title: Epidemiology, genetics, and subtyping of preserved ratio impaired spirometry (PRISm) in COPDGene.
abstract: BACKGROUND
  Preserved Ratio Impaired Spirometry (PRISm), defined as a reduced FEV1 in the setting of a preserved FEV1/FVC ratio, is highly prevalent and is associated with increased respiratory symptoms, systemic inflammation, and mortality. Studies investigating quantitative chest tomographic features, genetic associations, and subtypes in PRISm subjects have not been reported.
  
  
  METHODS
  Data from current and former smokers enrolled in COPDGene (n = 10,192), an observational, cross-sectional study which recruited subjects aged 45-80 with ≥10 pack years of smoking, were analyzed. To identify epidemiological and radiographic predictors of PRISm, we performed univariate and multivariate analyses comparing PRISm subjects both to control subjects with normal spirometry and to subjects with COPD. To investigate common genetic predictors of PRISm, we performed a genome-wide association study (GWAS). To explore potential subgroups within PRISm, we performed unsupervised k-means clustering.
  
  
  RESULTS
  The prevalence of PRISm in COPDGene is 12.3%. Increased dyspnea, reduced 6-minute walk distance, increased percent emphysema and decreased total lung capacity, as well as increased segmental bronchial wall area percentage were significant predictors (p-value <0.05) of PRISm status when compared to control subjects in multivariate models. Although no common genetic variants were identified on GWAS testing, a significant association with Klinefelter's syndrome (47XXY) was observed (p-value < 0.001). Subgroups identified through k-means clustering include a putative "COPD-subtype", "Restrictive-subtype", and a highly symptomatic "Metabolic-subtype".
  
  
  CONCLUSIONS
  PRISm subjects are clinically and genetically heterogeneous. Future investigations into the pathophysiological mechanisms behind and potential treatment options for subgroups within PRISm are warranted.
  
  
  BACKGROUND
  Clinicaltrials.gov Identifier: NCT000608764.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Wan
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Castaldi
authors.forename: Michael H
authors.initials: MH
authors.lastname: Cho
authors.forename: John E
authors.initials: JE
authors.lastname: Hokanson
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Regan
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Make
authors.forename: Terri H
authors.initials: TH
authors.lastname: Beaty
authors.forename: MeiLan K
authors.initials: MK
authors.lastname: Han
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Curtis
authors.forename: Douglas
authors.initials: D
authors.lastname: Curran-Everett
authors.forename: David A
authors.initials: DA
authors.lastname: Lynch
authors.forename: Dawn L
authors.initials: DL
authors.lastname: DeMeo
authors.forename: James D
authors.initials: JD
authors.lastname: Crapo
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D055106:Genome-Wide Association Study / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D013147:Spirometry / Q000379:methods
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