A critical clinical laboratory test result reflects either a life-threatening pathophysiological condition or one that might result in severe harm if not acted on immediately. CLIA regulation requires that laboratories “must immediately alert the individual or entity requesting the test and, if applicable, the individual responsible for using the test results when any test result indicates an imminently life-threatening condition, or panic or alert values.”

The Joint Commission included reporting critical results as a national patient safety goal for 2019, with facilities required to “report critical results of tests and diagnostic procedures on a timely basis.” The College of American Pathologists (CAP) also requires laboratories to include critical result reporting as a quality indicator in their quality management plans.

However, neither the Joint Commission nor CAP mandate a process for reporting critical results, nor do they provide instructions on establishing critical results or on repeating critical results prior to reporting them to clinicians.

A Question of Quality

Committed to ensuring analytical accuracy, many clinical laboratories in years past implemented the practice of repeating tests that yielded critical results to be doubly sure that these vital measurements were correct before notifying clinicians. This practice probably was due to instruments or testing procedures used in the past that had poor analytical performance. In modern clinical laboratories, however, the performance of our instruments and testing procedures has drastically improved, and we exercise vigorous quality management to ensure accuracy and precision.

Despite these advances, many labs continue to repeat critical results prior to reporting them out. This additional testing not only adds to laboratory costs but also delays reporting of critical results, which could cause patient harm. In contrast, labs expect that noncritical results are accurate and precise, and do not repeat these tests before reporting them out. If the accuracy and precision of our instruments and procedures truly are in doubt, one could argue that these initially noncritical results could become critical when retested.

Analyzing Practices, Changing Policies

During my 12 years as section head and medical director of clinical biochemistry at Cleveland Clinic, we debated this issue many times. At the beginning, our policy was to check on the quality of specimens that yielded critical results, including assessing whether they had visible particles and determining the serum index. If we found no quality issues with a specimen, we would repeat testing prior to reporting out critical results.

Proponents of eliminating this repeating step cited the outstanding analytical performance of our modern instruments and our vigorous quality management to ensure accuracy and precision. They also believed it hindered our ability to notify caregivers promptly about critical results, slowing in turn their opportunity to intervene earlier and achieve better patient outcomes. Those who supported the status quo were concerned about potential patient harms due to analytical errors.

Since we laboratorians are data driven, the team considering this issue carried out a retrospective study to help us decide which route we should take. Melissa Zimmer, BS, quality specialist at that time (2016), took on this project. We focused on glucose and potassium measurements in our automated clinical chemistry laboratory, which produced the most critical results.

In our study, we randomly selected critical values and the corresponding repeat results for glucose and potassium tests, all performed on a Roche Diagnostics cobas c 702 analyzer. We found that both the initial and corresponding retest values for glucose (n=100) and potassium (n=100) matched closely with a maximum difference of 2 mg/dL for glucose and 0.2 mmol/L for potassium, well within the CLIA criteria for assay precisions (glucose target: ±6 mg/dL or ±10% and potassium target: ±0.5 mmol/L).

In addition, we discovered that the mean elapsed time between initial and retesting results posted in the lab information system was 14 minutes for glucose (n=31; range, 11-49 minutes) and 4 minutes for potassium (n=197; range, 0-37 minutes).

Based on these observations, we concluded that we did not need to repeat testing for critical values prior to releasing the results because of both the high precision of our instruments and the sophisticated quality assurance programs that we employed. Eliminating this unnecessary step allowed our laboratorians to reach out more rapidly to our clinicians, thereby enabling them to respond more promptly to the critical values.

In addition, eliminating unnecessary analytical runs enabled us to improve our operational efficiency and overall turnaround time for all patient results in our high-volume laboratory. Of note, as we transitioned to not repeating critical results we allowed our technologists to repeat tests anytime they had concerns over the analytical accuracy or specimen integrity. This gave them peace of mind during the transition.

Sihe Wang, PhD, DABCC, FAACC, is director of clinical laboratories at Akron Children’s Hospital in Akron, Ohio. +Email: swang@akronchildrens.org