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Medical Errors Occur 10 Times More Than Previously Thought

Study finds mistakes affect 1 in 3 hospital patients

En español | Ten years after a landmark study outlined how to combat medical errors in U.S. hospitals, researchers have found that errors may be 10 times more common than experts had thought.

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That seminal report, released a decade ago by the Institute of Medicine — "Crossing the Quality Chasm" — inspired a whole wave of patient safety initiatives at hospitals across the country. Some progress was made; lives have been saved, experts say.

Hospital Errors

Photo Illustration; X-ray: Anthony Bradshaw; Forceps: Southern Stock; Man holding x-ray: Yo Oura. All Getty Images.

But the new research in the April edition of the journal Health Affairs found that medical errors and other "adverse events" are still rampant. This study, using a more sensitive method of measuring, found that mistakes occur in one out of every three hospital admissions.

Medical mistakes and adverse effects include medication errors, hospital-acquired infections, pressure ulcers (also called bedsores), medical device failures, patient falls, blood clots and other complications.

The lead author of the study, David C. Classen, M.D., an associate professor of medicine at the University of Utah, says the troubling findings might actually be conservative: If the researchers had been observing patient care in real time, not scrutinizing charts later, they may well have detected even more problems.

The United States does not have a consistent system for reporting all health care safety problems, although some hospitals and health care groups have stepped up research and surveillance in the last decade.

Indeed, hospitals and researchers use different systems for analyzing safety problems; the one used in this study was designed to be particularly sensitive in detecting errors.

The researchers found that the two main methods "commonly used to track patient safety in the United States today — voluntary reporting and the Agency for Healthcare Research and Quality's (AHRQ) Patient Safety Indicators — fared very poorly compared with other methods and missed 90 percent of the adverse events."

They added that "reliance on voluntary reporting and the Patient Safety Indicators could produce misleading conclusions about the current safety of care in the U.S. health care system and misdirect efforts to improve patient safety."

Carolyn M. Clancy, M.D., director of the federal Agency for Healthcare Research and Quality, says the findings were both "alarming," because the numbers were so high, and helpful, because they give safety researchers and hospitals a more accurate assessment of errors. "You can't fix something until you actually measure it," she says. Clancy says information like this will help her agency design better methods of analyzing and reporting errors.

Next: Part of the challenge is that care is more complex. >>

When it comes to improving the safety of health care, part of the challenge is that hospital patients now are much sicker and care is more complex than a generation ago, experts say. "You have to be quite ill to get into the hospital in the first place. It's a much more vulnerable population," Classen says. "The hospital patient today is like the ICU patient 20 years ago — much more complex, many more things going on, many more medications being given."

The study looked at nearly 800 patient records, measuring errors in three ways. One analysis found only four errors, one standard system identified 35 — and the third found a whopping 354. Some patients experienced more than one mistake, and older patients and those with more complex medical conditions were at higher risk.

And these errors didn't occur in mediocre hospitals, either. The study involved three high-quality teaching hospitals that were not named but were described as having "advanced patient safety programs, initiatives, and research projects."

Not all of the errors are fatal or catastrophic, the researchers say, and sometimes patients themselves can help head off problems. Patients and families should know what medications they are taking, understand the risks of procedures, and bring even minor changes or symptoms to the attention of doctors and nurses, Classen says. That little rash, that unfamiliar pain, that moment when a patient slipped but didn't quite fall, may be nothing to worry about — or it could be a warning. Many problems can be treated or corrected before they get worse.

Robert Wachter, M.D., a safety expert at the University of California San Francisco division of hospital medicine, says the study is a reminder that preventing mistakes is harder than it sounds.

"You put in place checklists or a computer system, and you think you'll clean things up a lot," he says. "But it turns out you clean things up a little."

Reducing errors will require better tools, ongoing education and a change, he says, in how hospitals and the people who work in them think about safety and risk.

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Joanne Kenen is a Washington writer who specializes in health policy issues.