Information-Motivation-Behavioral Skills (IMB) model: Testing direct and mediated treatment effects on condom use among women in low-income housing

Background: The Information-Motivation-Behavioral Skills (IMB) model of HIV preventive behavior (1-4) specifies that treatment effects on behavior occur largely as the result of treatment effects on behavioral skills, which follow from effects on information and motivation. Purpose: The objective was to determine whether the variables spec fled by the IMB model of HIV preventive behavior (1-4) accounted for the relation between an IMB-based treatment and resulting HIVpreventive behavior (condom use). Method: Women (n = 557) living in 18 low-income housing developments in 5 geographically dispersed cities were recruited to participate in an HIV-prevention studs,. Women (within housing developments) were randomly assigned to receive an IMB-based, HIV risk-avoidance intervention or a comparison intervention. Baseline and posttreatment (16 months after baseline) data were collected on condom use information, motivation (social norms, attitudes, intentions, and perceived risk), enactment of behavioral skills (condom negotiation and procurement), and rates of condom use in the past 2 months. Results: The IMB intervention led to a 12% to 16% increase in condom use rates over the course, whereas the comparison intervention led to 2% decrease. In addition, the IMB treatment led to greater increases in condom use information, it? the intentions and social norms components of motivation and the condom procurement and condom conversations components of behavioral skills. The IMB model provided an acceptable fit to the data (root mean square error of approximation <.05) and accounted for 50% of the variance in posttreatment condom use among the sample. Treatment effects on condom use were almost entirely mediated by the IMB variables; specifically, motivation and enactment of behavioral skills mediated the intervention's impact on condom use. Conclusions: These results provide supporting evidence as to how theoretical variables operate to effect change within a theory-based intervention and provide evidence as to the applicability of a prevailing theory of HIV risk behavior among low-income minority women.