Theoretical Models of HIV Prevention

In this discussion of behaviour change theory related to HIV prevention, author Martin Fishbein discusses elements that can be influenced by behaviour change, theories of behaviour changes, and conditions that influence a particular behaviour. In order to understand the role of behaviour change in preventing the further spread of HIV, the author recommends examining the May & Anderson (1987) model of the reproductive rate of a sexually transmitted disease: Ro =βcD, in which Ro = reproductive rate (of transmission), ß = measure of infectivity or transmissibility, c = measure of interaction rates between susceptibles and infectors, and D = measure of duration of infectiousness.

"Because each of the elements in the right side of the equation can be influenced by behavior change, the model suggests that there are many behaviors that affect the rate of HIV transmission. For example, the degree of infectivity or transmissibility (ß) can be decreased by increasing condom use or by delaying the onset of sexual activity. The interaction rate (c) can be influenced by decreasing the rate of new partner acquisition or increasing monogamy. Although there is no way at present to change the duration of infectiousness (D) for HIV, it should be noted that sexually transmitted diseases (STDs) serve as co-factors in HIV transmission (i.e., they influence ß) and duration of infectiousness (D) is a very important parameter in reducing the transmission of STDs. Thus, if one can increase the likelihood that people will participate in screening or if they can be motivated to seek early treatment for symptomatic STDs, this will reduce the duration of infectiousness (D) for an STD, which ultimately reduces seroincidence."

The document discusses introduction of condom use in a low prevalence vs. a high prevalence population, as a factor that will result in variability in influence of the rate of infection. "To produce change in a given behavior, however, it is important to first understand the factors underlying the performance (or nonperformance) of that behavior.... [T]here is a growing consensus that, at the theoretical level, only a limited number of variables need to be considered in order to predict and understand any given behavior."

The following three theories are reviewed: the Health Belief Model (Rosenstock, Strecher, & Becker, 1994), the Social Cognitive Theory (Bandura, 1994), and the Theory of Reasoned Action (Fishbein, Middlestadt, & Hitchcock, 1991) as representing a public health, a clinical, and a social-psychological approach to understanding behaviour and behaviour change. Also, representing clinical and social-psychological theories, the document reviews: the Theory of Self-Regulation and Self-Control and the Theory of Interpersonal Relations and Subjective Culture. From these, the variables that are central to predicting and understanding a given behaviour are listed. Of these, three variables were selected for which the "probability that a given behavior will be performed is very close to 1.0." The following are the three conditions: "(1) the person has formed a strong intention (or made a commitment) to perform the behavior, (2) he or she has the skills and abilities required for behavioral performance, and (3) there are no environmental constraints to prevent behavioral performance."

As stated here, "it is important to empirically identify those factors that most strongly influence a given behavior in a given population and then use this information to design interventions."

The document concludes: "Targeted, theory-based interventions can change behavior. There are only a limited number of theoretical variables (or psychosocial determinants) that need to be considered in attempts to predict, understand, and change behavior. The impact of a given behavior change on the AIDS epidemic will depend on local circumstances, such as prevalence of the disease and sexual mixing patterns in the population."