title: Minimal important difference in field walking tests in non-cystic fibrosis bronchiectasis following exercise training.
abstract: BACKGROUND
  The 6-min walk distance (6MWD) and incremental shuttle walk distance (ISWD) are clinically meaningful measures of exercise capacity in people with non-cystic fibrosis (CF) bronchiectasis, but the change in walking distance which constitutes clinical benefit is undefined. This study aimed to determine the minimal important difference for the 6MWD and ISWD in non-CF bronchiectasis.
  
  
  METHODS
  Thirty-seven participants with mean FEV1 70% predicted completed both field walking tests before and after an 8-week exercise program. The minimal important difference was calculated using a distribution-based and anchor-based method, with the global rating of change scale used.
  
  
  RESULTS
  The mean change in 6MWD in participants who reported themselves to be unchanged was 10 m, compared to 36 m (small change) and 45 m (substantial change) (p = 0.01). For the ISWD, the mean change in participants who reported themselves to be unchanged was 33 m, compared to 54 m (small change) and 73 m (substantial change) (p = 0.04). The anchor-based method defined the minimal important difference for 6MWD as 24.5 m (AUC 0.76, 95% CI 0.61-0.91) and for ISWD as 35 m (AUC 0.88, 95% CI 0.73-0.99), based on participant's global rating of change. The distribution-based method indicated a value of 22.3 m for the 6MWD and 37 m for the ISWD. There was excellent agreement between the two methods for the 6MWD (kappa = 0.91) and the ISWD (kappa = 0.92).
  
  
  CONCLUSIONS
  Small changes in 6MWD and ISWD may represent clinically important benefits in people with non-CF bronchiectasis. These data are likely to assist in the interpretation of change in exercise capacity following intervention.
authors.affiliation: Alfred Health, Commercial Road, Melbourne 3004, Victoria, Australia; Institute for Breathing and Sleep, Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia; Physiotherapy, Melbourne School of Health Sciences, The University of Melbourne, 161 Barry Street, Carlton 3010, Victoria, Australia. Electronic address: Annemarie.Lee@alfred.org.au.
authors.forename: A L
authors.initials: AL
authors.lastname: Lee
authors.affiliation: Institute for Breathing and Sleep, Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia; Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia. Electronic address: Catherine.Hill@austin.org.au.
authors.forename: C J
authors.initials: CJ
authors.lastname: Hill
authors.affiliation: Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Perth 6009, Australia; Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Hospital Avenue, Nedlands, Perth 6009, Australia. Electronic address: Nola.Cecins@health.wa.gov.au.
authors.forename: N
authors.initials: N
authors.lastname: Cecins
authors.affiliation: Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Perth 6009, Australia; Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Hospital Avenue, Nedlands, Perth 6009, Australia; Curtin University, Kent Street, Bentley, Perth 6102, Australia. Electronic address: S.Jenkins@curtin.edu.au.
authors.forename: S
authors.initials: S
authors.lastname: Jenkins
authors.affiliation: Institute for Breathing and Sleep, Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia; Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia. Electronic address: Christine.McDonald@austin.org.au.
authors.forename: C F
authors.initials: CF
authors.lastname: McDonald
authors.affiliation: Alfred Health, Commercial Road, Melbourne 3004, Victoria, Australia. Electronic address: A.Burge@alfred.org.au.
authors.forename: A T
authors.initials: AT
authors.lastname: Burge
authors.affiliation: Institute for Breathing and Sleep, Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia; Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia. Electronic address: Linda.Rautela@austin.org.au.
authors.forename: L
authors.initials: L
authors.lastname: Rautela
authors.affiliation: Alfred Health, Commercial Road, Melbourne 3004, Victoria, Australia; Department of Medicine, Monash University, Melbourne 3800, Australia. Electronic address: R.Stirling@alfred.org.au.
authors.forename: R G
authors.initials: RG
authors.lastname: Stirling
authors.affiliation: Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Perth 6009, Australia; Lung Institute of Western Australia and Centre for Asthma, Allergy and Respiratory Research, Hospital Avenue, Nedlands, Perth 6009, Australia; Curtin University, Kent Street, Bentley, Perth 6102, Australia. Electronic address: P.Thompson@liwa.uwa.gov.au.
authors.forename: P J
authors.initials: PJ
authors.lastname: Thompson
authors.affiliation: Alfred Health, Commercial Road, Melbourne 3004, Victoria, Australia; Institute for Breathing and Sleep, Austin Health, 145 Studley Road, Heidelberg 3084, Victoria, Australia; Physiotherapy, La Trobe University, 99 Commercial Road, Melbourne 3004, Victoria, Australia. Electronic address: A.Holland@alfred.org.au.
authors.forename: A E
authors.initials: AE
authors.lastname: Holland
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001987:Bronchiectasis / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation*; D003550:Cystic Fibrosis / Q000150:complications; D005080:Exercise Test / Q000379:methods*; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D016896:Treatment Outcome; D014797:Vital Capacity / Q000502:physiology; D016138:Walking
keywords: Bronchiectasis; Exercise capacity; Minimal important difference