Improvement Insights Blog
Mammograms are a Type of Inspection
Breast Cancer is Rare, yet we subject women to mammograms to try to detect it. False positives are 20X higher than true positives. Deming said: “Cease dependence on inspection to achieve quality.”
“Hi, I’m Jay Arthur, author of “Lean Six Sigma Demystified,” “Lean Six Sigma for Hospitals,” and the QI Macros [software].
“I found another interesting item in Malcolm Gladwell’s book; again, it was in the back notes. They were talking about mammograms. Breast cancer itself is really rare, it’s like less than a half of 1% of women who get a mammogram actually have cancer, so it’s like looking for a needle in a haystack. What epidemiologists know is that if you gave a mammogram to 100,000 women it would probably find maybe 400 of the 500 women who have cancer. It would miss a hundred. (No, these are not exact numbers, but I’m really close here. I’m just making it simple.)
“So what does that mean? Well, 400 women get diagnosed, 100 women are missed and that’s a problem, right there. My friend Janet – the doctors missed hers and she thought she had it and she beat on her doctor, [who said] “Well, you don’t have it.” Well, yes she did and she died. I want you all to be cautious. These false negatives are as bad as the false positives, but the false positives is another interesting story.
“In that same 100,000 women with mammograms, 9,000 get false positives, and what does that mean? Well, that means they probably have to have a needle biopsy and have that tested, and worry like crazy and that’s $10,000 plus a shot to get a needle biopsy and be terrified. It takes a week or more to get the biopsy results. That’s an awful lot of fear forced on 9,000 women so that we can detect 400 or 500 cancers. If you’re the one who should have been tested and wasn’t tested, that’s another story.
“What I think Gladwell says is, are you more concerned about the risk of a tiny chance that you’ll have cancer that will be missed or a much larger probability that you’ll be misdiagnosed with a cancer you don’t have?
“Deming (and I don’t usually quote Deming) Deming said “Cease forever the process of inspection.” Mammograms are a type of inspection. We’re looking for defects, right? Can’t we find a better way? Isn’t there a better way to do this than to subject all these women to unnecessary mammograms? Again, that’s a cost, right? It’s all inspection. I know you’ve done it that way for a long time, but isn’t there a better way? Why can’t we get smarter? Why can’t we find better answers?
“That’s my Improvement Insight for this week: Cease the process of inspection. That’s true in your manufacturing plant, it’s true in your hospital, it’s true in your life… …if you can.
“I’m Jay Arthur. Let’s go out and improve something this week.”
