HIV infection and risk factors among Bangkok prisoners, Thailand: a prospective cohort study

Background: Incarceration has been associated with HIV infection among injection drug users. However, data on HIV risk factors of the inmates during incarceration are rarely reported from Thailand. Methods: A prospective cohort of 689 male inmates in a Bangkok central prison was studied during 2001-2002. Follow up visits were conducted for 5 months, with testing for HIV and other infections and interviewing of demographics and risk behaviors. Results: Among 689 male inmates, half (50.9 %) were drug injectors. About 49% of the injectors had injection during incarceration. Most (94.9%) of the injectors had shared injection paraphernalia with others. Successful follow up rate was 98.7% after 2,581 person-months observation. HIV incidence was 4.18 per 100 person - years among all inmates, and 11.10 per 100 person - years among the injection inmates. Multivariate analysis identified variables associated with HIV prevalence: history of injection [OR = 2.30, 95% CI: 1.91-2.77], positive urine opiate test [OR = 5.04, 95% CI: 2.63-9.67], history of attendance to drug withdrawal clinics [OR = 2.00, 95% CI: 1.19-3.35] and presence of tattoos on the body [OR = 1.23, 95% CI: 1.01-1.52]. Conclusions: The main HIV risk factors of Bangkok inmates were those related to drug injection. Harm reduction measures and HIV intervention strategies should be implemented to prevent more spread of HIV among the inmates and into the community.