Time-location Sampling Survey Research Articles

Injecting drug use during sex (known as “slamming”) among men who have sex with men: Results from a time-location sampling survey conducted in five cities, France

BackgroundIn the last decade, European cities saw the development of “slamming,” a practice related to chemsex that combines three elements: a sexual context, psychostimulant drug use, and injection practices. Epidemiological data on this practice is still sparse and media attention might have unintentionally distorted the size of this phenomenon. Therefore, we aimed to estimate the prevalence of men practicing slam and to identify factors associated with this practice. MethodsWe used data from the Prevagay 2015 bio-behavioral survey to estimate the prevalence of slamming practices. A time-location sampling was performed among gay-labeled venues in five French cites. Behavioral information was recorded using a self-administered questionnaire. The HIV and HCV serostatus were investigated using ELISA tests on dried blood spots. The factors associated with slamming were assessed using a multiple logistic regression. We applied a weighting mechanism to enhance the generalizability of the estimates. ResultsAmong the 2646 men who have sex with men (MSM) included in our study, 3.1% reported slamming at least once during their lifetime (95% confidence interval (CI) = 2.2–4.3) and 1.6% (95% CI = 1–2.3) said they participated in a slamming session in the last 12 months. In the multivariate analysis, both HCV and HIV biological status were strongly associated with practicing “slam” in the last 12 months (OR = 13.37 (95% CI = 3.26–54.81) and 4.73 (95% CI = 1.58–14.44), respectively). Furthermore, a ten-point decrease in mental health scores was linked with the practice with an OR of 1.37 (95% CI = 1.08–1.73), indicating poorer mental health. ConclusionEven though slamming seems to involve a relatively small proportion of MSM, the vulnerability of this sub-group is high enough to justify setting up harm reduction measures and specific care. Training health professionals and creating services combining sexual health and drug dependence could be an effective response.

Changes in Prevalence of HIV or Syphilis among Male Sex Workers and Non-Commercial Men Who Have Sex with Men in Shenzhen, China: Results of a Second Survey.

BackgroundA previous time-location sampling survey (TLS) was performed in 2008 to evaluate the HIV or syphilis infection rate among male sex workers (MSWs) and non-commercial men who have sex with men (ncMSM) in Shenzhen, China. This is a second TLS performed in 2014. This article describes the findings and changes in the prevalence of HIV and syphilis.MethodsTLS was used to collect information as a second cross-sectional survey to an earlier TLS assessment. Data on behavior (e.g., sexual history and sexual behavior) were analyzed. Blood specimens were drawn for HIV and syphilis testing. To determine the changes in the prevalence of HIV and syphilis, we analyzed these results and compared them to the results of our first survey.ResultsA total of 965 participants were recruited, including 489 MSWs and 476 ncMSM. Overall, the prevalence of HIV was 9.7%: 2.9% for MSWs and 16.8% for ncMSM (P<0.001). 10.9% of the 965 participants tested positive for syphilis: 4.5% among MSWs and 17.4% among ncMSM (P<0.001). The HIV prevalence in MSWs decreased from 4.5% in 2008 to 2.9% in 2014 (P = 0.143) but increased in ncMSM (7.0% in 2008 vs 16.8% in 2014, P<0.001). Decreased syphilis rates were observed in both MSWs (12.9% in 2008 vs 4.5% in 2014, P<0.001) and ncMSM (20.2% in 2008 vs 17.4% in 2014, P = 0.221).ConclusionsOverall, there was a decline in the prevalence of HIV and syphilis in MSWs but not in ncMSM. The study indicated the need for continued efforts to improve public health, particularly to counter the rising rate of HIV in ncMSM.

Bio-behavioural HIV and STI surveillance among men who have sex with men in Europe: the Sialon II protocols.

BackgroundGlobally, the HIV epidemic continues to represent a pressing public health issue in Europe and elsewhere. There is an emerging and progressively urgent need to harmonise HIV and STI behavioural surveillance among MSM across European countries through the adoption of common indicators, as well as the development of trend analysis in order to monitor the HIV-STI epidemic over time. The Sialon II project protocols have been elaborated for the purpose of implementing a large-scale bio-behavioural survey among MSM in Europe in line with a Second Generation Surveillance System (SGSS) approach.Methods/DesignSialon II is a multi-centre biological and behavioural cross-sectional survey carried out across 13 European countries (Belgium, Bulgaria, Germany, Italy, Lithuania, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, and the UK) in community settings. A total of 4,966 MSM were enrolled in the study (3,661 participants in the TLS survey, 1,305 participants in the RDS survey). Three distinct components are foreseen in the study protocols: first, a preliminary formative research in each participating country. Second, collection of primary data using two sampling methods designed specifically for ‘hard-to-reach’ populations, namely Time Location Sampling (TLS) and Respondent Driven Sampling (RDS). Third, implementation of a targeted HIV/STI prevention campaign in the broader context of the data collection.DiscussionThrough the implementation of combined and targeted prevention complemented by meaningful surveillance among MSM, Sialon II represents a unique opportunity to pilot a bio-behavioural survey in community settings in line with the SGSS approach in a large number of EU countries. Data generated through this survey will not only provide a valuable snapshot of the HIV epidemic in MSM but will also offer an important trend analysis of the epidemiology of HIV and other STIs over time across Europe. Therefore, the Sialon II protocol and findings are likely to contribute significantly to increasing the comparability of data in EU countries through the use of common indicators and in contributing to the development of effective public health strategies and policies in areas of high need.

Design-based inference in time-location sampling.

Time-location sampling (TLS), also called time-space sampling or venue-based sampling is a sampling technique widely used in populations at high risk of infectious diseases. The principle is to reach individuals in places and at times where they gather. For example, men who have sex with men meet in gay venues at certain times of the day, and homeless people or drug users come together to take advantage of services provided to them (accommodation, care, meals). The statistical analysis of data coming from TLS surveys has been comprehensively discussed in the literature. Two issues of particular importance are the inclusion or not of sampling weights and how to deal with the frequency of venue attendance (FVA) of individuals during the course of the survey. The objective of this article is to present TLS in the context of sampling theory, to calculate sampling weights and to propose design-based inference taking into account the FVA. The properties of an estimator ignoring the FVA and of the design-based estimator are assessed and contrasted both through a simulation study and using real data from a recent cross-sectional survey conducted in France among drug users. We show that the estimators of prevalence or a total can be strongly biased if the FVA is ignored, while the design-based estimator taking FVA into account is unbiased even when declarative errors occur in the FVA.

High HIV Prevalence among Men who have Sex with Men in a Time-Location Sampling Survey, São Paulo, Brazil.

We conducted a time-location sampling sero-behavioral surveillance survey of men who have sex with men (MSM) in São Paulo, Brazil, the largest city in Latin America and the Southern Hemisphere (N=1,217 interviewed with serological results for 771). HIV prevalence was 15.4% (95% CI 11.6-20.1), with only 45.8% previously aware of their infection. HIV prevalence achieved 6.4% among youth 18-24years and was higher among MSM with lower socio-economic status. In multivariate analysis, correlates of HIV were older age, gay identity, lower socio-economic status, social networks with HIV-positive MSM, receptive anal sex, and internet sex partners. Policy change towards increasing avenues for HIV testing coupled with antiretroviral treatment regardless of CD4 count or stage of disease stand to benefit the MSM community if scaled up fast enough.

Time-location sampling with capture-recapture to assess specialised recreational fisheries

Specialisation in recreational fisheries has led to increasing diversification and segmentation of fishers into small ‘hard-to-reach’ populations that are inherently difficult and costly to sample using traditional methods. In this paper, we quantitatively assess, and expand upon, time-location sampling (TLS) for a specialised recreational sport fishery off eastern Australia using stratified random sampling of fishing tackle stores as aggregation points for fishers. Multiple TLS survey events facilitated the use of capture-recapture models to provide a minimum population size estimate of 3185 (SE 1338) fishers in the study region in 2010. Adopting a questionnaire with a long recall period (e.g. 12 months) may introduce biases in estimates of effort and catch from TLS. Therefore, these biases were corrected for using a ‘benchmark’ on-site survey, providing minimum estimates of effort and catch of 172,438 (SE 8440) angler hours and 4.7–31.4 (SE 2.6–6.8)t for six pelagic species, respectively, in the study region during 2010. TLS with capture-recapture is an efficient method for sampling hard-to-reach specialised fishers and may yield annual estimates of population size, effort and catch. Further research is needed to refine methods and develop systematic protocols that may be applied to a wide range of hard-to-reach populations, including recreational, artisanal and illegal fisheries.

Efficacy of novel sampling approaches for surveying specialised recreational fisheries

Advances in fishing technologies have increased the efficiency and diversification of recreational fisheries. This poses challenges for surveying specialised or ‘hard-to-reach’ recreational fishers (e.g. sport fishers) that may take the majority of the recreational catch for some species, but are too rare within the general population to be sampled cost-effectively using existing methods. We trialled two new methods—time-location sampling (TLS) and online diaries—for surveying specialised recreational longtail tuna (Thunnus tonggol) fishers. Results were compared with a concurrent traditional access point survey (APS). Online diaries were inexpensive but unsuitable for collecting representative data due to avidity, volunteerism, and differential recruitment bias. APS yielded high resolution data on catch, effort and size composition but was expensive and ineffective for sampling all components of the fishery. In contrast, TLS conducted at fishing tackle stores was cost-effective for accessing the breadth of fisher types due to the need for all fishers to purchase or to inspect fishing-related products at some point. Given the frequent absence of complete list frames for recreational fisheries, we suggest undertaking multiple TLS surveys to collect catch rate data and to simultaneously estimate population size using capture-recapture approaches in order to estimate the total recreational catch of species of interest.

P1-S4.08 Population size estimates for men who have sex with men in Guatemala City using time location sampling and respondent driven sampling

BackgroundMen who have sex with men (MSM) are highly vulnerable to HIV infection, but this population can be particularly difficult to reach in Central America due to stigma and violence....

A Comparison of HIV Infection and Related Risks Among Male Sex Workers in Different Venues in Shenzhen, China

Different risks of HIV infection have been reported among different types of male sex workers (MSW). In order to compare the prevalence of HIV infection and related risk behaviors of MSW in different venues in Shenzhen, China, a time-location sampling survey was conducted in 2008. 5.1% of the 394 MSWs were tested positive for HIV, with 6.9% in those working in parks (PMSW), 11.3% in small family clubs (FMSW) and 1.7% in entertainment venues. PMSWs and FMSWs reported a higher proportion of self-identified homosexual/gay. Moreover, FMSWs reported a lower coverage of HIV-related education and services and were more likely to self-report coming from provinces with higher HIV prevalence. The results indicated that MSWs in small venues and parks were comparatively at higher risk of being infected and suggested that current HIV preventive intervention needs to be expanded to the small venues in Shenzhen.

HIV prevalence and related risk factors among male sex workers in Shenzhen, China: results from a time–location sampling survey

BackgroundHIV transmission among men who have sex with men has recently become a major concern in China. Little is known, however, about HIV transmission among male sex workers (MSW). This...

An Empirical Comparison of Respondent-driven Sampling, Time Location Sampling, and Snowball Sampling for Behavioral Surveillance in Men Who Have Sex with Men, Fortaleza, Brazil

Obtaining samples of populations at risk for HIV challenges surveillance, prevention planning, and evaluation. Methods used include snowball sampling, time location sampling (TLS), and respondent-driven sampling (RDS). Few studies have made side-by-side comparisons to assess their relative advantages. We compared snowball, TLS, and RDS surveys of men who have sex with men (MSM) in Forteleza, Brazil, with a focus on the socio-economic status (SES) and risk behaviors of the samples to each other, to known AIDS cases and to the general population. RDS produced a sample with wider inclusion of lower SES than snowball sampling or TLS-a finding of health significance given the majority of AIDS cases reported among MSM in the state were low SES. RDS also achieved the sample size faster and at lower cost. For reasons of inclusion and cost-efficiency, RDS is the sampling methodology of choice for HIV surveillance of MSM in Fortaleza.

The Internet, HIV serosorting and transmission risk among men who have sex with men, San Francisco

In a community-based, time-location sampling survey in San Francisco, Internet-met partners were not more likely to be HIV seroconcordant among HIV-negative and HIV-positive men who have sex with men (MSM) compared with partners met at bars and dance clubs. In addition, HIV-negative MSM were more likely to have unprotected anal intercourse with potentially serodiscordant partners met on the Internet compared with those met at bars and dance clubs (adjusted OR 1.5, 95% CI 1.1-2.0, P = 0.01).