title: Autoimmune-featured interstitial lung disease: a distinct entity.
abstract: BACKGROUND
  Patients with interstitial lung disease (ILD) may have features of an autoimmune disorder that do not meet the diagnostic criteria for connective tissue diseases. We determined the prevalence and characteristics of autoimmune-featured ILD (AIF-ILD) and compared these with those of idiopathic pulmonary fibrosis (IPF) and known connective tissue disease-related ILD (CTD-ILD).
  
  
  METHODS
  Patients with ILD who did not meet the criteria for a connective tissue disease were defined as having AIF-ILD if they had a sign or symptom suggestive of a connective tissue disease and a serologic test reflective of an autoimmune process. Clinical characteristics, high-resolution CT images, and lung biopsy specimens were analyzed and compared with those of patients with IPF and CTD-ILD. Survival was evaluated using a Kaplan-Meier curve.
  
  
  RESULTS
  Two hundred subjects completed the questionnaire and serologic testing. AIF-ILD was identified in 32%, IPF in 29%, and CTD-ILD in 19%. Gender, age, and race differed among groups (P < .01). Sixty-two percent of patients with AIF-ILD had a typical usual interstitial pneumonia (UIP) pattern on CT images. In 31 patients with AIF-ILD, lung biopsy specimens showed UIP in 81% and nonspecific interstitial pneumonia in 6%. Patients with AIF-ILD and IPF had similar survival, worse than those with CTD-ILD (P < .01). Antinuclear antibody (ANA) titers ≥ 1:1280 were associated with improved survival in patients with AIF-ILD (P = .02).
  
  
  CONCLUSIONS
  Systematic evaluation of symptoms and serologic tests in ILD can identify AIF-ILD. A UIP pattern on CT images and histopathology is common in AIF-ILD. Although survival for patients with AIF-ILD is poor, ANA titers ≥ 1:1280 are associated with improved survival.
authors.affiliation: Section of Pulmonary and Critical Care Medicine, the Department of Medicine, University of Chicago, Chicago, IL.
authors.forename: Rekha
authors.initials: R
authors.lastname: Vij
authors.affiliation: Section of Pulmonary and Critical Care Medicine, the Department of Medicine, University of Chicago, Chicago, IL. Electronic address: inoth@medicine.bsd.uchicago.edu.
authors.forename: Imre
authors.initials: I
authors.lastname: Noth
authors.affiliation: Section of Pulmonary and Critical Care Medicine, the Department of Medicine, University of Chicago, Chicago, IL.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Strek
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D015995:Prevalence; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011658:Pulmonary Fibrosis / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D012129:Respiratory Function Tests; D011795:Surveys and Questionnaires; D015996:Survival Rate; D014057:Tomography, X-Ray Computed