Hospital racial segregation and racial disparity in mortality after

injury

Melanie Arthur

University of Alaska Fairbanks

Acknowledgments

• Working group: – Richard Mullins, MD, Oregon Health &

Science University– Jerris Hedges, MD, MS, University of Hawaii– Thomas LaVeist, PhD, Johns Hopkins

University

• Funding provided by: – Agency for Healthcare Research and Quality

Background

• Our previous work shows racial disparity in mortality among adults hospitalized after injury (Medical Care 2008)

• Potential causes of this disparity– Different injury patterns– Systematic differences in hospital resources– Differential treatment within institutions

Patient population

• Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample 1998-2002

• Approximately 20% sample of community hospitals

• All patients hospitalized with a primary diagnosis of injury

• Ages 18-64• Excluding patients transferred to an acute care

hospital (2.4%)• n=522510

Race

• Asian category includes Pacific Islanders• Not reliably reported for Hispanics or Native

Americans in this data• 11 participating states do not report race• Of the remaining patients, 6.4% were missing

race information– 2/3 of these came from hospitals which did not report

race– An additional 5982 patients came from hospitals that

reported race for less than 50% of patients– 13481 patients without reported race were included in

the analyses

Racial composition of sample

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

white black hispanic asian nativeamerican

other missingrace

Injury

• Injury severity imputed as ICISS

• ICD-9 based injury severity score

• Survival probabilities assigned for each injury code

• Product of survival probabilities gives overall injury severity

• 0=negligible probability of survival

• 1=virtual certainty of survival

Injury characteristics of sampleWhite Black Hispanic Asian Native

American

Other Missing race

ICISS .94±.11 .93±.12 .94±.11 .94±.12 .93±.12 .93±.12 .91±.15

Mechanism Motor vehicle crash 32.6 25.1 29.5 37.3 34.2 32.3 39.3

Fall from height 12.9 6.9 10.3 9.6 9.2 10.1 11.7

Low fall 17.3 10.4 10.5 14.9 11.7 11.5 13.3

Intentional injury 6.4 26.9 16.4 10.7 20.0 16.2 10.1

Other unintentional injury 15.6 14.4 18.0 16.2 13.3 15.8 15.1

Other mechanism 4.0 4.2 2.9 3.2 5.3 3.4 4.7

Unspecified 11.4 12.2 12.5 8.1 6.5 10.7 5.8

Comorbidity

• Morris (JAMA 1990) suggests 5 clinical conditions– COPD, coagulopathy, diabetes, liver disease, and

ischemic heart diseaseAny comorbidity

0

2

4

6

8

10

12

14

16

White Black Hispanic Asian NativeAmerican

Other Missing race

Hospital racial segregation

• Based on patient population for ALL hospital admissions

• Calculated % of all patients who were white

Hospital racial segregation of sample

0

10

20

30

40

50

60

White Black Hispanic Asian NativeAmerican

Other Missingrace

<20% white At least 80% white

Other covariates

• Age

• Gender

• Hospital location and teaching status (urban teaching, urban nonteaching, rural)

• Primary payer

• Median income of zip code of residence (<$25k, 25k-34999, 35k-44999, $45K+)

Multivariate models Not controlled for

hospital segregation

With hospital segregation

Race White Reference Reference

Black 1.17 (1.06-1.29) 1.11 (1.00-1.22)

Hispanic 0.96 (0.82-1.11) 0.87 (0.77-1.00)

Asian 1.35 (1.03-1.77) 1.21 (0.93-1.57)

Native 0.87 (0.63-1.20) 0.90 (0.65-1.23)

Other 1.17 (0.98-1.39) 1.05 (0.88-1.25)

Missing 1.41 (1.21-1.64) 1.35 (1.14-1.59)

Hospital racial composition <20% white 1.59 (1.28-1.98)

20-39% white 1.16 (0.94-1.43)

40-59% white 1.26 (1.06-1.49)

60-79% white 1.07 (0.93-1.24)

At least 80% white Reference

All models control for age, gender, injury severity, comorbid conditions, primary payer, hospital type, median income of zip code of residence.

Models were estimated using generalized estimating equations to account for clustering of patients within hospitals

Limitations

• Limited data regarding patients’ clinical condition

• Race measure is inconsistent across racial groups and settings

• In-hospital mortality is an incomplete measure of injury mortality

• Limited data on therapeutic interventions that might also contribute to probability of mortality

Implications• Racial disparity in injury mortality among

hospitalized patients is largely attenuated by control for hospital racial segregation

• Much of the observed disparity in injury outcome is attributable to treatment at racially segregated facilities

• Among facilities with >80% white patients, higher mortality rates remain evident for black patients

• Further research is needed to explore other characteristics of hospitals treating high proportions of minority patients, including treatment resources and patterns of care