A report published in May from researchers at Johns Hopkins claims that medical errors are the third leading cause of death in the U.S., behind only heart disease and cancer.
According to the researchers, medical errors account for 251,454 U.S. deaths each year – and they regard this figure as an underestimate.
That’s the sort of finding that makes headlines. Indeed, you might have read about this report in the newspaper or even seen it reported on the evening news.
But as we’ll argue, the methods the researchers used to draw this conclusion are flawed, and that means that the conclusion that medical error is the third leading cause of death is highly questionable.
When a report like this gets broad media coverage, it can foster unwarranted mistrust of medicine, which could prevent people from seeking needed care – a concern to everyone who takes care of patients.
What’s wrong with the methodology?
A medical error can be defined as a decision or action that results in patient harm and that experts agree should have been made differently, given the information available at the time. But applying such a definition in reviewing patient records is fraught with difficulty.
The study’s authors argue that death certificates should be redesigned to recognize that more deaths are attributable to medical error. That’s a reasonable suggestion. But the implication of many media reports that these findings prove hundreds of thousands of people are dying each year due to medical errors is highly problematic.
First, the authors of the Johns Hopkins report did not collect any new data. Instead, they based their conclusions on studies performed by other authors. There is nothing wrong with that in principle.
But in this case, the results are highly misleading because they are based on large extrapolations from very small data sets. The authors based their conclusions on four studies that included a total of only 35 deaths attributable to medical error out of nearly 4,000 hospital admissions. Extrapolating from 35 deaths to a population of 320 million is quite a leap.