Andrew J. Epstein, MPP, PhD a Mark J. Schlesinger, PhD a Bradford H. Gray, PhD b

1. Racial and Ethnic Differences in Use of High Volume Hospitals and Surgeons Andrew J. Epstein, MPP, PhDa Mark J. Schlesinger, PhDa Bradford H. Gray, PhDb Funding from the Robert Wood Johnson Foundation a Yale University School of Public Health Division of Health Policy and Administration b Urban Institute

2. Background • Hospital and surgeon volume have been associated with lower mortality rates • Minority patients suffer worse access to a range of surgical procedures, and worse outcomes • Do minority patients also suffer worse access to high quality medical care providers? If so, why?

3. Study Objective • To measure racial and ethnic differences in the use of high volume hospitals and surgeons in the New York City area • To decompose the influence of inter- and intra-hospital referral patterns on differences in high volume surgeon use

4. Project Scope • This presentation focuses on results for carotid endarterectomy (CE), percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) surgery • We examine 7 other procedures with a volume-mortality association: • Abdominal aortic aneurysm repair • Surgery for pancreatic, breast, colorectal, gastric and lung cancers • Total hip replacement

5. Data • New York hospital discharge data • All discharges for hospitals treating patients residing in New York City, Westchester and Nassau Counties • Contains demographic, diagnosis, procedure, payer, admission and discharge status data, and unique hospital and surgeon identifiers • Covers 2001-2002 • Surgeon volume calculated statewide and checked against discharge data during 1998-2000

6. Study Sample • Patient inclusion criteria • CE: ICD-9-CM principal procedure code 38.12 • PCI: procedure code 36.01, 36.02, 36.05 or 36.06 • CABG: procedure code 36.10-36.19 • ≥ 18 years of age • Residential ZIP Code in New York City area • Non-missing surgeon identifier • Sample size • CE: 4,638 (276 Black, 63 Asian, 225 Latino) • PCI: 34,598 (2,332 B, 668 A, 2,030 L) • CABG: 14,509 (988 B, 332 A, 919 L)

7. Provider Volume Thresholds To be designated high volume, a provider had to perform at least the following number of procedures annually on average during 2001-2002 a – Halm, Lee Chassin, Ann Int Med, 2002; b – Leapfrog Group, and Birkmeyer and Dimick, Surgery, 2004

8. Statistical Analysis • Χ2 tests and linear regression were used to determine association of race and high volume provider use • Regressions adjusted for patient sex, age, admission type and source, insurance status and number of Elixhauser comorbidities • Models alternatively included patient residence ZIP Code fixed effects and hospital fixed effects.

9. Crude Percent High Volume Provider Use by Race - CE p<0.0001 p<0.0001

10. Crude Percent High Volume Provider Use by Race - PCI p<0.0001 p<0.0001

11. Crude Percent High Volume Provider Use by Race - CABG p<0.0001 p<0.0001

12. Adjusted Probability of High Volume Hospital Use by Race *** p<0.01, ** p<0.05, * p<0.10 Findings expressed as the absolute difference in the probability of treatment at a high volume hospital for minority patients compared with white patients. A negative number indicates a lower probability for minority patients.

13. Adjusted Probability of High Volume Surgeon Use by Race *** p<0.01, ** p<0.05, * p<0.10 Findings expressed as the absolute difference in the probability of treatment by a high volume surgeon for minority patients compared with white patients. A negative number indicates a lower probability for minority patients.

14. Results Summary • Minorities significantly (p<0.10) less likely to use high volume hospitals • Baseline models: 8-9 procedures • ZIP Code fixed effects: 5-8 procedures • Minorities significantly (p<0.10) less likely to use high volume surgeons Baseline ZIP Code & models ZIP Code FEs Hospital FEs Blacks 10 5 2 Asians 6 4 3 Latinos 7 5 3

15. Limitations • Data do not reveal patients’ true sets of provider choices • We cannot rule out that referrals of patients to providers were based on other (i.e., non-volume) quality of care measures • Data field indicating operating physician is not audited

16. Conclusion • Minority patients in the New York City area were less likely to be treated by high volume providers • Differences in the geographic distributions of patients and providers explain a large proportion of racial and ethnic differences in access • However, minority patients from the same ZIP Codes were still less likely to be treated by high volume providers • For a few procedures, minority patients from the same ZIP Codes treated at the same hospitals were less likely to be treated by high volume surgeons

17. Policy Significance • Evidence that minority patients are steered to low volume surgeons within a hospital was found only for 3 of 10 procedures • This suggests systematic racial discrimination is not the primary driver • Instead, minority patients and their referring physicians appear to have both differing availability and preferences for providers than white patients • Is it easier to improve the quality of care at these institutions than it would be to shift minority referral patterns toward higher quality institutions?