Mathieu E, Barratt AL, McGeechan K, Davey HM, Howard K, Houssami N. (2010). Helping women make choices about mammography screening: An online randomized trial of a decision aid for 40-year old women. Patient Education & Counseling, 81 (1), 63-72.
Designed to enhance knowledge in the decision-making process for breast cancer screening among women about age 40 at average risk of breast cancer, this web-based decision aid intervention provides information about mammography risks and benefits, a worksheet for women to clarify their personal values regarding those risks and benefits, examples showing how other women make the decision, and statistically estimated outcomes for women who start screening now or wait until age 50. The study showed an increase in mammography screening knowledge and the rate of making a decision about whether to begin screening now or wait until age 50.
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Mammography screening reduces the risk of breast cancer death, but the current lack of consensus in the screening recommendations for women under 50 years old has created a special need for mammography decision aids for this age group. Research on the effects of mammography on breast cancer mortality among women aged 40-49 has produced inconsistent evidence as to whether the risks of screening outweigh the benefits for this population. When screening produces a false positive diagnosis, a woman may be exposed to unnecessary risks associated with diagnostic testing (e.g., radiation from extra imaging studies and biopsies) and subsequent treatments. However, when it accurately identifies cancer and leads to early treatment, screening can provide a potentially life-saving benefit to the individual.
The U.S. Preventive Services Task Force has stated that the decision to start mammography before the age of 50 years should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms. Provision of timely and accurate information is a high priority to support women in making an informed choice. There are few decision support tools that integrate this information through a systematic process, such as decision aids, which may provide a good foundation for informed decision making about screening.
Thinking About Starting Mammogram Screening for Breast Cancer? A Decision Aid is a website developed in Australia to help women think about whether they want to start having mammograms to screen for breast cancer. The Decision Aid is for women who are about 40 years old, do not have a family history of breast cancer and are therefore at average risk of developing breast cancer, and do not have any current symptoms of breast cancer (e.g., breast lump, itchiness, redness). The website contains (1) educational information about mammography risks and benefits, (2) an online worksheet to help women clarify their personal values toward those risks and benefits before deciding when to start screening, and (3) hypothetical examples of how other people might make the decision. Information on breast cancer screening options and outcomes is presented in a factual, non-directive way. Diagrams and text are presented to describe the probability of relevant outcomes for 40-year-old Australian women who start screening at 40 and continue screening every 2 years for the next 10 years, compared with the probability of the same outcomes for 40-year-olds who wait until they are 50 to begin screening.
The screening outcomes presented in the Decision Aid (e.g., numbers of breast cancers detected and breast cancer deaths) are derived from a Markov model estimating outcomes for women 40 years old who either start screening every 2 years for the next 10 years, or decline screening for the next 10 years. This model assumes a 23% relative risk reduction in breast cancer mortality for screened women (based on the results of all available trials of mammography screening, adjusting for 100% participation in screening). Health care providers and policy makers in countries other than Australia may want to consider using their own data to develop numerical estimates for their populations.
Community Preventive Services Task Force Finding
The estimated time to navigate through the Decision Aid and complete the worksheet is 15 minutes.
The Decision Aid is intended for women who are around 40 years old, do not have a family history of breast cancer, do not have any current symptoms of breast cancer (e.g., breast lump, itchiness, redness), and are thinking about whether to start having mammograms to screen for breast cancer.
The Decision Aid can be administered to women in any medical or other community setting.
The Decision Aid can be accessed online free of charge.
For costs associated with this program, please contact the developer, Erin Mathieu. (See products page on the RTIPs website for developer contact information.)
About the Study
In an Australian study, women between the ages of 38 and 45 years with no prior breast cancer diagnosis were recruited to participate in the online study through advertising on various websites and a feature in a radio program. Women who agreed to participate were given access to baseline questions. Once they had completed these questions, they were randomized to the intervention group (n=189) or control group (n=223). Women in the intervention group were given immediate access to the Decision Aid, and after reading all nine web pages, completed primary and secondary outcome questions on two web pages. Women in the control group completed the outcome questions first and then were given access to the Decision Aid.
Knowledge of the benefits and harms of screening for women in their 40s was measured using four quantitative/numerical questions (e.g., "Imagine 1,000 women aged 40 years who have an average risk of breast cancer; of these women, what is your best guess about how many will die from breast cancer over the next 10 years without mammography screening?") and five descriptive/concept questions (e.g., "What is meant by screening mammograms?"). Answers were scored using a marking scheme developed a priori, producing a score from 0 to 10, with a score of 6 or higher indicating "adequate" knowledge of the issues surrounding mammography screening. Intention to start or decline screening was assessed using a 5-point Likert scale, with anchors of "start having a mammogram every 2 years" and "not have a mammogram now, but reconsider when 50." Responses were categorized as intending to start screening now, undecided, and not intending to start screening.
This program was only evaluated for the RTIPs topic area, Informed Decision Making and not, Breast Cancer Screening.
- At posttest, women in the intervention group had higher scores for both domains of mammography screening knowledge (numerical and concept) compared with women in the control group (p<.001). The percentage of women considered to have adequate knowledge (i.e., a score of at least 6 out of 10) was greater in the intervention group than in the control group (94% vs. 83%; p=.01).
- At posttest, women in the intervention group were more likely to have made a decision about whether to start screening now or wait until age 50 compared with women in the control group (82% vs. 61%; p<.001).
Smith, S. K., Barratt, A., Trevena, L., Simpson, J., Jansen, J., & McCaffery, K. J. (2012). A theoretical framework for measuring knowledge in screening decision aid trials. Patient Education & Counseling, 89 (2), 330-336.
Barratt, A., Howard, K., Irwig, L., Salked, G., & Houssami, N. (2005). Model of outcomes of screening mammography: Information to support informed choices. British Medical Journal, 330 (7497).