Increased intra-individual variability in stride length and reaction time in recurrent older fallers.
OBJECTIVE
To study and compare both mean performance measures as well as intra-individual variability measures of stride length and reaction time in vulnerable recurrent and non-recurrent older fallers.


METHODS
Stride length during walking and walking while dual-tasking (GAITRite®) and choice reaction time (CANTAB®) were assessed in geriatric outpatients and their informal caregivers (n=60, ≥ 60 yrs). Logistic regression and Receiver Operating Characteristic (ROC) analysis were used to generate models with mean performance measures and intra-individual variability measures (coefficients of variation; CV=[sd/mean]x100)), as risk factors for recurrent falls.


RESULTS
Reaction-time CV was higher in recurrent fallers than in non-recurrent fallers: 21.3% [9.3-47.7] vs 15.8% [8.3-34.9] (p=0.04). Also, stride-length CV was higher in recurrent fallers during performance of the verbal fluency dual-task: 4.5% [1.2-31.4] vs 3.5% [0.9-9.7] (p=0.017). The model with CVs provided an explained variance of 23.7%, and an area under the curve (AUC) of 0.73, which was higher than that of the model including mean performance measures (8.6% and 0.65 respectively).


CONCLUSIONS
Older recurrent fallers are characterized by increased within-task variability in reaction time and stride length while dual-tasking. In addition, variability in performance is a more sensitive measure in discrimination of recurrent falls than mean performance itself, suggesting deterioration in neurocognitive regulation mechanisms as part of the causal pathway for recurrent falls.
Radboud University Nijmegen Medical Centre, Department of Geriatric Medicine 925, PO Box 9101, 6500 HB Nijmegen, The Netherlands. M.Reelick@ger.umcn.nl
Miriam F
MF
Reelick
Roy P C
RP
Kessels
Miriam C
MC
Faes
Vivian
V
Weerdesteyn
Rianne A J
RA
Esselink
Marcel G M
MG
Olde Rikkert
D000058:Accidental Falls / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D001288:Attention; D003071:Cognition; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D006801:Humans; D016015:Logistic Models; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D012372:ROC Curve; D011930:Reaction Time / Q000502:physiology*; D012008:Recurrence; D012307:Risk Factors; D013647:Task Performance and Analysis; D016138:Walking / Q000502:physiology