WHO USES NEEDLE EXCHANGE - A STUDY OF INJECTION-DRUG USERS IN TREATMENT IN SAN-FRANCISCO, 1989-1990

We examined use of the San Francisco needle exchange program (NEP) by 1093 injection drug users (IDUs) recruited in methadone maintenance an d out-patient detoxification programs in the first 2 years after the o pening of the NEP in 1988. Thirty-one percent of IDUs had ever used th e NEP. IDUs who were frequent injectors, homeless, and aware of their serostatus were more likely to use the NEP. To assess self-selection o f IDUs at risk for seroconversion for using needle exchange, we calcul ated pre-needle exchange seroconversion rates. Among 385 IDUs seen twi ce, the HIV seroconversion rate was 0.38% per person year among subjec ts who never used needle exchange, but it was 9.34% per person year am ong those who later used needle exchange (p = 0.003). NEP attracted a subset of IDUs at very high risk for HIV infection. Among injectors wh o were interviewed before and after the opening of the needle exchange s in San Francisco, the number of sharing partners did not change amon g IDUs who attended or among IDUs who never attended the NEP. The NEP attracted a very-high-risk subgroup of IDUs, as measured by risk behav ior and pre-needle exchange HIV-seroconversion rate. NEPs should be co nsidered prime sites for behavior-change interventions.