Determining Reliability of a Dual-Task Functional Mobility Protocol for Individuals With Lower Extremity Amputation

Published:January 06, 2018DOI:



      To determine the relative and absolute reliability of a dual-task functional mobility assessment.


      Cross-sectional study.


      Academic rehabilitation hospital.


      Individuals (N=60) with lower extremity amputation attending an outpatient amputee clinic (mean age, 58.21±12.59y; 18, 80% male) who were stratified into 3 groups: (1) transtibial amputation of vascular etiology (n=20); (2) transtibial amputation of nonvascular etiology (n=20); and (3) transfemoral or bilateral amputation of any etiology (n=20).


      Not applicable.

      Main Outcome Measures

      Time to complete the L Test measured functional mobility under single- and dual-task conditions. The addition of a cognitive task (serial subtractions by 3's) created dual-task conditions. Single-task performance on the cognitive task was also reported. Intraclass correlation coefficients (ICCs) measured relative reliability; SEM and minimal detectable change with a 95% confidence interval (MDC95) measured absolute reliability. Bland-Altman plots measured agreement between assessments.


      Relative reliability results were excellent for all 3 groups. Values for the dual-task L Test for those with transtibial amputation of vascular etiology (n=20; mean age, 60.36±7.84y; 19, 90% men) were ICC=.98 (95% confidence interval [CI], .94–.99), SEM=1.36 seconds, and MDC95=3.76 seconds; for those with transtibial amputation of nonvascular etiology (n=20; mean age, 55.85±14.08y; 17, 85% men), values were ICC=.93 (95% CI, .80–.98), SEM=1.34 seconds, and MDC95=3.71 seconds; and for those with transfemoral or bilateral amputation (n=20; mean age, 58.21±14.88y; 13, 65% men), values were ICC=.998 (95% CI, .996–.999), SEM=1.03 seconds, and MDC95=2.85 seconds. Bland-Altman plots indicated that assessments did not vary systematically for each group.


      This dual-task assessment protocol achieved approved levels of relative reliability values for the 3 groups tested. This protocol may be used clinically or in research settings to assess the interaction between cognition and functional mobility in the population with lower extremity amputation.


      List of abbreviations:

      ABC (Activities-specific Balance Confidence), CI (Confidence interval), ICC (Intraclass correlation coefficient), LEA (Lower extremity amputation), MDC95 (Minimal detectable change with a 95% confidence interval), MoCA (Montreal Cognitive Assessment), TFA (Transfemoral amputation), TTA (Transtibial amputation)
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