Showing posts with label RDS. Show all posts
Showing posts with label RDS. Show all posts

Saturday, March 5, 2016

Bio-Behavioural HIV & STI Surveillance among Men Who Have Sex with Men in Europe: The Sialon II Protocols

Background
Globally, 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/Design
Sialon 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.

Discussion
Through 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.

Purchase full article at:   http://goo.gl/ww013K

Veneto Region - Department of Health, CReMPE - Regional Coordination Centre for European Project Management, the Verona University Hospital, Verona, Italy
Department of Pathology, Infectious Diseases Section, the Verona University Hospital - Veneto Region, Verona, Italy
Department of Reproductive Health & Research, World Health Organization, Geneva, Switzerland
Department for Infectious Diseases Epidemiology, Robert Koch-Institute, Berlin, Germany
Centre for Health Research, University of Brighton, Brighton, UK
Institut Catala d’Oncologia (ICO), Centre for Epidemiological Studies on HIV/STI in Catalonia (CEEISCAT), Agencia de Salut Publica de Catalunya (ASPC), Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
Department of Monitoring and Evaluation, Public Health Agency of Sweden, Solna, Sweden
Institute of Hygiene and Tropical Medicine & GHTM, Universidade Nova de Lisboa, Lisbon, Portugal
Centro Operativo AIDS, Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Rome, Italy
NRC for HIV/AIDS, Slovak Medical University, Bratislava, Slovak Republic
Department of Epidemiology, National Institute of Public Health, National Institute of Hygiene, Warsaw, Poland
Centre for Communicable Diseases and AIDS, Vilnius, Lithuania
National Institute of Public Health, Ljubljana, Slovenia
National Reference Laboratory of HIV, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria
National Institute of Infectious Diseases Prof. Dr. Matei Bals, Bucharest, Romania




Saturday, October 3, 2015

If You Are Not Counted, You Don't Count: Estimating the Number of African-American Men Who Have Sex with Men in San Francisco Using a Novel Bayesian Approach

African-American men who have sex with men (AA MSM) have been disproportionately infected with and affected by HIV and other STIs in San Francisco and the USA. The true scope and scale of the HIV epidemic in this population has not been quantified, in part because the size of this population remains unknown. 

We used the successive sampling population size estimation (SS-PSE) method, a new Bayesian approach to population size estimation that incorporates network size data routinely collected in respondent-driven sampling (RDS) studies, to estimate the number of AA MSM in San Francisco. This method was applied to data from a 2009 RDS study of AA MSM. An estimate from a separate study of local AA MSM was used to model the prior distribution of the population size. Two-hundred and fifty-six AA MSM were included in the RDS survey. 

The estimated population size was 4917, using a flat prior estimated 1882 as a lower acceptable bound, and a large prior estimated 6762 as an acceptable upper bound. Point estimates from the SS-PSE were consistent with estimates from multiplier methods using external data. 

The SS-PSE method is easily integrated into RDS studies and therefore provides a simple and appealing tool to rapidly produce estimates of the size of key populations otherwise difficult to reach and enumerate.

Via: http://goo.gl/Zsz798 Purchase full article at: http://goo.gl/OfwN73

  • 1University of California, Berkeley, 101 Haviland Hall, Berkeley, CA, 94720-7358, USA
  • 2University of California, Los Angeles, 8125 Mathematical Sciences Building, Los Angeles, CA, 90095-1554, USA.
  • 3San Francisco Department of Public Health, 25 Van Ness Ave, Suite 500, San Francisco, CA, 94102, USA.

A Comparison Between Respondent-Driven Sampling and Time-Location Sampling among Men Who Have Sex with Men in Shenzhen, China

Men who have sex with men (MSM) are a key population for HIV control and prevention in China. It is difficult to acquire representative samples of this hidden population. Respondent-driven sampling (RDS), based on peer referral, and time-location sampling (TLS) based on random selection of venue-day-time periods, are among the most commonly used sampling methods. However, differences in HIV-related characteristics of MSM recruited by these two methods have not been fully evaluated. 

We compared sociodemographics, risk behaviors, utilization of HIV-related intervention services, and HIV/syphilis infection rates between samples of 621 RDS MSM and 533 TLS MSM in Shenzhen, China in 2010. We found that the HIV prevalence was comparable in RDS and TLS MSM. TLS recruited larger proportions of more marginalized MSM than RDS: MSM recruited by TLS were older, less educated and more likely to be migrants (without Shenzhen hukou registration), to be non-gay identified and to engage in risky sexual behaviors. 

On the other hand, MSM recruited by TLS were more likely to have been covered by HIV-related intervention services. To conclude, in Shenzhen, TLS is more effective to reach the marginalized population of MSM. But because TLS can only reach MSM who physically attend venues and HIV-related intervention services are already commonly available at gay venues in Shenzhen, RDS is more informative for allocating prevention efforts than TLS. 

Furthermore, researchers and public health authorities should take into account the different sample compositions of RDS and TLS and apply sampling methods consistently when evaluating trends over time.

Via: http://goo.gl/Z8MMId Purchase full article at: http://goo.gl/xX0uqo

  • 1Shenzhen Center for Disease Control and Prevention, No. 8 Longyuan Road, Longzhu Avenue, Nanshan District, Shenzhen, 518055, China.

Respondent-Driven Sampling as a Recruitment Method for Men Who Have Sex with Men in Southern Sub-Saharan Africa: A Cross-Sectional Analysis By Wave

Respondent-driven sampling (RDS) is a popular method for recruiting men who have sex with men (MSM). Our objective is to describe the ability of RDS to reach MSM for HIV testing in three southern African nations.

Data collected via RDS among MSM in Lesotho (N=318), Swaziland (N=310) and Malawi (N=334) were analysed by wave in order to characterise differences in sample characteristics. Seeds were recruited from MSM-affiliated community-based organisations. Men were interviewed during a single study visit and tested for HIV. χ2 tests for trend were used to examine differences in the proportions across wave category.

A maximum of 13-19 recruitment waves were achieved in each study site. 
  • The percentage of those who identified as gay/homosexual decreased as waves increased in Lesotho (49% to 27%). 
  • In Swaziland and Lesotho, knowledge that anal sex was the riskiest type of sex for HIV transmission decreased across waves (39% to 23% and 37% to 19%). 
  • The percentage of participants who had ever received more than one HIV test decreased across waves in Malawi (31% to 12%). 
  • In Lesotho and Malawi, the prevalence of testing positive for HIV decreased across waves (48% to 15% and 23% to 11%). 
  • Among those living with HIV, the proportion of those unaware of their status increased across waves in all study sites although this finding was not statistically significant.

RDS that extends deeper into recruitment waves may be a promising method of reaching MSM with varying levels of HIV prevention needs.

Via: http://ht.ly/SYEmY Purchase full article at: http://goo.gl/eolhkG

  • 1Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Center for Public Health and Human Rights, Baltimore, Maryland, USA.
  • 2Department of Global Health Sciences, University of California San Francisco, San Francisco, California, USA.
  • 3Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Center for Public Health and Human Rights, Baltimore, Maryland, USA Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, South Africa.
  • 4Rock of Hope, Manzini, Swaziland.
  • 5Center for the Development of People, Blantyre, Malawi.
  • 6Malawi College of Medicine, Blantyre, Malawi Centre for Global Health, Trinity College, Dublin, Ireland.
  • 7Rock of Hope, Mbabane, Swaziland.
  • 8Ministry of Health, Mbabane, Swaziland.