The incidence of human immunodeficiency virus type 1 (HIV-1) infection among opiate users was determined in a retrospective cohort of 436 patients with multiple admissions to the only inpatient drug treatment program in northern Thailand between October 1993 and September 1995. During 323.4 person-years of follow-up, 60 patients presenting for detoxification acquired HIV-1 infection, for a crude incidence rate of 18.6 per 100 person-years (95% confidence interval 14.4-23.9). All seroconverters were male. HIV-1 incidence varied by the current route of drug administration: 31.3 per 100 person-years for injectors and 2.8 per 100 person-years for noninjectors (smoking and ingestion). Significant differences were found by ethnicity: HIV-1 incidence was 29.3 per 100 person-years for Thai lowlanders and 8.5 per 100 person-years for hill tribes. Multivariate relative risk estimates showed that injecting opiates (vs. use by other routes), being unmarried, being under age 40 years, being a Thai lowlander, having a primary and secondary education, and being employed in the business sector were each independently associated with human immunodeficiency virus seroconversion. This HIV-1 incidence rate is double that reported for Bangkok and suggests that prevention and control programs for drug users need to be expanded throughout Thailand. Improved availability of more-effective treatment regimens and increased access to sterile injection equipment are needed to confront the HIV-1 epidemic among opiate users in northern Thailand.
PIP: The incidence of HIV-1 infection among opiate users was assessed in a retrospective cohort of 436 patients with multiple admissions to the only inpatient drug treatment program in northern Thailand between October 1993 and September 1995. During 323.4 person-years of follow-up, 60 patients presenting for detoxification acquired HIV-1 infection, for a crude incidence rate of 18.6/100 person-years. All seroconverters were male. HIV-1 incidence varied by the current route of drug administration: 31.3/100 person-years for injectors and 2.8/100 person-years among those who smoked or ingested the drug. HIV-1 incidence was 29.3/100 person-years for Thai lowlanders and 8.5/100 person-years for hill tribes. Multivariate analysis found that injecting opiates, being unmarried, being under age 40 years, being a Thai lowlander, having a primary and secondary education, and being employed in the business sector were each independently associated with HIV seroconversion. The HIV-1 incidence rate in this population is double that reported for Bangkok. As such, HIV prevention and control programs for drug users need to be expanded throughout Thailand. Moreover, improved availability of more effective treatment regimens and increased access to sterile injection equipment are needed to confront the HIV-1 epidemic among opiate users in northern Thailand.