Health plan use of immunization information systems for quality measurement.

OBJECTIVE: To evaluate a health plan's business case for using a state immunization information system (IIS) as the primary data source for members' immunization histories. STUDY DESIGN: Case study of Priority Health- a Michigan managed care organization- to investigate use of IIS data for Healthcare Effectiveness Data and Information Set (HEDIS) compliance- quality measurement- and a provider incentive program. METHODS: Primary data were collected through key informant interviews and group discussions with Priority Health and IIS managers. Priority Health's information systems were populated with claims data and supplemental data- before chart reviews- to simulate immunization and health plan quality measures for 2004 to 2007 in the absence of IIS data. Simulated rates were compared with historical rates that included IIS data. The study included a cost-benefit analysis. RESULTS: For 2007- IIS data increased observed immunization rates from 6.49 to 54.13 percentage points for childhood immunizations and 57.6