EVALUATING THE DISCRIMINATORY POWER OF THE VELOCITY-FIELD-DIAGRAM AND TIMED-UP-AND-GO TEST IN DETERMINING THE FALL STATUS OF COMMUNITY-DWELLING OLDER ADULTS

S.C. Ibeneme^1,2,3, J.C. Eze¹, U.P. Okonkwo⁴, G.C. Ibeneme⁵, G. Fortwengel⁶

¹University of Nigeria, Enugu Campus, Department of Medical Rehabilitation, Enugu, Nigeria, ²University of the Witwatersrand, Department of Physiotherapy, Johannesburg, South Africa, ³David Umahi Federal University of Health Sciences, Department of Physiotherapy, Enugu, Nigeria, ⁴Nnamdi Azikiwe University, Nnewi Campus, Department of Medical Rehabilitation, Nnewi, Nigeria, ⁵Ebonyi State University, Department of Nursing Sciences, Abakaliki, Nigeria, ⁶Hochschule Hannover University, Faculty III, Hannover, Germany

Background: Systematic reviews demonstrated that gait variables are the most reliable predictors of future falls, yet are rarely included in fall screening tools. Thus, most tools have higher specificity than sensitivity, hence may be misleading/detrimental to care. Therefore, this study aimed to determine the validity, and reliability of the velocity field diagram (VFD -a gait analytical tool), and the Timed-up-and-go test (TUG)-commonly used in Nigeria as fall screening tools, compared to a gold standard (known fallers) among community-dwelling older adults.

Purpose: The research question for this study was: What is the validity and reliability of the VFD test and TUG in fall screening compared to the gold standard (fallers), among community-dwelling older adults? The objectives of the study were to i. Determine the differences in the gait speed between fallers and non-fallers as a performance-based physical measure, ii. Determine the discrimination threshold of the VFD and TUG for fallers and non-fallers, iii. Determine the reliability and validity of the VFD and TUG in fall screening, and iv. Determine the relationship between E₁ and gait speed in males and females.

Methods: This is a cross-sectional observational study of 500 older adults (280 fallers and 220 non-fallers), recruited by convenience sampling technique at community health fora on fall prevention. Participants completed a 7-metre distance with the number of steps and time it took determined and used to compute the stride length, stride frequency, and velocity, which regression lines formed the VFD. TUG test was simultaneously conducted to discriminate fallers from non-fallers. The cut-off points for falls were: TUG times ≥13.5 seconds; VFD’s intersection point of the stride frequency, and velocity regression lines (E₁) ≥3.5velots. The receiver operating characteristic (ROC) area under the curves (AUC) was used to explore the ability of the E₁≥3.5velots to discriminate between fallers and non-fallers. The VFD’s and TUG’s sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined. Alpha was set at p<0.05.

Results: The VFD versus TUG sensitivity, specificity, PPV and NPV were 71%, 27%, 55%, and 42%, versus 39%, 59%, 55%, and 43%, respectively. The ROC’s AUC were 0.74(95%CI:0.597,0.882, p=0.001) for the VFD. The optimal categorizations for discrimination between fallers/non-fallers were ≥3.78 versus ≤3.78 for VFD (fallers versus non-fallers prevalence is 60.71% versus 95.45%, respectively), with a classification accuracy or prediction rate of 0.76 unlike TUG with AUC=0.53 (95% CI:0.353,0.700, p=0.762), and a classification accuracy of 0.68, and optimal characterization of ≥12.81s versus ≤12.81 (fallers and non-fallers prevalence = 92.86% versus 36.36%, respectively).

Conclusions: The VFD demonstrated greater reliability and validity in the determination of the fall status of community-dwelling older adults. Consequently, reliance on the TUG as a sole fall discriminatory tool in community-dwelling older adult populations may be misleading and detrimental to health and should be reviewed in favour of the VFD.

Implications: The VFD demonstrated a fair discriminatory power and greater reliability in identifying fallers than the TUG, and therefore, could replace the TUG as a primary tool in screening those at risk of falls.

Funding acknowledgements: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors

Keywords:
Community-dwelling older adults
Falls
Fall discriminatory tools

Topics:
Older people
Musculoskeletal
Disability & rehabilitation

Did this work require ethics approval? Yes

Institution: University of Nigeria

Committee: University of Nigeria Health Research Ethics Committee

Ethics number: NHREC/05/01/2008B