Postural control in the elderly: an analysis of test-retest and interrater reliability of the COP-COM variable.
OBJECTIVE
To estimate the test-retest and interrater reliability of the center of pressure-center of mass (COP-COM) variable of postural control in the elderly.


METHODS
The biomechanic variable COP-COM, which represents the distance between the COP and the COM, was determined from 2 AMTI force platforms and 3 OPTOTRAK position sensors. Measurements were taken in quiet position, double leg stance, and eyes open and eyes closed conditions.


METHODS
Laboratory environment.


METHODS
Forty-five healthy subjects, 8 patients with diabetes neuropathy, and 7 stroke survivors, all of whom were at least 60 years old.


METHODS
Subjects were evaluated on 2 separate occasions within 7 days by the same evaluator to determine test-retest reliability. Interrater reliability was determined the same day.


METHODS
The biomechanic variable COP-COM, which represents the distance between the COP and the COM in terms of root mean square. The mean of 4 trials of the COP-COM variable for each condition was used for statistical analysis. Intraclass correlation coefficients (ICCs) were used.


RESULTS
The COP-COM variable has good reliability for both the test-retest and interrater studies, but its reliability varies according to the direction of the COP-COM. For the test-retest and interrater studies, the ICC ranged from.89 to.93 in the anteroposterior direction and from.74 to.79 in the mediolateral direction.


CONCLUSIONS
The equivalence of the test-retest and interrater coefficients obtained suggests that the measurement error of the COP-COM variable is mainly linked to the biologic variability of this measure over a short period of time. Using the mean of 4 trials stabilizes the COP-COM variable enough to be potentially used to evaluate clinical change.
School of Rehabilitation Sciences, Physiotherapy, University of Ottawa, Ottawa, Ont, Canada. hcorrive@uottawa.ca
H
H
Corriveau
R
R
Hébert
F
F
Prince
M
M
Raîche
D000058:Accidental Falls / Q000517:prevention & control; D000368:Aged; D001696:Biomechanical Phenomena; D003929:Diabetic Neuropathies / Q000503:physiopathology; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D015203:Reproducibility of Results; D020521:Stroke / Q000503:physiopathology