title: Reproducibility of cadence-free 6-minute step test in subjects with COPD.
abstract: BACKGROUND
  Six-minute step test (6MST) has been used to assess functional capacity in chronic conditions; however, its reproducibility in the COPD population has not been evaluated. Our study objective was to evaluate 6MST reproducibility.
  
  
  METHODS
  The test was performed in a single 20-cm height step, and subjects were instructed to step up and down (cadence-free) for 6 min. Subjects underwent three tests. The first and second were controlled by the same assessor with a 30-min interval. The third test was controlled by a different assessor one week later. For intra-rater comparison, the first and second performances of the test were used, and for inter-assessor comparison, the better performance of the first two tests was compared with the third test.
  
  
  RESULTS
  Excellent intra-rater and inter-rater relative reproducibility was observed (intraclass correlation coefficient > 0.8), and there was no statistical difference (repeated measures of analysis of variance) among the performances of the three tests. Intra-rater error values were acceptable (mean error of 5.7 steps and limits of agreement between -7 and 18 steps). Inter-rater error values were not acceptable (mean error of 4.4 steps and limits of agreement between -20 and 29 steps.
  
  
  CONCLUSIONS
  6MST proved to be reproducible in the COPD population when performed by the same assessor.
authors.affiliation: Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil.
authors.forename: Joyce Nf
authors.initials: JN
authors.lastname: da Costa
authors.forename: Juliano F
authors.initials: JF
authors.lastname: Arcuri
authors.forename: Ivana L
authors.initials: IL
authors.lastname: Gonçalves
authors.forename: Simone F
authors.initials: SF
authors.lastname: Davi
authors.forename: Bruna V
authors.initials: BV
authors.lastname: Pessoa
authors.forename: Mauricio
authors.initials: M
authors.lastname: Jamami
authors.forename: Valéria Ap
authors.initials: VA
authors.lastname: Di Lorenzo
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D006801:Humans; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D015203:Reproducibility of Results
keywords: COPD; chronic obstructive pulmonary disease; exercise test; reproducibility