Background: Few studies have clarified the mechanisms that contribute to racial and ethnic disparities in primary care quality among comparably-insured patients.
Objective: To examine relative contribution of "between-" and "within-" physician effects on disparities in patients' experiences of primary care.
Design: Regression models using physician fixed effects to account for patient clustering were specified to assess "between-" and "within-"physician effects on observed racial and ethnic disparities in patients' experiences of primary care.
Participants: The Ambulatory Care Experiences Survey (ACES) was administered to patients visiting 1,588 primary care physicians (PCPs) from 27 California medical groups. The analytic sample included 49,861 patients (31.4 per PCP) who confirmed a PCP visit during the preceding 12 months.
Main results: Most racial and ethnic minority groups were significantly clustered within physician practices (p < 0.001). "Between-physician" effects were mostly negative and larger than "within-physician" effects for Latinos, Blacks, and American Indian/Alaskan Natives, indicating that disparities are mainly attributable to patient clustering within physician practices with lower performance on patient experience measures. By contrast, "within-physician" effects accounted for most disparities for Asians and Pacific Islanders, indicating these groups report worse experiences relative to Whites in the same practices. Practices with greater concentration of Blacks, Latinos and Asians had lower performance on patient experience measures (p < 0.05).
Conclusions: Targeting patient experience improvement efforts at low performing practices with high concentrations of racial and ethnic minorities might efficiently reduce disparities. Urgent study is needed to assess the contribution of "within-" and "between-" physician effects to racial and ethnic disparities in the technical quality of primary care.