Chance News 81

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Quotations

Eminence based medicine—The more senior the colleague, the less importance he or she placed on the need for anything as mundane as evidence. Experience, it seems, is worth any amount of evidence. These colleagues have a touching faith in clinical experience, which has been defined as “making the same mistakes with increasing confidence over an impressive number of years.” The eminent physician's white hair and balding pate are called the “halo” effect.

from Seven alternatives to evidence based medicine, British Medical Journal, 18 December 1999

Submitted by Paul Alper

Forsooth

Question of significance

“Ultrasounds Detect Cancers That Mammograms Missed, Study Finds”
by William Weir, The Hartford Courant, January 13, 2012

A 2009 CT law requires that “all mammogram reports include the patients' breast density information, and that women with greater than 50 percent density be recommended for additional ultrasound testing.” CT is apparently the first state to pass such a law.

For the period October 2009 to 2010, a University of Connecticut Hospital radiologist collected data on more than 70,000 cases, of which about 8,600 involved ultrasound screenings, and she found that the screenings “detected 3.25 cancers per 1,000 women that otherwise would have been overlooked.”

"When you think about it, we find four or five per thousand breast cancers in an overall screening population. So, then you add that extra three on," she said. "I think that's not insignificant."

Note that:

[The radiologist] told state officials that more data was needed to know whether ultrasound tests actually did a better job detecting tumors in breasts with high density. Ultrasounds typically cost patients more than a mammogram (particularly if their insurance has a high deductible), require skilled technologists and take longer to perform than a mammogram. .... [S]he called [the bill] a case of "putting the cart before the horse," [but that] the law presented a "golden opportunity."

The radiologist’s study has been accepted by publication in The Breast Journal.

Discussion

1. The radiologist commented that the finding of 3 additional cases of breast cancer per 1000 through the added ultrasound procedure - beyond the 4 or 5 per 1000 found through previous mammograms - was "not insignificant." What do you think she meant by that, if anything, statistically speaking?
2. Suppose that her finding was statistically significant. Do you think that it was, in a real-life sense, significant enough to justify the costs in time and money?

Submitted by Margaret Cibes

Item 2