The article points out that deaths due to "iatrogenic causes" during hospital care results in 225,000 deaths per year in the United States. That article is from the year 2000, you can read Medical Detective for more recent figures.
The "outpatient care" which follows that hospitalization results in an additional 199,000 deaths due to those "iatrogenic causes".
The not so grand total is 424,000 deaths per year that were due to negligence, accidents, or incompetence.
An "iatrogenic cause" is defined as:
i·at·ro·gen·ic: Induced in a patient by a physician's activity, manner, or therapy. Used especially of an infection or other complication of treatment.(Dictionary). What this boils down to is that, in the health care system discussed, the treatment is sometimes worse than the disease.