This study assessing the relative contribution of “between-”and “within-” physician effects to racial and ethnic disparities in patients’ experiences of primary care yields several important findings relevant to reducing disparities. First, our results are the first to highlight that, in California, most racial and ethnic minority groups are clustered within PCP practices at levels greater than one might expect by chance. This suggests there is potential for reducing racial and ethnic disparities in primary care quality through targeted interventions aimed at individual physician practices with substantial concentrations of specific patient groups.
Second, “within-physician” differences accounted for the bulk of disparities in patients’ experiences of primary care for Asians and Pacific Islanders. Our findings indicate that Asians and Pacific Islanders are more likely to report worse experiences relative to Whites in the same PCP practices. For some measures, including the quality of physician–patient interactions and care coordination, “between” physician effects account for a non-trivial amount of the overall disparity, particularly for Asians who primary speak a language other than English. In general, however, our findings are consistent with a recent study that finds that “within-physician” differences account for Asian-White disparities in clinical interaction quality.31
However, it remains unclear whether disparities in patients’ experiences are mainly attributable to differential treatment by physicians or to cultural norms that influence the reporting tendencies of Asian patients. Future research should clarify the determinants of Asian–White differences.
Finally, “between-physician” effects contributed more to disparities between Whites and Latinos, Blacks, and American Indian/Alaskan Natives than “within-physician” effects. This indicates that patients from these groups are more likely to attend PCP practices with low performance on patient experience measures compared to Whites, possibly because these groups tend to be more residentially segregated or located in markets with low physician supply.32,33
In order to significantly reduce disparities in patients’ experiences of primary care, especially with respect to organizational access,34,35
it will be important for performance improvement efforts to focus on low performing physician practices with high concentrations of patients from these groups. Our results indicate that Latinos and Blacks were significantly clustered in practices facing time constraints for clinical interactions and long in-office wait times. Previously observed differences in patients’ experiences of primary care might be reduced by ensuring that PCPs treating high percentages of patients from these racial and ethnic groups have adequate appointment access and/or are supported by multidisciplinary teams with strong orientation to patient-centered care.36,37
Inadequate reimbursement might also contribute to the observed performance deficits on patient experience measures for practices with high concentrations of Blacks and Latinos. Physicians who care for high concentrations of minority patients tend to have face appointment access constraints and perceive more challenges with providing high quality care.38
Our study is limited to commercially-insured patients, suggesting that spillover effects or that the low reimbursement from Medicaid and uninsured patients in the physician practices can negatively affect the care commercially-insured patients receive.39
Additional data on physician and practice characteristics, including the extent to which physicians care for Medicaid and uninsured patients, could clarify the extent to which spillover effects occur.
There are some limitations to this study. First, the response rate was modest but comparable to other patient experience performance measurement efforts nationally.40
We are unable to assess differential patient non-response bias by race and ethnicity because this information was ascertained in the survey and unavailable for non-respondents. Blacks and Latinos are less likely to be commercially-insured compared to Whites;41
however, underrepresentation relative to population estimates might reflect differences in insurance coverage status rather than a lower propensity to respond. Moreover, we examined the sensitivity of results to differential non-response by individual physician using non-response weights and results were consistent. Second, there might be unobserved heterogeneity within minority patient categories that explain differences associated with the practice concentration of patient racial/ethnic minority patients. Acculturation measures, for example, could enrich the analyses.42
Third, the results might not generalize to states with different demographic distributions and PCP supply. For example, Puerto Ricans and Cuban–Americans, who make up the majority of Latinos in many east coast states, are generally better integrated into primary care practices compared to Mexican-Americans,35,43
who constitute the majority of the California Latino population. Finally, we did not assess racial/ethnic disparities in the technical quality of primary care. A study of one physician organization found that racial disparities in the quality of diabetes care were mainly attributable to “within-physician” effects.44
Further study, however, is needed to examine the relative contribution of “within-” and “between-” physician effects on the technical quality of primary care.
Our findings have strong parallels with growing evidence that patient clustering can explain racial and ethnic disparities in the technical quality of medical care,45–47
and patient outcomes.48
This study is the first to demonstrate the influence of physician effects on disparities in patients’ experience of primary care and indicates that commercially-insured Latino, Black, and American Indian/Alaskan Native patients are more likely to receive care in PCP practices with low performance on patients’ experience measures compared to Whites. If reducing ethnic and racial disparities in patients’ experiences of primary care is a priority, initiatives might achieve the largest impact by focusing on low performing practices with high concentrations of racial and ethnic minority patients. Markets with high concentrations of Latinos face serious bilingual physician recruitment and retention problems32
so disparity reduction efforts should be sensitive to physician supply constraints when developing solutions.