Interstitial Lung Disease May Develop in Patients with Any AAV Subtype, Study Suggests

Interstitial lung disease — a group of conditions characterized by scarring of the lungs — may develop in patients with all three subtypes of ANCA-associated vasculitis (AAV), a retrospective study shows.

The study, “Interstitial Lung Disease in ANCA-Positive Vasculitis Patients,” will be presented at the American Thoracic Society 2018 International Conference, taking place May 18-23 in San Diego.

AAV patients can be classified into three subgroups based on clinical diagnosis: granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangitis (EGPA), and microscopic polyangiitis (MPA).

Interstitial lung disease (ILD) is a disorder that can sometimes affect AAV patients. However, due to its rarity, little is known about the clinical characteristics of patients with both AAV and ILD (ANCA-ILD). A previous study that investigated ANCA-ILD revealed that MPA patients were more likely to develop ILD.

To further characterize this patient population, researchers conducted a study of all patients diagnosed with ANCA-ILD in the past 10 years at the Mayo Clinic Florida.

Clinical characteristics of these patients were compared with patients that had other lung disorders, including idiopathic pulmonary fibrosis (IPF) and interstitial pneumonia with autoimmune features (IPAF).

Contrary to the prior study that only discovered a link between MPA and ILD, researchers in this study discovered that a sizable portion of patients with ANCA-ILD have the GPA subtype. In fact, among 24 patients with ANCA-ILD, 14 had MPA, 12 had GPA, and the remaining two had EGPA.

Of interest, 50% of the ANCA-ILD patients presented with AAV prior to a diagnosis of ILD, most of whom were MPA patients. On the other hand, 36% of patients with ANCA-ILD presented with ILD first, most of whom were GPA patients.

Most patients were treated with corticosteroids. Rituxan (rituximab) was used to treat more than half the patients.

When comparing lung function among ANCA-ILD, IPF, and IPAF patients, researchers discovered that lung function was lowest in IPF patients, followed by ANCA-ILD patients, and lastly, IPAF. In line with this, as expected, survival was also lowest in patients with IPF, followed by ANCA-ILD, and then IPAF.

In the largest study encompassing ANCA-ILD patients in North America, researchers were able to extensively describe the clinical characteristics and ILD-related lung function of these patients, in addition to “adding prognostic information in an era of newer therapeutics, such as rituximab.”