Mobility Measures in Older Cancer Survivors: An Examination of Reliability, Validity, and Minimal Detectable Change

Abstract

Background: Cancer and its treatment contribute to multiple sequelae affecting physical function, including difficulty in balance and walking. Although clinical tests should be used to assess fall risks in older cancer survivors, the literature describing the validity, reliability, measurement error, and minimal detectable change (MDC) of mobility measures is lacking. Objective: The purpose of this study was to describe the reliability, validity, standard error of the measurement (SEM), and minimal detectable change at 95% confidence (MDC 95 ) of mobility measures in older cancer survivors. Methods: Fifty cancer survivors (breast, prostate, lung, or colorectal) aged 65+ years participated. Measures of gait speed (GS) (usual, fast, and dual-task) and mobility (Timed Up and Go [TUG], TUG-cognitive, and TUG-manual) were performed once and then repeated 2 weeks later. Test-retest reliability was assessed using intraclass correlation coefficient (ICC 2,1 ). MDC 95 and SEM were calculated. Construct validity was examined using Pearson's correlation coefficient with 6-item Activitiesspecific Balance Confidence scale and Short Physical Performance Battery performance. Results: Test-retest reliability was excellent for all mobility measures, with ICC values ranging from 0.89 to 0.94 for GS and 0.95 to 0.98 for TUG measures. Construct validity was present for TUG (r = −0.53 to −0.73) and GS (r = 0.29 to 0.5) measures. Low SEM values demonstrated excellent reproducibility. To be considered real change, usual GS should be 0.14 m/s or more and TUG 2.49 seconds or more. Conclusions: Measures of GS and TUG have excellent reliability and construct validity and should be considered for use in older cancer survivors. Further study is indicated to establish the psychometric values of mobility measures by cancer type.

Physical function measurement in older long-term cancer survivors

“…Older cancer survivors ages 65 years and above were recruited from the community as a part of a larger study[ 32 ]. Recruitment occurred through advertisements, flyers, and word-of-mouth.…”

“…Timing began when the tester said “go” and ended when the participant’s body made contact with the chair. The TUG test has established validity and test-retest reliability in older cancer survivors[ 32 ].…”

Assessment of Gait Speed and Timed Up and Go Measures as Predictors of Falls in Older Breast Cancer Survivors

“…Participants in this study were selected from a larger study of mobility, balance, and cognitive measures in community-dwelling older cancer survivors. 9,17 Inclusion criteria for that study included being age of 65 years or more, English speaking, having a medically confirmed diagnosis of breast, lung, prostate or colorectal cancer, primary cancer treatment completion at least 3 months prior to testing, and being able to get up from a chair, stand, and walk 50 ft with or without the use of an assistive device. Only data from breast cancer survivors were used in this analysis as they comprised the majority of the sample population.…”

“…14,16 Two additional versions of the TUG exist which have been used to predict falls, including the TUG-Cognitive where a secondary cognitive task is performed during the measure, and the TUG-Manual. Similar to GS, the validity and reliability of the 3 TUG measures have been established in older cancer survivors, 9 but the prognostic ability to predict falls and the cut-off scores with the highest sensitivity and specificity have not been reported.…”

“…13 Speeds between 0.6 and 0.8 m/s have been determined as the cut-offs for increased fall risk in community-dwelling older adults. 10 Although some studies in older cancer survivors have reported mean GS above 1.0 m/s, 9,14,15 it is unknown if the cutoff speeds reported in the geriatrics literature for falling should be used for older cancer survivors as they often have sensory or balance impairments that increase their fall risk. 2,5,7 Additionally, GS is measured in a number of different ways including usual or normal walking speed, fast GS, and with the inclusion of a secondary cognitive task, known as dual-task GS.…”