Diagnostic errors are the most frequent adverse safety event patients can experience in outpatient care, according to a new ECRI Institute report.

The analysis, published Wednesday, found that diagnostic testing errors represented 47% of all patient safety events reported in an outpatient setting over a one-year period. The second-most common safety event was medication errors, accounting for 27% of total events.

Considering the volume of testing performed in the ambulatory setting and the complexity of the process, it's not surprising it's the most common mistake that happens in outpatient care, said Carol Clark, acting associate director of the ECRI Institute Patient Safety Organization.

Diagnostic testing has many phases including ordering the appropriate test, gathering and delivering the sample appropriately and interpreting the results. Additionally, about 40% of all primary-care office visits involve some medical test.

"There's a lot of opportunity for errors," Clark said.

The report says 4,355 adverse events were voluntarily reported from December 2017 to November 2018. Providers submit adverse events to the ECRI Institute as part of their participation in its patient safety organization. More than 1,800 providers are part of the organization and 3 million adverse events overall have been reported.

The report included data from ambulatory care centers, community health centers and physician practices. Ambulatory surgery centers were excluded from the analysis because they don't provide comparable services.

In its report, ECRI recommended providers establish a chain of command for communicating test results and use technology to track test results and ensure follow-up, among other practices that could prevent diagnostic errors.

Even with the recommendations, Clark said there is "no magic bullet" to preventing diagnostic errors. Solutions are likely unique to the practice and their resources.

There is more momentum recently to address diagnostic errors. The Society to Improve Diagnosis in Medicine has gathered stakeholders from across the country to enhance research and encourage greater attention from providers on the problem.

Society CEO Paul Epner said previous studies correlate with ECRI's findings that diagnostic mistakes are the most common medical errors in healthcare. Although he added that ambulatory settings have more complexities to deal with than acute settings, making the errors particularly challenging to prevent. Usually outpatient settings don't have labs in-house so they have to send off their samples, leaving room for samples to be mishandled or results to never get back to the doctor.

In terms of medication errors, most were caused by giving the patient the wrong drug, the report found.

Clark said this can occur because centers haven't implemented processes to ensure the right medications go to the correct patient. It can be an issue of how the medications are stored or the training of the personnel who distribute it. Medical assistants typically administer medications now rather than nurses and sometimes they aren't appropriately trained, she said.

The second-most common reason for a medication error involves ordering or administering treatments that trigger allergies or adverse reactions. It's particularly hard to prevent those errors in outpatient care because they typically don't have a complete medical history of the patient, Clark said. Incompatible electronic health records usually mean outpatient providers aren't aware of all medicines a patient is on. Reconciliation and thorough patient assessments are vital to prevent medication errors, Clark said.

Falls were the third most frequent adverse event reported during the period, accounting for 14% of total events.

Falls are likely common because most patients who see their physician frequently are elderly or have comorbidities, which can make them weak, frail or disoriented, Clark said.

One way to prevent falls is to screen the patient for fall risk during the initial assessment, according to the report.

Although it only represented 5% of the total events, security issues were addressed in the report.

Workplace violence is a well-known problem in healthcare, and clinicians who work in ambulatory care are particularly vulnerable because they lack the security and robust personnel that acute-care settings have, Clark said. She expects incidents are significantly underreported because many clinicians are so used to the conditions, but it can impact quality of care and contribute to burnout.

The report recommends doing risk assessments to evaluate potential opportunities for violence, provide staff with tools to recognize cues for combative behavior and train staff on how to deal with aggressive situations.