People who work in public health are familiar with the Accident Pyramid, sometimes called the Safety Pyramid.
In 1931, H.W. Heinrich theorized that for every major accident there are 29 minor accidents and 300 near misses. This theory has been reevaluated several times, including by Conoco Phillips in 2003, where it was determined that for every fatality in their business there are 30 lost day injuries, 300 recordable injuries, 3,000 near misses, and 300,000 unsafe acts.
A study in the Annals of Internal Medicine examined information that previous studies did not and concluded that there are 320,000 preventable deaths in medicine in the USA each year (see Preventable Deaths on this site).
That suggests that 90 billion unsafe acts were committed in medicine (320,000 x 300,000 rounded off) to produce that many unnecessary deaths. Patients have no means to discover which operators and which facilities commit the most unsafe acts. They cannot even discover where patients got murdered.
The number of insurance claims filed in a recent year was 4 billion which means there would be about 20 to 25 unsafe acts committed for each visit to a caregiver for which an insurance claim was filed. We could run through all of the small unsafe acts to which a patient could be exposed during a routine visit to a family doctor just to try to get a grip on how the numbers can be so large, but the point isn't the precise accuracy of the number.
The point is that the numbers are large and that lots of patients are dying because of them.
Yet in medicine unnecessary fatalities often are considered freak rarities and as such are not considered events to be learned from (they don't even do autopsies 95% of the time). But the causes of fatalities are different from the causes of injuries. Learning how to prevent one does not lead to preventing the other. Both must be studied. [Dan Petersen, 2nd edition, Safety Management] Unfortunately, in medicine, there is very little accurate record keeping of these events (almost none). It is difficult to find anyone in medicine who even is aware of that.
It is not possible for patients to give consent that is informed when there is no possibility of becoming informed about these things.