To the Editor.
—To estimate the incidence of human immunodeficiency virus (HIV) infection (seroconversions), a retrospective study of records from a voluntary HIV counseling and testing program at a New York City methadone maintenance treatment program (MMTP) was initiated. The study included records of patients who had 2 or more HIV tests and were HIV-negative on the initial test. A seroconverter was defined as a person with an initial HIV-negative test followed by an HIV-positive test. The seroconversion rate (incidence density of HIV infections) was calculated by dividing the number of seroconverters by the total number of personyears of follow-up. The follow-up time for nonseroconverters included the time between the initial test and the last test. For seroconverters, follow-up time was calculated as the midpoint between the last HIV-negative test and the first HIV-positive test.From July 1990 to April 1994, a total of 1833 voluntary HIV tests were conducted
Orr MF, Glebatis D, Friedmann P, Des Jarlais DC, Prevots DR. Incidence of HIV Infection in a New York City Methadone Maintenance Treatment Program. JAMA. 1996;276(2):99. doi:10.1001/jama.1996.03540020021011