One of Atul Gawande's books (Complications) mentions that amongst deaths where an autopsy is done, the cause of death was misdiagnosed by the doctor about 40% of the time. Quote from book [Page 197, Chapter name : "Final Cut"] ---
"How often do autopsies turn up a major misdiagnosis in the cause of death? I would have guessed this happened rarely, in 1 or 2 percent of cases at most. According to three studies done in 1998 and 1999, however, the figure is about 40 percent."
I think 100 years from now people will look back on our current medicine the same way we view medicine from 100 years ago. There is some impressive progress, but we know less than we think we do and conduct a lot of wasteful and harmful procedures.
It's disturbing to learn how thin the evidence is for a lot of modern medical operations. For example, the recommendations for certain cancer screenings have actually been reduced in recent years after it was found they were causing net harm.
It's a bit startling to realize just how young medical science is. I think it's not unreasonable to compare medicine (and a lot of biology) in the nineteenth century to the state of physics in the sixteenth century.
And certain major areas of medicine that people don't think about that much (outside of the field) such as medical informatics are younger still. This stuff has a huge impact on how medical care is actually delivered, but can be kind of left out of the broader public discussions around medicine due to the focus on the actual literal medicines.
"How often do autopsies turn up a major misdiagnosis in the cause of death? I would have guessed this happened rarely, in 1 or 2 percent of cases at most. According to three studies done in 1998 and 1999, however, the figure is about 40 percent."