title: Factors associated with the minimal clinically important difference for health-related quality of life after physical conditioning in patients with COPD.
abstract: OBJECTIVE
  To identify factors associated with the minimal clinically important difference (MCID) for health-related quality of life (HRQoL) after physical conditioning in patients with COPD.
  
  
  METHODS
  Thirty-five patients were submitted to a 12-week program of physical conditioning (strength training plus low-intensity aerobic exercise). Body composition, incremental treadmill test results, endurance treadmill test results, six-minute walk test results, peripheral muscle strength, MIP, baseline dyspnea index (BDI) and Saint George's Respiratory Questionnaire (SGRQ) scores were assessed at baseline and after the program, thus allowing the variations (Delta) to be calculated. The MCID for HRQoL was defined as a reduction of > 4% in the SGRQ total score. Subjects who responded to the program, achieving the MCID for HRQoL, were allocated to the responders (R) group (n = 24), and the remainder were allocated to the non-responders (NR) group (n = 11).
  
  
  RESULTS
  The values obtained for the following variables were significantly higher in group R than in group NR (p < 0.05): FEV1 (1.48 + or - 0.54 L vs. 1.04 + or - 0.34 L); VEF1/FVC (47.9 + or - 11.7% vs. 35.5 + or - 10.7%); PaO2 (74.1 + or - 9.7 mmHg vs. 65.0 + or - 8.9 mmHg); and DeltaBDI, expressed as median and interquartile range (2.0 [0.0-3.5] vs. 0.0 [0.0-1.0]). The DeltaBDI correlated significantly with the DeltaSGRQ symptoms domain score, activity domain score and total score (r = 0.44, 0.60 and 0.62, respectively, p < 0.01 for all). After logistic regression, only DeltaBDI remained as a predictor of MCID for HRQoL.
  
  
  CONCLUSIONS
  Achieving the MCID for HRQoL after physical conditioning is associated with dyspnea reduction in COPD patients. Therefore, there is a need to develop treatment strategies designed to interrupt the dyspnea-inactivity-dyspnea cycle in such patients.
authors.affiliation: Universidade Federal de São Paulo, Santos, SP, Brasil. vzdourado@yahoo.com.br
authors.forename: Victor Zuniga
authors.initials: VZ
authors.lastname: Dourado
authors.forename: Letícia Cláudia de Oliveira
authors.initials: LC
authors.lastname: Antunes
authors.forename: Suzana Erico
authors.initials: SE
authors.lastname: Tanni
authors.forename: Irma
authors.initials: I
authors.lastname: Godoy
mesh_terms: D004417:Dyspnea / Q000503:physiopathology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006304:Health Status; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000534:rehabilitation*; D011788:Quality of Life