually schedule their patients for STI testing every six months, along with the required HIV testing and regular medical check-ups (e.g., for creatinine levels).

With such recommendations and/or services offered by the providers, one would expect that there would be a positive association between STI testing adherence and being on PrEP. Indeed, some research (e.g., Hevey et al., 2018) found that a majority of general MSM PrEP users from a clinic in Wisconsin took the recommended numbers of STI tests (i.e., 82% took the recommended number of Syphilis tests, and 67% took the recommended numbers of Chlamydia and Gonorrhea tests). However, some other existing research shows much lower STI testing adherence rates among PrEP users. For example, Schumacher et al. (2020) found that the STI testing adherence rates from a Maryland clinic only achieved 28.2% at six months after PrEP initiation and 41.5% at twelve months among the general MSM population. As most previous studies remain descriptive, we set to explore the potential positive associations between PrEP uptake and STI testing adherence. Given the limited previous research and its mixed results, we ask the following research question:

RQ1: How are PrEP uptake and STI testing adherence correlated among non-single MSM?

Extra-relational sex

Extra-relational sex refers to sex outside one’s primary partner(s) in a relationship (Calabrese et al., 2018). This definition is similar to having multiple sexual partners among individuals who identify as single; however, non-single MSM may have multiple primary partners (e.g., those in a monogamous triad relationship). Further, simply having multiple sexual partners might not necessarily be correlated with higher sexual risks among non-single MSM. Therefore, extra-relational sex is arguably a more accurate way to assess sexual risk factors within this particular population. Notably, extra-relational sex could be common among non-single MSM (Hoff et al., 2012; Mor et al., 2011). A large-scale study in Israel (n = 2,569) showed that more than half of non-single MSM surveyed had at least one concurrent casual sex partner outside their steady relationships, and 30% of them had unprotected sex with both their primary partner and their casual partner(s) in the past six months (Mor et al., 2011). Extra-relational sex can lead to higher STI risks (e.g., Lyons, 2017; Reidy et al., 2016). For example, research showed that heterosexual young adults who have extra-relational sex reported higher STI diagnoses compared to those who do not have sex extra-relational sex (Lyons, 2017). To our knowledge, no prior work has focused on the relationship between extra-relational sex and STI diagnoses among MSM.

In terms of STI testing adherence, previous studies mostly focused on having multiple sex partners as a risk factor and whether it was associated with STI testing adherence within the general MSM population. The results are, however, mixed: having multiple sexual partners could be associated with more frequent STI testing rates (Lachowsky et al., 2014) but less frequent STI testing rates in some cases (Carballo-Diéguez et al., 2014). Given that non-single MSM have not been extensively studied in the current literature, it might not be surprising that the research has not explored the relationships between extra-relational sex and STI testing yet within this population. Given that having extra-relational sex may be prevalent among non-single MSM, its association with STI testing adherence should be explored. To fill this research gap, we ask the following research question:

RQ2: How are extra-relational sex and STI testing adherence correlated among non-single MSM?

Condomless sex

Having sex without a condom is a risk factor for STI transmission. It is common for many non-single MSM to engage in condomless sex with their primary partners to express intimacy, trust, and commitment (Goldenberg et al., 2015). While condomless sex within a mutually monogamous relationship poses limited STI risks, sexual risks remain high for non-single MSM who have extra-relational sex or sex with a primary partner(s) with unknown STI status. Descriptive evidence from previous studies showed that a majority of MSM engage in condomless sex within their relationships regardless of their partners’ HIV/STI status (Mitchell & Petroll, 2012); over half of MSM who had extra-relational sex did not use a condom with a casual sex partner (Mitchell & Petroll, 2012). Therefore, it is recommended that non-single MSM who have condomless anal sex should adhere to the STI testing guidelines (i.e., every six months per CDC’s recommendations) regardless of relationship type.

However, previous studies, though limited, reported unpromising results regarding having condomless sex and STI testing adherence among general MSM (e.g., Stupiansky et al., 2010; Zhang et al., 2017). While one study showed that men who never use condoms are more likely to have STI tests than those who always use condoms (Stupiansky et al., 2010), the results did not examine whether such testing frequency adhered to the recommended guidelines (i.e., every six months) even though the likelihood was higher. Another study’s descriptive data, on the other hand, showed that only 23% of MSM who had condomless sex during the past three months took the recommended number of HIV tests (Zhang et al., 2017). To the best of our knowledge, however, only one study examined the relationship between condomless sex and STI testing among non-single MSM. The study showed that only one-third of non-single MSM who had condomless sex either within or outside of their relationships (during the previous three months) reported willingness to test for HIV only about once a year or when they perceived they were at risk (Mitchell & Petroll, 2012). Since no study specifically examined the associations between condomless sex and STI testing adherence among non-single MSM, we ask the following research question:

RQ3: How are condomless sex and STI testing adherence correlated among non-single MSM?

Demographic predictors

Research indicates that certain demographic factors (e.g., sexual orientation, race, age, marital status, education status, and living situations) were associated with STI testing adherence among general MSM (e.g., Jenness et al., 2019). For example, identifying as a bisexual MSM is negatively associated with lifetime HIV testing (Feinstein et al., 2019) and STI testing guideline adherence rates (Mirandola et al., 2016). Prior work has also suggested that MSM who identify as Black (Sullivan et al., 2014); are younger (Holt et al., 2012), married (Liu et al., 2021), or less educated (Daas et al., 2016); and live outside of gay-friendly metropolitan areas (Zablotska et al., 2012) or live in rural areas (Jones et al., 2022), reported lower STI and/or HIV testing adherence than their MSM counterparts. However, the existing literature has not examined these demographic factors and their relationships with STI testing adherence among non-single MSM, which arguably might differ from those in the general MSM population.

Non-single MSM relationship-level demographic predictors, such as relationship type (e.g., monogamous relationship or others) and length of the relationship, have not been specifically examined to the best of our knowledge. However, STI rates are higher among those in non-monogamous heterosexual relationships (Lehmiller, 2015; Winter & Satinsky, 2014). Moreover, individuals tend to believe their partners are STI-free, especially when they are in long-term relationships or monogamous relationships (e.g., Dillow & Labelle, 2014). This may decrease people’s sexual STI risk perceptions and, in turn, affect their STI testing adherence. Thus, we propose the following overarching research question:

R4: How are the relevant demographic factors and STI testing adherence correlated among non-single MSM?

Methods

In this study, we focus on risk and demographic factors that may impact STI testing adherence among non-single cis-gender MSM. The study is part of a larger research effort examining the relational, sexual, and behavioral dynamics among cis-gender male couples who are not in a long-distance relationship, and the variables used in this manuscript were not published or utilized in any previous work (Chen et al., 2024).

Procedures

We recruited individuals to participate in our study through LGBTQ + community centers and research listservs, social media, and Qualtrics respondent services. The recruiting message stated, “Are you in a gay, romantic relationship? Do you want to earn up to $XX? To participate in this online study, you and your partner must be 18 years of age or older, live in the United States, and not be in a long-distance relationship currently. Interested? Please sign up here using this link or by scanning the QR code.” The link and the QR code then led potential participants to several screening questions, followed by the online consent form. Participants were eligible if they identified as a cis-gender male in a relationship with another cis-gender male. Both partners had to live in the United States and not be in a long-distance relationship. Among the 1,436 individuals who initiated the survey, a total of 478 individuals were deemed eligible, completed the survey, and were appropriately compensated. After data quality checks, including completion rate issues, attention checks, and response validity checks (e.g., a participant indicated having anal sex 500 times a day), a total of 296 participants remained in the final sample.

Participants

The average age of the participants (n = 296) was 38.76 (SD = 12.53, Mdn = 36.00, Range: 19–77). We measured a total of eight relevant demographic variables based on the current literature, and they were participants’ age, race, sexual orientation, level of education, type of relationship, length of the relationship (months), type of residency, and LGBTQ-friendly residency. See Table 1 for detailed demographic information.

Table 1 Demographic information (n = 296)

Measures

Risk factors

We measured three relevant risk factors: PrEP uptake, sex with someone who is not a primary partner, and frequency of condomless anal sex when in a non-monogamous relationship; all measured within the time frame of the last 12 months. First, 72 respondents (24.3%) identified as PrEP takers. We then created a dichotomous PrEP uptake variable in which those who take PrEP (either daily or on-demand) were coded as one. We created a dichotomous condomless extra-relational sex variable, where those who reported having sex with someone other than the partner were coded as one (n = 82, 27.7%). Lastly, we measured how frequently the participant had condomless anal sex on a 5-point ordinal scale (0 = Never, 4 = Always). We then created a dichotomous condomless sex variable, where those who had condomless anal sex while not in a monogamous relationship were coded as one (n = 61, 20.6%).

Demographic factors

We selected a total of eight demographic risk factors based on the current literature, and they were participants’ age, race, sexual orientation, level of education, type of relationship, length of the relationship (months), type of residency, and LGBTQ-friendly residency. The average length of the relationships was 88.43 months (SD = 106.57, Mdn = 44.5, Range: 2 – 546). On average, participants reported that they lived in a relatively LGBTQ-friendly area (M = 6.95 out of 10; SD = 2.14, Mdn = 7.00). The other detailed descriptive information for these variables is presented in Table 1.

STI Testing Adherence

We asked how many months ago the participant was tested for STI(s), with the option to indicate that the participant had “never tested for STI(s) before.” In the final sample, 18 participants (8.7%) reported never being tested for STIs before. On average, those (n = 278; 91.2%) who had been tested were tested 15.36 months ago (SD = 31.99, Mdn = 6.00, Range: 0–210). We then computed a dichotomous STI testing adherence variable based on the CDC’s guidelines on STI testing for MSM. The CDC (2021b) recommended that MSM should be tested for STI annually regardless of risk and tested for STI every six months if the individual had increased risk (i.e., MSM on PrEP or if they or their sex partners have multiple partners). Thus, we computed a variable in which adhering to the CDC’s STI testing guidelines was coded 1, and not following the guidelines was coded as 0. Those coded as 0 included those (1) who were not tested within the 12 months (individuals who never had sex were excluded) or those (2) those who were not tested within the last six months if they were on PrEP or reported having condomless extra-relational sex. A total of 96 (32.4%) respondents did not adhere to the CDC’s STI testing recommendations.

Analysis plans

No outliers (i.e., scored +/- 3 standard deviations from the grand mean of the scale) were detected in all continuous variables using the univariate outlier analysis. Regarding the assumptions of the dataset, none of the correlations between the two variables exceeded 0.94. Subsequently, we calculated the variance inflation factor (VIF) to assess potential multicollinearity among the exogenous variables. The VIF values for all exogenous variables remained below 3, thereby signifying an absence of significant multicollinearity issues.

For the analysis, we transformed participant’s race into a dichotomous variable that dichotomously indicated racial minority (0 = White, 1 = Other races); sexual orientation into a dichotomous variable that dichotomously indicated being gay (0 = Other orientations, 1 = Gay); type of relationship into a dichotomous variable that dichotomously indicated monogamy (0 = Other types, 1 = Monogamous relationship); type of residency into two dichotomous variables: one dichotomously indicated living in a rural area (0 = No, 1 = Yes) and the other dichotomously indicated living in an urban area (0 = No, 1 = Yes). Age, level of education, the length of the relationship, and LGBTQ-friendly residency were treated as ordinal variables in the analyses. To answer all the research questions, we performed one multivariate logistic regression analysis from the dichotomous STI testing adherence onto the non-single MSMs’ PrEP uptake (RQ1), frequency of non-single MSMs’ extra-relational sex (RQ2), the non-single MSMs’ frequency of condomless anal sex (RQ3), and all demographic risk factors (RQ4). We used chi-square, degree of freedom (df), adjusted odds ratio (AOR), confidence interval of the AOR, and p-value to determine the correlations between STI testing adherence and risk factors. We further computed the crosstab descriptive statistics to compare the STI testing adherence rates among those participants who were coded as 1 (Yes) versus 0 (No) in the three risk factors. All analyses were performed using SPSS 27.

Results

R1 asked how PrEP uptake and STI testing adherence were associated among non-single MSM. We found that PrEP uptake (1 = yes, 0 = no) was positively and significantly associated with STI testing adherence (χ2 = 10.53, df = 1, AOR = 3.96, p < .01). This means non-single MSM who are PrEP takers were 3.96 times more likely to adhere to CDC’s STI testing guidelines. Moreover, the STI testing adherence rate among the PrEP takers was 87.5%, compared to 61.6% among the PrEP non-takers. The current study also explored how extra-relational sex (R2) and condomless sex (R3) were associated with STI testing adherence, respectively. Results showed that neither extra-relational sex (χ2 = 1.98, df = 1, AOR = 0.86, p = .16) nor condomless anal sex (χ2 = 1.26, df = 1, AOR = 1.07, p = .26) was significantly associated with STI testing. In other words, non-single MSM were not more likely to adhere to CDC’s testing guidelines even when they reported having extra-relational sex or condomless sex. Respectively, the STI testing adherence rate among those who reported extra-relational sex was 47.7%, compared to 57.8% among those who did not; the STI testing adherence rate among those who reported condomless sex while not in a monogamous relationship was 65.6%, compared to 62.5% among all other participants.

R4 asked how demographic factors and STI testing adherence were associated. Our results showed that race (χ2 = 5.65, df = 1, AOR = 2.21, p < .05), length of relationship (χ2 = 12.53, df = 1, AOR = 0.993, p < .001), and LGBTQ+ friendly residency (χ2 = 6.73, df = 1, AOR = 1.21, p < .01) were significantly associated with STI testing adherence. In other words, those non-single MSM who identify as non-White, are in a shorter relationship, and live in an LGBTQ-friendly neighborhood were more likely to adhere to CDC’s STI testing guidelines. On the other hand, age (χ2 = 0.26, df = 1, AOR = 1.01, p = .61), type of relationship (χ2 = 3.49, df = 1, AOR = 0.50, p = .06), sexual orientation (χ2 = 2.44, df = 1, AOR = 0.50, p = .12), level of education (χ2 = 0.144, df = 1, AOR = 1.05, p = .70), and type of residency (i.e., whether or not living in rural areas: χ2 = 0.40, df = 1, AOR = 0.91, p = .84; whether or not living in the urban area: χ2 = 1.57, df = 1, AOR = 1.50, p = .21) were not significantly associated with STI testing adherence. The results of the multivariate logistic regression model are presented in Table 2.

Table 2 Multivariate logistic regression model results

Discussion

Divergent subpopulations of non-single MSM

Overall, our results showed that STI testing adherence rates among non-single MSM (67.4%) were higher than the rates of the general MSM population reported in a previous study (de Voux et al., 2019). Such results appear to be promising and align with previous research regarding the dyadic and relational influences on voluntary testing among MSM couples (Mitchell, 2014). Previous intervention efforts, such as Testing Together, utilized this couple-based approach to promote STI testing among non-single MSM and showed some promising results (Johnson, 2012; Wei et al., 2014). However, when we look closer at some of the non-significant results and prior research, certain subgroups of non-single MSM might have been overlooked and require public health attention.

First, the adherence rates also remain descriptively low among those non-single MSM who reported extra-relational sex and/or condomless anal sex, yet arguably these are the MSM who have higher risks of being infected and transmitting STIs. There are two possible explanations regarding the gap between risks and testing adherence among these subgroups. First, these non-single MSM might have engaged in these higher-risk sexual behaviors in concealed or ex-parte manners. MSM in non-consensual non-monogamous (i.e., open) relationships reported the highest rates of condomless anal sex compared to those in consensual non-monogamous or monogamous relationships (Brady et al., 2013). Given the dynamics of such behaviors and unique relationships, these MSM might not get STI tested due to fear of being exposed and potential relational turbulence (Levine et al., 2018). Second, non-single MSMs who engaged in these higher-risk sexual behaviors were more likely to be high sensation seekers, both sexually and in general (DeAndrea et al., 2009). Higher sensation seekers, both sexually and in general, are more likely to seek riskier experiences and underestimate the perceived risks (Bancroft et al., 2003). Thus, it is possible that these non-single MSM are less likely to voluntarily test for STIs due to an underestimation of STI infection risks while concurrently seeking out riskier sexual behaviors.

Second, our results revealed that PrEP uptake was positively associated with STI testing adherence, and those who took PrEP adhered to CDC’s STI testing guidelines at a healthy rate. It is likely because PrEP is often recommended as part of a comprehensive HIV prevention package, which includes STI screening and other risk prevention activities (Scott & Klausner, 2016). It is also possible that non-single MSM who voluntarily take PrEP might be more conscious of their own sexual health, given that one of the primary beliefs that predicts PrEP uptake and adherence is taking responsibility for one’s sexual health for MSM (Dai & Calabrese, 2022; Dai & Harrington, 2021). However, PrEP has traditionally been marketed and promoted among single MSM, especially those who reported higher sexual risks (Pichon et al., 2022). In some cases, the messages related to PrEP could be perceived by non-single MSM as “threatening the trust and legitimacy of the relationship” and “undermining current prevention strategies,” such as condom use and STI testing (Starks et al., 2019, p. 157).

Lastly, the results of the significant associations between certain demographic factors and STI testing adherence perhaps show some gaps in our current public health efforts. First, our results showed that non-White participants were more likely to adhere to the testing guidelines. Racial disparities are prominent in STI incident rates in the United States (Williams et al., 2021), especially among Black MSM, but there is sparse research on racial differences in STI testing among non-single MSM. Limited previous research suggests that Black MSM were less likely to be tested in a clinical or non-profit setting compared to other races (Lauby & Milnamow, 2009). However, as this subgroup is underexamined in the literature, we believe more research is needed related to this finding. Second, our results showed that the length of the relationship was negatively associated with STI testing adherence. One possible explanation is that non-single MSM in longer relationships trust their partners more, assuming that their partners are not engaging in higher-risk sex outside the relationship (Lorenc et al., 2011). As a result, they may perceive a lower need for STI testing. However, the paradox lies between such assumptions and two potential compounding risk factors: (1) MSM couples are more likely to be non-monogamous, whether consensual or not, as they have been together longer (Philpot et al., 2018), and (2) MSM couples who have been together longer are more likely to perceive STI/HIV prevention messages as “threatening to intimacy and trust” (Starks et al., 2019). LGBTQ-friendly residency may provide more inclusive healthcare services (e.g., more LGBTQ-friendly signages) and other community-based services, which might be perceived as safer environments for non-single MSM to disclose their sexual behaviors and undergo STI testing (e.g., Qiao et al., 2018). In addition to promoting more LGBTQ-friendly practices and inclusive patient-provider communication in clinical settings (Waad, 2019), another practice to highlight is community-based STI prevention and testing events. Such testing and prevention efforts at LGBTQ-oriented events, such as Pride, have been shown to be particularly effective among MSM (Mdodo et al., 2014). However, these events are typically held in highly LGBTQ-friendly geographic locations, and many non-single MSM do not reside in these areas or have limited access to these LGBTQ-friendly community resources (Hasenbush et al., 2014; Rosenberger et al., 2014).

Practical implications

Overall, our results highlight practical implications to effectively promote STI testing adherence among overall non-single MSM, especially those who might be in certain higher-risk subgroups. Effective promotion could potentially be achieved through improved clinical practices, persuasive and tailored messaging, and effective promotion strategies.

Clinical practices

Healthcare providers might benefit from understanding the diverse relationship structures among MSM, as well as how such relational dynamics might influence sexual risks. Healthcare providers in clinical settings could provide non-single MSM patients with comprehensive guidances on STI testing expectations based on risk factors, regardless of the patient’s relationship types/statutes, shifting the focus from negative beliefs about intimacy and trust toward positive beliefs about their collective goals. By incorporating patient-provider communication that highlights new or more positive beliefs about behavior like STI testing, couples may be more likely to approve of STI testing overall (Calabrese & Albarracín, 2023). Communicating the collective goal to “routinely improve your health as a couple” or to “support the elimination of HIV/STI as a community,” may be particularly effective at changing MSM couples’ perspectives toward STI testing. Future studies could collect and incorporate data from providers to better triangulate the best practices and confirm the feasibility of these suggestions.

Tailored persuasive messages

The effectiveness of persuasive messages might greatly vary across different subgroups of non-single MSM, so strategies should be tailored (Covey et al., 2016). For example, social stigma around non-monogamy may lead to fear of judgment (Vaughan et al., 2019) and pressure to disclose the number of sexual partners to the provider, which might prevent MSM in non-monogamous relationships from getting routine STI testing. To address this issue, social norm-based persuasion that communicates STI testing as “prevalent and common” among non-monogamous MSM may be effective. Alternatively, MSM in monogamous relationships may not take routine STI tests because they perceive STI testing discussion as contentious as it may imply infidelity suspicion (Parker et al., 2014) or they perceive themselves as safe from STI in a monogamous relationship although it is objectively unwarranted (Conley et al., 2013). Therefore, it may be effective to frame an open discussion of STI testing positively as taking responsibility for the partner’s health, as well as one’s own wellbeing (Lorenc et al., 2011) and to include statistics about STI risks among MSM in monogamous relationships as a cautionary message.

Another viable promotion strategy could involve PrEP in future prevention messaging. Our findings, along with others, call for tailored and inclusive PrEP promotional messages among at-risk MSM regardless of relationship types. Future campaigns and clinical guidelines could combine messages that promote PrEP, STI testing, and consistent condom use among non-single MSM who have higher sexual risks determined by risk factors (not by relationship status/type, as previously stated). Inspired by Brady et al.’s (2013) example promotional messages of condom use among MSM couples and based on our prior research on PrEP (Dai & Calabrese, 2022), some effective messages could be “Couples that play together stay together, and we have the best threesome: PrEP, condom, and regular testing.” For those who are in non-consensual nonmonogamy, more effective messages could be, “He doesn’t ask what I’m doing when I’m not with him. I know we would have a piece of mind if I protect us with PrEP, condom use, and regular testing.”

Lastly, future interventions and promotion efforts could encourage MSM couples to establish a “negotiated safety agreement,” which involves the encouragement of using condoms during extra-relational sex and disclosing sexual activities honestly (Guzman et al., 2005). Such agreement can be reached and promoted at Couples Voluntary HIV Counseling and Testing (CVCT), which is described in detail by the previous literature (Sullivan & Stephenson, 2011).

Promotion strategies

It is important to communicate tailored persuasive messages using strategies that would maximize their effectiveness. First, one could communicate the risks associated with engaging in extra-relational or condomless sex on geosocial networking apps that non-single MSM might use to seek extra-relational sex (Dai, 2023). Second, based on our previous discussion on the associations between STI-testing adherences rates and LGBTQ-friendly residence, future prevention efforts should focus on extending such events in a more discreet and protected manner to those non-single MSM who do not reside in those LGBTQ-friendly areas. Previous research identified Internet platforms, bars, gyms, and adult video stores being the most popular venues for MSM in rural areas to have both sexual and community engagement (Horvath et al., 2006). While it might not be feasible to host testing events at some of these venues, these could be effective venues to communicate important public health prevention messages targeting non-single MSM, especially those in higher-risk subgroups.

Limitations and future research

This current research has several limitations that could inform future research directions. First, the current study examined STI testing adherence among non-single MSM by categorizing their last test timing as falling within or outside the recommended testing intervals. This approach took STI testing behavior as a single event and did not capture the regularity of their testing behavior over a longer period of time found in prior research (e.g., Mitchell & Horvath, 2013). We operationalized STI testing in the current manner as this follows the more recognized guidelines provided by the CDC (2021b), which arguably has a large reach to MSM, providers, public health professionals, and researchers. Second, given the scope of the current study, we did not examine how relational factors (e.g., relationship satisfaction) are associated with STI testing adherence among non-single MSM. Research has found that some relationship-based factors, such as relationship satisfaction and trust toward the primary partner, are associated with more regular STI testing among non-single MSM (Mitchell & Horvath, 2013). As relationships may have dyadic influences, future studies should study how relational factors would influence STI testing adherence among non-single MSM and further explore the dyadic and interdependent influences of such factors on testing behaviors. Third, the current study could not test more nuanced racial differences in STI testing adherence due to limited sample size, and future studies could retest and further examine any more nuanced racial/ethnic differences in STI testing among non-single MSM using stratified sampling with a larger sample size. Lastly, we utilized a multivariate approach as it is more parsimonious and more sensitive to the potential influences of other confounding exogenous variables. Our exogenous variables could be intercorrelated based on the current literature, so controlling them was essential to our analysis. However, there could potentially be statistically significant associations that the analysis did not reveal, which could be further explored by future studies.