title: Evaluation of computer-based computer tomography stratification against outcome models in connective tissue disease-related interstitial lung disease: a patient outcome study.
abstract: BACKGROUND
  To evaluate computer-based computer tomography (CT) analysis (CALIPER) against visual CT scoring and pulmonary function tests (PFTs) when predicting mortality in patients with connective tissue disease-related interstitial lung disease (CTD-ILD). To identify outcome differences between distinct CTD-ILD groups derived following automated stratification of CALIPER variables.
  
  
  METHODS
  A total of 203 consecutive patients with assorted CTD-ILDs had CT parenchymal patterns evaluated by CALIPER and visual CT scoring: honeycombing, reticular pattern, ground glass opacities, pulmonary vessel volume, emphysema, and traction bronchiectasis. CT scores were evaluated against pulmonary function tests: forced vital capacity, diffusing capacity for carbon monoxide, carbon monoxide transfer coefficient, and composite physiologic index for mortality analysis. Automated stratification of CALIPER-CT variables was evaluated in place of and alongside forced vital capacity and diffusing capacity for carbon monoxide in the ILD gender, age physiology (ILD-GAP) model using receiver operating characteristic curve analysis.
  
  
  RESULTS
  Cox regression analyses identified four independent predictors of mortality: patient age (P < 0.0001), smoking history (P = 0.0003), carbon monoxide transfer coefficient (P = 0.003), and pulmonary vessel volume (P < 0.0001). Automated stratification of CALIPER variables identified three morphologically distinct groups which were stronger predictors of mortality than all CT and functional indices. The Stratified-CT model substituted automated stratified groups for functional indices in the ILD-GAP model and maintained model strength (area under curve (AUC) = 0.74, P < 0.0001), ILD-GAP (AUC = 0.72, P < 0.0001). Combining automated stratified groups with the ILD-GAP model (stratified CT-GAP model) strengthened predictions of 1- and 2-year mortality: ILD-GAP (AUC = 0.87 and 0.86, respectively); stratified CT-GAP (AUC = 0.89 and 0.88, respectively).
  
  
  CONCLUSIONS
  CALIPER-derived pulmonary vessel volume is an independent predictor of mortality across all CTD-ILD patients. Furthermore, automated stratification of CALIPER CT variables represents a novel method of prognostication at least as robust as PFTs in CTD-ILD patients.
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, SW3 6NP, UK. akelajacob@gmail.com.|Department of Radiology, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, SW3 6NP, UK. akelajacob@gmail.com.
authors.forename: Joseph
authors.initials: J
authors.lastname: Jacob
authors.affiliation: Division of Radiology, Mayo Clinic Rochester, Rochester, Minnesota, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Bartholmai
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, Minnesota, USA.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Rajagopalan
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, SW3 6NP, UK.
authors.forename: Anne Laure
authors.initials: AL
authors.lastname: Brun
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, SW3 6NP, UK.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Egashira
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, Minnesota, USA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Karwoski
authors.affiliation: Interstitial Lung Disease Unit, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Kokosi
authors.affiliation: Interstitial Lung Disease Unit, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
authors.forename: Athol U
authors.initials: AU
authors.lastname: Wells
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Royal Brompton and Harefield NHS Foundation Trust, London, SW3 6NP, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Hansell
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003240:Connective Tissue Diseases / Q000000981:diagnostic imaging* / Q000401:mortality; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000592:standards*; D012129:Respiratory Function Tests / Q000379:methods / Q000401:mortality / Q000592:standards; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000401:mortality / Q000592:standards*; D014796:Visual Perception
keywords: Computer tomography; Connective tissue disease; Interstitial lung disease; Pulmonary fibrosis; Quantitative CT