title: St. George's Respiratory Questionnaire has longitudinal construct validity in lymphangioleiomyomatosis.
abstract: BACKGROUND
  Lymphangioleiomyomatosis (LAM) is an uncommon, progressive, cystic lung disease that causes shortness of breath, hypoxemia, and impaired health-related quality of life (HRQL). Whether St. George's Respiratory Questionnaire (SGRQ), a respiratory-specific HRQL instrument, captures longitudinal changes in HRQL in patients with LAM is unknown.
  
  
  METHODS
  Using data from the Multicenter International Lymphangioleiomyomatosis Efficacy and Safety of Sirolimus trial, we performed analyses to examine associations between SGRQ scores and values for four external measures (anchors). Anchors included (1) FEV₁, (2) diffusing capacity of the lung for carbon monoxide, (3) distance walked during the 6-min walk test, and (4) serum vascular endothelial growth factor-D.
  
  
  RESULTS
  SGRQ scores correlated with the majority of anchor values at baseline, 6 months, and 12 months. Results from longitudinal analyses demonstrated that SGRQ change scores tracked changes over time in values for each of the four anchors. At 12 months, subjects with the greatest improvement from baseline in FEV₁ experienced the greatest improvement in SGRQ scores (Symptoms domain, -13.4 ± 14.6 points; Activity domain, -6.46 ± 8.20 points; Impacts domain, -6.25 ± 12.8 points; SGRQ total, -7.53 ± 10.0 points). Plots of cumulative distribution functions further supported the longitudinal validity of the SGRQ in LAM.
  
  
  CONCLUSIONS
  In LAM, SGRQ scores are associated with variables used to assess LAM severity. The SGRQ is sensitive to change in LAM severity, particularly when change is defined by FEV₁, perhaps the most clinically relevant and prognostically important variable in LAM. The constellation of results here supports the validity of the SGRQ as capable of assessing longitudinal change in HRQL in LAM.
authors: Autoimmune Lung Center and Interstitial Lung Disease Program, National Jewish Health, Denver, CO. Electronic address: swigrisj@njc.org.
authors: Jeffrey J
authors: JJ
authors: Swigris
authors: Pediatrics Epidemiology Center, University of South Florida College of Medicine, Tampa, FL.
authors: Hye-Seung
authors: HS
authors: Lee
authors: Women's Health Research Institute, Women's College Hospital, Toronto, ON, Canada.
authors: Marsha
authors: M
authors: Cohen
authors: National Hospital Organization Kinki-Chou Chest Medical Center, Osaka, Japan.
authors: Yoshikazu
authors: Y
authors: Inoue
authors: National Institutes of Health, Bethesda, MD.
authors: Joel
authors: J
authors: Moss
authors: Lung Transplantation Program, University of Toronto, Nashville, TN.
authors: Lianne G
authors: LG
authors: Singer
authors: Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN.
authors: Lisa R
authors: LR
authors: Young
authors: Department of Internal Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati, Cincinnati, OH.
authors: Francis X
authors: FX
authors: McCormack
mesh_terms: D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008175:Lung Neoplasms / Q000503:physiopathology*; D018192:Lymphangioleiomyomatosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D042643:Vascular Endothelial Growth Factor D / Q000097:blood; D016138:Walking / Q000502:physiology
chemical_list: D042643:Vascular Endothelial Growth Factor D