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Volume 5: No.
1, January 2008
LETTER
Use of Colonoscopy and Flexible Sigmoidoscopy Among African Americans and Whites in a Low-Income Population
Suggested citation for this article: Peterson NB, Murff HJ, Fowke JH, Cui Y, Hargreaves M, Signorello LB, et al. Use of colonoscopy and flexible sigmoidoscopy among African Americans and whites in a low-income population [letter]. Prev Chronic Dis 2008;5(1).
http://www.cdc.gov/pcd/issues/2008/
jan/07_0160.htm. Accessed [date].
PEER REVIEWED
To the Editor:
Colorectal cancer is the third most common incident cancer and the second most common cause of cancer-related death in the United States. The disease is largely preventable with screening. In the United States,
colorectal cancer mortality is higher among African Americans than among whites,
possibly because of inequalities in the delivery of screening, diagnostic, and therapeutic regimens (1,2).
To elucidate the role of race in the use of two recommended screening tests for
colorectal cancer (i.e., colonoscopy and flexible sigmoidoscopy),
we compared data on test use among African Americans and white participants in the Southern Community Cohort Study (SCCS).
The SCCS is a large-scale prospective cohort study of cancer (3). We analyzed baseline data collected from participants at enrollment
during 2002 through 2006 from 48 community health centers in a 12-state region in the southeastern United States.
Sixty-three percent of the participants reported annual household incomes of
less than $15,000, and an additional 21% reported annual household incomes of
less than $25,000. Questions included “Have you ever had a sigmoidoscopy?”
and “Have you ever had a colonoscopy?” If respondents had not had either of the
two tests within the recommended time frame or had never had either test, they were asked to indicate a
reason using a list we provided. We did not elicit
information about screening using fecal occult blood test or barium enema.
Men and women aged 50 years or older at enrollment were eligible for analysis
(n = 25,786). We excluded people who were not African American or white (n =
1370) and
people who reported a prior diagnosis of colon or rectal cancer (n = 134), resulting in 24,282 subjects for analysis. We defined outcome variables as
1) having ever had testing with a sigmoidoscopy or colonoscopy
or
2) having had recommended testing, which is defined by current guidelines
(4) as a sigmoidoscopy in the previous 5 years or a colonoscopy in the previous
10 years.
We used chi-square tests with P values to compare participants’ demographic characteristics (age, race, and sex) and socioeconomic (SES) indexes (annual household income, education, and marital and health insurance status) across categories of test-use status.
We used multivariable logistic regression to calculate odds ratios (ORs) and 95%
confidence intervals (CIs) summarizing the association between test-use
prevalence and race, stratified by sex, after adjustment for demographic and SES variables.
We used generalized estimating equations to fit the model to account for the possibility that data
were correlated from participants recruited within each community health center.
African American respondents were younger, were less likely to have completed high school, and reported slightly lower household incomes
than white respondents. Among all respondents, 38.2% reported having a sigmoidoscopy or colonoscopy, and 34.8% reported
having the recommended testing. Having any type of testing was positively associated with increasing age, higher household income, higher
education, having been married, having private or public health insurance, and having had a medical visit within the previous year.
Among African Americans, only 30.6% of men and 38.2% of women reported ever having
had a sigmoidoscopy or colonoscopy, compared with 38.8% of white men (adjusted OR, 0.93; 95% CI, 0.83–1.03) and 47.4% of white women (adjusted OR, 0.80; 95% CI, 0.72–0.88)(Table 1). When we
examined prevalence by type of test, however, we found that the reduced use of endoscopy was entirely accounted for by the reduced
use of colonoscopy. African American men and women were similarly likely to have ever
had a sigmoidoscopy. The deficit among African Americans in the number who had
ever had a colonoscopy was seen in both sexes, but was particularly marked among
women (men, adjusted OR, 0.89; 95% CI, 0.80–0.98; women, adjusted OR, 0.70; 95%
CI, 0.65–0.76). For both sigmoidoscopy and colonoscopy among African American
men and women, the ORs associated with recommended
testing were higher (i.e., less of a deficit) than the ORs associated with ever
having had the tests. African Americans were significantly more likely than
whites to have had a sigmoidoscopy at recommended intervals.
When participants who had not had either recommended test were asked to indicate
why, most reported their doctor had not recommended the test (Table 2). The next most common reason was cost.
The limitations of our study included not distinguishing between colonoscopies and sigmoidoscopies performed for screening versus diagnostic purposes, not asking about fecal occult blood tests
or barium enemas, and relying on self-reported data.
In summary, we found lower use of colonoscopy among African Americans than
among whites. Although future studies are needed to confirm these findings, we suggest that the lower use of colonoscopy may contribute to the higher rates of colorectal cancer mortality among African Americans.
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Acknowledgments
We thank Ms Heather Munro for providing statistical review assistance during the preparation of this manuscript. Support was received from
the National Cancer Institute of the National Institutes of Health through grant R01CA092447 (William J. Blot, principal investigator).
Neeraja B. Peterson, MD, MSc
Department of Medicine, Vanderbilt University Medical Center
Vanderbilt-Ingram Cancer Center
Nashville, Tennessee
Harvey J. Murff, MD, MPH
Department of Medicine, Vanderbilt University Medical Center
Department of Veteran Affairs
Nashville, Tennessee
Jay H. Fowke, PhD, MPH
Department of Medicine, Vanderbilt University Medical Center
Vanderbilt-Ingram Cancer Center
Nashville, Tennessee
Yong Cui, MD, MSPH
Margaret Hargreaves, PhD
Meharry Medical College
Nashville, Tennessee
Lisa B. Signorello, ScD
William J. Blot, PhD
Department of Medicine, Vanderbilt University Medical Center
Vanderbilt-Ingram Cancer Center
Nashville, Tennessee
International Epidemiology Institute
Rockville, Maryland
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References
- Mayberry RM, Coates RJ, Hill HA, Click LA, Chen VW, Austin DF, et al.
Determinants of black/white differences in colon cancer survival. J Natl Cancer Inst 1995;87(22):1686-93.
- Ries LA, Wingo PA, Miller DS, Howe HL, Weir HK, Rosenberg HM, et al.
The annual report to the nation on the status of cancer, 1973-1997, with a special section on colorectal cancer. Cancer 2000;88(10):2398-424.
- Signorello LB, Hargreaves MK, Steinwandel MD, Zheng W, Cai Q, Schlundt DG, et al.
Southern community cohort study: establishing a cohort to investigate health disparities. J Natl Med Assoc 2005;97(7):972-9.
- U.S. Preventive Services Task Force.
Screening for colorectal cancer: recommendation and rationale. Ann Intern Med 2002;137(2):129-31.
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