Interstitial pneumonia with autoimmune features: challenges and controversies

Area of Science:

• Pulmonology
• Rheumatology
• Immunology

Background:

• Interstitial lung disease (ILD) patients often present with features suggesting connective tissue disease (CTD) without a confirmed diagnosis.
• The European Respiratory Society and American Thoracic Society introduced Interstitial Pneumonia with Autoimmune Features (IPAF) criteria in 2015 for standardized research.
• Existing IPAF research cohorts exhibit considerable heterogeneity in clinical presentation, outcomes, and patient selection.

Purpose of the Study:

• To review the current status of IPAF criteria and the evidence base.
• To identify conclusions that can be drawn from existing IPAF research.
• To highlight uncertainties requiring further expert deliberation for potential IPAF reclassification.

Main Methods:

• Literature review of published IPAF patient series.
• Analysis of variations in clinical characteristics, outcomes, and IPAF criteria application.
• Synthesis of current evidence to inform future revisions.

Main Results:

• Significant variability exists across published IPAF cohorts.
• The current IPAF criteria have led to diverse patient populations in research.
• Further refinement is needed to consolidate IPAF as a distinct clinical entity.

Conclusions:

• Revision of IPAF criteria is essential.
• Updated criteria could support the transition of IPAF from a research entity to a standalone diagnosis.
• Ongoing expert discussion is crucial to address remaining uncertainties.