Geographic variation of racial/ethnic disparities in colorectal cancer testing among medicare enrollees

Abstract

Background: The Medicare population has documented racial/ethnic disparities in colorectal cancer (CRC) screening, but it is unknown whether these disparities differ across geographic regions.

Methods: Among Medicare enrollees within 8 US states, we ascertained up-to-date CRC screening on December 31, 2003 (fecal occult blood testing in the prior year or sigmoidoscopy or colonoscopy in the prior 5 years). Logistic regression models tested for regional variation in up-to-date status among white versus different nonwhite populations (blacks, Asian/Pacific Islanders [APIs], Hispanics). We estimated regression-adjusted region-specific prevalence of up-to-date status by race/ethnicity and compared adjusted white versus nonwhite up-to-date prevalence across regions by using generalized least squares regression.

Results: White versus nonwhite up-to-date status varied significantly across regions for blacks (P = .01) and APIs (P < .001) but not Hispanics (P = .62). Whereas the white versus black differences in proportion up-to-date were greatest in Atlanta (Georgia), rural Georgia, and the San Francisco Bay Area of California (range, 10%-16% differences, blacks<whites); there were no significant white versus black differences in Connecticut, Seattle (Washington) or Iowa. Whereas APIs had significantly lower up-to-date prevalence than whites in Michigan and the California regions of San Francisco, Los Angeles, and San Jose (range, 4%-15% differences, APIs<whites), APIs in Hawaii had higher up-to-date status than whites (52% vs 38% P < .001). White versus Hispanic differences were substantial but homogeneous across regions (range, 8%-16% differences, Hispanics<whites). In contrast to nonwhites, there was little geographic variation in up-to-date status among whites.

Conclusions: Significant geographic variation in up-to-date status among black and API Medicare enrollees is associated with heterogeneous racial/ethnic disparities for these groups across US regions.

Figure 1

Adjusted percentages of blacks and whites with up-to-date colorectal cancer testing by SEER region are shown for 2003. Estimated black versus white difference in up-to-date status (in percentage points) is also depicted for each region. The analyses are adjusted for age, sex, income, rurality of residence, and Charlson comorbidity. Error bars indicate 95% confidence intervals; SEER, Surveillance, Epidemiology, and End Results. *Signifies that the white versus black difference is significantly different from zero within region.

Figure 2

Adjusted percentages of Asian/Pacific Islanders and whites with up-to-date colorectal cancer testing by SEER region are shown for 2003. Estimated API versus white difference in up-to-date status (in percentage points) is also depicted for each region. The analyses are adjusted for age, sex, income, rurality of residence, and Charlson comorbidity. Error bars indicate 95% confidence intervals; SEER, Surveillance, Epidemiology, and End Results. *Signifies that the white versus Asian/Pacific Islanders difference is significantly different from zero within region.

Figure 3

Adjusted percentages of Hispanics and whites with up-to-date colorectal cancer testing by SEER region are shown for 2003. Estimated Hispanic versus white difference in up-to-date status (in percentage points) is also depicted for each region. The analyses are adjusted for age, sex, income, rurality of residence, and Charlson comorbidity. Error bars indicate 95% confidence intervals; SEER, Surveillance, Epidemiology, and End Results. *Signifies that the white versus Hispanic difference is significantly different from zero within region.