The typical two-year time lag between health plan performance measurement and the action taken based on that performance underscores the importance of understanding that performance measures are only moderately stable over time.
This study assessed the stability of health plan performance over time when multiple indicators of performance exist. Researchers used longitudinal data from the National Committee for Quality Assurance Health Care Effectiveness Data and Information Set to examine whether plan quality ratings are stable from year to year.
- Findings show moderate persistence in plan performance over time. A plan performing in the upper tier in 1999 had only a 0.47 probability of remaining in that tier in 2001.
- Multiple years of good performance increase the probability of good performance in the future.
- Better performance in the more recent past is more indicative of better performance in the future than better performance in the more distant past.
These results suggest that consumers and purchasers should use more relevant data, such as past performance, to help them make informed decisions about enrollment, and policy-makers should develop methods to address the time lag and its consequences on quality improvement efforts.