Patients Are Injured Due to Missed or Delayed Diagnosis Analysis Shows

Studies show that diagnostic errors cause twice as many adverse events as medication errors, but the subject has received little attention; Pennsylvania Patient Safety Authority reviews 100 events related to diagnostic error.       

Harrisburg, Pennsylvania, September 1, 2010 — Errors related to missed or delayed diagnosis are frequently a cause of patient injury and therefore an underlying cause of patient safety related events. Autopsy analysis spanning several decades show error rates at four to 50 percent, according to an article released today by the Pennsylvania Patient Safety Authority and published in its September Pennsylvania Patient Safety Advisory.

Diagnostic error is a diagnosis that is missed, incorrect, or delayed as detected by a subsequent definitive test or finding. Not all misdiagnosis results in harm and harm may be due to either disease or intervention.

Diagnostic errors are encountered in every specialty and are generally lowest (less than five percent) for certain specialties that rely on visual pattern recognition and interpretation (e.g., radiology, pathology, dermatology). Error rates in specialties that rely more on data gathering and the combination of different elements for a conclusive diagnosis are higher (10 to 15 percent).

“Diagnostic errors are often the first or second leading cause of medical malpractice claims in the United States,” Dr. John Clarke, clinical director of the Pennsylvania Patient Safety Authority said. “They account for twice as many ongoing and settled claims as medication errors.”

Clarke added that studies have also shown that both cognitive errors and system design flaws contribute to diagnostic error.

“Communication issues, along with reasoning errors and system breakdowns all contribute to diagnostic errors,” Clarke said. “The Advisory article reviews the common causes of diagnostic error and gives healthcare providers and patients information on how they can decrease the risk of a diagnostic error and thereby increase patient safety.”

The Authority reviewed 100 events related to diagnostic error between June 2004 and November 2009 in an effort to determine if there were system solutions to diagnostic error, or if diagnostic error was so closely connected to doctors’ cognitive processing that system solutions were not possible. Examples of reports were found in the Pennsylvania Patient Safety Reporting System (PA-PSRS) by searching on terms such as delayed diagnosis, wrong diagnosis, missed diagnosis, misdiagnosed, failure to diagnose, failure to treat and medical follow-up. Some of the sample reports with possible cognitive error examples include:

Report 1:
Patient seen in ED (emergency department) on day one and day two for complaints of shortness of breath and chest pain. Diagnosed with an upper respiratory infection and sent home each time. Subsequently later admitted and died. Coroner preliminary report indicated PE [pulmonary embolus] as cause of death.

Report 2:
A young man came to the ED for fainting and syncope, including the inability to speak for a few seconds with lateralizing symptoms and staring. In the ED, lab work was done but no CT [computed tomography] scan was ordered. Patient was discharged home with diagnosis of syncope and dehydration secondary to stress, with instructions to follow up with primary care physician. Subsequently, the primary care physician admitted the patient directly into the hospital, where a CT scan was performed and a brain lesion diagnosed.

Report 3:
Patient is an infant seen in the ED during high flu season after an episode of vomiting and period of apnea observed by family. Was discharged, but returned later. Family reported that the patient had another episode of apnea. Patient was evaluated and transferred to another facility for clinical impression of apnea and reflux.

One study cited in the article argued that even though doctors are well aware of the possibility of diagnostic error, doctors rarely believe that their own error rates are significant, further compounding the difficulty in analyzing diagnostic error.

The Pennsylvania Patient Safety Authority is a non-regulatory independent state agency created through legislation (Medical Care Availability and Reduction of Error, “MCare Act”) to help reduce and eliminate medical errors by identifying problems and recommending solutions that promote patient safety.