Recent studies claiming that medical errors are one of the leading causes of death in the United States may suffer from methodological flaws and paint a sensationalist picture, Aaron Carroll writes for the New York Times' "The Upshot."
The Institute of Medicine (IOM) in 1999 published a seminal report on medical errors concluding that up to 98,000 people were dying in U.S. hospitals annually as the result of preventable medical errors. In May of this year, a study published in BMJ claimed the problem had gotten worse and that more than 250,000 medical errors now occur annually.
Background on the controversy
Those are huge numbers: The BMJ study authors, for instance, claimed that medical errors were the third-leading cause of death in the United States in 2013. But the estimates have provoked considerable controversy.
A report published in JAMA by Indiana University researchers, for instance, noted that the 98,000 medical errors documented in IOM's study had been extrapolated from 7,743 "high-severity" patients—the sickest of the sick—in a New York hospital admissions database.
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According to the original study, 13.6 percent of those patients died, at least partially, as the result of an adverse event. But the Indiana University researchers estimate that 13.8 percent of the high-severity patients would have been expected to die anyway. That, Carroll writes, "means that the death rate in the group with medical errors was probably similar to the death rate in a group without medical errors, casting doubt on those errors as being the cause of death."
As for the BMJ study estimate that 250,000 patients die each year from medical errors, some experts have pushed back on its plausibility and its methodology. Carroll notes that about 2.5 million people die each year in the United States, of whom 700,000 are hospitalized when they die. "This means that medical errors—in hospitals—would have to account for up to 10 percent of all deaths, or up to more than a third of hospitalized patients," Carroll writes. "That's hard to fathom."
And Vinay Prasad, a senior scholar at the Center for Ethics in Health Care at Oregon Health & Science University, argued that the definition of medical errors the BMJ study used—any action "that does not achieve its intended outcome" or has the potential to harm a patient—is "uselessly broad."
'Preventable' errors are tough to define
For instance, a 2001 study published in JAMA asked doctors to review whether a preventable error contributed to various cases of death, as well as how likely the death would have been in the absence of a medical error. Doctors judged nearly 25 percent of deaths as "partially preventable," but only 6 percent as "probably preventable." Moreover, doctors often disagreed about which particular deaths could have been prevented. "This isn't to say that these error-associated deaths aren't sad or meaningful," Carroll writes. "But the potential harms of hospitals have to be weighed against the potential benefits."
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Generating "sensationalistic" headlines on the number of medical errors, he says, "may be draining resources and attention from more effective harm reduction."
"It makes headlines to say that medical errors in hospitals kill more people than guns or cars," he concludes. "But that's debatable" (Carroll, "The Upshot," New York Times, 8/15).
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