title: The SAFE (SGRQ score, air-flow limitation and exercise tolerance) Index: a new composite score for the stratification of severity in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  This study was proposed to develop a composite of outcome measures using forced expiratory volume percentage of predicted, exercise capacity and quality of life scores for assessment of chronic obstructive pulmonary disease (COPD) severity.
  
  
  METHODS
  Eighty-six patients with COPD were enrolled into a prospective, observational study at the respiratory outpatient clinic, National University Hospital Malaysia (Hospital Universiti Kebangsaan Malaysia--HUKM), Kuala Lumpur.
  
  
  RESULTS
  Our study found modest correlation between the forced expiratory volume in 1 s (FEV(1)), 6 min walk distance and the SGRQ scores with mean (SD) values of 0.97 (0.56) litres/s, 322 (87) m and 43.7 (23.6)%, respectively. K-Means cluster analysis identified four distinct clusters which reached statistical significance which was refined to develop a new cumulative staging system. The SAFE Index score correlated with the number of exacerbations in 2 years (r = 0.497, p<0.001).
  
  
  CONCLUSIONS
  We have developed the SGRQ, Air-Flow limitation and Exercise tolerance Index (SAFE Index) for the stratification of severity in COPD. This index incorporates the SGRQ score, the FEV(1) % predicted and the 6 min walk distance. The SAFE Index is moderately correlated with the number of disease exacerbations.
authors.affiliation: Department of Medicine, International Islamic University Malaysia, Jalan Hospital Campus, Kuantan, Pahang, Malaysia. risman1973@hotmail.com
authors.forename: Mohd Shah
authors.initials: MS
authors.lastname: Azarisman
authors.forename: Mohd Anshar
authors.initials: MA
authors.lastname: Fauzi
authors.forename: Mohd Perdaus Ahmad
authors.initials: MP
authors.lastname: Faizal
authors.forename: Zaharim
authors.initials: Z
authors.lastname: Azami
authors.forename: Abdul Manap
authors.initials: AM
authors.lastname: Roslina
authors.forename: Harun
authors.initials: H
authors.lastname: Roslan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016000:Cluster Analysis; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D011788:Quality of Life; D011795:Surveys and Questionnaires