Factors associated with chemsex in Portugal during the COVID-19 pandemic

Objective: to investigate the factors associated with the practice of sex under the influence of drugs (chemsex) among Portuguese men who have sex with men during the period of social distancing to prevent the COVID-19. Method: online survey applied in May 2020 to a sample of 1,301 participants living in Portugal, recruited according to Respondent Driven Sampling and via social media Facebook®. Descriptive and bivariate analyses were performed along with logistic regression to calculate adjusted Odds Ratio (ORa). Results: the prevalence of chemsex was 20.2%. The likelihood of practicing chemsex increased with group sex (ORa: 28.4, 95%CI 16.93–47.49); unprotected sex (ORa: 7.1 95%CI 4.57–10.99); the use of pre-exposure prophylaxis (PrEP) to prevent COVID-19 (ORa: 4.2, 95%CI 2.71–6.39) and COVID-19 testing (ORa: 1.9, 95%CI 1.15–3.10). Conclusion: the practice of chemsex among men who have sex with men during the COVID-19 pandemic in Portugal was very frequent and may support greater understanding of the role and impact of sexual behavior on the COVID-19 transmission rates and the current pandemic situation in Portugal.

consumed in isolation or combined, which increases the potential risk of overdose and chemical dependency among users (17) .
Depending on the substance used, the perception of risk and adoption of protective measures may be impaired (18) and as suggested by a multi-center study (11) , investigating the practice of chemsex among MSM during social distancing can provide important information regarding the emergence and rapid growth of new cases of COVID-19 in Portugal, a subject that has not been explored thus far.
In this context, this study's objective was to investigate the factors associated with the practice of sex under the influence of drugs (chemsex) among Portuguese men who have sex with men during the period of social distancing to prevent the COVID-19.

Method Study design
This online survey is part of a macro-project called

Study setting and period
The study was conducted in 15

Sampling and participants
A standard sampling calculation for proportions was performed using G Power (version 3.1.9.7) (19) , considering the population of Portuguese men over 18 years of age with an assumed prevalence of 50% to maximize the sample, also considering it is a new phenomenon and there were no data concerning its prevalence) (20) with a tolerable standard error of 3% and a confidence level of 95%, the final sample was 1,301 MSM.

Data collection
The participants were recruited using snowball sampling adapted to the virtual environment (11)(12)21) . In this method, the participants are responsible for recruiting other individuals with similar characteristics using social media. Fifteen MSM with different social and economic characteristics (commonly related to selection bias) were initially selected considering: country's region, race (Caucasian and non-Caucasian), age (young, adult or elderly) and educational level. These participants, called seeds, received a link that granted access to the survey after they provided their consent to participate. They were asked to invite other MSM from their social network to participate. Two of the most popular worldwide geo-based dating apps (Grindr and Hornet) were used to identify the initial seeds (21) . The individuals were approached via online chat and data were collected by adapting the Time Location Sampling (TLS) technique to the virtual environment. The researchers purposely modified their location in the application for the regions selected to access a given area's users, following the methods previously described (22)(23)(24) .
The researchers also promoted the survey on Facebook ® , directing it to the MSM population aged from 18 to 60 years old (a Facebook-imposed age restriction), using a fixed post on the official page of the survey (https:// www.facebook.com/taafimdeque/), accompanied by an electronic link that granted access to a Free and Informed Consent Form (FICF) and the survey's questionnaire. This procedure is essential to ensure that MSM living outside large cities or metropolitan areas are included (23) .
Only individuals who identified themselves as men (cisgender or transgender), 18+ years old and residing in Portugal were included; non-Portuguese speakers or tourists were excluded.
The online form was hosted by a specific data collection site that enabled only one response per IP (internet protocol), i.e., only one response per electronic device, to avoid selection bias. The form was content validated (25) by three expert/specialist in the topic and was divided into four sections with 46 questions, most were multiple-choice questions, and some were mandatory; without answering those questions, the participant could not proceed with the questionnaire.
The questions addressed social and demographic information (age, education, gender identity, housing and type of relationships, according to prior studies) (10)(11)(26)(27) , mental health (self-perception of stress and strategies to cope with the pandemic), behaviors adopted to protect against the pandemic (social distancing, In this study, the participants were asked whether they had consumed drugs immediately before and/or during sexual intercourse since restrictive measures had been imposed in Portugal. Those who answered "yes" were asked to check the drugs consumed in a multiplechoice list. Considering there is not a universally accepted definition of what drugs compose the "chemsex phenomenon" (28)(29) , in this study, both legal and illegal drugs that alter an individual's perception and lead to the neglect of protective measures against SARS-CoV-2 were included: alcohol; opioids (e.g., heroin, codeine and other synthetic substances); cannabinoids (marijuana, hashish, synthetic cannabinoids, spice); sedatives or hypnotics (barbiturates, benzodiazepines); cocaine; stimulants (e.g., amphetamines); hallucinogens (LSD; ecstasy); sex-performance-enhancing drugs (poppers) and others. To facilitate the identification and discrimination of drugs, some drugs were identified by other nomenclatures commonly used in Portugal.
We also included an open category, "other drugs," in which the participants could specify the drug used if it was not already listed.
Social distancing measures (also called, by the participants as social isolation and/or quarantine) were defined as avoiding personal contact for non-essential activities with people outside one's shelter (10) and an assessment and measurement of compliance to measures followed the literature's guidelines (10,26,(30)(31) .

Data analysis and treatment
Data were analyzed using the Statistical Package for the Social Sciences -SPSS v. 26. Descriptive statistics such as absolute and relative frequencies were considered.
Bivariate and multivariate analyses were performed with the chemsex practice being the dependent variable and sociodemographic variables, sexual behavior and strategies to prevent COVID-19 as the independent Rev. Latino-Am. Enfermagem 2021;29:e3474.
variables. Tolerance coefficients and VIF (Variance Inflation Factor) were verified to assess multicollinearity and proceed with the multivariate analysis. Odds Ratio (OR) and adjusted Odds Ratio (aOR) were used to measure the intensity of association between chemsex and associated factors considering their respective 95% confidence intervals. The model was developed using the stepwise method and the best goodness of fit and performance, according to the Hosmer and Lemeshow test, were considered.

Ethical aspects
The Institutional Review Board at the Instituto de  Table 1. testing (p<0.001), as shown in Table 2.  (Table 3).

Discussion
The data from this study show a high frequency of chemsex (20.2%) in this population, considering the results reported by a research addressing this same population before the pandemic (9.2%) (29) . In this sample, one in every four MSM engaged in casual sex using at least one substance capable of changing cerebral functioning and altering an individual's mental and psychological state.
One finding that illustrates this situation is that the practice of anal sex without condoms increased 7.1 times the likelihood of an individual engaging in chemsex. This piece of information reinforces that MSM who practice chemsex might be more willing to engage in risky behavior.
The use of illegal or legal drugs in a sexual context leads to decreased discernment among vulnerable populations such as MSM, considering they are more likely to acquire HIV and STIs, highlighting the risks they are exposed to (29) . In a context of the coronavirus pandemic, the likelihood of new cases emerging among the Portuguese population increase due to sexual behavior and a high risk of acquiring the COVID-19 (14) .
This study's results corroborate previous studies (38 -41) , which report that the use of drugs in a sexual context PrEP neglecting the effective protective measures (45) recommended by sanitary agencies during the social isolation and being infected with SARS-CoV-2.
Another questionable measure, but which increased the likelihood of MSM engaging in chemsex, is based on the COVID-19 testing as those who reported testing for COVID-19 were, almost, 2 times more likely to engage in chemsex than those who did not.
We believe that the testing may lead to a false sense of security. A belief that individuals who tested positive for COVID-19 acquire immunity against the disease, hence would not be re-infected, may have led MSM to take more risks. However, this is a misleading belief, considering that it is unknown how immunological memory (46)(47)