Many in the lab community have advocated a more active role for laboratorians in test utilization management. However, it is not always clear how the lab can best influence clinicians’ selection and interpretation of tests. This issue of Strategies explores a study in which laboratorians used a collaborative approach to improve test ordering patterns for diagnosing celiac disease.

As public awareness of celiac disease has climbed steadily, so too has the demand for diagnostic testing related to this condition. In fact, studies have shown that during the past 50 years the prevalence of undiagnosed celiac disease in the U.S. has increased nearly five-fold . Of the four common antibody tests currently available, only anti-tissue transglutaminase (tTG) has been recommended in clinical practice guidelines as an initial test for diagnosis—by the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition in 2005, and the American Gastroenterological Association (AGA) in 2006. Two other tests have also received favorable assessments, anti-endomysial (EMA) and deamidated gliadin peptide antibodies. Testing for anti-gliadin (GA) antibodies is no longer recommended due to the test’s lower sensitivity and specificity.

In a recent study, researchers from McMaster University in Hamilton, Ontario, Canada targeted celiac disease testing for a utilization audit and found that ordering patterns did not reflect clinical practice guidelines. A combination of interventions proved successful in effecting a significant change in adherence to the guidelines (Clin Biochem 2012 Apr;45:455-459). The study began with an audit of celiac disease test orders during a 3-month period in 2008 and included 1178 tests representing 666 patients. The researchers found that the test recommended in guidelines—tTG—made up only 52.8% of test orders, whereas GA and EMA comprised 41% and 6.2%, respectively.

After disseminating the audit results and discussing the problem with clinicians, the researchers implemented several interventions, the most significant of which was changing the lab’s celiac panel. Whereas the panel originally included both tTG and GA, clinicians who continued to order the celiac panel after the intervention effectively ordered only tTG testing; GA testing remained available only when specifically ordered, as did EMA. A second audit in 2010 found a significant shift in test ordering patterns. In 793 tests representing 666 patients in the second audit, 79.3% were for tTG, with GA down to 17% and EMA at 3.7%.

The study revealed a lot about why clinicians ordered so many GA tests despite the clear preference for tTG in clinical practice guidelines, noted co-author Andrew Don-Wauchope, MD. Rather than a case of clinicians intentionally disregarding guidelines, much of the non-recommended GA testing originated with use of the celiac panel itself. “We found that for most clinicians, they were ordering the celiac panel just because it was easier to order than the tTG,” he explained. “This was an important finding because it shows that in this kind of situation, the lab shares responsibility for the inappropriate orders.” Don-Wauchope is associate professor of pathology and molecular medicine and consults for the clinical chemistry/clinical immunology service at the Hamilton Regional Laboratory Medicine Program that services McMaster University Medical Centre.

While GA has fallen out of favor in in recent years, the problem of ordering inappropriate tests as a part of panels has been ongoing, according to Sheila Crowe, MD, professor of medicine and director of research in the division of gastroenterology at the University of California, San Diego. Crowe was not associated with the study. “I’ve seen the trends of different panels packaged by labs over time, and I think often clinicians order these because they think it’s the only thing available to them,” she said. “There’s also the phenomenon that some clinicians think the more tests they order the better.”

Crowe emphasized that evidence gathered even after publication of AGA’s guidelines in 2006 continues to point to tTG as the best first-choice diagnostic test for celiac disease. Although EMA shows sensitivity and specificity comparable to tTG, it should not be used routinely due to cost, she added. “EMA is quite expensive because it is an immunofluorescence assay, and there is really no additional value in using this as a routine test,” Crowe said. For patients deficient in the IgA isotype, tTG IgG or deamidated gliadin peptide IgG assays are still appropriate.

The findings of the study underscore the need for labs to pay careful attention to test panels they offer, Don-Wauchope stressed. “We realized that the lab had a big role in why these inappropriate tests continued to be ordered,” he said. “From a lab perspective, it’s important that we be aware of what we put into panels and that we be proactive in making changes in response to clinical practice guidelines.”

The study also shows that when a lab aims to make significant changes in how testing is offered, a collaborative strategy with physicians who order the testing works best, noted co-author David Armstrong, MD. In this study, the researchers discussed the problem with clinicians during academic presentations, displayed posters at departmental research meetings, and circulated a memo to all hospital physicians. “It’s rare that one intervention on its own will achieve the same effect as coordinated messaging,” Armstrong said. “If people understand why the lab is suggesting a change, and how it improves patient care, they’re more likely to implement the changes and be sure that they’re constructing a test strategy that’s aligned with the patient’s needs rather than just the lab’s needs.” Armstrong is associate professor of medicine at McMaster University and consultant gastroenterologist at Hamilton Health Sciences.

In presenting data to clinicians, laboratorians should also remember to fully explain not just the new practice, but also current practice as well, according to Armstrong. “We all respond hugely to data,” he said. “We need to hear what we are actually doing, how to measure it, what the changes are and why, and then to show the change again in practice. Unless one knows precisely what one does, it’s awfully difficult to change.”

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