The ICU Mobility Scale Has Construct and Predictive Validity and Is Responsive. A Multicenter Observational Study

Ann Am Thorac Soc. 2016 Jun;13(6):887-93. doi: 10.1513/AnnalsATS.201510-717OC.


Rationale: The ICU Mobility Scale (IMS) is a measure of mobility milestones in critically ill patients.

Objectives: This study aimed to determine the validity and responsiveness of the IMS from a prospective cohort study of adults admitted to the intensive care unit (ICU).

Methods: Construct and predictive validity were assessed by comparing IMS values at ICU discharge in 192 patients to other variables using Spearman rank correlation coefficient, Mann-Whitney U tests, and logistic regression. Responsiveness was assessed using change over time, effect size, floor and ceiling effects, and percentage of patients showing change.

Measurements and main results: The IMS at ICU discharge demonstrated a moderate correlation with muscle strength (r = 0.64, P < 0.001). There was a significant difference between the IMS at ICU discharge in patients with ICU-acquired weakness (median, 4.0; interquartile range, 3.0-5.0) compared with patients without (median, 8.0; interquartile range, 5.0-8.0; P < 0.001). Increasing IMS values at ICU discharge were associated with survival to 90 days (odds ratio [OR], 1.38; 95% confidence interval [CI], 1.14-1.66) and discharge home (OR, 1.16; 95% CI, 1.02-1.32) but not with return to work at 6 months (OR, 1.09; 95% CI, 0.92-1.28). The IMS was responsive with a significant change from study enrollment to ICU discharge (d = 0.8, P < 0.001), with IMS values increasing in 86% of survivors during ICU admission. No substantial floor (14% scored 0) or ceiling (4% scored 10) effects were present at ICU discharge.

Conclusions: Our findings support the validity and responsiveness of the IMS as a measure of mobility in the ICU.

Trial registration: NCT01674608.

Keywords: cohort studies; critical illness; intensive care units; outcome assessment; rehabilitation.

Publication types

  • Multicenter Study
  • Observational Study
  • Validation Study

MeSH terms

  • Adult
  • Aged
  • Australia
  • Critical Illness / rehabilitation*
  • Female
  • Humans
  • Intensive Care Units / organization & administration
  • Logistic Models
  • Male
  • Middle Aged
  • Mobility Limitation
  • Muscle Strength / physiology*
  • New Zealand
  • Patient Discharge / statistics & numerical data*
  • Prospective Studies
  • Reproducibility of Results
  • Severity of Illness Index*
  • Survivors / statistics & numerical data*

Associated data