For sample definition we used a modification of time location sampling (TLS). This technique seeks to approach probabilistic sampling by mapping the universe of places where the target population can be found in large numbers and then randomly selecting a specific day, time and place for recruitment and systematically selecting participants from that location.15 Volunteers who were specifically approached through the applications and who agreed to respond to the online questionnaire were considered. The inclusion criteria were: identified as a cisgender male; being 50 years or older; and being online at the time of data collection. Users who did not reside in Brazil were excluded.

To find participants, four apps commonly used by MSM were selected: Grindr®, Hornet®, Scruff® and Daddy Hunter®.8 The computer-assisted self-interview (CASI) technique was used for data gathering.15 The participants were approached through the selected apps for four consecutive months (February to May of 2017), in the afternoon, evening and at night. The participants were informed about the research objectives and the importance of their participation. After gaining consent, the researchers shared the hyperlink to the survey form, where the participants answered specific questions of interest to this study.

To cover the participants’ social and demographic characteristics, sexual behavior, and health information, the questionnaire was divided into four sections, which included both mandatory and optional questions: personal information; sociocultural information; health issues; and sexual practices. The system only allowed participants to proceed to the next section if all the mandatory questions were answered. Furthermore, the questionnaires were only computed if, at the end, all the conditions were met. Incomplete surveys were not saved by the system.

To answer the questionnaire, participants provided their email address, preventing duplicated entries. If a participant was unwilling to participate, the next online user was approached. Recruitment was conducted by two adult cisgender male researchers who are experts in the studied field. They created accounts with public profiles (open, with a photo) in the apps to gain access to the users.

The analysis of the data was based on the adopted vulnerability framework.13,14 The research variables were grouped according to the three domains of vulnerability:

• 1)

  Individual: age, marital status, living situation, number of partners, type of sexual partnership established, sexual practices (sex positions, consistent use of condoms, bareback sex, group sex), forms of prevention (condoms, withdrawal, no penetration), chemsex (using drugs during sexual relations), use of erectile dysfunction drugs, and the presence of STIs;

• 2)

  Social: educational level, sexual orientation, religion and going to saunas; and

• 3)

  Health care (programmatic): being familiar with post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP); going to healthcare services; and prior testing for HIV.

Variables that allowed more than one response, such as prevention and sexual position, were presented to the participants in multiple-choice format.

Descriptive analysis was employed to describe the vulnerability factors and other factors of interest, for both the numerical and categorical variables. The data were analyzed using IBM® SPSS version 23.0. Associations between positive serological status for HIV and the categorized vulnerability factors were assessed using the Pearson’s chi-squared test and Fisher’s exact test, with a 0.05 significance level. To construct the confidence interval, the reliability was set at 95%. The outcome of interest was positive HIV status, which was assessed using the question: Do you know your HIV status? The answer options were: "I am HIV positive", "I am HIV negative", and "I do not know/I'm not sure".

Multivariate logistic model was adopted to produce the adjusted odds ratios (ORa), considering the factors that presented statistical significance in univariate analysis.

The study was approved by the CEP/CONEP system (no. 1.523.003) and strictly complied with all the ethical precepts that guide research with human subjects. The participants read the free and informed consent form and then signed it, indicating their agreement with the proposed objectives and willingness to participate in the study. This consent was applied and obtained online.

Although most of the social vulnerability factors related to app use did not present statistical significance in the multivariate analysis, it is important to discuss these findings, since they differed from other studies24 and have direct implications for the sexual practices of MSM. Analysis of app use showed characteristics that clearly defined differences between the consumption of different generations of MSM, which can contribute to the understanding of some aspects of these men’s vulnerability. For example, in relation to reasons for using these apps, younger MSM used them for sexual purposes (64.7%),8 a lower rate than that found among MSM aged 50 years or older (88.0%). This may reflect the importance of this tool in the daily lives of the participants and corroborates other studies indicating that older adults tend to better adopt technologies that serve specific objectives.25,26

These factors can affect the sexual behavior of users because the more an app is used, the greater the familiarity with its tools, and the greater the ease and speed of finding partners, as evidenced by previous studies.5,27,28 This familiarity can influence the speed and ability of establishing partnerships. A study revealed that the average time of use of these apps among youths was 50% less than among participants of the present study (12 months and 27 months, respectively).5 Accordingly, the number of partnerships established through the apps was also higher in the present study (2.7 partners in the last 30 days) when compared with other studies with younger MSM who used apps in the United States (2.03 and 1.9).29,30

It is important to highlight that the safety that comes from the anonymity and discretion provided by the apps is useful for some MSM, especially those who identify themselves as heterosexual or bisexual and who do not choose to disclose their affective and sexual behavior to protect themselves against violence, stigma, discrimination, homophobia and family rejection.31,32 The use of new digital technologies makes it easier to contact friends and establish new relationships (affective and sexual), and this is constantly being updated. Consequently, new issues emerge, such as relationships between older and younger MSM.33

It is worth remembering that “believing that apps help prevent HIV infection,” that is, believing that using apps to establish partnerships can somehow help prevent HIV infection, was statistically associated with being a protecting factor against HIV infection. In other words, the participants perceived that this form of digital interaction mediated by social media can somehow help prevent infections.

The sex position preferred by men, whether insertive or receptive, is an important factor in the sexual experience of MSM. Preference for the insertive position (insertive-only or versatile-insertive position) is associated with an image of greater masculinity, which is highly valued in gay sociability,34–36 and also presents a lower risk of infection by HIV and STIs.20,37

Even though the participants in the present study reported preferring the insertive position, other risk factors for HIV (Table 2) presented high frequency, which can increase the chances of transmission of HIV.38 These results were similar to those found in the literature, where many of the findings of the present study (erection difficulties, using condoms only with casual partners and not with steady partners or when engaging in chemsex) are factors associated with HIV infection among MSM.39,40

However, there is also evidence that people with undetectable HIV viral load, or who use PrEP, can maintain safe sexual relations even with serodiscordant partners.41 The repertoire of sexual practices involves factors from the individual dimension of vulnerability, issues that must be addressed to prevent HIV and STIs,42 because “not being familiar with PEP,” “having a partner with HIV,” and openness to “having relations with someone with HIV” and “chemsex” emerged as significantly associated with HIV infection in this study.

Chemsex is a differentiated, non-unitary and intentional sexual behavior that combines sexual activity and consumption of psychoactive substances. This is an important factor associated with positive HIV status, and has recently been addressed by the literature, which has identified an increase in this behavior among MSM.43 Among the reasons for this increase are growing capacity for engaging in the desired form of sex (increased arousal and libido, sexual confidence and increased sexual stamina), coupled with the improvement of qualities valued in sex, such as intensified sensation, reduced inhibitions, and greater ease of having sexual adventures.44

These effects are due to the substances used in chemsex, which provide men with the ability to improve their performance and sexual experiences, increasing arousal, endurance, and pleasure. For older men, the invigorating effect of these substances seems to be the main motivation for their use, enabling improved sexual performance that corresponds to the ideals of masculinity shared by the gay community, especially when having relations with younger partners.45

In Brazil, MSM face difficulties when accessing health services because of issues relative to stigma and social violence, in addition to discrimination suffered in health services.46 Even though a set of national health policies is directed toward the LGBT community,47 effective implementation of these services and reducing discrimination are still a challenge for the Brazilian Unified Health System.48 The results of the present study showed that “visiting health services at least once a year” was a protective factor against HIV infection, which reinforces the importance of improving access to health services for these men.

One of the important issues in the context of the HIV epidemic that still need to be addressed is late diagnosis of HIV infection among MSM,46 especially those over 50 years old,49,50 since this is an important marker for access to HIV and STI prevention strategies in health services.46,51 Programmatic vulnerability is associated with barriers to access to health services, which are still discriminatory environments for MSM, in addition to flaws in prevention policies, since dissemination of and access to these services and supplies for MSM is still notably limited.

It is imperative that Brazilian society and public health managers face the reality of the vulnerability of MSM presented by various studies in terms of the HIV and Aids epidemics. It is urgent that existing health policies be implemented, and efforts be made to strengthen prevention and intervention actions that effectively reduce the spread of HIV and Aids in Brazil.

The present study has some limitations: a convenience sample consisting of MSM aged 50 years or older was used; a portion of the key variables for the study (testing and HIV status) were self-reported; incomplete responses were not saved in Google Forms; and the finding that the majority of participants in this study had a high level of education.

Furthermore, the study was limited to reporting findings for a specific population who used mobile social networks for given purposes, which can influence results and hinder generalizations about the MSM population over 50 years who do not use these apps. Much of the discussion was based on research involving younger MSM, due to lack of research with MSM 50 years old or older who are users of dating apps.

Despite these limitations, the results effectively reflect important aspects of individual, social and healthcare vulnerabilities of MSM aged 50 years and older in Brazil.