Multiple Factors Affect Rates of Colon Cancer Screening

Although Medicare coverage for colorectal cancer screening has increased, there are still significant disparities in screening practices by ethnicity, sex, age, education and income level, according to researchers at the Medical College of Wisconsin in Milwaukee. The study was reported in the February 12, 2007, issue of Archives of Internal Medicine (Arch Intern Med. 2007;167:258-264).

"Blacks (9.7%) and Hispanics (8.1%) had lower rates of colon cancer screening compared with whites (19.3%)," the authors note. "Individuals living in ZIP codes with a higher per capita income were more likely to undergo a colon screening test (21%) than were those living in ZIP codes with a lower per capita income (14.6%)."

The study also found that women were less likely to undergo an invasive screening test or colonoscopy and that residing in a ZIP code with a greater amount of high school graduates was associated with undergoing colon cancer screening.

Colorectal cancer is the third most common cancer affecting men and women in the United States, with approximately 145,290 new cases in 2005. "There is evidence that screening for colorectal cancer decreases incidence and mortality from the disease," says Joan Neuner, MD, MPH, Medical College of Wisconsin Assistant Professor of Medicine, and senior author of the study.

Ashwin N. Ananthakrishnan, MD, MPH, and colleagues at Medical College examined the Medicare physician billing claims file for New York, Florida and Illinois for 2002 and 2003 to identify the rates of colon cancer screening tests in the population at average risk for the disease.

Data from the US Census and the Medicare database were used to verify the sex, race or ethnicity, age and social characteristics of the population, such as the educational achievement and per capita income level of each patient based on their ZIP codes of residence. The type of test screening completed by each patient (fecal occult blood test, flexible sigmoidoscopy, double contrast barium enema and colonoscopy) was also noted.

A total of 596,470 Medicare recipients were included in the study population with an approximately even number of patients in each age category (65 to 69, 70 to 74, 75 to 79, and 80 or older) and more women than men in all three states.

The population was 89.5 % white, 7% African American and 2.1% Hispanic. An estimated 18.3% of the sample population had been screened for colon cancer during the study 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%).

"Despite expanded Medicare coverage, there are still significant disparities in colorectal cancer screening practices," the authors conclude. "Further research is needed to determine the basis for the observed ongoing disparities to develop interventions to reduce and eliminate these differences."

This study was supported in part by a grant from the National Institutes of Health. See the article for additional information, including authors, author contributions and affiliations, financial disclosures, funding and support.

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