IPAF Shows Demographic and Imaging Similarities with CTD-ILD

September 12, 2020

These findings suggest the possibility of a common underlying disease process between the two pathologies.

According to new research presented at the North American Young Rheumatology Investigator Forum (NYRIF 2020), patients diagnosed with interstitial pneumonia with autoimmune features (IPAF) were found to have similar demographic and imaging characteristics as those with connective tissue disease-associated interstitial lung disease (CTD-ILD).

Furthermore, these commonalities were distinct from patients with idiopathic pulmonary fibrosis (IPF).

Those who are diagnosed with IPAF have ILDs with specific clinical, serologic, and/or morphologic autoimmune characteristics that fail to meet criteria for any specific CTD. And yet, it has been uncertain whether its clinical presentations and prognoses have any similarities with CTD.

A team led by Nikhil Jiwrajka, MD, resident at the Hospital of the University of Pennsylvania, conducted a retrospective review of patients with ILD to compare characteristics, treatment patterns, and outcomes between IPAF patients and CTD-ILD and IPF patients.

Each patient was given an ILD diagnosis by a panel consisting of pulmonologists, a radiologist, and a pathologist and which was based on a comprehensive multidisciplinary evaluation.

Using medical records to aggregate further information from the patients’ initial presentation, Jiwrajka and team then recategorized patients as IPAF, CTD-ILD, or IPF.

They then proceeded to compare clinical characteristics, imaging findings, baseline pulmonary function tests, treatment patterns, and transplant-free survival rates among the groups.

According to their analysis, the investigators identified 56 patients with IPF, 122 with CTD-ILD, and 129 with IPF.

Compared with IPF patients, those with IPAF and CTD-ILD were mostly female (67.4% vs. 30.2% IPF; P < .05), less likely to have smoked (45.5% vs 68.2%; P < .05). and more likely to have seen a rheumatologist (77.5% vs 5.5%; P < .05).

The investigators also noted that baseline imagining findings were similar between IPAF and CTD-ILD groups.

Although CTD-ILD patients were more likely than IPAF patients to have received immunosuppression prior to their initial visit (70.5% vs 49.1%; P < .05), treatment patterns during follow-up were reported as similar between the groups.

A greater proportion of IPF patients, however, received antifibrotic agents during follow-up (35.7% vs 6.2%; P < .05).

Finally, the team found there to be no significant difference in median transplant-free survival between IPAF patients and CTD-ILD or IPF patients. There was, however, a longer median survival in CTD-ILD patients than in IPF patients.

They acknowledged that the many similarities in demographic and imaging characteristics between IPAF and CTD-ILD patients suggest a possibility of a common underlying disease process.

“Ultimately, the future identification and study of IPAF patients requires a comprehensive clinical and diagnostic evaluation by a multidisciplinary team that includes both pulmonologists and rheumatologists,” they concluded.

The study, "Phenotypic Characteristics and Treatment Patterns of Patients with CTD-ILD, Idiopathic Pulmonary Fibrosis, and Interstitial Pneumonia with Autoimmune Features," was presented at NYRIF 2020.