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Background: Drug overdose persists as a leading cause of death in the United States, but resources to address it remain limited. As a result, health authorities must consider where to allocate scarce resources within their jurisdictions. Machine learning offers a strategy to identify areas with increased future overdose risk to proactively allocate overdose prevention resources. This modeling study is embedded in a randomized trial to measure the effect of proactive resource allocation on statewide overdose rates in Rhode Island (RI). Methods: We used statewide data from RI from 2016 to 2020 to develop an ensemble machine learning model predicting neighborhoodlevel fatal overdose risk. Our ensemble model integrated gradient boosting machine and super learner base models in a moving window framework to make predictions in 6-month intervals. Our performance target, developed a priori with the RI Department of Health, was to identify the 20% of RI neighborhoods containing at least 40% of statewide overdose deaths, including at least one neighborhood per municipality. The model was validated after trial launch. Results: Our model selected priority neighborhoods capturing 40.2% of statewide overdose deaths during the test periods and 44.1% of statewide overdose deaths during validation periods. Our ensemble outperformed the base models during the test periods and performed comparably to the best-performing base model during the validation periods. Conclusions: We demonstrated the capacity for machine learning models to predict neighborhood-level fatal overdose risk to a degree of accuracy suitable for practitioners. Jurisdictions may consider predictive modeling as a tool to guide allocation of scarce resources. [ABSTRACT FROM AUTHOR]

Background: The United States is in the midst of an opioid overdose crisis. Little is known about the role of environmental factors in increasing risk of fatal opioid overdose.Methods: We conducted a case-crossover analysis of 3,275 opioid overdose deaths recorded in Connecticut and Rhode Island in 2014-2017. We compared the mean ambient temperature on the day of death, as well as average temperature up to 14 days before death, to referent periods matched on year, month, and day of week.Results: Low average temperatures over the 3-7 days before death were associated with higher odds of fatal opioid overdose. Relative to 11°C, an average temperature of 0°C over the 7 days before death was associated with a 30% higher odds of death (odds ratio: 1.3; 95% confidence interval, 1.1, 1.5).Conclusions: Low average temperature may be associated with higher risk of death due to opioid overdose. [ABSTRACT FROM AUTHOR]

Sex tourism affects the sexual health of tourists and locals with whom they interact. However, a few studies have examined whether sex tourism is a risk factor for the acquisition of HIV and other sexually transmitted infections among men who have sex with men, and no such studies have been conducted in Western Europe. Almost 28% of our respondents reported engaging in sex tourism in their lifetime. Sex tourism was associated with an elevated risk of engagement in condomless receptive anal intercourse, use of alcohol/drugs during sex, participation in group sex, and an elevated risk of diagnosis with any type of sexually transmitted infection over the previous year, specifically gonorrhea and chlamydia. Research with men who have sex with men who engage in sex tourism should explore high-risk sexual behavior during sex tourism and also the feasibility and acceptability of the use of episodic pre-exposure prophylaxis for short periods of participation in elevated risk behaviors by tourists and local sex partners. [ABSTRACT FROM AUTHOR]

Background Geosocial-networking smartphone applications (apps) have been used increasingly by men who have sex with men (MSM) to meet new sexual partners. The purpose of this study was to examine associations between contexts of app use (e.g. using apps when drinking) and condomless anal intercourse among a sample of MSM who use these apps.Methods: MSM (n=174) in New York City were recruited through Grindr, a geosocial-networking app popular among MSM, using broadcast advertisements asking MSM to complete an Internet-based survey about their app use and sexual behaviours. Log-binomial regression models were fit to assess the association between each of the six app-use contexts (e.g. using apps when lonely, when drinking) and engagement in condomless insertive and receptive anal intercourse with one or more partners in the past 3 months.Results: Engagement in condomless receptive and insertive anal intercourse with one or more partners in the preceding 3 months was common (39.7% and 43.1% respectively) and was associated with several app-use contexts. For example, significant associations (P<0.05) were observed between alcohol and other drug use when using these apps and engagement in condomless receptive and insertive anal intercourse.Conclusion: Given that 57.5% of respondents had engaged in condomless anal intercourse in the preceding 3 months and the associations of app-use contexts with condomless sexual behaviours, these findings suggest that reductions in substance use may lead to safer sexual practices among MSM who use apps to meet sexual partners. [ABSTRACT FROM AUTHOR]

Background This study explored the relationships between participation in group sex and risk for HIV and other sexually transmissible infections (STIs).Methods: An anonymous online survey collected data from 580 gay and bisexual men using a mobile sex and dating application in Paris, France. Logistic regression analyses were conducted, which controlled for HIV status, HIV pre-exposure prophylaxis (PrEP) use and participants' sociodemographic characteristics.Results: Compared with men with no recent group sex experience, those reporting group sex in the 3 months before the survey (30.7% of the sample) were more likely to have had condomless receptive anal sex at least once in the same period [adjusted odds ratio (aOR)=1.6, 95% confidence interval (CI)=1.1-2.4, P = 0.02], condomless insertive anal sex (aOR=2.0, 95%CI: 2.4-8.7, P < 0.001) and substance use before or during sex (aOR=1.6, 95%CI: 1.1-2.3, P = 0.02). Even when controlling for condom use, men involved with group sex were more likely to be have been diagnosed with a bacterial STI in the previous year (aOR=2.1, 95%CI: 1.3-3.3, P = 0.002).Conclusions: Group sex remains a useful marker of risk among gay and bisexual men, but research is needed that moves beyond individual practice in order to assess the epidemiological networks comprising group sex and the risks they pose relevant to HIV and other STIs. [ABSTRACT FROM AUTHOR]

Geosocial-networking smartphone applications such as Grindr can help men who have sex with men (MSM) meet sexual partners. Given the high incidence of HIV in the Deep South, the purpose of our study was to assess HIV risk and preexposure prophylaxis (PrEP) awareness and use in a sample of HIV-uninfected, Grindr-using MSM residing in Atlanta, Georgia ( n = 84). Most ( n = 71; 84.6%) reported being somewhat or very concerned about becoming HIV infected. Most ( n = 74; 88.1%) had been tested for HIV in their lifetimes. About three fourths ( n = 65; 77.4%) were aware of PrEP, but only 11.9% currently used the medication. HIV continues to disproportionately impact MSM and represents a significant source of concern. As the number of new infections continues to rise, it is important to decrease risks associated with acquisition and transmission of HIV by increasing rates of HIV testing and the use of biobehavioral interventions such as PrEP. [ABSTRACT FROM AUTHOR]

• Compared modeled networks to that observed in an HIV outbreak among PWID in Indiana. • Our model was comparable to the observed with respect to several network metrics. • Our model was able to reproduce outbreaks of comparable size to the observed data. • Our simulated networks had incomparable values of transitivity. As HIV incidence among people who inject drugs grows in the context of an escalating drug overdose epidemic in North America, investigating how network structure may affect vulnerability to rapid HIV transmission is necessary for preventing outbreaks. We compared the characteristics of the observed contact tracing network from the 2015 outbreak in rural Indiana with 1000 networks generated by an agent-based network model with approximately the same number of individuals (n = 420) and ties between them (n = 913). We introduced an initial HIV infection into the simulated networks and compared the subsequent epidemic behavior (e.g., cumulative HIV infections over 5 years). The model was able to produce networks with largely comparable characteristics and total numbers of incident HIV infections. Although the model was unable to produce networks with comparable cohesiveness (where the observed network had a transitivity value 35.7 standard deviations from the mean of the simulated networks), the structural variability of the simulated networks allowed for investigation into their potential facilitation of HIV transmission. These findings emphasize the need for continued development of injection network simulation studies in tandem with empirical data collection to further investigate how network characteristics played a role in this and future outbreaks. [ABSTRACT FROM AUTHOR]

• Most studies investigating the role of neighborhoods in HIV-related outcomes among men who have sex with men (MSM) exclusively focus on the residential environment. • Spatial mobility was documented with both self-reported survey data and objective GPS data, which provided uncorrelated information. • Almost two-thirds (62.9%) of participants' GPS points were recorded in NYC ZIP code tabulation areas within the highest quartile of HIV prevalence. • Compared to males, it was found that transfemale, genderqueer, and other MSM spent a much higher fraction of their non-home GPS time in high HIV prevalence areas. The purpose of this study was to examine and quantify spatial mobility among HIV-negative young men who have sex with men (YMSM) within and across high prevalence HIV neighborhoods in New York City (NYC). We completed an analysis with global positioning system (GPS) and survey data to quantify spatial mobility for participants enrolled in the P18 Neighborhood Study (analytic n = 211; 83.4%). Spatial mobility was documented with self-reported survey data and objective GPS data, which was uncorrelated. Nearly one-quarter of participants (26.1%) said that they consider the neighborhood in which they currently live to differ from the neighborhood in which they had sex most frequently. In addition, 62.9% of participants' GPS points were recorded in NYC ZIP Code Tabulation Areas within the highest quartile of HIV prevalence. Future studies of YMSM populations should be conducted to examine how environments beyond the residential neighborhood can influence sexual health, which may guide HIV prevention services. [ABSTRACT FROM AUTHOR]

Background: Geosocial-networking apps like Grindr have been used increasingly among men who have sex with men (MSM) to meet anonymous partners. These mobile dating apps employ global positioning system technology to facilitate connections with other users based on their current location. These new technologies have generated quicker and easier modes for men who have sex with men to meet potential partners based on attraction and physical proximity. Objective: The aim of this study is to describe geosocial-networking app use and recent sexual behaviors of MSM in the Atlanta metropolitan statistical area. Methods: Our sample was recruited from Grindr, the most commonly used of these mobile apps among MSM, using broadcast advertising. Advertisements were displayed over the course of a 72-hour period and participants were directed to a Web-based survey. Results: In total, 604 men clicked through the advertisement, and 92 users completed the survey. One-third (38.0%) of the men reported using these mobile apps to meet new sexual partners, and one-fifth (18.5%) used them to "kill time" when bored. Men reporting currently being in a relationship were less likely to report using these mobile apps to meet other MSM to date or to find a boyfriend or romantic partner, but more likely to report using these mobile apps to meet other MSM to have sex, X224=12.1, P=.016. Respondents had current accounts on 3.11 mobile apps (SD 1.84) on average, with Grindr being the most common (100%), followed by Scruff (52.5%), and Jack'd (45.7%). Most men were most active in the late night (40.2%), and on weekdays (64.1%). Each day, on average, men reported opening these mobile apps 8.38 times (SD 8.10) and spent 1.31 hours (SD 1.15) on these mobile apps. The age respondents began using these mobile apps was associated with the age at their first instance of insertive anal sex (r80=.527, P<.001) and receptive anal sex (r76=.527, P<.001). Conclusions: These findings suggest that MSM use multiple mobile apps and spend significant time on them. For these reasons, HIV prevention interventions could be delivered on these mobile apps. [ABSTRACT FROM AUTHOR]