The Clinical, Radiological, and Laboratory Profile of Patients With Interstitial Pneumonitis With Autoimmune Features From India: An Observational, Cross-Sectional Study

Introduction Interstitial pneumonia with autoimmune features (IPAF) refers to interstitial lung disease (ILD) with co-existing features of other clinical, serologic, or pulmonary features that suggest the presence of an underlying systemic autoimmune condition that does not fulfill the current rheumatologic criteria for connective tissue disorder (CTD). It is a relatively newly described clinical syndrome with only a handful of reports describing it. This study aimed at studying the clinical, radiological, and laboratory profiles of IPAF patients from a tertiary care hospital in South India. Methods This was an observational cross-sectional study conducted in a tertiary care hospital in South India over a period of one year. Patients diagnosed to have IPAF as per the European Respiratory Society (ERS)/American Thoracic Society (ATS) criteria were included in the study, and their demographics, clinical features, radiological features, and laboratory markers were collected along with a descriptive analysis. Results A total of 14,433 patients were screened during the study period. Twenty-four patients were diagnosed to have IPAF during the study period with a prevalence of 0.17%. Out of these 24 patients, 11 (45.8%) patients were males. The mean (M) ± standard deviation (SD) age was 47.8±10.7 years. Twenty-one (87.5%) of the patients reported having a cough, 18 (75%) patients had breathlessness, and 10 (41.7%) patients had digital clubbing. On radiological imaging, five (20.8%) patients had features of usual interstitial pneumonia (UIP) and 14 (58.3%) had nonspecific interstitial pneumonia (NSIP). On pulmonary function testing, the M±SD forced expiratory volume in the first second (FEV1) was 56.4±13.9%. The M±SD forced vital capacity (FVC) was 44.2±24.1%. The M±SD FEV1/FVC ratio was 0.8±0.04. On performing diffusing capacity of the lungs for carbon monoxide (DLCO), the M±SD was 34.2±21.9%. Of the patients, 95.8% had a positive antinuclear antibody (ANA) while 25% of patients had a positive anti-AMA-M2. Conclusions The prevalence of IPAF in the studied population was very low. IPAF had nonspecific clinical features, pulmonary function tests, and radiological findings. Further large-scale studies are required from different parts of the world in order to understand the epidemiology of IPAF. Research is also required into developing effective management options for IPAF.