Abstract
Mobile unit (MU) HIV testing is an alternative method of providing healthcare access. We compared demographic and behavioural characteristics, HIV testing history and HIV prevalence between participants seeking testing at a MU vs. fixed clinic (FC) in Lima, Peru. Our analysis included men and transgender women (TW) in Lima aged ≥ 18 years old seeking HIV testing at their first visit to a community-based MU or FC from October 2007 to November 2009. HIV testing history, HIV serostatus and behavioural characteristics were analysed. A large percentage of MU attendees self-identified as transgender (13%) or heterosexual (41%). MU attendees were more likely to engage in transactional sex (24% MU vs. 10% FC, p < 0.001), use alcohol/drugs during their last sexual encounter (24% MU vs. 20% FC, p < 0.01) and/or be a first-time HIV tester (48% MU vs. 41% FC, p < 0.001). MU HIV prevalence was 9% overall and 5% among first-time testers (49% in TW and 11% in men who have sex with men [MSM] first-time testers). MU testing reached large numbers of at-risk (MSM/TW) populations engaged in unsafe sexual behaviours, making MU outreach a worthy complement to FC testing. Investigation into whether MU attendees would otherwise access HIV testing is warranted to determine the impact of MU testing.
Keywords
Introduction
Early HIV testing and treatment initiation are widely accepted ways to decrease morbidity and mortality and reduce HIV transmission. Such strategies traditionally include public HIV/sexually transmitted infection (STI) clinics that offer voluntary counselling, testing and referral services. 1 While these clinics are effective in testing and treating those with access to care, they may miss potentially at-risk populations such as men who have sex with men (MSM), transgender women (TW) and those who have never before been tested for HIV.2,3 In order to reach those most at risk, innovative voluntary counselling, testing and referral services techniques are needed.
Mobile units (MUs) offering HIV/STI testing services have proven to be an effective outreach tool to at-risk groups around the world.4–8 HIV testing barriers such as stigma have been reduced, and HIV testing has been shown to increase fourfold when voluntary counselling, testing and referral services are provided in a non-traditional setting, according to one recent multi-national study in sub-Saharan Africa and Thailand.7,8 In Guatemala, MU participants were significantly less likely to have had a prior HIV test than those seen at traditional clinics. 5 MUs in the United States have been shown to reach high-prevalence groups of MSM, injection drug users and persons engaging in transactional sex.6,9,10 Additionally, acceptability of MU testing is high, with one study in Louisiana, USA, reporting 97% of respondents viewing neighbourhood screening as ‘good’ or ‘very good’. 4
In Latin America, however, there is a dearth of information on MU testing initiatives and their effectiveness in reaching high-risk populations and determining HIV/STI prevalence, HIV testing patterns and related risk behaviours among MU users. With the HIV epidemic in Peru relatively stable and concentrated in MSM and TW with a prevalence greater than 10% over the past decade,11–13 creative efforts such as MU testing programmes need to be evaluated for implementation in order to test, treat and link to care high-prevalence groups, in which the majority have never been previously tested.14,15 One large online study in 2008 in Peru enrolled 1301 MSM and found that almost half (49%) of participants had never been tested for HIV. The most common reason for not testing among high-risk MSM (participants reporting unprotected intercourse with their last sexual partner) in this online study was not knowing where to get tested. 16 MU may be able to extend the reach of traditional testing centers and provide care to those who do not use services in traditional clinic settings, 6 thus increasing the number of HIV cases detected that would likely not otherwise be found.
Our study aimed to evaluate demographic and behavioural characteristics and HIV and syphilis prevalence and associated factors of a non-profit HIV/STI testing MU in Lima, Peru, to determine whether mobile testing could provide an effective complement to traditional, clinic-based testing services.
Methods
Study setting and participant selection
From October 2007 to November 2009, Vía Libre (www.vialibre.org.pe), a community-based Peruvian non-profit organization that provides HIV/STI voluntary counselling, testing and referral services in downtown Lima, implemented the SOMOS project (Servicios Optimos Para Mejorar las Oportunidades en Salud or Optimizing Services to Improve Health Opportunities) in collaboration with the European Commission, HIVOS (Humanist Institute for Development Cooperation, The Netherlands) and the Peruvian Ministry of Health (MoH). This multi-level community outreach programme aimed to control HIV/STI transmission among high-prevalence groups of MSM and TW in metropolitan Lima, the area of Peru with the highest HIV prevalence.17,18 As part of the SOMOS project, two community-based MUs offering HIV and syphilis voluntary counselling, testing and referral services were utilized to target at-risk vulnerable populations in the municipalities of metropolitan Lima and Ica. Two research workers who explained the study, consented participants, and catalogued and stored serum samples, one community health promoter who stood outside the van and encouraged testing and answered questions and one HIV testing counsellor who took serum samples staffed the mobile clinic. The van included two consultation rooms equipped for rapid HIV and syphilis testing and the provision of voluntary counselling, testing and referral services.
Site selection for outreach visits was based on formative work completed prior to project implementation and included sites such as saunas and clubs frequented almost exclusively by MSM/TW as well as public areas of high foot traffic such as main plazas. 18 Site selection was based on volume of visitors, accommodation for MU services and business–owner consent. Screenings were scheduled for 4–6 h blocks during hours of highest foot traffic, for example from 9 p.m. to 2 a.m. when outside of bars or clubs. Outreach visits were programmed according to a rotating schedule, returning to each site every four weeks. Testing services were provided to all interested persons regardless of risk profile. Flyers, banners, pamphlets, newspaper ads and web-based promotional tools, such as video and radio advertisements on the SOMOS project website and websites frequented by MSM/TW in Peru, such as www.gayperu.com and www.peruesgay.com, were used to publicize outreach efforts beginning approximately one month before the project. To minimize potential stigma associated with HIV testing, services were advertised as ‘routine health screenings’ available to all visitors without restrictions. Participants could choose to be tested for HIV, syphilis or both. Consistent with Peruvian MoH regulations, all participants provided written consent for HIV testing. Verbal consent was obtained for syphilis testing. Implementation of the SOMOS project took tremendous collaboration between Vía Libre, its testing and laboratory staff and the Peruvian Ministry of Health. Determining logistics of the mobile van (who was needed on board, where to go, how to advertise, how to get blood samples to the laboratory in sufficient amount of time) were details worked out over the course of several months by Vía Libre staff.
Information was also collected from visitors to the Vía Libre STI clinic in Lima, Peru. Vía Libre is an established non-governmental organization providing community-based HIV testing, treatment and prevention services in downtown Lima. For our analyses, inclusion was restricted to genetically born male participants at least 18 years of age at their first visit to either Vía Libre (the fixed clinic, FC) or the MU in any of the sites visited in metropolitan Lima. Data collected from subsequent visits and from MU participants in Ica, Callao and Lima’s outer provinces were excluded from analysis.
All data were collected by Vía Libre personnel as part of the SOMOS project, a community public health outreach programme sanctioned by the Peruvian MoH, and not a research study. Data used in this analysis were de-linked from any unique patient identifiers with no code or code key available to link the data, directly or indirectly, to specific individuals. Accordingly, the study was considered exempt from institutional review board oversight.
Testing procedures
Following informed consent, pre-test counselling was given and finger-prick blood was collected to test for HIV and/or syphilis. HIV rapid test results were delivered within 20 min, and post-test counselling was performed. Referral to follow-up testing or treatment resources for both HIV and syphilis was provided when appropriate.
Screening for syphilis was performed using the Determine Syphilis rapid test (Inverness Medical Laboratories, Yavne, Israel). Consistent with Peruvian MoH guidelines, participants with a reactive syphilis rapid test received a quantitative Rapid Plasma Reagin (RPR) test for confirmation (BioSystems, Barcelona, Spain), and those with titres >1:8 were considered positive.
Following informed consent and pre-test counselling, HIV screening was conducted using the Determine HIV-1/2 rapid test (Inverness Medical, Yavne, Israel), and participants received their results within 20 min. Participants who were positive on rapid testing were notified of their result, provided with post-test counselling, and asked to return to the Vía Libre clinic site the following day to receive a confirmatory ELISA test (Vironostika, bioMerieux, Marcy, l'Étoile, France or Genscreen Plus, Biorad, CA, USA). In accordance with national protocol, if ELISA positive, a second ELISA test was performed from the same sample. If this second ELISA was positive, confirmatory testing using HIV immunofluorescence antibody testing (Instítuto Naciónal de Salud, house assay) was performed.
Treatment and follow-up
The Peruvian MoH standard of care for HIV/STI screening and treatment was followed. Persons testing positive for syphilis with titres > 1 : 8 were given a follow-up appointment at the Vía Libre clinic site and treated with the standard antibiotic regimen of three weekly intramuscular injections of 2.4 million units of benzathine penicillin G, as recommended by the U.S. Centers for Disease Control and Prevention. 19 Participants with titres ≤ 1 : 8 were clinically evaluated and treated at the Vía Libre clinic site with the same antibiotic regimen detailed above if deemed clinically appropriate by medical staff. Persons testing positive for syphilis who were not given a follow-up appointment at the time of testing were immediately contacted by telephone and referred to the Vía Libre clinic site for diagnosis, consultation and treatment.
Participants with confirmed HIV infection were referred to designated MoH treatment facilities (including the Vía Libre clinic) for treatment and counselling, which included partner notification strategies. Project volunteers helped HIV-infected participants enrol in anti-retroviral therapy programmes and were responsible for maintaining contact with participants and ensuring appropriate follow-up.
Data collection
Data collection procedures were similar between FC and MU settings. Sociodemographic characteristics, behavioural risk factors including condom use, engagement in transactional sex and alcohol/drug use, HIV testing history and reasons for testing were collected using anonymous written surveys administered by trained project personnel that were later manually entered into a computerized database.
Data analysis
To assess the effectiveness of MU outreach, our analyses included data from the FC Vía Libre, an HIV/STI clinic in central Lima, as a means of comparison. Primary outcomes were HIV and syphilis prevalence and HIV prevalence among participants who have never before been tested for HIV (first-time testers) in the MU. Independent variables including age, condom use, partner type, alcohol/drug use with sexual encounter, self-reported symptoms compatible with an STI over the past year and self-reported sexual identity were used both to describe the population of interest and to determine any associations to the primary outcomes.
Self-reported symptoms over the past year such as genital warts, dysuria, genital secretions, genital ulcers and other symptoms were categorized into one composite, dichotomous variable, ‘STI symptoms’. The variable ‘Condom use in the past three months’, was dichotomized, with check box responses of ‘Never’ and fill-in responses of ‘0’ re-categorized as ‘Never’, and all other responses coded as ‘at least once’.
Sociodemographic and behavioural characteristics and HIV/syphilis prevalence were described using percentages or medians and interquartile ranges, as appropriate. We used Chi-square/Fisher’s exact tests or Wilcoxon rank-sum tests for categorical variables and continuous variables, respectively, to determine associations between variables of interest and testing site (FC or MU). Bivariate logistic regression analyses were conducted to examine the relationship between independent variables and HIV/syphilis prevalence. We computed the unadjusted odds ratios (ORs) and the 95% confidence interval (CI) to assess the association between each variable and the outcomes of interest.
Variables that were statistically significant (p < 0.05) in bivariate analyses were included in multivariate logistic regression analyses. Multivariate analysis controlled for self-reported sexual identity, risk behaviours within the past three months, partner type and self-reported STI symptoms within the past year, and these variables were added simultaneously to make our multivariate model.
For each question of interest, data coded as ‘does not apply’ were recoded as ‘missing’ and excluded from our analyses. Those with missing data for one variable of interest were excluded from that particular question (coded as ‘missing’), but not from the entire analysis. All data analyses were conducted using Stata 12.0 (College Station, TX, USA).
Results
Subjects’ characteristics and STI prevalence
Description of participants at each test site in Lima, Peru, 2007–2009.
STI: sexually transmitted infection.
Median (interquartile range)
Student's t-test or Wilcoxon rank-sum result.
N = 1673 in fixed STI clinic and N = 1353 in mobile unit.
*p < 0.05, **p < 0.01, ***p < 0.001.
MU participants self-identified as MSM (24%), bisexual (22%), heterosexual (41%) and transgender (13%). The MU had significantly higher proportions of participants engaging in transactional sex in the past three months (24% vs. 10% FC, p < 0.001), having sexual relations under the influence of alcohol/drugs during their most recent sexual partner (24% vs. 20% FC, p < 0.01) and/or self-identifying as TW (13% vs. 3% FC, p < 0.001) than FC participants (Table 1). Participant age, alcohol/drug use in the past three months with a sexual encounter and testing positive for syphilis infection were not statistically significant characteristics between MU and FC participants.
Overall syphilis prevalence in the MU was 8.3%. Thirty-four MU participants and 68 FC participants were co-infected with HIV and syphilis (Table 1).
Overall HIV prevalence was 8.8% in the MU. The MU detected 140 cases of HIV (49 cases among MSM, 64 cases among TW, 16 cases among bisexual men and 11 cases among heterosexual men).
STI correlates
Factors associated with HIV infection in mobile unit participants in Lima, Peru, 2007–2009.
STI: sexually transmitted infection.
Covariates include self-identified sexual identity, no condom use in the past three months, engaging in transactional sex in the past three months, having no prior HIV test, testing positive for syphilis infection and having symptoms of an STI in the past year.
N = 1199.
*p < 0.05, **p < 0.01, ***p < 0.001.
HIV prevalence among first-time testers
HIV prevalence in mobile unit participants.
MSM: men who have sex with men; TW: transgender women.
Discussion
MU testing services in Lima reached a population with high overall HIV and syphilis prevalence (9% and 8%, respectively) furthering the idea that MU outreach may be an effective means of bringing prevention and testing services to high-prevalence groups. HIV and syphilis prevalence was significantly higher in the fixed, MSM-friendly HIV/STI clinic, suggesting that traditional voluntary counselling, testing and referral services effectively identify high-risk persons. However, the MU was successful in diagnosing a large number of new cases of HIV and syphilis and providing services to participants who had never before been tested for HIV. Our study found that nearly half (48%) of all MU visitors had never before been tested for HIV, of whom 5.4% were HIV-infected. We detected 41 new cases of HIV infection among first-time testers, including 12 MSM, 16 TW, eight bisexual men and five heterosexual men, suggesting that MU testing accessed an important, underserved population with a high disease burden. 20
Multivariate analysis revealed that participants who self-identified as a TW were over twice as likely to test positive for HIV when compared with MSM. This is likely due to the marginalization of TW in Lima and the fact that the most common occupations for TW are currently either hairdressing or sex work.
With the HIV epidemic in Lima remaining consistently over 10% in MSM and TW both currently and over the past decade,11,17,21 innovative outreach efforts are needed to prevent and control the spread of HIV in Peru. In screening a high proportion of TW (49%) and MSM (11%) with previously undiagnosed HIV infection, MU testing should now be a viable consideration to help stop the spread of HIV in Lima.
As a secondary analysis of a public health outreach programme, our findings are subject to several limitations. Participant duplication might exist between the MU and FC site entries (i.e. the same individual could have been recorded as both a MU and FC participant). To avoid duplicate entries, we restricted our database to participants attending the FC or MU for their first visit only and further analysed any responses to questions suggesting duplicate data entries. Upon further analyses, only three clinic visitors may have previously received testing in the MU, a number that would have minimal impact on our data. Participant bias is another limitation, since voluntary HIV/syphilis testing requires willing persons to seek and enter the MU to access testing services. We did not record the number of individuals who were approached by outreach staff who declined testing services, which may affect our ability to assess the efficacy of MU outreach in the community. Additionally, we do not know whether MU testers would have accessed other clinic-based testing services if the outreach unit were not present, though the MU did access a large number of participants who had never before received HIV testing. Finally, our prevalence data cannot be considered representative of larger communities in Lima or Peru due to issues of selection bias in targeting high-risk populations and the lack of any random sampling methodology.
Our data suggest the possibility of using MU as a means to reach high-prevalence populations and those who have not been tested for HIV in Peru, serving as a viable complement to extend the reach of stationary STI clinics. Future research focusing on linkage to care and follow-up among MU attendees diagnosed with HIV or syphilis infection and is needed to determine utility. Cost-benefit analyses are needed to assess the feasibility and sustainability of MU testing services and to determine the role of community outreach testing in Peruvian HIV control systems.
Conclusions
MU testing detected a large number of new cases of HIV and syphilis in this sample of 1602 participants, including among individuals with no previous HIV testing history. MU testing may serve as a viable complement to FC voluntary counselling, testing and referral services and as a way to bring testing services to high-prevalence populations such as MSM, TW and persons without regular access to counselling and testing services.
Footnotes
Acknowledgements
The authors thank their partners at Vía Libre for their efforts, especially laboratory director Martín Gutierrez for his help in manuscript preparation.
Conflict of interest
The authors declare no conflict of interest.
Funding
This work was supported by the South American Program in HIV Prevention Research (SAPHIR) through the David Geffen School of Medicine Program in Global Health [NIH R25 MH087222 (South American Program in HIV Prevention Research)]. Funding for the SOMOS project was provided by HIVOS and the European Commission.
