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Diagnostic errors in ICU cause numerous fatalities


Each year as many as 40,500 ICU patients in the U.S. die with an unknown medical condition that may have caused or contributed to their death, according to a study.

Patient safety experts with Johns Hopkins said although diagnostic errors in the ICU may claim as many lives each year as breast cancer, they remain an underappreciated cause of preventable patient harm.

“Our study shows that misdiagnosis is alarmingly common in the acute care setting,” Bradford Winters, MD, PhD, the study’s lead author and associate professor in the Johns Hopkins University School of Medicine, said in a news release.

“To date, there’s been very little research to determine root causes or effective interventions,” Winters added, noting that less lethal patient safety risks have received greater attention.

By reviewing studies that used autopsy to detect diagnostic errors in adult ICU patients, experts in the Johns Hopkins Armstrong Institute for Patient Safety and Quality discovered that 28% of patients had at least one missed diagnosis at death.

In 8% of patients, the diagnostic error was serious enough that it may either have caused or directly contributed to the individual’s death and, if known, likely would have changed treatment, the researchers said. Infections and vascular maladies accounted for more than three-quarters of those flaws.

Overall, the medical conditions most commonly missed by diagnosticians included myocardial infarction, pulmonary embolism, pneumonia and aspergillosis. These four conditions accounted for about a third of all illnesses that physicians failed to detect.

Study methodology and findings

The review of 31 studies included 5,863 autopsies from a range of ICU types. The prevalence of autopsy-detected misdiagnoses, which were stratified by severity, ranged from 5.5% to 100% by study.

After collecting and classifying all error data, the researchers calculated how frequently misdiagnoses would be discovered if every patient who died in the ICU underwent an autopsy. Although autopsy is more frequently performed in complex patient cases in which the clinician may have a lower level of diagnostic certainty, the authors took this potential bias into account. Based on those adjustments, they said their calculations are conservative estimates.

Winters and his colleagues also found that, when compared with adult hospital patients overall, individuals in the ICU face up to twice the risk of suffering a potentially fatal diagnostic mistake.

“It may be counterintuitive to think that the patients who are the most closely monitored and frequently tested are more commonly misdiagnosed, but the ICU is a very complex environment,” Winters said. Clinicians face a deluge of information in a distracting environment in which the sickest patients compete for attention, most without being able to communicate with the medical team. “We need to develop better cognitive tools that can take into account the 7,000 or more pieces of information that critical care physicians are bombarded with each day to ensure we’re not ruling out potential diagnoses.”

Although two-thirds of discovered misdiagnoses did not directly contribute to the patient’s death, Winters said, they are an important indicator of accuracy and not without costs. Patients may endure lengthened hospital stays, unnecessary surgical procedures and reduced quality of life because of nonfatal diagnostic mistakes.

The Armstrong Institute patient safety experts said the study points to the need for additional research to pinpoint the causes of misdiagnosis and identify tools to help diagnosticians more accurately assess patients.

This research was supported by a National Institute of Health training grant awarded to the Johns Hopkins University School of Medicine and a grant from the Agency for Healthcare Research and Quality.

The study is scheduled for publication in BMJ Quality & Safety. The study abstract is available at


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