Diagnostic errors, defined as a wrong diagnosis, a missed diagnosis, or an unintentionally delayed diagnosis, are increasingly being recognized as a quantifiable problem in healthcare (1). A variety of studies, including comparison of autopsy results with physician diagnoses, suggest that such errors occur in an astounding 10–15% of diagnostic encounters (2,3). Furthermore, a review of malpractice data suggests that problems in laboratory services play a significant role in diagnostic errors. In a study by Gandhi and colleagues of 307 ambulatory cases involving a diagnostic error, failure to order appropriate diagnostic or laboratory tests was a contributing factor in 55% of cases, incorrect interpretation of diagnostic or laboratory tests contributed to 37% of cases, and failure to retrieve diagnostic or laboratory test results was a factor in 13% of cases (4). In contrast, incorrect performance of diagnostic tests was a contributing factor in only 8% of the diagnostic error cases.
These and other published studies suggest that laboratorians should shift some of their quality improvement efforts away from the laboratory toward helping physicians order the right tests, receive the tests promptly, and interpret the test results appropriately. In order to reduce diagnostic errors related to laboratory services, it is helpful to look at where errors occur in the total testing process and then devise appropriate strategies and interventions (Table 1).
How Diagnostic Errors Result from the Total Testing Process
1. Inappropriate test is ordered.
2. Appropriate test is not ordered.
3. Appropriate test result is not used properly.
- Knowledge deficit—Clinician doesn’t know the meaning of the result.
- Failure of synthesis—Clinician inappropriately integrates the result with other findings.
- Misleading result—Clinician is misled by normal test limitations.
4. Appropriate test result is delayed.
5. Appropriate test result is wrong.
The biggest impact on reducing diagnostic errors in the testing process is likely to come from helping physicians improve test ordering practices. Laboratory leaders are ideally situated in healthcare organizations to promote a number of strategic improvements in the testing process (Table 2). For example, as the keeper of the laboratory menu, laboratory directors can eliminate obsolete tests and particular reference labs from the send-out formulary. A specific strategy to reduce misdiagnosis of allergy would be to eliminate IgG- and hair-allergy testing from the lab menu because experts do not consider these tests useful for diagnosis or monitoring of human allergic disease. Laboratory leaders also may want to stop using a reference laboratory that offers tests of little or no value.
Strategies to Help Physicians Improve Test Ordering Practices
- Include computerized reminders in the CPOE system.
- Use CPOE templates for particular care settings (e.g., diabetes care) that increase likelihood of appropriate ordering.
- Incorporate reflex testing strategies (e.g., autoantibody panel after positive ANA test).
- Decrease the number of synonyms for the same test.
- Remove obsolete tests from the lab menu.
- Create physician report cards that grade appropriateness of specific ordering practices.
- Implement a send-outs formulary that eliminates orders for tests of no value.
- Provide readily accessible consults.
- Restrict ordering of specific tests to a defined set of physicians or specialists (e.g., medical geneticists).
- Require approval of pathologist or other doctoral-level laboratorians for specific specialized tests.
Abbreviation: CPOE, computerized physician order entry
Laboratory leaders can not only improve patient safety with these strategies, but they also have an opportunity to raise their visibility by participating in development of test utilization strategies, where the goal is not to reduce testing but rather to ensure appropriate testing (5). These strategies include: consulting for particular areas of care; restricting ordering privileges for specialized tests to specific physicians; requiring that some tests be approved by a pathologist or other doctoral-level laboratorian; and requiring review of genetics tests by a laboratory-provided genetic counselor (6). Implementing these interventions requires collegial conversations and negotiations with care providers, including the medical directors of various divisions of the hospital. When such strategies are implemented carefully, the reputation of the laboratory will be enhanced, and the value proposition presented by the laboratory will be better understood.
In general, focusing on decreasing diagnostic errors is a good strategy for clinical laboratorians, because it de-emphasizes lab tests as a commodity and focuses on the value we add. In other words, it changes our mission from providing accurate, timely, low-cost test results to rapidly and efficiently enabling accurate diagnosis, selection of appropriate treatments, and effective monitoring of health status. In addition, because many diagnostic errors related to laboratory services involve physician behavior, it motivates us to collaborate beyond our walls and show our value to our colleagues who provide direct patient care.
- Graber ML, Franklin N, Gordon R. Diagnostic error in internal medicine. Arch Int Med 2005;165:1493–1499.
- Berner ES, Graber ML. Overconfidence as a cause of diagnostic error in medicine. Am J Med 2008; 121:S2–23.
- Shojania KG, Burton EC, McDonald KM, Goldman L. Changes in rates of autopsy-detected diagnostic errors over time: a systematic review. JAMA 2003;289: 2849–2856.
- Gandhi TK, Kachalia A, Thomas EJ, Puopolo AL, Yoon C, Brennan TA, Studdert DM. Missed and delayed diagnoses in the ambulatory setting: a study of closed malpractice claims. Ann Intern Med 2006; 145:488–496.
- Laposata M, Dighe A. Pre-pre and post-post analytical error: high incidence patient safety hazards involving the clinical laboratory. Clin Chem Lab Med 2007; 45:712–719.
- Miller C. Making sense of genetic tests. Clinical Laboratory News 2012 (January). Available at: www.aacc.org/publications/cln/2012/January/Pages/PSFGeneticTests.aspx#.
Paul Epner, MBA, MEd, is an independent consultant focused on strengthening the link between laboratory services and patient outcomes.
Michael Astion, MD, PhD, is chair of the Patient Safety Focus Editorial Board, division chief of laboratory medicine at Seattle Children’s Hospital, and clinical professor of laboratory Medicine in the University of Washington Department of Laboratory Medicine, Seattle, Wash.