title: Prevalence and severity of interstitial lung disease in mixed connective tissue disease: a nationwide, cross-sectional study.
abstract: BACKGROUND
  Mixed connective tissue disease (MCTD) is an immune-mediated, systemic disorder of unknown cause.
  
  
  OBJECTIVE
  To assess the prevalence, pattern and severity of interstitial lung disease (ILD) in a cross-sectional study of the nationwide, Norwegian MCTD cohort.
  
  
  METHODS
  126 patients with MCTD were systematically examined for ILD by high-resolution CT (HRCT), pulmonary function tests (PFT), 6 min walk test (6MWT) and by the New York Heart Association (NYHA) functional classification of dyspnoea. The extent and type of HRCT lung abnormalities were scored according to the CT criteria of ILD recommended by the Fleischner Society.
  
  
  RESULTS
  All 126 patients were Caucasian, 75% women. At the time of the cross-sectional ILD study, the patients had a mean disease duration of 9.0 years. 52% of the patients had abnormal HRCT findings, most commonly reticular patterns consistent with lung fibrosis (35%). Lung fibrosis was quantified as minor in 7%, moderate in 9% and severe in 19% of the patients. Fibrosis was uniformly concentrated in the lower parts of the lungs and was not associated with smoking. Patients with severe lung fibrosis had lower PFT values, shorter 6MWT and a higher mean NYHA functional class. After a mean 4.2 years' follow-up, overall mortality was 7.9%. Mortality in patients with normal HRCT was 3.3%, as compared with 20.8% in patients with severe lung fibrosis (p<0.01).
  
  
  CONCLUSIONS
  Severe lung fibrosis is common in MCTD, has an impact on pulmonary function and overall physical capacity and is associated with increased mortality.
authors.affiliation: Rheumatology Unit, Oslo University Hospital Rikshospitalet, PO Box 4950 Nydalen, 0424 Oslo, Norway. ragunnar@gmail.com
authors.forename: Ragnar
authors.initials: R
authors.lastname: Gunnarsson
authors.forename: Trond Mogens
authors.initials: TM
authors.lastname: Aaløkken
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Molberg
authors.forename: May Brit
authors.initials: MB
authors.lastname: Lund
authors.forename: Georg Karl
authors.initials: GK
authors.lastname: Mynarek
authors.forename: Ase Stavland
authors.initials: AS
authors.lastname: Lexberg
authors.forename: Kari
authors.initials: K
authors.lastname: Time
authors.forename: Alvilde Sofie Strand
authors.initials: AS
authors.lastname: Dhainaut
authors.forename: Liv-Turid
authors.initials: LT
authors.lastname: Bertelsen
authors.forename: Oyvind
authors.initials: O
authors.lastname: Palm
authors.forename: Karen
authors.initials: K
authors.lastname: Irgens
authors.forename: Andrea
authors.initials: A
authors.lastname: Becker-Merok
authors.forename: Jan Leidulf
authors.initials: JL
authors.lastname: Nordeide
authors.forename: Villy
authors.initials: V
authors.lastname: Johnsen
authors.forename: Sonja
authors.initials: S
authors.lastname: Pedersen
authors.forename: Anne
authors.initials: A
authors.lastname: Prøven
authors.forename: Lamya Samir Noori
authors.initials: LS
authors.lastname: Garabet
authors.forename: Jan Tore
authors.initials: JT
authors.lastname: Gran
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000401:mortality* / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008947:Mixed Connective Tissue Disease / Q000401:mortality* / Q000473:pathology / Q000503:physiopathology*; D009043:Motor Activity; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D011658:Pulmonary Fibrosis / Q000401:mortality / Q000473:pathology / Q000503:physiopathology; D012720:Severity of Illness Index