Antiretroviral Therapy among HIV-1 Infected Female Sex Workers in Benin: A Comparative Study with Patients from the General Population

Objective: The aim of this study conducted in Benin was to compare HIV-1 infected female sex workers (FSW) and patients from the general population (GP) to see whether there was a difference in adherence level, mortality rate and immuno-virologic response to antiretroviral therapy (ART). Methods: Fifty-tree FSW and 318 patients from the GP were recruited and followed for at least one year. We compared both cohorts according to poor-adherence (taking <95% of the pills), CD4 count increase, undetectable viral load (VL;≤50 copies/mL) and crude mortality rate. We constructed a multivariate regression model to assess factors associated with undetectable VL. Results: During the first year, the proportion of FSW with poor-adherence was significantly higher than that of the GP patients (19.3% versus 7.5%;p < 0.0001) and median gain in CD4 count among FSW was slightly lower (103/mm3 versus 129/mm3;p = 0.085). In the multivariate model (including CD4 at ART initiation and the sub-cohort i.e. FSW vs GP patients), duration under ART (p = 0.003) as well as CD4 count at enrolment in the study (p < 0.0001) and good-adherence (0.057) were independently associated with undetectable VL. When adherence was withdrawn from this model, there was a borderline significant association between detectable VL and being a FSW (p = 0.074). The crude mortality rate was 1.11 per 100 persons-years among the GP patients and 4.65 per 100 persons-years among FSW. Conclusion: Response to ART was lower among FSW compared to GP patients, as a result of poorer adherence. Specific behavioural interventions are needed to improve adherence and response to ART among FSW.

Using data from‘visible’populations to estimate the size and importance of‘hidden’populations in an epidemic:A modelling technique

We used reported behavioural data from cisgender men who have sex with men and transgender women(MSM/TGW)in Bangalore,mainly collected from‘hot-spot’locations that attract MSM/TGW,to illustrate a technique to deal with potential issues with the representativeness of this sample.A deterministic dynamic model of HIV transmission was developed,incorporating three subgroups of MSM/TGW,grouped according to their reported predominant sexual role(insertive,receptive or versatile).Using mathematical modelling and data triangulation for‘balancing’numbers of partners and role preferences,we compared three different approaches to determine if our technique could be useful for inferring characteristics of a more‘hidden’insertive MSM subpopulation,and explored their potential importance for the HIV epidemic.Projections for 2009 across all three approaches suggest that HIV prevalence among insertive MSM was likely to be less than half that recorded in the surveys(4.5e6.5%versus 13.1%),but that the relative size of this subgroup was over four times larger(61e69%of all MSM/TGW versus 15%).We infer that the insertive MSM accounted for 10e20%of all prevalent HIV infections among urban males aged 15e49.Mathematical modelling can be used with data on‘visible’MSM/TGW to provide insights into the characteristics of‘hidden’MSM.A greater understanding of the sexual behaviour of all MSM/TGW is important for effective HIV programming.More broadly,a hidden subgroup with a lower infectious disease prevalence than more visible subgroups,has the potential to contain more infections,if the hidden subgroup is considerably larger in size.