iMPACT3: Internet-based development and administration of utility elicitation protocols.

iMPACT3 (Internet Multimedia Preference Assessment Instrument Construction Tool, version 3) is a software development environment that helps researchers build Internet-capable multimedia utility elicitation software programs. The program is a free, openly accessible Web site (http.// preferences.ucsd.edu/impact3/asp). To develop a utility elicitation software program using iMPACT3, a researcher selects modular protocol components from a library and custom tailors the components to the details of his or her research protocol. iMPACT3 builds a Web site implementing the protocol and downloads it to the researcher's computer. In a study of 75 HIV-infected patients, an iMPACT3-generated protocol showed substantial evidence of construct validity and good internal consistency (logic error rates of 4% to 10% and procedural invariance error rates of 10% to 28%, depending on the elicitation method) but only fair 3- to 6-week test-retest reliability (intraclass correlation coefficient= 0.42 to 0.55). Further work may be needed on specific utility assessment procedures, but this study's results confirm iMPACT3's feasibility in facilitating the collection of health state utility data.