Study design
This was a cross-sectional survey among MSM using respondent driven sampling (RDS). RDS is a peer-recruitment sampling method designed to collect rigorous, representative data from hard-to-reach populations [23,24,25]. In preparation for this first integrated biological and behavioral survey, formative pre-survey research included formal meetings in each site with MSM, local organizations, and government officials to explore MSM’s willingness to recruit their peers, challenges in finding diverse segments of this hidden population, and preferences expressed by MSM for all study procedures.
Setting
The study took place in Burkina Faso’s two largest cities: Ouagadougou (the capital) in the Centre and Bobo-Dioulasso in the West.
Study population and recruitment
MSM were eligible to participate if they were (i) at least 18 years old, (ii) assigned male sex at birth, (iii) reported they had anal sex with a man at least once in the past 12 months, (iv) were able to provide informed consent in French, Mòoré, or Dioula, (v) had a valid RDS coupon, (vi) lived in either Ouagadougou or Bobo-Dioulasso for at least the past three months, and (vii) agreed to complete a survey and HIV testing.
Six MSM seeds in Ouagadougou and four MSM seeds in Bobo-Dioulasso were purposely selected to initiate recruitment chains. We chose seeds who met the study eligibility criteria, represented diverse demographics (age, education, marital status, language, and HIV status), and who were willing to promote the study. Three seeds of 45, 30 and 23 years old started in Ouagadougou and failed to recruit.
After giving informed consent, seeds were required to complete a survey and have their blood drawn for HIV testing. These seeds were each provided with three coded coupons, which were valid for four weeks, to recruit peer MSM from their social networks. Individuals who were recruited by seeds and enrolled in the study were then provided with three coded study coupons for further recruitment of peers. This process continued until the target sample size was reached in each city. To assess whether convergence of key characteristics was achieved [26], we examined convergence plots of age, educational status and sexual orientation, that we anticipated to could be associated with network structure and HIV infection. As we approach the sample size in each city, the number of coupons was reduced from 3 to 2. The last wave of study participants did not receive a coupon to recruit their peers. The maximum numbers of sample waves per site were 15 in Ouagadougou and 16 in Bobo-Dioulasso. Figure 1 presents RDS recruitment chains of MSM in Ouagadougou and Bobo-Dioulasso.
Participants received male condoms, condom-compatible lubricants, HIV education materials, and information regarding existing services. They also received 2000 West African Communauté Financière Africaine franc (XOF, ~ $4 United States dollars [USD]) for their time and transportation costs for each study visit and 1500 XOF (~ $3 USD) per successfully eligible peer recruited to be part of the study (for up to three peers). To avoid individuals participating multiple times, a single survey office was used in each study site. At each site, trained staff included a site manager, a coupon manager, two data collectors, an HIV test counselor, and a lab technician. Each of them was trained to avoid multiple participations through facial and physical recognition.
Sample size
The recruitment framework entailed 345 MSM in each city (Ouagadougou and Bobo Dioulasso). Sample size calculations were based on the assumption that populations who always use condoms have a 75% lower HIV prevalence than populations who do not, and the effectiveness of condoms is roughly 80%, with 73% used as a conservative estimate [27]. Overall, HIV prevalence was assumed to be 15%, with a 19% prevalence among those who did not consistently use condoms. A design effect of 1.5 associated with RDS, a significance level of 0.05 and a power of 80% were employed. Condom use was used to calculate sample size because we were interested in using the study data as a baseline for behavior change.
Data collection
Data were collected from January to April 2013 in Ouagadougou and May to August 2013 in Bobo-Dioulasso. Following written informed consent, MSM participants completed interviewer-administered face-to-face surveys in a private room. Topics included participants’ socio-demographic characteristics, concurrence sexual partnerships and sexual behaviors during the last 12 months (with men and women), condom use during the last 12 months and the last sex with regular or casual male and female sexual partners, knowledge and practices related to STIs and HIV. Information on concurrent sexual partners was obtained by asking participants if in the last 12 months, there was any time when they had two or more regular sexual partners (males or females) at the same time.
Laboratory method for HIV testing
Following completion of the survey, HIV counseling and testing, based on the Burkina Faso official guidelines, were conducted for all participants. A trained nurse and lab technician from Institut de Recherche en Sciences de la Santé (IRSS, Ouagadougou) respectively conducted pre- and post-test counseling and venous blood specimen collection (~ 5 ml) and HIV testing. The first step was to perform a rapid test using Alere Determine™ HIV-1/2 kit (Alere, Inc., Waltham, Massachusetts). This was followed by ImmunoComb® II HIV 1&2 BiSpot kit (Orgenics Ltd., Israël) as a second test for differential detection of antibodies to HIV types 1 and 2, only if the first test was positive. Any discordant results were tested using the ImmunoComb II HIV 1&2 CombFirm kit. (Orgenics Ltd., Israël) positive or negative status. Participant codes were used to link results of the surveys with test results as well as facilitate the provision of test results and appropriate treatment or referrals. Participants who chose to receive their results could do so on-site shortly after testing.
Data processing
Data were entered using EpiData 3.1 (The EpiData Association, Odense, Denmark) and exported into Stata 14 (StataCorp, College Station, TX) for analysis. RDS original seeds were included for the analysis. For each city, population prevalence estimates and 95% confidence intervals (CI) adjusted for the RDS design were conducted using the RDS Analysis Tools (RDSAT) version 6.0.1 (RDS, Inc., Ithaca, NY). We present proportions separately for each city because the RDS networks were separate. RDS adjustment takes into consideration the probability of each participant to be included in the study. This probability was measured through weighting based on the size of each participant’s network. Network size was determined using the survey question: “How many different people do you know personally who are men who have sex with men? i.e., you know them and they know you, you have seen them in the last 2 years, and you could contact them if you needed to?” The mean network size was 17 in Ouagadougou (range: 1 to 600) and 21 in Bobo-Dioulasso (range: 1 to 150). Bivariate logistic regression analyses were conducted using Stata to assess correlates of testing positive for HIV in each city. RDS weights were included in the logistic regression analyses for each city. Due to low number of HIV positives, multivariate analysis was not performed.
Ethical considerations and protection of the participants
The study received ethical approval from the Johns Hopkins Bloomberg School of Public Health Institutional Review Board and the Ethics Committee for Health Research (Comité d’éthique pour la recherche en santé, CERS) of Burkina Faso. Procedures were put in place to protect participants against risks. Surveys were conducted in a private setting. To minimize physical risks, collection of blood samples were performed by trained staff. Psychological risks for study staff that work first time with MSM were minimized by providing research ethics training and sensitivity for all staff on the study objectives and the specific needs of MSM. Confidentiality was maintained by using a unique study identifier rather than names on surveys, protecting all electronic data with passwords, and storing hard copies of data in locked cabinets. Participants who tested positive for HIV were referred to an appropriate HIV treatment center.