At the CHEST meeting, researchers from Virginia Commonwealth University reported that sphingolipids in exhaled breath condensate could distinguish idiopathic pulmonary fibrosis (IPF) from fibrotic hypersensitivity pneumonitis. The presence of sphingomyelin C24:0 correctly identified fibrotic hypersensitivity pneumonitis in 80% of cases and IPF in 85.7%, yielding an area under the curve of 0.897.
A blood-based marker, plasma dihydrosphingosine, was less accurate on its own (AUC 0.737) and added little when combined with the breath test (AUC 0.906). The authors noted that the two conditions can look similar at end-stage disease, but treatment and prognosis differ, so a noninvasive test could help avoid incorrect management.
The study included 101 blood samples and 49 breath condensate samples. The breath test is cheap and noninvasive, but collection takes 15–20 minutes and can be difficult for patients with severe lung disease. The assay is not yet widely available, and researchers say external validation is needed before clinical use.