ASSESSING INTERVENTION EFFICACY - AN EXAMPLE-BASED ON CHANGE PROFILESOF UNPROTECTED SEX AMONG DRUG-USERS

Over 700 active drug users recruited in East Harlem, New York City, to participate in an AIDS prevention project were interviewed on two occ asions, 6 months apart, to assess changes in HIV-related risk behavior s. This paper presents an example of a method for analyzing patterns o f risk behavior change over time as a means of comparing the effective ness of two interventions. Results described in this paper focus on th e number of unprotected sex acts reported in the 30 days prior to each interview and reflect five distinct patterns of risk level over time (i.e., a decrease, an increase, remaining at low risk, remaining at hi gh risk, or no sexual activity at either time). Bivariate and multivar iate analyses indicated that (1) compared to persons at high levels of unprotected sex at follow-up (time 2), those who remained al a low le vel or decreased were more likely to be HIV positive; and (2) age, liv ing alone, and having a stable source of income were also significant predictors of risk pattern. Risk pattern was not associated with type of risk reduction intervention (standard or enhanced) or with drug tre atment (yes or no) between baseline and follow-up, Implications of the findings were discussed with respect to (a) the assessment of efficac y of AIDS prevention interventions and (b) the analysis of risk behavi or changes over time.