Sampling design and recruitment

Each round associated with the IBBSS utilized respondent driven sampling given to your concealed nature of MSM and therefore permits contrast between and across rounds. Respondent driven sampling (RDS) is described at length in past studies 22, 23. Shortly, RDS is really a modified chain referral non-random sampling technique of recruitment that adjusts for the non-randomness employing a mathematical model that weights each sample recruited 23. Inclusion criteria ended up being male aged 16 years and above with a history of dental and/or anal intimate connection with another man when you look at the a few months before the study. Known MSM, designated as “seeds” began the chain for the recommendation community and make use of vouchers to recruit their peers to the research. Ten seeds had been chosen for every circular and seeds had been diversified by age, academic status and socioeconomic status. In order to avoid an over-representation of MSM with comparable attributes, vouchers limited by three per recruit was utilized 23, 24. In addition, in order to prevent repeat enrollment, only 1 screener ended up being utilized, just one individual had been authorized to reimburse MSM that has effectively recruited their peers and just one location ended up being utilized. Each voucher had been redeemable and yielded N500 approx. $3 USD being a motivation for participating, with one more N500 provided to a recruit for every effective participant that is additional. Total settlement ended up being restricted to a maximum settlement of n2000 approximately $12 USD. Test size when it comes to 2007 IBBSS had been projected according to an thought HIV prevalence of 15%, a design aftereffect of 2.0 and amount of accuracy of 0.05. When it comes to 2010 and 2014 IBBSS, test size ended up being calculated to identify a 10% differ from the subsequent round.

Data collection

Structured close-ended interviewer administered questionnaires elicited information about socio-demographic faculties, sort of sex lovers and sexual danger habits. Interviews had been carried out in MSM friendly businesses identified in all the research states. Transactional sex ended up being examined both with feminine and male lovers. Kind of rectal intercourse practiced ended up being classified as “insertive penile intercourse” or “receptive penile intercourse” into the past a few months. HIV danger perception ended up being examined by asking MSM “do you’re feeling you are vulnerable to disease with HIV? ” with reaction options being “yes or no”. Consistent condom use with sexual partners during transactional and non-transactional intercourse ended up being examined by asking the concerns “how frequently did you or your male partner work with a condom each time you had intercourse in the final 6 months? ” while condom usage at final intercourse had been examined by the concern “the last time you’d anal intercourse did you or your partner make use of a condom? ”. Transactional sex ended up being evaluated by asking “have you received cash or present in return for intercourse within the last six months? ” Written permission had been acquired from all participants for both behavioural and biological aspects of the study.

Laboratory testing

Detection of HIV during all of the studies ended up being regularly carried out by quick test making use of whole bloodstream samples acquired from the hand prick. On the basis of the HIV that is national testing, a synchronous algorithm of Determine (Alere health, United States Of America) and Unigold (Trinity Biotech, Plc, Bray, Ireland) had been utilized to recognize HIV sero-positivity while status of discordant tests had been confirmed if you use Stat Pak (Chembio Diagnostic techniques, ny, United States Of America).

Information administration and analysis

Data from each research state were entered CS that is centrally using Pro 3.2 and 25% of questionnaires underwent double-data entry to make sure data quality. Behavioural and biological information had been connected by research unique recognition quantity for every participant. Information from each round were merged and analyzed utilizing STATA 14.0 (STATA Corporation). Descriptive statistics of demographic, behavioural, and variables that are biological carried out. The Cochran-Armitage Chi Square trend test had been used to compare differences between categorical factors across various rounds of IBBSS, although the Kruskal-Wallis test had been used to compare variations in constant factors across different rounds of IBBSS. To determine associations between HIV and predictor variables (Tables), bivariate regression that is logistic ended up being carried out with p value ?0•2 designated as the cutoff for inclusion in multivariate logistic regression models. Factors were retained when they attained a p value ?0•05 within the analysis that is multivariate. The predictor factors had been predicated on information from literary works that revealed a link between your variables and HIV.


Table 1 highlights the sociodemographic information of MSM throughout the three rounds associated with IBBSS. An overall total of 897, 1545 and 3611 MSM had been surveyed in 2007, 2010 and 2014 correspondingly. Most of the participants had been aged 20–24 years in 2007 (61%) and 2014 (46%), whilst in 2010, almost half (47%) of this participants had been 25 years or older. Over 85% associated with participants had never ever hitched in each round for the study. Almost all the participants had finished at the very least additional degree training, and also this had been greatest among participants in 2007 with 63% accompanied by respondents in 2014 (55%).

Sexual danger Behaviours

The median amount of insertive anal lovers ended up being consistent between 2007 and 2010 with about 50% associated with participants insertive that is reporting sex (IAS) with at the least two lovers interquartile range (IQR 1–4) within the last half a year. For receptive anal sex (RAS), a median of two partners that are sexual reported in 2007 although it ended up being one partner both in 2010 and 2014. Overall, about a third had engaged in transactional intercourse in 2007 (95% self- confidence period (CI): 30–36%) and 2014 (32–35%), although it had been about two-fifths this season (36–41%). Consistent condom use, whenever intercourse ended up being offered increased steadily from 35% (27–44%) to 79per cent (74–83%) between 2007 and 2014. Likewise, constant condom use within days gone by six months before the study during compensated intimate encounters increased from 35% (30–41%) in 2007 to 61per cent (58–64%) in 2014. For non-commercial lovers, constant condom usage increased from 32per cent (29–36%) in 2007 to 51per cent (49–53%) in 2014. For self-reported experiences of sexually transmitted illness (STI), there clearly was a rise from 7% (5–9%) in 2007 to 15per cent (13–17%) this year and 19per cent (17–20%) in 2014.