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
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?
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 intrahospital referral patterns on differences in high
volume surgeon use
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 volumemortality association:
– Abdominal aortic aneurysm repair
– Surgery for pancreatic, breast, colorectal, gastric
and lung cancers
– Total hip replacement
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
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
– PCI: 34,598
– CABG: 14,509
(276 Black, 63 Asian, 225 Latino)
(2,332 B, 668 A, 2,030 L)
(988 B, 332 A, 919 L)
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
Hospital
Surgeon
CE
50a
30a
PCI
400b
138a
CABG
450b
150a
a – Halm, Lee Chassin, Ann Int Med, 2002; b – Leapfrog Group, and Birkmeyer and Dimick, Surgery, 2004
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.
Crude Percent High Volume Provider
Use by Race - CE
High Volume Hospital
High Volume Surgeon
p<0.0001
p<0.0001
83%
77%
64%
62%
48%
44%
37%
34%
29%
21%
White
Black
Asian
Latino
Other/
Unknown
Crude Percent High Volume Provider
Use by Race - PCI
High Volume Hospital
High Volume Surgeon
p<0.0001
p<0.0001
100%
99%
98%
94%
84%
64%
60%
55%
47%
43%
White
Black
Asian
Latino
Other/
Unknown
Crude Percent High Volume Provider
Use by Race - CABG
High Volume Hospital
High Volume Surgeon
p<0.0001
p<0.0001
71%
61%
61%
55%
46%
40%
26%
24%
White
Black
39%
36%
Asian
Latino
Other/
Unknown
Adjusted Probability of High Volume
Hospital Use by Race
Baseline Model
CE
PCI
CABG
Black
-0.315***
-0.138***
-0.190***
Asian
0.01
-0.035***
-0.244***
Latino
-0.182***
0.017***
-0.086***
Incl. Patient ZIP Code
Fixed Effects
CE
PCI
CABG
Black
-0.147***
-0.105***
-0.164***
Asian
0.052
-0.027***
-0.168***
Latino
-0.066*
0.036***
0.025
*** 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.
Adjusted Probability of High Volume
Surgeon Use by Race
Baseline Model
CE
PCI
CABG
Black
-0.235***
-0.161***
-0.268***
Asian
-0.098
-0.048**
-0.154***
Latino
-0.172***
-0.133***
-0.232***
Incl. Patient ZIP Code
& Hospital Fixed
Effects
CE
PCI
CABG
Black
-0.034
-0.006
-0.087***
Asian
-0.087
0.023
-0.047
Latino
-0.098*
0.004
-0.074***
*** 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.
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
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
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
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?