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

Table 1. Comparison of age among 3 racial/ethnic groups

Age (years) Caucasians African Americans

Hispanics

n % n % n %

Median age (range)

73 (65-103) 72 (65-103) 71 (65-101)

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 Score

Caucasians African Americans

Hispanics

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 Scores

Caucasians African Americans

Hispanics

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 2.3Watchful 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 SES (quartile)

Caucasians African Am Hispanics

(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 and SES

3-year survival (%)(cases in 1992-1999)

5-year survival (%)(cases in 1992-1997)

10-year survival (%)(cases in 1992-1993)

All-cause Disease-specific

All-cause Disease-specific

All-cause Disease-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 (1.07-1.16)

1.11 (1.07-1.16)

1.26 (1.09-1.44)

1.25 (1.09-1.44)

3rd 1.22 (1.17-1.27)

1.22 (1.17-1.27)

1.24 (1.07-1.43)

1.22 (1.05-1.41)

4th (Low SES) 1.31 (1.25-1.36)

1.31 (1.25-1.37)

1.48 (1.28-1.70)

1.40 (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 (1.02-1.33)

1.15 (1.01-1.32)

3rd 1.19 (1.14-1.24) 1.19 (1.14-1.24) 1.12 (0.97-1.30)

1.11 (0.96-1.28)

4th 1.28 (1.23-1.34) 1.28 (1.22-1.34) 1.36 (1.18-1.55)

1.31 (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

Caucasians

1.00 1.00 1.00 1.00

African Am

1.14 (1.09-1.19)

1.01 (0.97-1.06)

1.33 (1.16-1.53)

1.17 (0.99-1.37)

Hispanics 0.85 (0.76-0.94)

0.78 (0.70-0.87)

0.84 (0.57-1.24)

0.78 (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!