Medical Errors Causing Missed or Late Diagnoses in Ambulatory Care
Led to ‘Significant Harm’ To Patients, Study of Malpractice Claims Finds
HOUSTON – (Oct. 3, 2006) – Medical errors stemming from missed and delayed diagnoses cause significant harm to patients treated in physicians’ offices or other ambulatory care settings, according to a new review of medical malpractice claims. Such errors were alleged in nearly 60 percent of medical malpractice claims, and nearly one-third of these errors were associated with a patient’s death, reports a new study in the Oct. 3 issue of the Annals of Internal Medicine.
Eric Thomas, M.D.
Eric Thomas, M.D., associate professor in general internal medicine at The University of Texas Medical School at Houston, is one of the co-authors of the article. Thomas, who also is the principal investigator for the UT Medical School’s Center of Excellence for Patient Safety Research and Practice, for years has been studying the adverse events that occur due to breakdown in communications within health-care teams.
The study, co-funded by the U.S. Department of Health and Human Services’ Agency for Healthcare Research and Quality (AHRQ) and the Harvard Risk Management Foundation, is among the first to examine potential causes of medical errors in health care settings other than hospitals.
Researchers led by Tejal Gandhi, M.D., at Brigham and Women’s Hospital in Boston, David Studdert, L.L.B., Sc.D., at the Harvard School of Public Health, and Thomas, reviewed 307 medical malpractice claims, 181 of which were determined to have involved diagnostic errors that led to an adverse outcome.
The study found that a delayed or inaccurate diagnosis of cancer – notably breast, colorectal or skin cancer – was the most frequent result of the errors causing significant patient harm. Most errors (85 percent) occurred in physicians’ offices, and primary care doctors were most often involved (42 percent). Failing to order the appropriate diagnostic test was the most frequent cause of the breakdown in the diagnostic process, followed by failure to create a proper follow-up plan, to obtain an adequate physician examination, and to interpret a diagnostic test correctly.
“These findings provide new and compelling information on errors that we know occur in ambulatory care settings every day but for which we had very little scientific evidence,” said AHRQ Director Carolyn M. Clancy, M.D. “Although we are have made great strides toward measuring and improving patient safety in hospitals, this study shows how much work remains to be done in other care settings to eliminate harm to patients.”
Reviewers used the Institute of Medicine’s definition of error, which is “the failure of a planned action to be completed as intended (i.e. error of execution) or the use of a wrong plan to achieve an aim (i.e. error of planning).”
Claims data were provided by four malpractice insurance companies based in three regions of the United States. Collectively, their companies insured approximately 21,000 physicians, 46 acute-care hospitals, and 390 outpatient facilities, including a variety of primary care and outpatient specialty practices.
Looking at the reasons for breakdowns in the diagnostic process, researchers found that missed cancer diagnoses were more likely to involve tests that were incorrectly performed (13 percent) or misinterpreted (46 percent). In contrast, missed non-cancer diagnoses, such as infection, fracture, or myocardial infarction, more often resulted from delays by patients in seeking care, inadequate patient histories or physical examinations, or by physician failing to refer the patient for additional follow-up care.
“Outpatient diagnostic errors are due to multiple breakdowns in care processes and will therefore require multiple interventions to prevent them,” Thomas said. “Physicians will need more computerized decision support and better methods to follow up diagnostic tests. We also need to make it easier for patients to follow through with complicated outpatient evaluations, and to give them more access to their medical information.”
Biopsies were the specific diagnostic test that clinicians failed most often to order, followed by computed tomography scans, mammography and colonoscopy. The most common explanation for the failure to order a diagnostic test was that the physician may not have known to order that particular test, given the patient’s clinical circumstances.
The resulting delays tended to be long, setting diagnosis back more than 1 year on average, the study found. Researchers also identified a number of factors that contributed to errors in diagnosis. Failure in judgment by clinicians was the leading contributing cause, followed by vigilance or memory, knowledge, patient-related factors and handoffs in care. Patient-related factors included non-compliance, unusual clinical presentation, and complicated medical history.
Diagnostic errors frequently involved multiple process breakdowns, contributing factors, and involvement by several clinicians, according to the study.
In nearly half (43 percent) of the diagnostic errors identified, two or more clinicians contributed to the missed diagnosis, and in 16 percent, three or more clinicians contributed. More than one-third (36 percent) of errors involved cognitive factors alone, 16 percent involved judgment or vigilance and memory factors alone, and 9 percent involved judgment factors alone.
“Unfortunately, there will be no magic bullet to prevent diagnostic errors,” Thomas said. “But we might begin by helping physicians order and follow up appropriate tests, and by helping patients adhere to treatment and evaluation plans and keep better record of their medical information.”
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