title: The Duke Activity Status Index in patients with chronic kidney disease: a reliability study.
abstract: OBJECTIVE
  Exercise capacity is impaired at a younger age in CKD patients than in the general population. This study examined the reliability of the Duke Activity Status Index (DASI) questionnaire as a measure of exercise capacity in medically stable adults with stage 3-4 CKD (estimated GFR [eGFR], 15-59 ml/min per 1.73 m(2)).
  
  
  METHODS
  Peak oxygen uptake (VO(2)peak), estimated from DASI responses and cardiopulmonary exercise test measurements, was obtained at baseline and 6 months in a derivation sample (n=23) and once in a validation sample (n=20). Bland-Altman analysis and linear mixed models were used to estimate bias, concordance correlation coefficients, and intraclass correlation coefficients as the proportion of the variance due to participant (intertest reliability) and method (test-retest reliability).
  
  
  RESULTS
  The two samples were homogeneous with respect to age (mean 60 ± 14 years), eGFR (35.5 ± 15 ml/min per 1.73 m(2)), male sex (53%), and diabetes (56%). Mean measured VO(2)peak was 16.5 ± 4 ml/kg per min. The DASI questionnaire overestimated VO(2)peak by 4.3 ml/kg per min. Intertest reliability was 53% when eGFR was ≥35 ml/min per 1.73 m(2) (median) and 60% when eGFR was <35 ml/min per 1.73 m(2) (P<0.01). Test-retest reliability was 81% when eGFR was <35 ml/min per 1.73 m(2) and 71% when eGFR was ≥35 ml/min per 1.73 m(2) (P<0.01).
  
  
  CONCLUSIONS
  The DASI questionnaire may be a reliable measure of exercise capacity in CKD patients, especially when eGFR is <35 ml/min per 1.73 m(2). Larger prospective studies are needed to determine its prognostic value.
authors.affiliation: Department of Medicine, Faculty of Medicine, University of Calgary, Alberta, Canada. pravani@ucalgary.ca
authors.forename: Pietro
authors.initials: P
authors.lastname: Ravani
authors.forename: Brett
authors.initials: B
authors.lastname: Kilb
authors.forename: Harman
authors.initials: H
authors.lastname: Bedi
authors.forename: Sharon
authors.initials: S
authors.lastname: Groeneveld
authors.forename: Serdar
authors.initials: S
authors.lastname: Yilmaz
authors.forename: Stefan
authors.initials: S
authors.lastname: Mustata
mesh_terms: D000368:Aged; D000416:Alberta; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005919:Glomerular Filtration Rate; D006304:Health Status; D006305:Health Status Indicators; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D007674:Kidney Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires