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The following is a summary of “Characteristics and risk factors of interstitial pneumonia with autoimmune features,” published in the January 2024 issue of Pulmonology by Vahidy, et al.
Interstitial pneumonia with autoimmune features (IPAF) shares characteristics with connective tissue disease-associated interstitial lung disease (CTD-ILD) but does not meet specific CTD criteria. For a study, researchers sought to compare baseline characteristics, survival outcomes, and treatment responses of IPAF to CTD-ILD and unclassifiable ILD.
Data were extracted from a prospective registry, and baseline features and survival were compared between IPAF, CTD-ILD, and unclassifiable ILD. Linear trajectory of lung function decline (%-predicted forced vital capacity [FVC%] and diffusion capacity of the lung for carbon monoxide [DLCO%]) before and after initiation of mycophenolate or azathioprine were assessed using linear mixed models.
Compared to CTD-ILD (n = 1,240), IPAF patients (n = 128) were older, more frequently male, and had higher smoking history. Compared to unclassifiable ILD (n = 665), IPAF patients were younger, more frequently female, and had worse baseline lung function. IPAF exhibited higher mortality than CTD-ILD and similar mortality to unclassifiable ILD. Mycophenolate initiation stabilized FVC% and DLCO% in all ILD subtypes except for FVC% in IPAF patients, while azathioprine initiation stabilized FVC% and DLCO% in all ILD subtypes except for FVC% decline in IPAF and DLCO% decline in CTD-ILD.
IPAF patients had poorer survival compared to CTD-ILD and similar mortality to unclassifiable ILD. Treatment was associated with lung function stabilization across all ILD subtypes. However, the status of IPAF as a distinct ILD diagnostic subgroup remains uncertain. Further research was warranted to clarify the classification.
Reference: resmedjournal.com/article/S0954-6111(23)00388-8/abstract