de Morton Mobility Index Is Feasible, Reliable, and Valid in Patients With Critical Illness

Background. Intensive care unit (ICU) stays often lead to reduced physical functioning. Change in physical functioning in patients in the ICU is inadequately assessed through available instruments. The de Morton Mobility Index (DEMMI), developed to assess mobility in elderly hospitalized patients, is promising for use in patients who are critically ill. Objective. The aim of this study was to evaluate the clinimetric properties of the DEMMI for patients in the ICU. Design. A prospective, observational reliability and validity study was conducted. Methods. To evaluate interrater and intrarater reliability (intraclass correlation coefficients), patients admitted to the ICU were assessed with the DEMMI during and after ICU stay. Validity was evaluated by correlating the DEMMI with the Barthel Index (BD, the Katz Index of Independence in Activities of Daily Living (Katz ADL), and manual muscle testing (MMT). Feasibility was evaluated based on the percentage of participants in which the DEMMI could be assessed, the floor and ceiling effects, and the number of adverse events. Results. One hundred fifteen participants were included (Acute Physiology and Chronic Health Evaluation II [APACHE II] mean score=15.2 and Sepsis-related Organ Failure Assessment [SOFA] mean score=7). Interrater reliability was .93 in the ICU and .97 on the wards, whereas intrarater reliability during the ICU stay was .68. Validity (Spearman rho coefficient) during the ICU stay was .56, -.45, and .57 for, the BI, Katz ADL, and MMT, respectively. The DEMMI showed low floor and ceiling effects (2.6%) during and after ICU discharge. There were no major adverse events. Limitations. Rapid changes in participants' health status may have led to underestimation of intrarater reliability. Conclusion. The DEMMI was found to be clinically feasible, reliable, and valid for measuring mobility in an ICU population. Therefore, the DEMMI should be considered a preferred instrument for measuring mobility in patients during and after their ICU stay.