And unlike prior studies based on patient self-reports of mammography screening, the new study suggests that older African-American, Asian-American and Hispanic women all receive less screening than do white women.
"The rate of screening mammography among elderly American women is significantly lower than what has been reported based on the self-reported data sources" said lead author Christopher Kagay, M.D. Yet, he said, these inflated rates "are the most frequently cited data by policy makers."
The study, to be published in the August issue of the American Journal of Preventive Medicine, analyzed national Medicare data involving 146,669 women ages and older. Researchers compared these data to patient self-reports collected by the Behavioral Risk Factor Surveillance System (BRFSS) and the National Health Interview Study (NHIS).The data were amassed between 1991 and 2001.
"The screening rate for most groups of non-white women is substantially lower than that for white women, even while adjusting for factors of health status, access to care, education and income," said Kagay, a radiology resident at Massachusetts General Hospital and a clinical fellow at Harvard Medical School.
"Self-reported studies of mammography screening had suggested that there were no significant differences in screening frequency by race -- our study found just the opposite," Kagay said.
While self-reported studies suggested that as many as 70 percent to 80 percent of women ages 65 to 69 received at least one mammogram every two years, the new study paints a far less rosy picture -- with just 61.1 percent of women in this age group overall receiving regular screening, and even lower rates seen among older African-American, Asian-American and Hispanic women.
The study was not designed to illuminate the reasons for the gap between actual mammograms received and self-reported data -- only to measure it. But Kagay surmises that several factors may be at play.
"Some respondents may misremember a screening mammogram from, for example, three years ago as having occurred more recently than it actually did," he said. "Alternatively, some women may know that they 'should' be screened, and may therefore unconsciously tend to over-report their own screening."
The study has practical clinical implications for physicians, according to Kagay. "We're not as close to our goal of screening all the elderly women who might be able to benefit from breast cancer therapy as we thought we were. That's feedback referring physicians can use as they assess their own referral patterns." "This study highlights once again the need for awareness and education about the benefits of screening, especially in the aging population where the risk for breast cancer is the greatest," said Cheryl Perkins, M.D., senior clinical advisor for the Susan G. Komen Breast Cancer Foundation.
"By examining data from Medicare, this study has highlighted the differences between data interpretation based on clinical records versus self-reported data," said Perkins. "Self-reported data may inaccurately represent the true screening levels in a given population."
"These findings could have significant impact on how we interpret future population data," she added.
Breast cancer is the most common cancer of women in the United States, affecting more than 211,000 American females each year. Deaths from breast cancer are highest in women under 35 and in women older than 75. Yet it is predominantly a disease of older women, with a woman's chances of getting breast cancer increasing as she ages.
If more women were screened, it is possible that more breast cancer would be discovered, and it could be treated at an earlier stage when the chances of a good outcome would be enhanced in women otherwise healthy enough to undergo treatment, Kagay said.
The Breast Cancer Foundation recommends annual screening mammography for women ages 40 and older.
By Joel R. Cooper, Contributing Writer
Health Behavior News Service
FOR MORE INFORMATION
Health Behavior News Service: (202) 387-2829 or www.hbns.org
American Journal of Preventive Medicine: Contact the editorial office at (858) 457-7292.
Kagay CR, Quale C, Smith-Bindman R. Screening mammography in the American elderly. Am J Prev Med 31(2), 2006.
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