DIAGNOSTIC ERROR IN THE UNITED STATES: A SUMMARY OF THE REPORT OF A NATIONAL ACADEMY OF MEDICINE COMMITTEE

Abstract

This review article summarizes the conclusions of the National Academy of Medicine committee on diagnostic error. The committee deliberated during five in-person meetings and during numerous conference calls between April 2014 and April 2015. At three of the meetings, the committee invited multiple speakers to inform its deliberations. The 21 members of the committee represented a broad range of expertise related in some way to diagnostic errors, their potential causes, or their consequences. The members’ specialized knowledge included patient safety, health care quality and measurement, patient engagement, health policy, health care professional education, cognitive psychology, health disparities, human factors and ergonomics, health information technology, decision analysis, nursing, radiology, anatomic pathology, laboratory medicine (clinical pathology), law, and health economics.

INTRODUCTION

Medical error includes medical mistakes of all types. These include procedural errors such as perforation of the aortic arch with a catheter, pharmaceutical mistakes such as administration of four times the recommended dose of chemotherapy, and diagnostic error such as providing a diagnosis of asthma instead of a correct diagnosis of pulmonary embolism in a patient who is short of breath (1,2). The first of the National Academy of Medicine committees to address medical error produced the report “To Err Is Human” in 1999 (1). The second report, entitled “Crossing the Quality Chasm,” was published in 2001 (2). After publication of this report, there was concern that the major source of medical error involved mistakes in diagnosis. Upon acquisition of funding to support a committee to investigate this third topic on medical error, a 21-member group was formed to evaluate the extent of this problem and to make recommendations. It was also hoped that existing solutions to minimize diagnostic error would be revealed that the committee could endorse. The report issued in 2015 on diagnostic error is entitled “Improving Diagnosis and Healthcare” (3).

QUANTITATING THE NUMBER OF DIAGNOSTIC ERRORS AND THE NUMBER OF PREVENTABLE DEATHS IN THE UNITED STATES

It has been difficult to determine the number of preventable deaths due to diagnostic error because the way inpatient and outpatient diagnoses are listed does not easily capture diagnostic errors. For example, there is no code for a myocardial infarction that has been misdiagnosed as anxiety rather than coronary artery ischemia. At the time of the diagnostic error committee’s deliberations, two papers had been published that addressed the question of number of deaths associated with the broad topic of medical error, inclusive but not limited to diagnostic errors. The reported numbers were surprisingly large. The number was 80,000 to 160,000 per year in the United States in one report (4); in a second paper, the number was estimated at 400,000 per year (5). In a study later published in 2016 by investigators at Johns Hopkins University using data from 2013, medical error was estimated to have caused 251,454 deaths in 2013, making it the third most common cause of death in the United States (6). [The conclusions from this report (6) have been widely challenged, despite the fact that the number of deaths is on the same order of magnitude as the reports in references (4) and (5).] From the committee’s work involving the analysis of hundreds of manuscripts on diagnostic mistakes, it was concluded that diagnostic error-related deaths represented approximately 25% of all medical error deaths. The calculated result was approximately 64,000 preventable deaths annually in the United States due to diagnostic error. If four years are considered, this number is roughly equivalent to the number of U.S. combat deaths in the Second World War over a span of four years (7). These numbers made it obvious to the committee that there is a mostly unspoken major problem in health care associated with diagnostic error. The committee’s principal recommendation was that a clinical “team” was needed to reduce this high incidence of diagnostic error. Contributions from experts in other specialties to providers who face patients must come far more easily and effectively than they currently do. Specifically, input from nurses, pharmacists, clinical laboratory scientists, and others must be encouraged and welcomed by patient-facing health care providers to help them make an accurate diagnosis.

The committee on diagnostic error developed its own definition of diagnostic error, in the face of many previous definitions. The committee defined diagnostic error as “the failure to (a) establish an accurate and timely explanation of the patient’s health problems or (b) communicate that explanation to the patient. This definition states that establishing the correct diagnosis but failing to explain it to the patient constitutes a diagnostic mistake (3). One of the committee’s major observations made early in its deliberations was that the most common misdiagnoses involved frequently encountered disorders, both in adults and in children. To the surprise of many committee members, diagnostic mistakes were not primarily limited to rare disorders, but instead involved commonly encountered disorders. For example, concluding that a hemorrhoid explained an episode of rectal bleeding when the true cause of bleeding was a large tumor in the sigmoid colon was the most common mistake in failing to diagnose colon cancer.

DIAGNOSTIC ERRORS ASSOCIATED WITH ORDERING THE INCORRECT TESTS, NOT ORDERING THE CORRECT TESTS, OR MISINTERPRETING TEST RESULTS

A variety of presentations informed the committee that many diagnoses are overlooked because physicians are unfamiliar with new tests that are constantly being made available. These are often genetic tests with complex terminology for many providers that were not ordered and may have been helpful if they were (8-13). It was apparent that physicians and administrators failed to understand that a test costing $1,000 that could establish a diagnosis, when a day in the hospital costs $2,000 per day, which was both clinically valuable and financially advantageous. This led the committee to recommend that both new and experienced practitioners need information from diagnostic experts, not just from radiology and anatomic pathology but also from expert pathologists in laboratory medicine (clinical pathology) and genetics (3).

A major topic of discussion was why such a large number of diagnostic errors have been so overlooked for so long. One of the reasons uncovered is that a diagnostic mistake may precede the clinical consequences of the mistake by months or even years. An example was given of a surgeon who did not know how to evaluate a prolonged partial thromboplastin time (PTT) prior to surgery and transfused fresh frozen plasma to minimize the prolonged PTT, without determining if the cause of the PTT elevation was associated with a risk for bleeding. Commonly, a prolonged PTT is produced by a lupus anticoagulant which does not predispose to bleeding. When fresh frozen plasma transfusion occurred between 1981 and 1984, one out of approximately 20 units of fresh frozen plasma and other blood products contained active hepatitis C virus or HIV, for which there were no tests at the time. If a patient who unnecessarily received fresh frozen plasma contaminated with hepatitis C needed a liver transplant many years later, it is unlikely that the surgeon’s diagnostic error years earlier was recognized as the root cause of error.

However, the major cause of diagnostic errors was identified as physicians not recognizing what they do not know. Too many physicians are comfortable with diagnostic methods they have used in the past that do not provide as accurate or as expeditious a diagnosis as newer tests with which they may be unfamiliar. Unfortunately, although radiologists read images and provide interpretive reports, the major diagnostic modality, by orders of magnitude, are the tests from the clinical laboratory. At this time, relatively few pathologists knowledgeably provide consultation on the selection of appropriate laboratory tests and integrative diagnostic reports that consider all of the diagnostic information for an individual patient, despite the need for such experts (8-12).

POTENTIAL SOLUTION DISCUSSED TO REDUCE THE CHALLENGE FACED BY CLINICIANS IN SELECTING THE CORRECT LABORATORY TEST AND INTERPRETING THE RESULTS CORRECTLY

A solution was presented to reduce diagnostic error. It involved the growth of diagnostic management teams (DMT), specifically created to provide advice on selection of appropriate diagnostic tests and interpretation of complex diagnostic studies of all types. Such expert teams are active in a limited number of institutions currently (8,14,15,16). A diagnostic management team allows an ordering physician to request tests to “evaluate a prolonged PTT,” for example, without asking the provider to identify specific coagulation factor tests or other studies that should be performed. A DMT provides a patient-specific, expert-driven narrative interpretation of the results, following a review of the medical record for clinical context, and inserts it into the patient’s medical record. In another example, hematologic oncologists confronted with dozens of possible mutations for the many different forms of leukemia can obtain a “molecular evaluation for leukemia” with the expectation that testing for all relevant mutations will be included in an evaluation. A major goal for the narrative report is to take a very complex collection of laboratory data with numbers and abbreviations for test names and create understandable, actionable information for all health care providers.

One of the major advantages of using a DMT is that errors in ordering are identified and corrected early in the patient evaluation (17). Adverse clinical consequences and, in many cases litigation, are avoided as a result of early intervention in the diagnostic process (17). A number of published reports have shown the clinical and financial benefits of expert-driven, patient-specific consults on test selection and result interpretation. One study reported shortened length of stay and lower supply costs for patients with pulmonary embolism or with intracranial hemorrhage, as a result of the implementation of a coagulation-specific DMT (18). Another large study showed that patients with hematologic malignancies were managed with less cost and better patient outcomes when all of the diagnostic testing was directed by physicians specializing in hematopathology (15).

RECOMMENDATIONS MADE BY THE COMMITTEE ON DIAGNOSTIC ERRORS

The diagnostic error committee’s recommendations to reduce diagnostic errors in the United States included the following:

• Facilitate more effective teamwork among health care professionals, patients, and their families in the diagnostic process.

• Develop and deploy approaches to identify, learn from, and reduce diagnostic errors and near misses in clinical practice.

• Establish a work system and culture that support the diagnostic process and improvements in diagnostic performance.

• Design a consultative service for widespread use that supports the diagnostic process.

• Enhance health care professional education and training in the diagnostic process.

DISCUSSION

The diagnostic error committee concluded that virtually every adult American who has encountered a health care professional has experienced at least one diagnostic error (3). A report created by an expert group sponsored by the Centers for Disease Control focused on errors in diagnostic testing. They determined that there are tens of millions of cases annually in which physicians are uncertain about the correct tests to order and even more encounters in which physicians are confused about the test results (9). In a widely cited report by Singh, it was shown that on average one in seven outpatient physician encounters requiring a diagnosis involved a mistake in the diagnosis chosen (19). There is a significant mismatch between the number of individuals who believe they have been victims of errors and those who actually experience a diagnostic mistake (3). In America, only 20% of individuals believed that they have been the victim of a diagnostic mistake. The number who have actually been so victimized is likely much higher.

Given the rapid increase in the amount and complexity of available diagnostic testing, particularly when it is genetic, it is understandable that physicians who face patients are finding it increasingly difficult to select the correct tests and interpret the results correctly. This is because such decisions require learning substantial amounts of new terminology and newly introduced clinical indications for thousands of diagnostic tests (20). It has been long recognized that health care providers cannot interpret imaging studies independently, or knowledgeably review histopathology through the microscope, and that expert radiologists and anatomic pathologists are required for these tasks. However, there is a false impression that doctors who interact with patients can continue to understand and synthesize the results from the thousands of clinical laboratory tests. For many years, the number of errors associated with further evaluation of abnormal screening tests, such as prothrombin time, PTT, and the antinuclear antibody test, has been significant.

In more recent times, the diagnosis of cystic fibrosis has evolved from a simple test for sweat chloride to a genetic analysis that identifies one or two of more than 2,000 mutations in the gene for the cystic fibrosis transmembrane regulator protein. The results of this analysis are clinically important because extremely costly drugs are targeted to individuals with certain mutations and not others. Cystic fibrosis has now been divided into six mechanistic and prognostically driven subcategories. The presence of many different mutations in a single gene introduces enormous diagnostic complexity.

Therefore, it is now clear that to greatly reduce diagnostic errors in America, the diagnostic specialties will benefit from consultative advice on test selection and result interpretation.

SUMMARY

Diagnostic error in the United States is a major contributor to medical error and accounts for tens of thousands of preventable deaths annually. The growth of diagnostic information is occurring at a rate that prevents most health care providers from knowing the most useful tests that can accurately establish the correct diagnosis in the most cost-effective manner. Creating disease-related DMTs to provide widespread consultation on test selection and result interpretation has the potential to significantly reduce diagnostic error.

DISCUSSION

Goodenberger, St. Louis: I have a concern that the electronic medical record may inhibit the kind of interaction you’re talking about. As an example, I wanted to look at a chest radiograph with my team several years ago and the senior resident had no idea where the chest reading room was. Is this a problem in your institution in terms of professional interaction, and, if so, how have you addressed it?

Laposata, Galveston: Yes, I can say it can be—it depends on what the parameter is. Obviously, if it’s an imaging study, and other lab work that requires discussion, it really does matter. On the other hand, if it’s a coagulation study result, for example a 35% coagulation factor XI, it may be more straightforward.