OBJECTIVE: To compare physician versus practice-level primary care continuity and their association with expenditure and acute care utilization among Medicare beneficiaries and evaluate if continuity of outpatient primary care at either/both physician or/and practice level could be useful quality measures. DATA SOURCE: Medicare Fee-For-Service claims data for community dwelling beneficiaries without End-Stage Renal Disease who were attributed to a national random sample of primary care practices billing Medicare (2011-2017). STUDY DESIGN: Retrospective secondary data analysis at per Medicare beneficiary per year level. We used multivariable linear regression with practice-level fixed effects to estimate continuity of care score at physician vs. practice level and their associations with outcomes. DATA COLLECTION/EXTRACTION METHOD: We calculated clinician and practice level Bice-Boxerman continuity of care index scores, ranging from 0 to 1, using primary care outpatient claims. Medicare expenditures, hospital admissions, emergency department visits, and readmissions were obtained from the Medicare Beneficiary Summary File: Cost and Utilization Segment. Ambulatory care sensitive conditions (ACSC) were defined using diagnosis codes on inpatient claims. PRINCIPAL FINDINGS: We studied 2,359,400 beneficiaries who sought care from 13,926 physicians. Every 0.1 increase in physician continuity score was associated with a $151 reduction in expenditures per beneficiary per year (P<0.01), and every 0.1 increase in practice continuity score was associated with $282 decrease (P<0.01) per beneficiary per year. Both physician- and practice-level continuity were associated with lower Medicare expenditures among small, medium, and large practices. Both physician- and practice-level continuity were associated with lower probabilities of hospitalization, emergency department visit, admissions for ACSC, and readmission. CONCLUSIONS: Primary care continuity of care could serve as a potent value-based care quality metric. Physician-level continuity is a unique value center that cannot be supplanted by practice level continuity.
