Choice stepping reaction time: a composite measure of falls risk in older people.
BACKGROUND
This study investigated the neuropsychological, sensorimotor, speed, and balance contributions to a new test of choice stepping reaction time (CSRT) and determined whether this new test is an important predictor of falls in older people.


METHODS
A total of 477 retirement-village residents aged 62 to 95 years (mean +/- SD, 79.2 +/- 6.2 years) took the CSRT test, which required them to step onto one of four panels that were illuminated in a random order. The subjects also took tests that measured neuropsychological, sensorimotor, speed, and balance function.


RESULTS
Multiple regression analysis revealed that poor performance in Part B of the Trail Making Test (a neuropsychological test) and impaired quadriceps strength, simple reaction time, sway with eyes open on a compliant surface, and maximal balance range were the best predictors of increased CSRTs (multiple r(2) =.45). Subjects with a history of falls had significantly increased CSRTs compared with nonfallers (1322 +/- 331 milliseconds and 1168 +/- 203 milliseconds, respectively). Impaired CSRT was a significant and independent predictor of falls, as were two complementary sensory measures (visual contrast sensitivity and lower limb proprioception). Of these measures, CSRT was the most important in predicting falls. Furthermore, the inclusion of CSRT in the model excluded measures of strength, central processing speed, and balance, because these could not provide nonredundant information for the prediction of falls.


CONCLUSIONS
This study identifies a new test that provides a composite measure of falls risk in older people and elucidates the relative importance of specific physiological and neuropsychological systems in the initiation of fast and appropriate step responses.
Lord
S R
SR
Prince of Wales Medical Research Institute, Sydney, Australia. s.lord@unsw.edu.au
Fitzpatrick
R C
RC
D000058:Accidental Falls / Q000517:prevention & control* / Q000706:statistics & numerical data*; D000367:Age Factors; D000368:Aged / Q000502:physiology*; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001315:Australia; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D004856:Postural Balance / Q000502:physiology*; D011237:Predictive Value of Tests; D015995:Prevalence; D011336:Probability; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time; D012307:Risk Factors; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D012737:Sex Factors