HIV-1 incidence among opiate users in northern Thailand

The incidence of human immunodeficiency virus type 1 (HIV-1) infection amon g opiate users was determined in a retrospective cohort of 436 patients wit h multiple admissions to the only inpatient drug treatment program in north ern Thailand between October 1993 and September 1995. During 323.4 person-y ears 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% co nfidence 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-ye ars for injectors and 2.8 per 100 person-years for noninjectors (smoking an d ingestion). Significant differences were found by ethnicity: HIV-1 incide nce was 29.3 per 100 person-years for Thai lowlanders and 8.5 per 100 perso n-years for hilltribes. Multivariate relative risk estimates showed that in jecting 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 associa ted with human immunodeficiency virus seroconversion, This HIV-1 incidence rate is double that reported for Bangkok and suggests that prevention and c ontrol programs for drug users need to be expanded throughout Thailand. Imp roved availability of more-effective treatment regimens and increased acces s to sterile injection equipment are needed to confront the HIV-1 epidemic among opiate users in northern Thailand.