Diagnostic errors—missed opportunities to make a timely or correct diagnosis based on available evidence—occur in about 5 percent of adults in the United States, according to a new study led by a researcher at Baylor College of Medicine and the Michael E. DeBakey VA Medical Center in Houston.  The study, published in the April 21 issue of BMJ Quality & Safety and partially funded by the Agency for Healthcare Research and Quality and the Department of Veterans Affairs, estimates that approximately 12 million adults in the U.S. could experience an outpatient diagnostic error each year. 

Dr. Hardeep Singh, chief of the health policy, quality & informatics program at the Center for Innovations in Quality, Effectiveness and Safety, based at MEDVAMC in Houston and an associate professor at Baylor College of Medicine, led the study. 

“The findings of this study are consistent with recent data from the general public about diagnostic errors,” Singh said.  “This study is significant because it is based on a large sample size and is the most robust estimate thus far to address the frequency of diagnostic error in routine outpatient care.” 

Singh and his fellow researchers built estimates of diagnostic error by compiling and analyzing data from three previous studies.  These studies evaluated situations such as unexpected return visits and lack of timely follow up and provided researchers with an estimated frequency of diagnostic error. This frequency was then applied to the general adult population.

“Keeping patients safe begins with a correct and timely diagnosis,” said AHRQ Director Dr. Richard Kronick. “Diagnostic errors made in outpatient care can be difficult to measure, and this is a relatively new area for patient safety researchers. Health care professionals are typically accurate in making diagnoses, but finding ways to improve diagnoses and eliminate errors is an important goal. This study helps us better understand the extent of the problem and focus our efforts on reducing the harm to patients.”

Diagnostic errors can harm patients by delaying their treatment. For example, a delayed or incorrect cancer diagnosis could make the disease harder to treat or more deadly. 

“Misdiagnosis is clearly a serious problem for the health care field,” said Singh. “This population-based estimate should provide a foundation for policymakers, health care organizations, and researchers to strengthen efforts to measure and reduce diagnostic errors.”