Gene Expression Test Improves IPF Diagnosis

A diagnostic product assessing the pulmonary “transcriptome” in a series of cases drawn from real life helped pulmonologists arrive at correct diagnoses of idiopathic pulmonary fibrosis (IPF), according to a study presented at CHEST 2021.

When adding results of the test, called Envisia, to conventional information that pulmonologists rely on to diagnose IPF, the likelihood of diagnosing IPF in these cases was more than doubled in the survey-based study, reported Joseph Lasky, MD, of Tulane University in New Orleans.

Use of the test, which is commercially available, also substantially improved physicians’ confidence in their diagnoses, he told attendees at CHEST, the American College of Chest Physicians’ annual meeting, which is being held online this year. Without the test, nearly half the physicians expressed less than 70% confidence in their initial views of the cases.

The Envisia test evaluates bronchial biopsy samples obtained via bronchoscopy for transcripts of 190 genes, looking for certain patterns associated with “usual interstitial pneumonia” (UIP), the clinical syndrome that is ultimately diagnosed as IPF when no particular cause can be identified. A positive finding with Envisia is a “rule-in” for IPF, Lasky explained.

Previous studies in well-defined patient cohorts provided the underpinning for getting Envisia onto the market, showing specificity of 91% and sensitivity of 63%. The point of Lasky’s study was to see how it would work in the hands of rank-and-file pulmonologists in dealing with challenging cases.

For the survey study, his group put together 11 cases drawn from its earlier clinical studies, including CT scans lacking a “typical” UIP appearance, and thus not easy to diagnose correctly. All these cases had been reviewed by a multidisciplinary team with access to all the patients’ information — in other words, the gold standard. Lasky and colleagues then contacted U.S.-based pulmonologists to participate.

A total of 81 were each given five cases to review, randomly chosen from the set of 11. They were initially shown the patient information without the Envisia findings, and then were asked to reconsider with the results.

Without Envisia, 30% of cases were diagnosed as IPF. The remainder were spread among several conditions that often resemble IPF, such as nonspecific interstitial pneumonia. When given the Envisia results, however, these physicians diagnosed IPF in 69% of cases.

Whereas only 6% of the group expressed at least 90% confidence in their pre-Envisia diagnoses, this rose to 42% in light of the findings.

Lasky and colleagues also posed the cases to two other groups of pulmonologists, one of which was given the results (group B, n=82) and the other not (group C, n=88). The differences were less marked in these comparisons — group C diagnosed 30% of cases as IPF, whereas group B saw about 45% as IPF. However, access to Envisia results also boosted group B’s diagnostic confidence in this analysis as well.

Along with the increased confidence came increased willingness to initiate treatment without first obtaining additional, more invasive biopsy specimens. In the first cohort, who weren’t initially given the Envisia results but then could change their minds after seeing them, only about 10% wanted to start IPF therapy right away, but that figure rose to 50% with the results in hand. (This difference, too, was attenuated when comparing groups B and C, with only 20% of the former recommending therapy without further testing.)