Autopsy Study Shows Misdiagnoses Are Common in ICU

Laurie Barclay, MD

August 30, 2012

August 30, 2012 — Each year in the United States, up to 40,500 adult patients admitted to the intensive care unit (ICU) may die because of misdiagnoses, according to a systematic review of autopsy studies. The review was published online July 21 in BMJ Quality and Safety.

"Our study shows that misdiagnosis is alarmingly common in the acute care setting," lead author Bradford Winters, MD, PhD, associate professor of anesthesiology and critical care medicine and neurology and surgery at the Johns Hopkins University School of Medicine in Baltimore, Maryland, said in a news release. "To date, there's been very little research to determine root causes or effective interventions."

The study authors note that the prevalence, nature, and effects of misdiagnoses in the ICU may be underrecognized, but add that they could contribute significantly to preventable morbidity and mortality. The goals of this study were to compare the prevalence of potentially fatal ICU misdiagnoses with that in the general inpatient population (approximately 5%), as well as the proportion of misdiagnosed infections and vascular events.

Electronic and manual searches of MEDLINE and other databases from 1966 through 2011, as well as of bibliographies of retrieved articles, identified appropriate studies, without language restriction, for inclusion in the systematic review. Selection criteria were observational studies of autopsy-confirmed diagnostic errors in the adult ICU. Exclusion criteria were studies of misdiagnosis of a single, specific disease.

The investigators abstracted data and calculated descriptive statistics regarding autopsy rate, overall prevalence of misdiagnosis, specific diseases misdiagnosed, and Goldman error class. They also modeled the prevalence of potentially fatal, class 1 misdiagnoses as a nonlinear function of the autopsy rate. Misdiagnoses in this class could have either caused or directly contributed to death, and if patients had received the correct diagnosis, treatment would likely have been different.

Study Findings

The investigators screened 276 abstracts and identified 31 studies meeting inclusion criteria, which they selected for analysis. Median autopsy rate was 43%, with a total of 5863 autopsies performed, 28% of which revealed at least 1 misdiagnosis and 8% of which revealed a class 1 diagnostic error. Overall, the prevalence of misdiagnoses ranged from 5.5% to100%. Assuming an autopsy rate of 100%, the investigators projected that the prevalence of class 1 misdiagnoses would be 6.3% (95% confidence interval, 4.0% - 7.5%).

"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," Dr. Winters said in the news release.

"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 their medical team," the release states.

"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," Dr. Winters concludes.

The most common fatal misdiagnoses were vascular events and infections (41% each). Pulmonary embolism, myocardial infarction, pneumonia, and aspergillosis were the most frequent individual class 1 misdiagnoses, cumulatively accounting for about one third of all class 1 misdiagnoses.

To put the findings in perspective, the investigators note that diagnostic errors in the ICU may result in as many deaths each year as breast cancer. When compared with the general population of adult inpatients, ICU patients have up to twice the risk for potentially fatal diagnostic errors.

Two thirds of discovered misdiagnoses did not directly contribute to death but may have resulted in longer hospital stays, unnecessary surgery, and reduced quality of life.

Limitations of this study include the inability to measure morbidity associated with misdiagnosis in survivors, a possible publication or selection bias, the retrospective design of most of the included studies, and heterogeneity in the study populations.

"Our data suggest that as many as 40 500 adult patients in an ICU in [the United States] may die with an ICU misdiagnoses annually," the study authors conclude. "Despite this, diagnostic errors receive relatively little attention and research funding. Future studies should seek to prospectively measure the prevalence and impact of diagnostic errors and potential strategies to reduce them."

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 supported this study. Dr. Winters reports receiving fees for expert testimony at several defense and plaintiff law firms and speaking honoraria from 3M corporation and various health systems to speak on patient safety and Rapid Response Systems. One author reports receiving grant or contract support from the Agency for Healthcare Research and Quality, the National Institutes of Health, the Robert Wood Johnson Foundation and the Commonwealth Fund for research related to measuring and improving patient safety; honoraria from various hospitals and healthcare systems and the Leigh Bureau to speak on quality and safety; consultancy with the Association for Professionals in Infection Control and Epidemiology, Inc.; and book royalties for authoring Safe Patients, Smart Hospitals: How One Doctor's Checklist Can Help Us Change Health Care from the Inside Out. The other authors have disclosed no relevant financial relationships.

BMJ Qual Saf. Published online July 21, 2012. Abstract

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