Disparities Persist in Medicare Colon Cancer Screening

MILWAUKEE, Feb. 13 -- Despite increased Medicare coverage for colorectal cancer screening, women, nonwhites, and those with lower educational achievement and income are less likely to have a colonoscopy, researchers reported.

Among 596,470 Medicare recipients, 9.7% of blacks and 8.1% of Hispanics were screened compared with 19.3% of whites, Joan Neuner, M.D., of the Medical College of Wisconsin here, and colleagues, reported in the Feb. 12 issue of the Archives of Internal Medicine.

Overall women were less likely to have an invasive screening test such as sigmoidoscopy or colonoscopy compared with men.

These findings came from a multivariate logistic regression analysis of physician-supplied Medicare billing claims for New York, Florida, and Illinois for the years 2002 and 2003.

There were approximately the same number of average-risk patients in each age category (65 to 69, 70 to 74, 75 to 79, 80 and older) and more women than men in each of the three states. Most of the population (89%) was white, with African Americans (7%) and Hispanics (2.1%) representing the largest minority groups.

Screening tests included fecal occult blood testing (53.7%) and colonoscopy (42.1%), as well as sigmoidoscopy, and double contrast barium enema.

Approximately 18.3% of the study population had been screened during this period. A larger percentage of the population had undergone a screening colon test in Florida (21.5%), compared with Illinois (16.6% and New York (16.2%), the researchers said.

Nonwhites were only half as likely as whites to undergo screening for colorectal cancer (relative risk [RR], 0.52; 95% confidence interval [CI], 0.50-0.53).

Overall, persons living in ZIP codes with a higher per capita income were more likely to undergo a colon screening test than those living in ZIP codes where income was lower (21% and 14.6% in the highest and lowest tertiles respectively), the researchers reported.

Also, residence in a ZIP code with a greater proportion of high-school graduates was strongly associated with colon cancer screening (RR, 1.52, CI 1.48-1.55 for the highest tertile).

The lowest relative risk (RR) of colonoscopy in women compared with men was in the oldest age group and in the highest income tertile (RR for whites, 0.64 CI, 0.59-0.70), perhaps because of women's preference for a fecal occult blood test, the researchers said.

Women were more likely than men to undergo a screening test, the researchers explained, but were more likely to have a fecal occult blood test than screening colonoscopy.

Commenting on this preference, the researchers said that women may perceive colorectal cancer to be predominantly a disease of men and that this preference may be harmful.

Analysis of sex disparities in all screening tests and screening colonoscopy revealed "interesting patterns," the researchers said. Actually, the sex disparity in screening colonoscopy in whites, the major proportion of the study group, was greatest in the highest income tertile. Future studies, they said, should further examine a possible sex and income interaction, the researchers said.

Additionally, the researchers found, that overall, a higher income level was somewhat associated with screening colonoscopy in white patients (men: RR, 1.19; CI, 1.14-1.25; women: RR, 1.09; CI, 1.05-1.15) but not, they said, in nonwhite patients (men: RR, 0.97; CI, 0.78-1.22; women: RR, 0.94; CI, 0.78-1.14).

The overall lower screening rate in the nonwhite population is worrisome, the researchers said, because both colon cancer incidence and mortality are higher than in whites.

These finding suggest that, while higher income, in general, is associated with increased screening, the benefits of a higher socioeconomic class was not evident in minority racial/ethnic groups. This emphasizes the need to target this population as a whole rather than limiting intervention to only individuals with lower income levels, the researchers said.

Listing the study's limitations, the authors wrote that because the study was cross-sectional, some individuals may have undergone an endoscopic screening test or a fecal occult blood test shortly before the study began and might have been current with screening during the study.

The outcome variables and exclusion data based on HCFA's (now CMS) coding system might have underestimated the total tests done or may have allowed a small number of high-risk patients into the study.

Educational achievement and income levels were recorded on the basis of Zip code, and while this method might be fairly accurate, it should not be taken to represent individual levels of either income or education.

Finally, the relatively small number of nonwhites in the study may have limited the power to examine multiple interactions between variables in this subgroup, the researchers noted.

Summing up, Dr. Neuner's team wrote, "There are complex interactions between the demographic and socioeconomic variables that need to be considered in future studies. Further research is needed to determine the basis for the observed ongoing disparities to develop interventions to reduce and eliminate these differences.

"Policy initiatives are necessary to increase the awareness of colorectal cancer screening, especially in women and in racial/ethnic minorities, and to increase physician awareness about screening," they concluded.