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Racial Disparities and
Socioeconomic Status in
Association with Survival in Older
Men with Local/Regional Stage
Prostate Cancer
Xianglin L. Du, M.D., Ph.D.
Associate Professor
University of Texas School of Public Health at Houston
Division of Epidemiology
and Center for Health Services Research
Thanks to
Coauthors and Collaborators
Xianglin L. Du, M.D., Ph.D.*
Shenying Fang, MD, MS,
Ann L. Coker, PhD,
Maureen Sanderson, PhD,
Corrine Aragaki, PhD,
Janice N. Cormier, MD, MPH,
Yan Xing, MD, MS,
Beverly J. Gor, EdD, RD,
Wenyaw Chan, PhD
Brief Background
• Racial/Ethnic Disparities in mortality and
survival present in the U.S.
• Higher mortality for prostate cancer in
African Americans compared to Caucasians
are attributed to:
– More aggressive tumors
– More advanced stage at diagnosis
– Health insurance and access to care
– Difference in screening-early detection
– Differences in receiving optimal treatments
– Socioeconomic status
– Healthcare Providers (physicians and hospitals)
Evidence of Racial/Ethnic
Disparities in Healthcare
Consistent Findings
• Disparities consistently found across a wide range
of disease areas and clinical services
• Disparities are found even when clinical factors,
such as stage of disease presentation, co-
morbidities, age, and severity of disease are taken
into account
• Disparities are found across a range of clinical
settings, including public and private hospitals,
teaching and non-teaching hospitals, etc.
• Since disparities in health care are associated with
poor outcomes – they are not acceptable
Evidence of Racial/Ethnic
Disparities in Mortality/Survival
not Consistent Findings
• Numerous studies showed that the outcomes
(survival) were similar among different racial/ethnic
groups, after controlling for differences in treatment
and socio-demographic factors
• Whereas
• Other studies showed racial/ethnic disparities still
existed even after controlling for socioeconomic
factors and for access to equitable care and
treatment
• These inconsistency is also apparent in prostate
cancer mortality by race/ethnicity
Objective and Hypothesis
• Main objective is to determine whether there
is racial/ethnic disparity in long-term survival
in a large nationwide, population-based
cohort of older men who were diagnosed
with locoregional stage prostate cancer and
who had universal fee-for-services Medicare
insurance coverage (both part A and B).
• We hypothesized that there were no
racial/ethnic difference in long-term survival
of prostate cancer patents after controlling
for differences in patient characteristics
(age), tumor characteristics (grade-Gleason
score), comorbidity, treatment, and
socioeconomic status.
Study Population and Methods
• Retrospective cohort study of 61,228
men diagnosed with incident (new)
local/regional stage prostate cancer at
age ≥65 (1992-1999 and 11 regions)
• Identified from the NCI’s 11 SEER-
Medicare data (covering >14% of the U.S.
population).
• Last follow-up: 12/31/2002 with up to 11
years of FU
• >98% completeness of case
ascertainment (incident cases)
Study Variables
• Outcomes
– All-cause mortality
– Prostate cancer-specific mortality
– Time to event (in months from date of diagnosis to date of
death)
• Exposures
– Race/ethnicity: African American, Caucasian, and Hispanics
• Other covariates
– Demographics (age)
– Comorbidity index adjustment (created from Medicare
claims)
– Locoregional stage, but control for grade and AJCC stage
for residual confounding
– Treatment (discuss below)
– Year of diagnosis (1992 to 1999)
– Geographic areas (11 areas)
– Socioeconomic factors (discuss below)
Socioeconomic Factors
(from 1990 census)
• Education - percent of adults aged ≥25 who had
less than 12 years of education at the zip code
level, which was categorized into quartiles.
Poverty - percent of persons living below the
poverty line at the census tract level
• Income - median annual household income at the
zip code level
• Composite SES (socioeconomic status) – that
summed the normal scores of the above three
variables that were equally weighted and
categorized the total scores into quartiles
Treatment
• Primary Treatment:
– radical prostatectomy, or
– radiation therapy, or
– watchful waiting (observational
management)
– all standard of care (for local stage tumor).
• Adjuvant therapy:
– hormonal therapy and
– chemotherapy
– efficacy not confirmed in RCTs.
Figure 1. Kaplan-Meier survival curve by 3 ethnic groups
1.0
0.8
0.6
Probability
0.4
Hispanic
0.2 White
Black
0.0
0 2 4 6 8 10 12
Time (years)
Table 1. Comparison of age
among 3 racial/ethnic groups
Age (years) Caucasians African Hispanics
Americans
n % n % n %
Median age 73 (65-103) 72 (65-103) 71 (65-101)
(range)
65-69 15,416 28.7 2,131 33.7 411 36.0
70-74 17,324 32.2 2,023 32.0 390 34.1
75-79 12,271 22.8 1,314 20.8 221 19.3
≥80 8,753 16.3 853 13.5 121 10.6
Total 53,764 100.0 6,321 100.0 1,143 100.0
Table 2. Comparison of tumor grades
among 3 racial/ethnic groups
Gleason Caucasians African Hispanics
Score Americans
n % n % n %
2-4 7,475 13.9 740 11.7 198 17.3
5-7 33,218 61.8 3,789 59.9 650 56.9
8-10 10,438 19.4 1,410 22.3 240 21.0
u/k 2,633 4.9 382 6.0 55 4.8
Table 3. Comparison of comorbidity
among 3 racial/ethnic groups
Comorbidity Caucasians African Hispanics
Scores Americans
n % n % n %
0 34,402 64.0 3,394 53.7 669 58.5
1 12,565 23.4 1,611 25.5 290 25.4
2 4,342 8.1 747 11.8 96 8.4
>=3 2,455 4.6 569 9.0 88 7.7
Table 4. Comparison of treatment
among 3 racial/ethnic groups
Surgery and Caucasians African Am Hispanics
Radiation n % n % n %
Prostatectomy 12,907 24.0 1,070 16.9 328 28.7
Radiation 20,536 38.2 2,463 39.0 327 28.6
Both 1,205 2.2 89 1.4 26 2.3
Watchful Waiting 19,116 35.6 2,699 42.7 462 40.4
Chemotherapy
No 44,219 82.3 5,345 84.6 861 75.3
Yes 9,545 17.8 976 15.4 282 24.7
Hormone
No 39,266 73.0 4,808 76.1 815 71.3
Yes 14,498 27.0 1,513 23.9 328 28.7
Table 5. Comparison of socioeconomic
status (SES) among 3 ethnic groups
Poverty Caucasians African Am Hispanics
(quartiles) n % n % n %
1st 14,861 27.6 267 4.2 69 6.0
2nd 14,429 26.8 529 8.4 132 11.6
3rd 13,974 26.0 838 13.3 208 18.2
4th 9,603 17.9 4639 73.4 693 60.6
Missing 897 1.7 48 0.8 41 3.6
Total 53,764 100.0 6,321 100.0 1,143 100.0
Table 8. Comparison of socioeconomic
status (SES) among 3 ethnic groups
Composite Caucasians African Am Hispanics
SES (quartile)
(high to low) n % n % n %
1st (High SES) 14059 26.2 204 3.2 56 4.9
2nd 13732 25.5 460 7.3 121 10.6
3rd 13199 24.6 914 14.5 199 17.4
4th (Low SES) 9128 17.0 4528 71.6 661 57.8
Missing 3646 6.8 215 3.4 106 9.3
Total 53764 100.0 6321 100.0 1143 100.0
Table 9. Observed survival rate* by
ethnicity and socioeconomic status
Race/ethnicity 3-year survival (%) 5-year survival (%) 10-year survival (%)
and SES (cases in 1992-1999) (cases in 1992-1997) (cases in 1992-1993)
All-cause Disease- All-cause Disease- All-cause Disease-
specific specific specific
Ethnic Groups
Caucasians 87.8 98.2 78.0 96.4 52.6 94.0
African Am 84.1 97.5 72.6 95.3 43.3 91.1
Hispanics 91.0 98.9 83.5 97.3 61.3 95.6
Composite SES
1st 90.6 98.7 82.5 97.2 58.6 94.9
2nd 88.3 98.1 79.1 96.3 53.9 93.9
3rd 86.9 98.3 76.4 96.3 50.5 94.0
4th 84.0 97.5 72.1 95.4 44.1 92.0
Total 87.5 98.2 77.5 96.3 51.9 93.7
*unadjusted
Table 10. Hazard ratio of mortality
by socioeconomic status
SES Hazard ratio (95% CI) of mortality*
(high to low) All-cause mortality CA-specific mortality
Model 1 Model 2 Model 3 Model 4
Composite SES
1st (High SES) 1.0 (ref) 1.0 (ref) 1.0 (ref) 1.0 (ref)
2nd 1.11 1.11 1.26 1.25
(1.07-1.16) (1.07-1.16) (1.09-1.44) (1.09-1.44)
3rd 1.22 1.22 1.24 1.22
(1.17-1.27) (1.17-1.27) (1.07-1.43) (1.05-1.41)
4th (Low SES) 1.31 1.31 1.48 1.40
(1.25-1.36) (1.25-1.37) (1.28-1.70) (1.20-1.64)
*Models 1 & 3: adjusted for age, comorbidity, AJCC-stage, Gleason score, year of
diagnosis, SEER region, and treatment.
*Models 2 & 4: adjusted for race/ethnicity, in addition to factors in Models 1 & 3.
Table 12. Hazard ratio of mortality
by Poverty
SES Hazard ratio (95% CI) of mortality*
All-cause mortality CA-specific mortality
Model 1 Model 2 Model 3 Model 4
Poverty
1st 1.0 1.0 1.0 1.0
2nd 1.11 (1.06-1.15) 1.11 (1.06-1.15) 1.17 1.15
(1.02-1.33) (1.01-1.32)
3rd 1.19 (1.14-1.24) 1.19 (1.14-1.24) 1.12 1.11
(0.97-1.30) (0.96-1.28)
4th 1.28 (1.23-1.34) 1.28 (1.22-1.34) 1.36 1.31
(1.18-1.55) (1.13-1.52)
*Models 1 & 3: adjusted for age, comorbidity, AJCC-stage, Gleason score, year
of diagnosis, SEER region, and treatment
*Models 2 & 4: adjusted for ethnicity, in addition to factors in Models 1 & 3.
Table 17. Hazard ratio of mortality
by race/ethnicity
Race/ Hazard ratio (95% CI) of mortality*
ethnicity All-cause mortality CA-specific mortality
Model 1 Model 2 Model 3 Model 4
1.00 1.00 1.00 1.00
Caucasians
African Am
1.14 1.01 1.33 1.17
(1.09-1.19) (0.97-1.06) (1.16-1.53) (0.99-1.37)
Hispanics
0.85 0.78 0.84 0.78
(0.76-0.94) (0.70-0.87) (0.57-1.24) (0.53-1.16)
* Models 1 & 3 - Adjusted for age, comorbidity, AJCC stage, Gleason score,
year of diagnosis, SEER region, and treatment.
* Models 2 & 4 - Adjusted for composite SES, in addition to above factors.
Further Analysis
• Apart from composite SES, the similar
results were achieved by controlling for
education, poverty, and income.
• There was no significant interaction
between race/ethnicity and
socioeconomic status.
Conclusions and
public health implications
• Racial disparity in survival among men with
locoregional prostate cancer was largely
explained by their socioeconomic status.
• Lower socioeconomic status appeared to be
one of the major barriers to achieving
comparable outcomes for men with prostate
cancer.
• Important public health implications if we are
to achieve the goals of Healthy People 2010,
one of which is to eliminate health disparities.
Strengths
• Large population-based cohort study, covering
all (>98%) incident cases of prostate Ca,
pathologically confirmed by the 11 SEER
registries.
• Reliable information on cancer stage, grade,
primary therapy (surgery and radiation), and
long-term follow-up on vital status.
• Linked with Medicare claims, providing
important data on comorbidity – a strong
confounder of survival.
• Adjuvant chemotherapy and hormonal therapy
data can be uniquely identified from Medicare
claims.
• Several measures of SES variables
consistent findings.
Limitations
• SES at the level of census tract may be imperfect
proxy measure for individual SES ecological
fallacy, but studies showed individual and
community level SESs in good agreement
• Local-regional stage Residual confounding (even
after adjusting for AJCC stage and tumor grade
etc.)
• Hispanic ‘Paradox’ – low SES and RFs for mortality
but has mortality advantage
• Lack of info. on providers (physicians and
hospitals), on patient/physician preference on the
choice of the therapy, and on PSA screening and
surveillance
• Men age 65 or older, and in 11 SEER areas
Generalizability to younger men and other regions
or country?
Questions/Comments
Thanks for your attention!
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