Assessing influenza immunization rates in Medicare managed care plans: a comparison of three methods

In an effort to improve care delivered to Medicare beneficiaries, the Health Care Financing Administration (HCFA) has encouraged competitive Medicare risk plans to collaborate on quality improvement projects. PRO-West, a private, nonprofit quality improvement organization, fostered a collaboration of all Medicare risk plans in Washington State in order to assess and improve influenza immunization rates among seniors enrolled in managed care.

After the 1994-1995 influenza immunization season, immunization rates were determined for each participating plan from administrative data and medical record review. In the 1995-1996 season, these methods were supplemented with a telephone survey. The survey was used to identify perceived barriers to immunization and to estimate immunization rates.

Immunization rates, as estimated by administrative data and medical record review, were similar for both years. The average immunization rate using administrative data for the 1995-1996 flu season was 60.6% (range, 42.8% to 72.3%). The estimated rate increased to 77.8% (95% confidence interval, 75.3% to 80.3%) when the telephone survey data were added. Medical record review contributed little additional information.

Influenza immunization rates for seniors enrolled in Medicare risk plans in Washington State exceed those reported for fee-for-service Medicare beneficiaries. Telephone surveys resulted in higher and probably more valid estimates of influenza immunization rates than did analysis of administrative data and medical records. Plans with lower rates can emulate "benchmark" plans that are explicit about the methods they use to achieve high coverage rates. Medicare risk health plans competing in the same markets can collaborate in quality assessment activities in an effective manner.