In patients with hypersensitivity pneumonitis, presence of radiologic honeycombing suggests a poor prognosis in line with what might be expected with idiopathic pulmonary fibrosis, results of a recent study suggest.
When radiologic honeycombing was present, event-free survival was uniformly poor, regardless of whether the patient had hypersensitivity pneumonitis (HP) or idiopathic pulmonary fibrosis (IPF). By contrast, HP patients with nonhoneycomb fibrosis had longer event-free survival than IPF patients with honeycomb features on CT, wrote researchers led by Margaret L. Salisbury, MD, of the division of pulmonary and critical care medicine at the University of Michigan, Ann Arbor.
“Given the uniformly poor outcome among subjects with radiologic honeycombing, pursuit of invasive diagnostic tests directed at differentiating IPF from HP may be of limited value,” Dr. Salisbury and her coinvestigators wrote in Chest.
In the study, 117 patients with HP and 161 with IPF underwent high-resolution CT, results of which were evaluated by three thoracic radiologists. Patients with HP who had no fibrosis on CT had the best event-free median survival, or time to transplant or death, at greater than 14.73 years. For HP patients with nonhoneycomb fibrosis, that median survival was greater than 7.95 years, compared with just 5.20 years in IPF patients without honeycomb features.
Looking specifically at patients with honeycomb features, median event-free survival was poor for both HP and IPF patients, at 2.76 and 2.81 years, respectively.
The HP patients with no fibrosis had a significant improvement in percent predicted forced vital capacity over time, while fibrotic patients experienced significant declines, the investigators wrote. Thus, HP patients with nonhoneycomb fibrosis had forced vital capacity declines despite longer transplant-free survival.
“These results highlight the importance of making a correct diagnosis of HP versus IPF in patients with nonhoneycomb fibrosis, as well as the limited utility in differentiating HP from IPF among patients with radiologic honeycombing,” Dr. Salisbury and her coinvestigators concluded.
Dr. Salisbury reported grants from the National Institutes of Health during the study. Her coauthors reported disclosures related to the NIH, Bayer, Centocor, Gilead, Promedior, Ikaria, Genentech, Nycomed/Takeda, Pfizer, and others.
SOURCE: Salisbury ML et al. Chest. 2019 Apr;155(4):699-711.