Missed diagnoses may be present in more than a quarter of patients who die in hospital intensive care units, and they may result in the deaths of more people each year than breast cancer.
In an important meta-analysis out of Johns Hopkins University School of Medicine published in the online journal BMJ Quality and Safety, researchers found that as many as 40,500 critically ill patients in the United States may die annually when clinicians fail to diagnose hidden life-threatening conditions such as heart attack and stroke.
The unexpectedly high frequency of deadly misdiagnosis in hospital intensive care units or ICUs was "surprising and alarming," said Dr. Bradford Winters, the lead author of the study. After a systemic analysis of 31 different studies in the medical literature from 1966 to 2011 involving autopsy-confirmed diagnostic errors in adult ICU patients, the Hopkins researchers calculated that more than one in four patients -- 28 percent -- had a missed diagnosis at the time of their death. In about 8 percent of patients, the misdiagnosis was serious enough to have caused or contributed to the patients' deaths, Winters said in an interview yesterday.
The Hopkins study found that misdiagnosis in ICU patients was as much as 50 percent more common than that in general hospital patients. In the United States, about half of all deaths occur in hospitals, and half of hospital deaths take place in ICUs or immediately following ICU stays. Winters said that the Hopkins study suggests that as many 40,500 of the 540,000 ICU-related deaths in the US annually may result from a major diagnostic failure.
While hospital critical care units are renowned for their valiant life-saving efforts involving the sickest of patients, there has been growing recognition of the potentially preventable hazards involved in such intensive care, with a particular focus on hospital-caused infections or medication errors.
The problems identified in the recent Hopkins study, however, were errors of omission -- "not something you did, but something you didn't do," said Winters, a professor of critical care medicine. Had the diagnosis been made in a timely manner, he noted, patient treatment might have been changed and lives potentially saved.
The commonest missed diagnoses identified in the study were heart attack; pulmonary embolism (artery blockage in the lungs); pneumonia; and a deadly fungal condition called aspergillosis that attacks patients with weakened immune systems. Together, they accounted for about one-third of the illnesses that doctors failed to detect in the ICU patients. Misdiagnosis of infections and vascular problems, such as heart attack and stroke, accounted for about three-fourths of the fatal errors.
These findings are especially surprising in light of the fact that the patients in intensive care units are the most monitored, tested, and examined patients in the hospital. "These patients are under a microscope, and yet clinicians still missed these diagnoses," Winters said. Identifying some of the commonest causes of misdiagnosis provides crucial clues for improving ICU diagnosis and treatment, with potentially life-saving results. "This is an area that has received little attention and little funding," he said.
The ICU unit itself presents an intensely challenging environment, Winters said, in which clinicians "are bombarded with more than 7,000 independent pieces of information each day," creating the potential for missing critical signs of an unrecognized deadly medical condition in a patient who is already critically ill.
Because the study focused on autopsy reports, it did not identify increases in non-lethal complications that patients suffered because of a missed or delayed diagnosis that can be costly, require additional tests and procedures as well as time in the hospital, and potentially reduce quality of life.
Hopkins has long been a leader in patient safety efforts nationwide. An earlier effort focused on the insertion of central lines into patients to introduce drugs and fluids has reduced the incidence of potentially lethal hospital-acquired bloodstream infections by almost 60 percent, he said. The improvements resulted in part from awareness campaigns to increase hospital staff adherence to patient safety regimens involving better teamwork and checklists of best medical practice.
The Hopkins researchers hope that the study, will point toward new strategies for preventing misdiagnosis, including better understanding of the appropriate staffing ratio per critical care patient, as well as cognitive tools and checklists that focus on better detection of the most frequently missed conditions.
In the long run, while new technologies to pinpoint the problems earlier may also be needed, patients don't have to wait for this to happen. "Clearly the human component," Winters said, "how the staff absorbs the information and improved teamwork and communication is crucial too."