Detectable changes in physical performance measures in elderly African Americans.

BACKGROUND: African American older adults have higher rates of self-reported disability and lower physical performance scores compared with white older adults. Measures of physical performance are used to predict future morbidity and to determine the effect of exercise. Characteristics of performance measures are not known for African American older adults. OBJECTIVE: The purpose of this study was to estimate the standard error of measurement (SEM) and minimal detectable change (MDC) for the Short Physical Performance Battery (SPPB), Timed "Up & Go" Test (TUG) time, free gait speed, fast gait speed, and Six-Minute Walk Test (6MWT) distance in frail African American adults. DESIGN: This observational measurement study used a test-retest design. METHODS: Individuals were tested 2 times over a 1-week period. Demographic data collected included height, weight, number of medications, assistive device use, and Mini-Mental Status Examination (MMSE) scores. Participants then completed the 5 physical performance tests. RESULTS: Fifty-two participants (mean age=78 years) completed the study. The average MMSE score was 25 points, and the average body mass index was 29.4 kg/m(2). On average, participants took 7 medications, and the majority used assistive devices. Intraclass correlation coefficients (ICC [2,1]) were greater than .90, except for the SPPB score (ICC=.81). The SEMs were 1.2 points for the SPPB, 1.7 seconds for the TUG, 0.08 m/s for free gait speed, 0.09 m/s for fast gait speed, and 28 m for 6MWT distance. The MDC values were 2.9 points for the SPPB, 4 seconds for the TUG, 0.19 m/s for free gait speed, 0.21 m/s for fast gait speed, and 65 m for 6MWT distance. LIMITATIONS: The entire sample was from an urban area. CONCLUSIONS: The SEMs were similar to previously reported values and can be used when working with African American and white older adults. Estimates of MDC were calculated to assist in clinical interpretation.

Predictors of gait speed in patients after hip fracture.

PURPOSE: Following hip fracture, patients demonstrate greatly reduced walking speeds 1 year later compared with age-matched elders. The purpose of our study was to examine the factors that relate to gait speed in patients after hip fracture. METHODS: Forty-two men and women (mean age 79 +/- 7.5 years) who sustained a hip fracture participated in this study. Linear regression analysis was used to determine a statistical model that best predicted gait speed, the dependent variable. Gait speed was measured with a computerized gait mat. The independent variables were age, sex, height, weight, time post-fracture, medications, mental status, depression, balance confidence, Medical Outcome Studies, Short Form (SF-36), balance, and lower extremity isometric force. All subjects were discharged from physical therapy services, and measurements were taken, on average, 17 weeks post-fracture. RESULTS: Using stepwise regression, 72% of the variance in gait speed was explained by summed lower extremity strength normalized by body weight, general health (SF-36), and balance confidence (Activities-specific Balance Confidence Scale). CONCLUSIONS: Impairments (summed lower extremity strength) and risk factors (perception of general health and balance confidence) are important predictors of gait speed in elders after hip fracture.

Determining meaningful changes in gait speed after hip fracture.

BACKGROUND AND PURPOSE: Older subjects after hip fracture walk more slowly than age-matched peers. The extent to which they walk more slowly is difficult to define because the standard error of the measure (SEM), sensitivity to change, and clinically important change have not been reported for gait speed. The purposes of this study were to quantify the SEM for habitual and fast gait speeds among older subjects after hip fracture, to define the minimal detectable change (MDC), and to estimate the minimal clinically important difference (MCID) for habitual gait speed. SUBJECTS: A sample of 92 subjects after hip fracture was drawn from 3 studies that collected gait speed data. METHODS: An estimate of the MDC was determined by use of the SEM. The MCID was determined from expert opinion and from a receiver operating characteristic (ROC) curve. RESULTS: The SEM and the MDC were 0.08 m/s and 0.10 m/s for habitual speed and fast speed, respectively. Both methods of MCID estimation identified 0.10 m/s as a meaningful change in habitual gait speed. DISCUSSION AND CONCLUSION: The estimated MCID for gait speed of 0.10 m/s was supported by clinical expert opinion and the cutoff point of the ROC curve.