Psychometric Properties of the Barthel Index Used at Intensive Care Unit Discharge

Background The Barthel Index, originally developed and validated to assess activities of daily living in patients with neuromuscular disorders, is commonly used in research and clinical practice involving critically ill patients. Objectives To evaluate the internal consistency, reliability, measurement error, and construct validity of the Barthel Index used at intensive care unit discharge. Methods In this observational study, 2 physiotherapists measured the physical functioning of 122 patients at intensive care unit discharge, using the Barthel Index and other measurement instruments. Results The patients had a median (IQR) age of 56 (47-66) years, and 62 patients (51%) were male. The primary reason for intensive care unit admission was sepsis (28 patients [23%]), and 83 patients (68%) were receiving mechanical ventilation. The Cronbach α value indicating internal consistency was 0.81. For interrater reliability, the intraclass correlation coefficient for the total score was 0.98 (95% CI, 0.97-0.98; P < .001) and the κ statistic for the individual items was 0.54 to 0.94. The standard error of measurement was 7.22, the smallest detectable change was 20.01, and the 95% limits of agreement were –10.3 and 11.8. The Barthel Index showed moderate to high correlations with the other physical functioning measurement instruments (ρ = 0.57 to 0.88; P < .001 for all). Conclusion The Barthel Index is a reliable and valid instrument for assessing physical functioning at intensive care unit discharge.