Willingness to use microbicides is affected by the importance of product characteristics, use parameters, and protective properties.

Background: Along with efficacy, a microbicide's acceptability will be integral to its impact on the pandemic. Understanding Product Characteristics that users find most acceptable and determining who will use which type of product are key to optimizing use effectiveness.

Objectives: To evaluate psychometrically the Important Microbicide Characteristics (IMC) instrument and examine its relationship to willingness to use microbicides.

Results: Exploratory and confirmatory factor analyses revealed 2 IMC subscales (Cronbach's coefficient alpha: Product Characteristics subscale (alpha = 0.84) and Protective Properties subscale (alpha = 0.89)). Significant differences on Product Characteristics subscale scores were found for history of douching (P = 0.002) and employment status (P = 0.001). Whether a woman used a method to prevent pregnancy or sexually transmitted disease (STD) in the last 3 months (P < 0.001) and whether she used a condom during the last vaginal sex episode (P < 0.001) were significantly related to her rating of the importance of microbicides being contraceptive. Product Characteristics (r = 0.21) and Protective Properties (r = 0.27) subscale scores and whether a microbicide had contraceptive properties (r = 0.24) were all significantly associated (P < 0.001) with willingness to use microbicides.

Conclusions: Formulation and use characteristics and product function(s) affect willingness to use microbicides and should continue to be addressed in product development. The IMC instrument serves as a template for future studies of candidate microbicides.