Primary care redesign and care fragmentation among Medicare beneficiaries.

OBJECTIVES: To determine associations between a large-scale primary care redesign-the Comprehensive Primary Care Plus (CPC+) Initiative-and the extent of continuity or fragmentation of ambulatory care for Medicare fee-for-service beneficiaries during the first 3 years of CPC+. STUDY DESIGN: We used a difference-in-differences framework with a comparison group of practices that were similar to CPC+ practices at baseline (eg, practice size, demographics, Medicare spending). Regressions controlled for clustering, baseline patient characteristics, and practice fixed effects. Our study covered January 2016 through December 2019 and included 1,085,707 beneficiaries attributed to 2883 CPC+ practices and 2,274,068 beneficiaries attributed to 6912 comparison practices. METHODS: We focused on beneficiaries with highly fragmented care at baseline because they may have changed the most in response to CPC+. Key outcome measures were the numbers of ambulatory visits and unique practitioners, reported by specialty category; the percentage of visits with the usual provider of care (measuring continuity); and the reversed Bice-Boxerman Index (rBBI; measuring fragmentation). RESULTS: Medicare beneficiaries with high fragmentation (rBBI ≥ 0.85) at baseline (40% of the sample) had a mean of 13 ambulatory visits across 7 practitioners; the most frequent provider of care accounted for only 28% of visits. By contrast, the remaining beneficiaries had a mean of 10 visits across 4 practitioners, with the most frequent provider accounting for 54% of visits. There were no differences in continuity or fragmentation of care for CPC+ vs comparison beneficiaries. CONCLUSIONS: We find no evidence that CPC+ increased continuity or decreased fragmentation of care.