Within-subject variation in the cognitive timed up and go test as an explanatory variable in fall risk in patients with parkinson's disease.

Abstract

ObjectiveTo explore the use of within-subject variation in the Cognitive Timed Up and Go test (Cognitive TUGWSV) as an explanatory variable in fall risk in the Parkinson’s disease population.DesignCross-sectional study.MethodsFifty-three patients with Parkinson’s disease completed 3 trials of the Cognitive TUGWSV. Within-subject variation was calculated using the standard deviation of an individual’s repeated measurements, and compared on the basis of the fall history reported in the previous 6 months. Participants who reported < 2 falls were classified as “non-recurrent fallers” (n = 31) and those who reported ≥ 2 falls were classified as “recurrent fallers” (n = 22). Univariate and a multivariate logistic regression were used to investigate the statistical impact of the Cognitive TUGWSV as an explanatory variable in fall risk. Discriminative ability and cut-off score were determined based on receiver operating characteristic analysis.ResultsThere was a significant difference between groups in the Cognitive TUGWSV (p = 0.002). Univariate logistic regression indicated a significant association between Cognitive TUGWSV and fall risk (χ2=12.365, p < 0.001), with an odds ratio of 2.5 (95% confidence interval (95% CI) = 1.34–4.65). Multivariate logistic regression showed that body mass index (BMI), Falls Efficacy Scale-International (FES-I), Cognitive TUGWSV, and the mean velocity of the centre of foot pressure under closed eyes condition (Velocity COP (CE)) were significant explanatory variables in fall risk. Cognitive TUGWSV was the most important independent variable. Receiver operating characteristic analysis revealed an acceptable discriminative power (area under the curve (AUC) = 0.757, 95% CI = 0.619– 0.864, p < 0.001) and a cut-off point of 1.53 s.ConclusionA higher Cognitive TUGWSV correlated significantly with higher fall risk. Thus, diagnostic tests and exercise programmes could consider Cognitive TUGWSV when assessing fall risk in the Parkinson’s disease population.LAY ABSTRACTMotor deficits in patients with Parkinson’s disease usually worsen when tasks are performed simultaneously or under maximal challenge conditions. Assessment of these motor complications has an important role in the prediction of fall risk. A range of parameters is used to assess motor alterations. Among them, within-subject variation is normally used as a parameter of reliability in validation studies. Nevertheless, the use of within-subject variation during a single session in the Timed Up and Go test with the addition of a cognitive dual task (Cognitive TUGwsv) performed at maximum speed has not yet been studied as a predictor of fall risk in the Parkinson’s disease population. The results of this study support the hypothesis that a higher Cognitive TUGwsv is related to a higher risk of falling in patients with Parkinson’s disease. Therefore, health professionals could consider this variable when assessing the risk of falling in this population.