ROCHESTER, Minn. -- Many patients come to Mayo Clinic for a second opinion or diagnosis confirmation before treatment for a complex condition. In a new study, Mayo Clinic reports that as many as 88 percent of those patients go home with a new or refined diagnosis -- changing their care plan and potentially their lives. Conversely, only 12 percent receive confirmation that the original diagnosis was complete and correct.

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These findings were published online today in the Journal of Evaluation in Clinical Practice. The research team was led by James Naessens, Sc.D., a health care policy researcher at Mayo Clinic.

Why get a second opinion

When people are sick, they look to their doctor to find solutions. However, physicians don't always have the answers. Often, because of the unusual nature of the symptoms or complexity of the condition, the physician will recommend a second opinion. Other times, the patient will ask for one.

This second opinion could lead to quicker access to lifesaving treatment or stopping unnecessary treatments. And a second opinion may reduce stress in a patient's extended family, when they learn the new diagnosis does not carry dire genetic implications. These scenarios can result from diagnostic error.

Odds are good the diagnosis will be adjusted

To determine the extent of diagnostic error, the researchers examined the records of 286 patients referred from primary care providers to Mayo Clinic's General Internal Medicine Division in Rochester over a two-year period (Jan. 1, 2009, to Dec. 31, 2010). This group of referrals was previously studied for a related topic. It consisted of all patients referred by nurse practitioners and physician assistants, along with an equal number of randomly selected physician referrals.

The team compared the referring diagnosis to the final diagnosis to determine the level of consistency between the two and, thus, the level of diagnostic error. In only 12 percent of the cases was the diagnosis confirmed.

In 21 percent of the cases, the diagnosis was completely changed; and 66 percent of patients received a refined or redefined diagnosis. There were no significant differences between provider types.

"Effective and efficient treatment depends on the right diagnosis," says Dr. Naessens. "Knowing that more than 1 out of every 5 referral patients may be completely [and] incorrectly diagnosed is troubling -- not only because of the safety risks for these patients prior to correct diagnosis, but also because of the patients we assume are not being referred at all."

Risks of cost containment

To manage costs in a health care environment with ever-increasing costs, health insurers often limit access to care outside their network, effectively limiting referrals. Further, primary care providers may be more confident in their diagnostic expertise than warranted in a particular case, or patients may lack the knowledge or assertiveness to request a referral.

"This may prevent identification of diagnostic error, and could lead treatment delays, complications leading to more costly treatments, or even patient harm or death," says Dr. Naessens. "We want to encourage second opinions when the provider is not certain."

The National Academy of Medicine cites diagnostic error as an important component in determining the quality of health care in its new publication, Improving Diagnosis in Health Care:

Despite the pervasiveness of diagnostic errors and the risk for serious patient harm, diagnostic errors have been largely unappreciated within the quality and patient safety movements in health care. Without a dedicated focus on improving diagnosis, these errors will likely worsen as the delivery of health care and the diagnostic process continue to increase in complexity.

"Referrals to advanced specialty care for undifferentiated problems are an essential component of patient care," Dr. Naessens says. "Without adequate resources to handle undifferentiated diagnoses, a potential unintended consequence is misdiagnosis, resulting in treatment delays and complications, and leading to more costly treatments."

The researchers identified costs associated with second opinions, and Dr. Naessens notes, "Total diagnostic costs for cases resulting in a different final diagnosis were significantly higher than those for confirmed or refined diagnoses, but the alternative could be deadly."

He says that he and his team are pleased by the National Academy of Medicine's call for dedicated federal funding for improved diagnostic processes and error reduction. They also plan further research on diagnostic errors and hope to identify ways to improve the process.

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Dr. Naessens leads quality and safety research initiatives within the Office of Health Care Practice and Policy in the Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery. He is also the scientific director for the Florida team within the center.

About Mayo Clinic

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Journalists: Video soundbites with Dr. Naessens are available in the downloads.