A prospective study of laboratory and clinical measures of postural stability to predict community-dwelling fallers.

BACKGROUND: The identification of specific risk factors for falls in community-dwelling elderly persons is required to detect early changes and permit a preventative approach to management. This study determines the ability of various laboratory measures and clinical tests of postural stability to prospectively predict fallers in community-dwelling elderly women.

METHODS: One hundred elderly women (65-86 years, mean age 73 +/- 5 years) performed a reaction-time step task, a limits of stability, and a quiet stance balance task. Postural muscle timing and movement speed were recorded during the step task. Center of pressure (COP) motion was recorded in quiet stance and at the limits of stability. Four common clinical balance tests were performed, and balance confidence, medical and activity history questionnaires were completed. Subjects were followed up regularly for a 6-month period following testing to determine the frequency and characteristics of any falls that occurred. Predictive capabilities of the balance measures to determine fallers were determined through logistic regression models.

RESULTS: The clinical balance tests investigated were not able to predict fallers in this community-dwelling elderly population. A combination of variables from the laboratory tasks provided the best overall prediction rate (77%) of fallers (sensitivity 51%) and nonfallers (specificity 91%) from laboratory measures. Of these, step movement time and gluteus medius onset times were the factors best able to predict fallers. Alone, measures of COP motion in quiet stance and at the limits of stability had a poor ability to predict fallers, although they could correctly identify most nonfallers. Prediction was not significantly improved when clinical balance test results were added to the most predictive laboratory measures.

CONCLUSIONS: Not all older adults with a reduction in balance ability reported a fall over a 6-month period. Of those who did, a combination of measures reflective of different aspects of mediolateral postural stability during a rapid step task, quiet stance, and movement to the limits of stability were best able to predict faller status, with nonfallers better predicted than fallers. These results emphasize the importance of the multifactorial nature of falls in the community-dwelling elderly population in that the clinical and laboratory measures did not predict a high proportion of fallers.