Unclassified Interstitial Lung Disease Leads to Poor Outcomes

Laura Fabbri, MD

Interstitial lung diseases (ILD) are a heterogeneous group representing more than 200 distinct diseases. However, despite a thorough assessment and multidisciplinary discussion, about 12% of ILD patients are unclassifiable, up to 45% in the elderly.

A team, led by Laura Fabbri, MD, University of Modena, determined whether a significant proportion of patients with unclassified interstitial lung diseases (uILD) at the time of their first multidisciplinary discussion (MDD) are later given a specific diagnosis through either disease progression or availability of further data in a poster presented at the European Respiratory Society International Congress 2020.

In the single-center retrospective study, the investigators reviewed medical notes for patients diagnosed with unclassified ILD of idiopathic pulmonary fibrosis (IPF) by multidisciplinary discussion between January 2015 and June 2018 and completed at least 1 year of follow up before July 2019 to assess any change in diagnosis.

The investigators sought primary outcomes of the determination of whether a significant proportion of patients with unclassified disease at the time of the first MDD are later given a specific diagnosis through either disease progression or the availability of further data.

The team also sought secondary outcomes the evaluation of the reasons patients are labeled with an unclassified disease with their clinical and radiological features.

The study included 93 patients diagnosed with IPF and 90 patients with unclassified ILD, 35 of which had surgical biopsy.

A total of 3 patients (3.3%) with unclassified interstitial lung disease had a change in diagnosis during follow-up—1 to dermatomyositis and 2 to hypersensitivity pneumonitis.

In addition, 66.6% of these patients had at least 1 course of corticosteroids or immunosuppressive drugs.

The investigators also found that 23.3% of unclassified patients and 84% of IPF patients received antifibrotic treatment.

The median delay between the first disease-related manifestation and the multidisciplinary discussion for the unclassified arm of the study was 3.23 ±4.35 years.

The investigators also found patients with unclassified ILD had worse outcomes than the comparison group (mean survival from the date of MDD to last follow-up was 36.1 months [31.6- 40.5] versus 48.6 months [39.8-45.7], respectively; P <0.0001).

The main clinical findings were exertional dyspnea (86.6%), cough (61.1%), and crackles (72.2%). CT scans also showed subpleural reticulations (88.8%), bronchiectasis (51.7%), bronchiectasis (73.3%), and ground-glass opacities (72.2%). The mean annual forced vital capacity decline for the unclassified cohort was -272±465 ml (-5-49 ±15-22%).

“[Unclassified] ILD may represent a distinct diagnostic category rather than a provisional diagnosis, and is characterized by a considerable delay to diagnosis and a poorer outcome,” the authors wrote. “Further prospective studies are needed to design disease behavior better.”

However, the researchers listed several limitations because it is monocentric and has a retrospective design. The study also presented preliminary data that has not been adjusted for lung function and severity at diagnosis between IPF and unclassified ILD.

They also said the antifibrotic treatment could influence the survival of IPF patients

The study, “A single-centre retrospective study to phenotype unclassifiable interstitial lung disease,” was published online by ERS International Congress 2020.