PROSPECTIVE COHORT STUDY OF FEMALE SEX WORKERS AND THE RISK OF HIV-INFECTION IN ALICANTE, SPAIN (1986-96)

Objective: To measure the incidence of HIV infection over a 10 year fo llow up in a cohort of female commercial sex workers in Alicante (Spai n), and to determine factors associated with high risk of infection. M ethods: A prospective cohort study was carried in an AIDS information and prevention centre in Alicante, Spain. Of the 1388 female sex worke rs who initially sought the services of the centre since September 198 6, 657 completed at least one additional follow up visit before Decemb er 1996. Main outcome measures were infection with HIV-1 and reported risk behaviours. Results: During 1815 person years of observation amon g 657 female sex workers who were free of HIV infection (negative test ), 16 women developed the HIV infection (incidence rate of HIV infecti on = 8.8 cases/1000 woman years, 95% confidence interval (CI): 5.4-14. 4). Reported current use of injecting drugs at the first visit was ass ociated with an increased risk of HIV infection (relative risk, RR=12. 87, 95%CI: 4.81-34.15) as well as having an usual partner with injecti ng drug addiction (RR=20.89, 95%CI: 7.44-58.70). Infection also was as sociated with younger age (RR for 1 year=0.86, 95%CI: 0.76-0.96). Afte r multivariate adjustment using Poisson regression analysis, the facto rs that remained significantly associated with the risk of HIV infecti on were current use of injecting drugs (RR=4.61, 95%CI: 1.37-15.46), a nd having a usual partner with injecting drug addiction (RR=10.08, 95% CI: 2.94-34.57). There was also some evidence that a younger age could be related to infection. Conclusion: These data suggest that the risk of HIV infection among this cohort of female sex workers in Alicante is predominately associated with the use of injecting drugs, and havin g a regular partner with injecting drug addiction. An increasing numbe r of clients did not play a role in the risk of infection.