March 5, 2020
Thoughts around overdiagnosis after a visit to a medical specialist.
A FASCINATING STUDY was published last month in Australia. It may not have got much press here in Victoria, but confirmed a lot of what the world is learning about overdiagnosis.
That study, carried out by Paul Glasziou and colleagues, compared the year 1982 to 2012, analyzing changes in lifetime risks for prostate, breast, renal, thyroid cancers and melanoma. They concluded that 18 percent of all cancers diagnosed in Australian women (11,000 diagnoses each year), and 24 percent of those in men (18,000 each year) are overdiagnosed cancers. Screening programs (for cancers and other things) look for signs of disease detected in healthy people. Often those signs are just “prediseases,” benign signs which never go on to be lethal. Predisease is what might be diagnosed when a screening result isn’t quite normal, but is below the threshold of true disease. It is considered a potential precursor to a disease which may or may not be worrisome.
The seriousness of “false positives” is also gaining worldwide attention, as this Australian study demonstrated.
I wrote about the problems of overdiagnosis in my 2012 book Seeking Sickness and made the same case, where in condition after condition which involves some kind of medical screening, there is always overdiagnosis. There’s both benefits and harm in screening healthy people. It’s worthwhile if it finds signs of potential disease that will stop you getting a more serious disease. It can, however, lead to anxiety and often substantial medical activity, including biopsies, more screening, more procedures, surgery, radiation, and prescription drugs. Often all this anxiety and medical activity never actually extends the quality or quantity of your life.
Here’s a scene that happened when I was partway through writing that book: I am in the chair at the optometrist, as he was about to blow a puff of air into my eyeball, checking for eyeball pressure. It dawned on me: “This is a screening test!” This is how I described it:
“Things look different when you’re sitting in the chair, playing the role of the trusting patient. It was like I had two angels sitting on my shoulders. One was whispering in one ear: ‘What’s the big deal? It was just a puff of air to the eyes. C’mon.” On the other shoulder, the naysayer angel, armed with a pitchfork, was jabbing me in the ear: “Are you nuts? Do you have any idea what this screening test will lead to? False positives. False negatives. Overdiagnosis. Downstream effects. Worry. Anxiety. Depression. Say no!’”
I was being overdramatic, yet I wrote that I learned a vital lesson: if you are about to face a health professional offering you a screening test, you need to have already done your research. Doing it afterward is getting things backward. The air-puff test showed normal eye pressure, but what if it didn’t? Thankfully, I didn’t find out.
That experience became my operating axiom of why people need to go into medical screening test with their “eyes wide open.”
Fast-forward eight years, and it was time for another trip to the optometrist. To get my eyes checked, maybe see if I needed a new eyeglass prescription. But darned if this didn’t turn out to be another “teachable moment,” this time with a much more potentially serious intervention.
My optometrist said he saw something unusual in one of my eyes. He said I had a suspected case of narrow-angle glaucoma, a condition that could lead to an acute eye emergency and the potential loss of sight.
That opened my eyes.
He referred me to an ophthalmologist. The first trip to the ophthalmologist was just for a few tests and pictures of my eyes, collecting data. I was invited to watch a video of the doctor explaining the procedure he would offer, a quick operation called a laser peripheral iridotomy (LPI). Perfectly safe, right? But…
Let’s be clear. I am a healthy patient, normal eyeball pressure, and a normal optic nerve. No history of eye disease and no family history either. I was what the literature called a PACS, which stands for “primary angle closure suspect.” I don’t have disease—I have the younger sister, predisease.
I found an excellent paper by Dr H. George Tanaka, an ophthalmologist in Arkansas whose 2018 Review of Ophthalmology study gives considerable detail about the pros and cons of such a procedure. I learned quickly this was no slam-dunk, and I was right to be cautious.
I tracked him down and arranged a phone interview. The main thing I learned is that for people without symptoms or family history of other types of eye diseases, there is no way to know how many PACS patients go on to have an “acute episode” that involves losing your eyesight. Is it one in ten, or one in ten thousand? We don’t know. He admitted that “unfortunately, we don’t have any good evidence for how to manage a PACS patient, and that we don’t know how many PACS patients go on to develop more serious eye problems.”
For the sake of everyone in Victoria who (at a certain age) may well be diagnosed with suspected angle-closure glaucoma, there are a few things to know about the LPI surgery being offered. Angle- closure glaucoma can be an aggressive disease, probably the leading cause of glaucoma blindness in the world, and it is one of the few emergencies in ophthalmology. But as Dr Tanaka wrote: “We don’t actually know how many future angle-closure attacks we’re preventing by performing LPIs. That’s why we can’t say to a patient with narrow angles, ‘Mrs Smith, your risk of going blind is X percent (or your risk of getting glaucoma is Y percent), but the odds will improve by this much if I perform this procedure.’ We don’t have the numbers to support that.” It’s the conclusion that bothers me: “so we just treat everybody.” Clearly, this is textbook overdiagnosis: finding “predisease” in normal people, who are then given the impression they are now living under a dark cloud.
The research suggests the LPI may delay or prevent primary-angle glaucoma. Luckily, the LPI is fairly benign. This operation used to be major surgery, but now is a couple of minutes in the clinic, with minimal risks of infection or bleeding.
As for the cons, sometimes things go sideways. Sometimes patients get extra spots of light in their vision—dysphotopsias—which won’t go away. And believe it or not, some research says the LPI can accelerate cataract development, as well as make you more predisposed to getting a condition called posterior synechiae, making future cataract surgery more difficult.
For me, saying no to the procedure was a no-brainer. If I had higher risks, a personal or family history of eye disease, high eyeball pressure, or if I was going to be hiking in the outback for months at a time where getting emergency medical care was difficult, my decision might have been different. But the doc was not impressed.
I really liked the ophthalmologist. He was a very nice gentleman. He explained things well, but at the same time, I could tell he was taken aback when I refused the procedure. Perhaps he’s not used to patients doing a deep dive into the literature on the potential benefits and harms of surgical procedures. He pressed me, eventually turning up his hands and saying: “Oh well, I just want to tell you the risks, but you’re on your own,” later adding, “well, you’re the ticking time bomb.”
Luckily I have a thick skin, though if you had taken my blood pressure at the time it, would have been through the roof. Not only does his comment not reflect the real research, it’s the height of insensitivity to call a patient a “ticking time bomb.”
No one deserves to be intentionally frightened into getting an elective procedure, especially one with many unknowns and potential harms. As an aside, if the average person knew how much these doctors make by five minutes of lasering your eyes, they would be astounded (all in, close to $400 per eye—$116.76 for the actual few minutes of surgery, $35 for the office visit, $96 for the consultation, $60.42 for “orthooptic evaluation,” with likely extra charges for the photography of the eyes, etc. ). I found in the MSP bluebook that this ophthalmologist billed MSP $749,000 last year.
Later, when I calmed down, I reflected on the “ticking time bomb” comment. Listen, dear reader. Like everyone on the planet, you could live another five minutes or another fifty years. We are all ticking time bombs, more or less. We are all “prediseased” and suffering from “predeath.” Being called a “ticking time bomb” made me angry but also sad for all the patients who are worried, who crave the trusted advice of a health professional, but then get bullied into procedures (or drugs) that they would rather not have.
When I was in the navy, we had a principle: if you don’t know where you are, stop the ship. All signs of disease have uncertainties, and all surgeries and drugs have potential harms and potential benefits. Any honest health professional will tell you those uncertainties. When you don’t know where you are, don’t keep sailing.
Alan Cassels studies pharmaceutical policy and works at UBC. His book Seeking Sickness: Medical Screening and the Misguided Hunt for Diseases is available from bookstores and libraries. You can follow him on twitter @akecassels.