title: Relationship between quantitative radiographic assessments of interstitial lung disease and physiological and clinical features of systemic sclerosis.
abstract: OBJECTIVE
  Extent of systemic sclerosis (SSc)-related interstitial lung disease (ILD) assessed from thoracic high-resolution CT (HRCT) predicts disease course, mortality and treatment response. While quantitative HRCT analyses of extent of lung fibrosis (QLFib) or total interstitial lung disease (QILD) are more sensitive and reproducible than visual HRCT assessments of SSc-ILD, these analyses are not widely available. This study evaluates the relationship between clinical disease parameters and QLFib and QILD scores to identify potential surrogate measures of radiographic extent of ILD.
  
  
  METHODS
  Using baseline data from the Scleroderma Lung Study I (SLS I; N=158), multivariate regression analyses were performed using the best subset selection method to identify one to five variable models that best correlated with QLFib and QILD scores in both whole lung (WL) and the zone of maximal involvement (ZM). These models were subsequently validated using baseline data from SLS II (N=142). Bivariate analyses of the radiographic and clinical variables were also performed using pooled data. SLS I and II did not include patients with clinically significant pulmonary hypertension (PH).
  
  
  RESULTS
  Diffusing capacity for carbon monoxide (DLCO) was the single best predictor of both QLF and QILD in the WL and ZM in all of the best subset models. Adding other disease parameters to the models did not substantially improve model performance. Forced vital capacity (FVC) did not predict QLF or QILD scores in any of the models.
  
  
  CONCLUSIONS
  In the absence of PH, DLCO provides the best overall estimate of HRCT-measured lung disease in patients from two large SSc cohorts. FVC, although commonly used, may not be the best surrogate measure of extent of SSc-ILD at any point in time.
  
  
  BACKGROUND
  SLS I: www.clinicaltrials.gov NCT 00000-4563; SLS II: www.clinicaltrials.gov NCT 00883129.
authors.affiliation: Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Donald P
authors.initials: DP
authors.lastname: Tashkin
authors.affiliation: Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Volkmann
authors.affiliation: Department of Biostatistics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Chi-Hong
authors.initials: CH
authors.lastname: Tseng
authors.affiliation: Department of Radiology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Radiology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Goldin
authors.affiliation: Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Clements
authors.affiliation: Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Furst
authors.affiliation: Department of Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan, USA.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Khanna
authors.affiliation: Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Kleerup
authors.affiliation: Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Roth
authors.affiliation: Department of Biostatistics, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Elashoff
mesh_terms: D000328:Adult; D002248:Carbon Monoxide; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011653:Pulmonary Diffusing Capacity; D011658:Pulmonary Fibrosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D013902:Radiography, Thoracic / Q000379:methods / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012595:Scleroderma, Systemic / Q000150:complications / Q000401:mortality / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D014797:Vital Capacity
chemical_list: D002248:Carbon Monoxide
keywords: Pulmonary Fibrosis; Systemic Sclerosis; Treatment