Public health researchers have long attributed the disparity in colonoscopy rates between whites and minorities to a lack of health insurance or access to doctors. Now, a new study suggests the reasons for the differences are more complex.

Researchers at the University of Texas Medical Branch in Galveston found greater in rates in areas where more doctors were available. Associate Surgery Professor Taylor S. Riall, M.D., Ph.D. and colleagues looked at nearly one million Texas and – even after adjusting for the availability of colonoscopists and primary-care physicians – found blacks still were 20 percent less likely and Hispanics were 32 percent less likely than whites to receive a colonoscopy. Indeed, as the availability of colonoscopists and primary care physicians increased, whites had slight increases in colonoscopy use while blacks and Hispanics had decreases in use.

By only examining Medicare patients, the study, published in the journal Health Services Research, ruled out insurance coverage as a possible inhibitor. However, the authors surmised that the cost of the procedure might be another barrier. “Colonoscopies, even when covered by , are still expensive [due to co-pays],” Riall said.

Cultural differences and existing attitudes toward health care in could contribute to the disparity, Riall suggested. “We think that a combination of things may inhibit certain racial and ethnic minorities from taking advantage of an increased supply of colonoscopists,” she said, adding that colonoscopies might not be realistic for those of lower socioeconomic status.

The trend toward a colonoscopy-only approach to detecting colorectal cancer could further widen disparities in screening, Riall said.

Electra D. Paskett, Ph.D., professor of epidemiology at Ohio State University, said fecal occult blood testing, which checks stool samples for hidden blood, is an acceptable, less invasive alternative form of colon-cancer screening. The United Kingdom has implemented the test countrywide with such success that its incidence of colon cancer has dropped, she said.

“I think we need as a society to start opening up our minds and not just think colonoscopy is the only validated colorectal cancer screening, because it’s not,” Paskett said.

More information: Benarroch-Gampel, J., et al. (2011). Colonoscopist and primary care physician supply and disparities in colorectal cancer screening. Health Services Research, In Press.