Informed choice in mammography screening

Oct 24 2007

While patient education decision aids can help older women make better-informed decisions about whether to continue mammography screening, they do not influence whether the women will actually change their minds about having the test.

In a new Australian study appearing in the October 22 issue of the Archives of Internal Medicine , women who received decision aid materials were better prepared to make the choice, but an equal percentage of women participated or planned to participate in mammography screening one month following the intervention, whether or not they received the decision aid.

“Studies of patient decision aids show that decision aids increase patients' knowledge and create more realistic expectations without increasing anxiety,” said study co-author Alexandra Barratt, Ph.D. of the School of Public Health at the University of Sydney. “It's quite common for decision aids to have little or no impact on the direction of people's decisions, so our findings are very consistent with the effects others have observed for decision aids.”

According to the study, while mammography screening reduces mortality from breast cancer, it also contributes to “over-detection and over-treatment” of breast cancers that would not affect women within their lifetimes. The authors write that screening guidelines generally are for women ages 50 to 69, but are “less clear cut” when the benefit-harm ratio drops as a woman reaches age 70.

Carol Lee, M.D., chair of the Commission on Breast Imaging at the American College of Radiology, agreed that mammography guidelines are not specific for all ages.

“Women and their doctors should use common sense,” Lee said. “We know that the benefits of screening take about five to seven years to be realized. If a woman's health status is such that she has at least that life expectancy, screening with mammography might be a good choice. By the same token, a woman of any age who has such severe, serious health problems that it is unlikely that she will survive for that length of time would probably not be well served by having screening.”

The study evaluated 734 women, all 70 to 71 years old, who had undergone at least two screening mammograms in the past five years. Researchers separated the women into two groups, with only one group receiving the decision aid.

The decision aid was a self-administered booklet that described the women's options — to continue or stop screening — and the possible outcomes of each option. Researchers later mailed follow-up questionnaires to members of both groups to measure knowledge and attitudes about mammography.

The study found the decision aid group better informed than the control group, with 76.6 percent showing an “adequate” knowledge (at least six correct answers of 10 on the questionnaire) compared with 56.9 percent in the control. The researchers also measured how the groups' knowledge and values affected their ability to make an “informed choice” whether to continue or stop screening. The decision aid increased the percentage of women who were able to make an informed choice from 49 percent to 73 percent.

Barratt and her fellow authors concluded their results show that screening programs should consider providing women older than age 70 years with evidence-based information, such as a decision aid, to help them in their decision-making.

Mathieu E, et al. Informed choice in mammography screening: a randomized trial of a decision aid for 70-year-old women. Arch Intern Med 167(19), 2007