Introduction: Measurement instruments are important in clinical practice and research for assessing physical function in critically ill patients in the intensive care unit (ICU).
Objective: To investigate inter-rater reliability and responsiveness of the Danish version of the CPAx (CPAx-D).
Method: Critically ill patients from three Danish ICUs were included. Patients were assessed with CPAx-D by two blinded testers during a regular physiotherapy session. Follow-up tests were performed in patients who stayed in the ICU for more than 24 hours, were not transferred to another hospital or received palliative care. Floor and ceiling effects were examined in all assessments.Results For the reliability analysis 66 patients were included.
Results Showed no significant difference between raters. For the total score, intra class correlation coefficient (ICC) was 0.996 (95% CI: 0.993; 0.997), standard error of measurement was 0.72 point and minimal detectable change 2.0 points. Bland-Altman plot revealed no heteroscedacity. The responsiveness results of 24 patients showed that the effect size was 1.2 and the standardized response mean 1.1, which was in accordance with the hypothesis. No ceiling or floor effect was revealed.
Conclusion: The CPAx-D showed excellent inter-rater reliability and responsiveness.
Keywords: CPAx; inter-rater reliability; measurement error; responsiveness.