That chart is worldwide, not US. And iatrogenic deaths wouldn't be in the chart anyway because there are ten or fifteen different types, most of which would fall under another category.
Fine, here's the US data for 2005 from the CDC. I don't think you can ascribe deaths from heart disease, cancer, stroke, lung disease, diabetes, and Alzheimer's to doctor error. Most come from lifestyle choices. Cigarettes, junk food, and no exercise make Homer something something (DIE EARLY).
You might strengthen your argument for me if you talk about proximate vs underlying causes of death. We're all going to die.
I understand that iatrogenic deaths aren't in the table. And I do think the 800,000 figure the site I linked to may be too high. But almost certainly medical errors are the number three cause of death.
Think about it this way. If your chance of getting MRSA during surgery drops from 4% to 0% if your doctor uses a simple 6-item checklist, imagine all the other ways that doctors are hurting people. Plus, heart attacks are usually the cause of death when your doctor prescribes either the wrong medicine or the wrong dosage, or prescribes the right medicine but gives it to the wrong person.
