Impact of star ratings on Medicare health plan enrollment: A systematic literature review.

Background: The Medicare star ratings program was developed by the Centers for Medicare and Medicaid Services in 2007 as an approach to evaluate health plan performance and quality.

Objective: This study aimed to identify and narratively describe studies that attempted to quantitatively assess the impact that Medicare star ratings have on health plan enrollment.

Methods: A systematic literature review (SLR) was conducted of PubMed MEDLINE, Embase, and Google to identify articles that quantitatively assessed the impact of Medicare star ratings on health plan enrollment. Inclusion criteria consisted of studies that conducted quantitative analyses to estimate the potential impact. Exclusion criteria consisted of qualitative studies and studies that did not directly assess plan enrollment.

Results: This SLR identified 10 studies that sought to measure the impact of Medicare star ratings on plan enrollment. Nine of the studies found that plan enrollment increased in accordance with increases in star ratings or that plan disenrollment increased with decreases in star ratings. One study conducted of data before the implementation of the Medicare quality bonus payment found contradictory results from one year to the next, whereas all the studies that assessed data after implementation found increases in enrollment in accordance to increases in star ratings or increases in disenrollment for decreases in star ratings. One concerning finding from some of the articles included in the SLR is that increases in star ratings had less of an impact on enrollment in higher-rated plans for ethnic and racial minorities and older adults.

Conclusions: Increases in Medicare star ratings led to statistically significant increases in health plan enrollment and decreases in health plan disenrollment. Future studies are needed to assess whether this increase has a causal association or is caused by additional factors outside of or in addition to increases in overall star rating.