Specialist Referral Patterns Vary Based on Race

Findings of a new study suggest differences exist in specialist referral patterns by race among Medicare beneficiaries.

The findings provided additional evidence that physicians may make different treatment decisions for their Black and White patients.

Bruce E. Landon, M.D., M.B.A., and colleagues examined whether differences existed between Black and White Medicare beneficiaries in the observed patterns of patient sharing between primary care physicians and physicians in the six specialties patients were most frequently referred. The team used data on 100% of traditional Medicare beneficiaries from 51 hospital referral regions for 2009-2010 to examine patient-sharing networks among physicians. They identified the hospital referral regions for which the percentage of Black patients identified in the Beneficiary Summary File was at least 10%. There were 17 markets identified and the investigators restricted the analyses to the 12 markets with the greatest total number of physicians — all had at least 750 physicians.

Physicians encounters were defined based on paid claims in the carrier file. Landon and the team excluded claims for non-direct patient care specialties or specialties where individual physicians were not typically selected by patients.

The investigators constructed networks using three approaches: one based only on encounters for White patients, one based only on encounters for Black patients, and one based on encounters for Black and White patients. The analyses were focused on shared care between primary care physicians and those from the most frequently visited specialties — cardiology, pulmonary disease, gastroenterology, orthopedic surgery, general surgery, and neurology.

Of the 12 selected markets, size ranged from Manhattan, New York (187,054 Black or White beneficiaries seen by at least two physicians within an episode of care; 9,794 total physicians) to Tallahassee, Florida (44,644 Black or White beneficiaries seen by at least two physicians within an episode of care; 847 total physicians). The percentage of Black beneficiaries ranged from 11.5% in Huntsville, Alabama to 46.8% in Chicago, Illinois.

The mean number of specialists a primary care physician shared patients with was lower for Black patients than for White patients. The mean primary care physician-cardiologist degree across all markets for White patients was 17.5 compared with 8.8 for Black patients. The degree difference narrowed after sampling White patients to equalize the numbers of patients seen, but they still were not equivalent in most markets.

Among White patients, specialist networks were much larger than those based just on Black patients (for cardiology across all markets: 135 for Black patients vs 330 for White patients), even after equalizing the numbers of patients seen per primary care physician (123 for Black patients vs 211 for White patients).

Overall, the test for differences in referral patterns was statistically significant for all six specialties examined in seven of the 12 markets and in five specialties for another three markets.

The reasons for the differences may be multifactorial and additional work is needed to better understand the associations, the investigators noted.

The study, “Assessment of Racial Disparities in Primary Care Physician Specialty Referrals,” was published online in JAMA Network Open.