Overuse of laboratory tests is a chronic problem in high-throughput facilities such as a hospitals, but it’s unclear how widespread this problem is. A group of European researcher did an analysis and survey of reordered tests at an Austrian hospital and found that more than two-thirds of the tests were either likely clinically unimportant or unnecessary.

The results, published in Clinical Biochemistry, show that providing the expertise of laboratory specialists to clinicians is desperately needed, to bring the best possible diagnostic service to the patient, Janne Cadamuro, MD, the study’s lead author and a physician at the Paracelsus Medical University’s Department of Laboratory Medicine, Salzburg, Austria, told CLN Stat.

Clinicians often rely on lab results to inform their decisions on patient care. “Since primary care physicians are often uncertain about the appropriate test to order or its proper interpretation, there is a reasonable risk that laboratory tests may be ordered inappropriately,” stated the researchers.

To find out how frequently lab tests are used inappropriately in clinical practice, investigators conducted a survey of clinicians and nurses at the University Hospital of Salzburg, using a novel retrospective approach to gather their results.

The first step was to conduct a retrospective evaluation of lab data of patients at the hospital to identify results that had been canceled due to preanalytical nonconformities. Such alterations may occur if a tube isn’t filled properly or when blood collection or transport causes a rupture of red blood cells, resulting in hemolysis, which interferes with many tests, according to Cadamuro.

The investigators looked at how often these deleted analyses were reordered in affected patients. In those for whom tests were reordered, they determined how fast reorders were placed. This evaluation helped them assess whether a test was actually needed in the first place. “If deleted tests were reordered after more than 24 hours, we suggested that it was probably not really necessary for acute patient care,” explained Cadamuro.

The analysis included commonly ordered tests vulnerable to hemolysis, such as potassium (K), lactate dehydrogenase (LD) and aspartate-aminotransferase (AST). In addition, the researchers looked at activated partial thromboplastin-time (APTT) and prothrombin time/INR (PT/INR) tests, the most commonly ordered tests in the field of coagulation. “By using these tests, we were able to evaluate a large number of orders, thereby making a more profound statement,” said Cadamuro.

In a subgroup analysis, Cadamuro and his colleagues looked at associations between sample types (routine or urgent) and outcomes and wards (inpatient, outpatient, emergency department, intensive care, pediatrics, surgery, internal medicine). Nearly 300 nursing staff and clinicians took part in a subsequent survey. Specifically, they were asked why tests weren’t reordered after cancellation and were given five possible reasons to choose from. They could also provide comments about their testing practices.

From the pool of initially canceled tests, investigators found that about 60% and 70% of canceled coagulation orders and canceled clinical chemistry tests, respectively, had either been reordered after a week or not at all. “Estimates on inappropriate laboratory utilization vary vastly because of different appropriateness criteria and different regions of investigation. However, an overutilization of 60 to70% is ranging in the top part of this scale,” they observed. In comparison, reorders within 24 hours took place for about 20% of selected clinical chemistry tests, including K, LD, AST, and 30% for selected coagulation APTT and PT/INR tests.

Reorder rates were the highest in intensive care units compared with other settings, most likely because these facilities handle patients with serious or life-threatening conditions. Outpatient clinics had much lower rates. “This is not surprising since outpatients are usually no longer present in the phlebotomy service when the information that the test has been cancelled is notified to the phlebotomist, as confirmed by the very high rate of replies with this type of answer collected in our survey,” the study’s authors noted.

Most survey participants, particularly those from emergency departments cited routine laboratory panels as a reason for not reordering canceled tests. Other common reasons included short outpatient stays, obsolete test results, and avoiding additional phlebotomies. Most of the clinicians and nurses surveyed seemed aware that there was an overuse problem.

A big takeaway for labs is they shouldn’t focus solely on the analytical part of the testing process, Cadamuro said. “We are lab specialists, and we were specially trained to know which test to order at what time in which patient. This is our contribution to patients’ health. We should start putting our expertise closer to the patient and collaborating more with clinicians rather than to blindly process everything that is being ordered,” he suggested. “We know how to interpret test results. We also know what harm so-called ‘overdiagnosis’ may bring. This should be our future focus.”

Education programs, implementing retesting intervals, widely using diagnostic algorithms, harmonizing test panels with the design of lab request forms, and implementing gatekeeping strategies are ways to overcome inappropriate utilization of laboratory resources, the authors suggested.