Study Population and Setting Clause Samples

Study Population and Setting. In 1970, the Senegalese government legalized prostitution and mandated FSW registration at clinics implemented at major urban centers for this purpose of the registration program. This registration program consists of compulsory periodic evaluation and treatment, if required, for sexually transmitted infections (STI). At each visit, FSWs are counseled on STI and HIV prevention and offered condoms and medical care if necessary at no cost. An annual blood screening for HIV-1 and/or HIV-2 antibodies is performed on all registered FSWs (9,10,18). Since 1985, registered FSWs visiting the clinic in Dakar (Institut d’Hygiene Sociale) have been prospectively followed for studies on the clinical and immunologic outcome of HIV-1 and HIV-2 and the evaluation of a candidate HIV vaccine, when available. Protocols for study enrolment and cohort design have been previously described (9-11,31). Our study population consisted of an open cohort of FSWs registered and attending the clinic in Dakar from 1992 to 2010. Inclusion criteria included a completed enrollment questionnaire with demographics and sexual behaviors, availability of data from a baseline and one or more follow-up visits at the Dakar clinic, two or more HIV serology results and a negative HIV baseline serum. Our outcome variable was seroconversion to HIV. Demographic and behavioral characteristics such as age at registration, time in the prostitution business, time in the registration program, condom use, history of scarifications, excisions, nationality, number of partners, price for services, and education were used to determine potential factors for HIV seroconversion. All analyses were performed using SAS version 9.3 (SAS Institute, Cary, North Carolina). Routine medical records of study participants were used to provide estimates of HIV incidence among FSWs and identify potential predictors of seroconversion. Demographic and baseline characteristics of FSWs who seroconverted to HIV were compared to those of FSWs who did not seroconvert. Depending on whether distributional assumptions were met, continuous outcomes were examined using either t tests or Wilcoxon rank sum tests. Similarly, binary outcomes were examined using either ▇▇▇▇▇▇▇ ▇▇▇-square or ▇▇▇▇▇▇’▇ exact test. Seroconversion date was arbitrarily calculated as the midpoint between the last negative HIV-1 and/or HIV-2 antibody test and the first positive HIV-1 and/or HIV-2 antibody test. Censoring was considered at the last negative HIV-1 and/or...