How Many False-positives are Worth the Life of a Woman?

The following is a guest post written by Edward A. Sickles, M.D., Professor Emeritus.

A study published in the April 2011 issue of Radiology found that by increasing the experience requirement for readers of mammograms in the U.S., the number of false-positives would decrease, along with the amount of money spent on mammography each year.

Perhaps a more important finding of the study, which was not covered in some media reports, was that raising total volume requirements will cause some women to have their cancers missed, which will presumably lead to some extra deaths. As one of several co-authors of the study, I believe this issue needs to be well understood as health care planners make policy decisions about mammography.

Another important finding from the study was under-reported in the media. Increasing the number of mammograms needed to be read would reduce the number of radiologists who are available to do the reading. Because there are many remote rural areas in our country, this might create workforce shortages in low-population regions, thus limiting access to mammography screening in some parts of the U.S. Policymakers must understand that accessibility is a major issue in this country, with its wide open spaces, whereas it is not an issue in most other countries with established screening programs because there are few remote rural areas in those other countries.

Something else that was misrepresented in certain media reports was a statistic of $1.6 billion. Some articles would lead the reader to believe that $1.6 billion a year could be saved if there were a change in the experience requirement for radiologists. Our study points out that $1.6 billion per year is spent for all of the mammogram false-positives, not just for the ones that might be changed by a difference in regulation. In fact, by discussing four different changes in experience requirements for mammogram readers, our study shows how there would be fewer false-positives and associated cost savings.  The cost savings actually would range from $22 million to $59 million. While anyone would be very happy with that amount of money in the bank, it is nothing close to $1.6 billion, it represents less than 25 cents per person in the U.S., and it is certainly not an amount of money that will have a meaningful effect on reducing our deficit.

As a side note, I want to point out that at UCSF we have been operating at very low false-positive rates for the last 30 years. The false-positive rate at UCSF is about half of the national average, so women who are concerned about false-positives should understand that if they come to UCSF they actually get a high cancer detection rate and a low false-positive rate, a very good high-accuracy combination.

Interestingly, the skill of UCSF radiologists doesn’t necessarily relate to the volume of exams that they interpret. Some of the current staff at UCSF are not high-volume readers, yet they have very accurate readings because they have been specially trained by experts at UCSF.

So, in summary, while the study provides fairly good evidence that increased experience reduces false-positives, changing the volume requirement would save a very small amount of money in proportion to total costs. Increasing the requirement may adversely affect workforce issues and access. It would also mean somewhat fewer true-positives, fewer cancers found and thus fewer lives saved.

As health care policymakers weigh the relative value of volume among mammogram readers, I believe the information in this study will contribute important points that otherwise might not have been considered.