It’s all about the Group

Amy Finkelstein’s video for MRU about the economics of mammograms just popped into my email. She and her colleagues are wondering about the efficacy of the present policy for screening for breast cancer. The blurb following the video explains.

One in eight women will be diagnosed with breast cancer. The current recommendation is that women should receive annual mammograms starting at age 40. But who is actually following this recommendation, and does that affect the test’s efficacy? MIT’s Amy Finkelstein and two of her coauthors, Tamar Oostrom and Abigail Ostriker, explore this question in this video. This video is based on the following paper: Screening and Selection: The Case of Mammograms Liran Einav, Amy Finkelstein, Tamar Oostrom, Abigail Ostriker, and Heidi Williams https://economics.mit.edu/files/20062

Past studies suggested dividing women into two groups in order to tackle a public health response to cancer: those under age 40 and those over age 40. Once over forty years of age, women are considered at a higher risk and thus were encouraged to have mammograms on a regular basis. The Susan G Komen organization provides data on how screening has saved lives. “From 1989-2017 (most recent data available), breast cancer mortality decreased by 40 percent due to improved breast cancer treatment and early detection [60]. Since 1989, about 375,900 breast cancer deaths in U.S. women have been avoided [60].”

It wasn’t long, however, that the drawbacks of misdiagnosis became apparent. False positive tests were causing patients unnecessary mental and physical costs. The fear and treatment associated with a false positive took time, energy and resources away from women who were in fact not likely to acquire the disease.

Amy and her MIT colleagues found that grouping by age was not specific enough. They observed that women who comply, and get screened, share habits that actually make them less likely to be prone for a positive test. Based on information from the medical community, women who disregarded screenings were more likely to eventually experience breast cancer.

By regrouping the women in consideration of their norms and lifestyles, the MIT professors are acknowledging that the public health of women in regards to breast cancer is multidimensional. They do not propose a new public policy but rather further insight into how the topic should be considered. Tamar Oostrom voices in the video: “our paper brings an additional dimension” to the issue.

When you think of the nature of people who would follow the recommendations and comply with regular testing, they are probably folks who can afford to be tested, both in the sense of the medical services expense and in the time it takes out of their lives. They probably have access to transportation to be tested. They have the willpower and ability to prepare and eat a healthy diet and exercise. It’s interesting to note that many if not all of these activities are tied into access to other public goods.

This video confirms a couple of things. Putting public resources towards a problem reaches a point of no additional returns, and can cause additional costs to the targeted group. Secondly, solving for the optimal amount of screening involves an understanding of how to distinguish groups and there access to other public goods markets.

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