In their excellent but unfortunately titled book Ending Medical Reversal, Adam Cifu Dr. Cifu talked to Russ Roberts recently, in one of the best episodes of EconTalk so far this year. Dr. Prasad’s interview with Russ was also quite good, though the topic was not my cup of tea. and Vinay Prasad note the practice of “medical reversals”, which is a tendency of medicine to reverse practice — or self-correct — once evidence suggests that something that was thought to work actually doesn’t. Typical examples are starting prophylactic anti-arrhythmics after a heart attack, using estrogen to treat symptoms of menopause and performing kyphoplasty to treat vertebral compression fractures. The RCTs that led to reversals are: CAST, Women’s Health Initiative and ACTRN12605000079640, and guess which one of these was done in New Zealand. For each of those, there was a randomized controlled trial that showed no benefit — or, even worse, more harm — of the intervention compared to placebo. And presto, medical reversal was official and doctors around the world stopped doing what they now knew was harmful.
Just kidding: it took years to stop those practices, and kyphoplasty/vertebroplasty is still being performed, in select cases, based on little to no evidence. There is a long tail of doctors who either don’t believe RCTs in general, or don’t know about some of those in particular, or what is most common know and believe in RCTs when they affect someone else’s practice but find a million faults in those that investigate their own bread and butter. These doctors perform what I’d like to call Zombie Medicine, a term inspired by Lisa Feldman Barret’s Zombie Ideas (↬Andrew Gelman): Incidentally, “Zombie Medicine” would have made a much better book title than “Ending Medical Reversal”. Add a subtitle (Zombie Medicine: How Doctors' Inertia and Bad Science Harm Patients and Waste Billions) and you have a best-seller. Maybe for the second edition?
Zombie ideas abound in our culture, nibbling away at the brains of their victims. The mistaken belief that vaccinations cause autism — a celebrated zombie idea — is responsible for rising rates of vaccine-preventable diseases. The belief that a person’s personality type, assessed by the Myers-Briggs Type Indicator (MBTI), predicts job performance is another zombie idea that continues to lure otherwise capable managers into making decisions that benefit neither employees nor their companies.
But inertia to a big, unexpected medical reversal isn’t even the most common type of zombie medicine. There are some undead concepts so ingrained that a million RCTs couldn’t reverse them: the belief that atelectasis (partial lung collapse, common after surgery due to immobility) causes fevers (high body temperature, common after surgery due to infection, transient bacteraemia, and general inflammation), that early cancer detection is an absolute good, that Vitamin C cures anything other than scurvy, that vitamin D prevents anything other than osteoporosis and rickets. And it’s insidious, for I bet every reader will have felt a pang for at least one of these concepts. (“Wait, why does he think this is zombie medicine when I know it’s true!?") That’s how zombie practices become undead: with a sliver of doubt, a shimmer of hope, a dollop of wishful thinking.
And on the very edge of zombification sit tempting ideas that have greater than 99% chance of being false, but that you know will never truly die: that mTOR inhibitors can prolong human life spans, that with enough sequencing we will find genetic causes of most diseases, that the gut microbiome influences anything other than gastrointestinal health and quality of stool. This kind of zombie medicine adds another item to the list of harms: opportunity cost in both money and time.
The first step in addressing a problem is to identify it, the second is to name it. Now comes the time to make lists.