Physician- versus practice-level primary care continuity and association with outcomes in Medicare beneficiaries

Objective To compare physician-level versus practice-level primary care continuity and their association with expenditure and acute care utilization among Medicare beneficiaries and evaluate whether 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 versus 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 (ED) 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 expenditure 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, ED 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.