Invited commentary: needle exchange--no help for hepatitis?

In 1993, Heimer, Kaplan, and associates (1) showed a reduction in the proportion of human immunodeficiency virus (HTV)-infected syringes among those returned to the New Haven, Connecticut, needle exchange in the months following the opening of the program. This reduction suggested a decrease in the circulation time of used needles among injectors who use the exchange, and this decrease can in turn be modeled as corresponding to a reduction in the HTV seroconversion rate of 25-30 percent. This is still the only real estimate of the actual effect of a needle exchange on HTV seroconversion in a US population. The New Haven study was extremely influential in providing an intellectual underpinning to the rapidly expanding needle exchange movement, which began in the United States in the late 1980s. A second study providing support was Hagan and collaborators' casecontrol study of hepatitis in injectors in Tacoma, Washington State, which showed an apparent major reduction in clinical hepatitis attributable to exchange use (2). However, that study has now been directly contradicted by a new study, carried out by some of the same researchers, of hepatitis B and C seroconversion in Seattle, Washington, injectors, which is published in this issue (3). The new study by Hagan et al., a large cohort study, is the first prospective study of the effect of needle exchange on blood-borne infections in the United States; it shows no effect of needle exchange use on hepatitis B virus (HBV) and hepatitis C virus (HCV) seroconversion. The study by Hagan et al. (3) comes on the heels of studies in Montreal and Vancouver, Canada (4, 5), which showed no effect of needle exchange use on seroconversion for HTV. (The HTV seroconversion rate