Serological and morphological prognostic factors in patients with interstitial pneumonia with autoimmune features

BACKGROUND To identify the prognostic factors for survival in patients with interstitial pneumonia with autoimmune features (IPAF) who meet the serological domain of the IPAF criteria. METHODS We retrospectively analysed 99 IPAF patients who met the serological domain and were hospitalised at the Respiratory Medicine Unit of Kurashiki Central Hospital from 1999 to 2015. The high-resolution computed tomography findings were usual interstitial pneumonia (UIP; n = 1), non-specific interstitial pneumonia (NSIP; n = 63), NSIP with organizing pneumonia (OP) overlap (n = 15), and OP (n = 20). One patient who had radiological UIP pattern, and met the serological and clinical domains was excluded. The clinical characteristics, radiological findings, administered therapy, and prognosis of the remaining 98 IPAF patients who met the serological and morphological domains were analysed. RESULTS The median age of the 98 IPAF patients was 68 years, and 41 (41.8%) of them were men. Twelve (12.2%) of the 98 IPAF patients developed other characteristics and were diagnosed with connective tissue disease (CTD) later during the median follow-up of 4.5 years. Univariate Cox analysis revealed systemic sclerosis (SSc)-specific and SSc-associated antibodies (ANA nucleolar pattern, ANA centromere pattern, anti-ribonucleoprotein and anti-Scl-70) positive IPAF, radiological NSIP pattern, bronchoalveolar lavage fluid lymphocytes >15%, and age as significant prognostic factors for survival. Multivariate Cox analysis revealed radiological NSIP pattern (hazard ratio [HR], 4.48; 95% confidence interval [CI], 1.28-15.77, p = 0.02) and age (HR, 1.07; 95% CI, 1.02-1.11, p = 0.01) were significantly associated with worse survival. CONCLUSIONS We confirmed that radiological NSIP pattern and age are poor prognostic factors for the survival of IPAF patients. This study suggested that the autoantibodies that are highly specific for certain connective tissue diseases might be less important for the prognosis of IPAF compared with the radiological-pathological patterns. The relatively high proportion of IPAF patients who developed CTD later suggests the importance of careful observation for evolution to CTD in IPAF.