The report, called “Improving Diagnosis in Health Care,” asserts that diagnostic errors occur daily in every health care setting nationwide, yet they have never been adequately studied. No one knows how many people suffer from misdiagnoses or delays that affect their care.

Despite the sketchy evidence, the authors conclude that “most people will experience at least one diagnostic error in their lifetime, sometimes with devastating consequences.”

“This problem is significant and serious [yet] we don’t know for sure how often it occurs, how serious it is or how much it costs,” says Dr. John Ball, of the American College of Physicians, who chaired the committee that carried out the analysis. He called the lack of evidence one of the committee’s most “surprising” and distressing findings.

“It’s huge that diagnosis is finally getting the attention it deserves,” says Helen Haskell, co-chair of the patient committee at the Society to Improve Diagnosis in Medicine, who was invited by the committee to review a draft of the report. “There are lots of people who think our failure to tackle this is one reason why patient safety hasn’t progressed farther.

“Improving Diagnosis in Health Care,” is the latest installment in a series which began with “To Err is Human: Building a Safer Health System,” which made national headlines 16 years ago by estimating that 44,000 to 98,000 people die from preventable medical errors each year. Each report in the series has focused on lapses responsible for poor quality health care and how to correct them.

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Despite the committee’s inability to offer even a rough estimate of the pervasiveness of faulty diagnoses–a limitation likely to disappoint patient advocates and others who were anticipating the committee’s answer to that question–the report does offer some indications of the problem’s seriousness.

Studies show:

• About 5 percent of adults who seek outpatient care annually suffer a delayed or wrong diagnosis.
• Postmortem research suggests that diagnostic errors are implicated in one of every 10 patient deaths. Not every death is scrutinized, however, so the findings can’t be generalized to all hospital patients.
• Chart reviews indicate that diagnostic errors account for up to 17 percent of hospital adverse events.
• Diagnostic errors are the principle cause of paid malpractice claims and are almost twice as likely to end in a patient’s death than claims for other medical mishaps. They also represent the biggest share of total payments.

Getting the right diagnosis is critical, because it is the starting point for every other health care decision. Sometimes diagnostic errors or delays stem from poor judgment, including “shortcuts that people take,” such as a physician who makes superficial assumptions based on past experience rather than current information, Ball says.

Often diagnostic errors result from poor coordination of care. “Not all errors are individual human errors,” he says. “They occur in a system that leads you into [certain] kinds of errors.” He cited the emergency room, a chaotic setting with a constant stream of patients and information, where doctors, nurses, technicians and laboratory personnel must multi-task amid countless distractions.

One vital check on the accuracy of a diagnosis is following up with the patient, a cycle that promotes better care and reinforces learning, says Dr. Donald Berwick, president emeritus and senior fellow at the Institute of Healthcare Improvement. “The diagnosis is the hypothesis, the treatment is a test. If we don’t know what happened to the patient it’s difficult to improve either our diagnosis or treatment.”

The glut of tests–some ordered by doctors who are practicing defensive medicine to protect against malpractice lawsuits–compounds the problem. “There’s a tremendous reliance on tests,” says Haskell, of the Society to Improve Diagnosis in Medicine. “You have to know to order the right test, and the test has to be interpreted correctly all along the line. It’s a complicated system with a lot of opportunities for error.”

Clumsy health information technology, including electronic medical records, also represents a “barrier to good health care,” Ball says, because information isn’t easily accessible and is often presented in a confusing manner.

Berwick, who also reviewed the report for the institute, cited one crucial omission–the committee decided not to address over-diagnosis, a diagnosis that is made that is not helpful to patients. “They might not define that as an error,” he says, “But I think the task of addressing over-diagnosis is critical.”

Finally, Berwick says, it’s important to factor into any assessment of medical errors the heavy administrative demands placed on doctors. “Physicians today spend so much time filling out forms, seeking approvals and ordering things–you can’t increase work pressure so much without expecting errors to increase.

There is no easy fix, the report concludes. What’s required is a major reassessment of the diagnostic process and a commitment to change. It must begin with a common definition of what constitutes a diagnostic error–and the data to figure out possible remedies and measure progress.

“What I like is that the report emphasizes that teamwork is necessary to have a system that works,” says Haskell. “You have to have coordinated care, patient involvement and the involvement of non-physician personnel.”

Absent a better solution, Haskell says, “you need to do your own research to find out what tests are needed and be sure they’re being done. You need to get the results.”

“Patients bear the financial burden of all this,” she adds. “Patients or their insurers. The medical system profits from it.”