Factors Explaining the Disparity in Breast Cancer Screening Rates between Dual Eligible and Non-Dual Eligible Medicare Advantage Members

background: Health plans with large proportion of dual eligible (DE) members tend to have lower performance on the CMS Five Star Rating System. The objective of this study was to identify factors contributing to the disparity between DE and non-DE Medicare Advantage (MA) members in one Five Star measure, Breast Cancer Screening (BCS), and to quantify these factors’ relative contributions to the performance gap.

methods: The study sample consisted of MA beneficiaries from a large nationally representative administrative claims database supplemented with socioeconomic and community resource data. BCS rates were calculated using 2013 Healthcare Effectiveness Data and Information Set specifications. Blinder-Oaxaca decomposition analysis was used to assess factors contributing to the disparity in BCS rates between DE and non-DE members.

results: Of 247,774 eligible women, the BCS rate was 3.2% lower in DE members (74.8% vs. 77.3%). Decomposition analysis showed that differences in member characteristics explained 90.5% of the performance gap for BCS (“explained” proportion).  The remaining 9.5% of the gap was due to the differential impact of these factors on the likelihood of receiving BCS in DEs compared to non-DEs (“unexplained” proportion). DE members were more concentrated in the Middle Atlantic (41.5% vs. 21.6%) and less in the East North Central (5.5% vs. 30.1%) compared to non-DE members.  This geographic variation accounted for 61.4% of the gap.  Percent of members with disability or End Stage Renal Disease as their original reason for Medicare entitlement was significantly higher in DE members (49.3% vs. 20.6%) and these members were less likely to receive BCS.  Members living in neighborhoods with low home ownership rate (≤54% of households) were less likely to have BCS.  Higher proportions of DE members reside in such areas (52.6% vs. 41.0%), accounting for 49.2% of the disparity.  Race and Ethnicity; however, reduced the performance gap.  A larger proportion of DE members were Black or Hispanic and those groups were more likely to receive BCS than white DE with otherwise similar risk profiles.

conclusions: Over 90% of the BCS performance gap between DE and non-DE members was explained by differences in member characteristics. Future measure development efforts can focus on these factors as potential risk adjustors to improve the usefulness of this measure in MA plan evaluation and quality improvement efforts.