One leg balance is an important predictor of injurious falls in older persons

One-Leg Balance Is an Important Predictor of Injurious Falls in Older Persons Bruno J Vellas, M D , PhD,*+Sharon] Wayne, MS,' Linda Romero, M D , * Richard N Baumgartner, PhD,$ Laurence Z Rubenstein, MD, MPH,$ and Philip J Garry, PhD' _ - OBJECTIVE:To test the hypothesis that one-leg balance is a significant predictor of falls and injurious falls DESIGN: Analysis of data from a longitudinal cohort study SUBJECTS: Healthy, community-living volunteers older than age 60 enrolled in the Albuquerque Falls Study and followed for years ( N = 316; mean age 73 years) MAIN OUTCOME MEASURES: Falls and injurious falls detected via reports every other month INDEPENDENT VARIABLES: Baseline measures of demographics, history, physical examination, Iowa Self Assessment Inventory, balance and gait assesessment, and one-leg balance (ability to stand unassisted for seconds on one leg) RESULTS: At baseline, 84.5% of subjects could perform one-leg balance (Impairment was associated with older age and gait abnormalities.) Over the 3-year follow-up, 71% experienced a fall and 22% an injurious fall The only independent significant predictor of all falls using logistic regression was age greater than 73 However, impaired one-leg balance was the only significant independent predictor of injurious falls (relative risk: 2.13; 95% CI: 1.04, 4.34; P = 03) CONCLUSION: One-leg balance appears to be a significant and easy-to-administer predictor of injurious falls, but not of all falls In our study, it was the strongest individual predictor However, no single factor seems to be accurate enough to be relied on as a sole predictor of fall risk or fall injury risk because so many diverse factors are involved in falling J Am Geriatr SOC45:735-738, 1997 S everal risk factors for falls have been documented repeatedly The most important of these risk factors include leg weakness, impaired gait, and balance dysfunction.'-" How~ _ - ~ From the 'New Mexico Aging Process Study, Clinical Nutrition Program, Department of Pathology, University of New Mexico, School of Medicine, Albuquerque, New Mexico; tService dc Gerontoltrgie Clinique, Departement de Medecine Interne, C.H.U Toulousc-Purpan, Toulouse, France; *Department of Biochemistry, University of New Mexico, School of Medicine, Albuquerque, New Mexico; and SGeriatric Research Education and Clinical Center (GRECC) Sepulveda VA Medical Center (1l E ) , Sepulveda, California Supported by Grants AG 02049, AG10149,HL36158, and GCR DRR, M0100997-13-13,14 from the United States Public Health Service Address correspondence to Laurence Rubenstein, MD, MPH, Director, GRECC, Sepulvcda VA Medical Center ( 1E).Sepulveda, CA 91.343 - -_ _ _ _ - - JAGS 45:735-738,1997 1997 by the American Geriatrics Society - ever, these factors are complex and often require special expertise or explicit protocols to measure ac~urateIy.~,' There is need for simple, accurate, reproducible indicators of fall risk Based on observational experience with a number of balance maneuvers and discussion with other investigators, we hypothesized that one-leg balance (defined as the ability to stand on one leg unsupported for seconds) might be a simple predictive factor for injurious falls and frailty To test this hypothesis, we studied the relationship between one-leg balance and falls among subjects in the Albuquerque Falls Study, a prospective study of falls in healthy older persons living in the community,6 which is part of a larger longitudinal study on aging: the New-Mexico Aging Process Study METHODS Subjects Entrance to the Albuquerque Falls Study (AFS)(n= 482) was limited to volunteers older than 60 years of age with no known serious medical conditions All participants were white, more than 40% had attended college, and most of them lived at home or in residences for older persons Baseline Examination All subjects underwent an initial examination consisting of an interview, a physical examination, and an assessment of gait and balance performance These tests are described in detail below The Iowa Self-Assessment Inventory (ISAI)' was administered to all subjects The ISAI is a 56 item self-administered questionnaire reported to be a reliable and valid instrument to assess sense of well being The subjects underwent a medical history questionnaire and a general physical exam including blood pressure, Mini-mental State Exam (MMSE),' and assessment of drug prescription and consumption Balance and gait performance was assessed using the instrument developed by Tinetti.' In addition, we tested one-leg balance, i.e., asking the subject to stand unassisted on one leg for seconds, again using a method reported by Tinetti We asked the subject being tested to choose a leg to stand on (whichever he felt more comfortable with), flex the opposite knee allowing the foot to clear the floor, and balance on one leg as long as possible; the nurse recorded whether the subject was able to balance for seconds These balance and gait tests satisfied the need for an instrument that ( ) required n o equipment and little experience to master so that it could be used in a typical clinical setting without intensive training; 0002-86 14/9 7/$3.50 73fi VELLAS ET AL _ _ _ _ ~ JUNE 1997-VOL.45, NO - (2) was reliable yet sensitive to significant changes; and (3) most importantly, reflected position changes and gait maneuvers used during normal daily activities The geriatric assessment was repeated annually to assess the evolution of gait, balance, activity and health status Repeat measures allow investigation of possible associations of the above changes with falls and better documentation of post-fall sequellae Assessment of Falls The subjects were instructed to report a fall event by calling the study coordinator We used the definition of fall defined by the World Health Organization (WHO) and the Kellogg International Work Group on the Prevention of Falls by the Elderly: “A fall is an event which results in a person coming to rest inadvertently on the ground or other lower level and other than as a consequence of a violent blow; loss of consciousness or sudden onset of paralysis” In order to capture unreported falls, all participants were sent a stamped post-card every other month inquiring specifically about whether or not a fall had occurred If no response was received after 15 days, a second card was sent Each subject was interviewed as soon as possible after each reported fall in order to review the circumstances and determine whether the incident met the study definition of a fall If it did meet the definition, a WHO Falls Questionnaire was completed by the study coordinator during a telephone interview We were also able to assess aspects of the severity of falls Injurious falls were defined as falls for which medical attention was sought Follow-up data were collected on all study subjects for years Statistical Analyses Analysis was conducted using the Statistical Analysis System for personal computers Tests of statistical significance were done using chi-square tests when comparing percents and either a t test (for normally distributed data) or a Wilcoxon rank sum test (for non-normally distributed data) when comparing means A significance level of 05 was used for all tests The present report gives results for the 36-month study period All falls and fall-related injuries reported during this period constituted the outcome variables Predictor variables are those assessments (including one-leg standing balance) made at the subjects’ annual visit before the study period RESULTS The mean age (SD) of the participants at entry into the study was 72.7 (k6.1) years, and 59% percent were women As reported previously, the cognitive status of this population was generally excellent, and no subject was severely demented The community mobility was generally good, and few participants had difficulty with transportation or doing their own shopping as determined by specific questions in the ISAI questionnaire.6 In 1990,483 subjects were enrolled in the Albuquerque Falls Study Six of these subjects were dropped because they did not have a one-leg balance measured in 1990 Another 113 subjects dropped out of the study in the subsequent years, leaving 364 remaining subjects In order to use a dichotomous outcome for falls and injurious falls, it was necessary for subjects to have nearly complete follow-up over the years we were following them for occurence of falls and JAGS ~~ injuries We decided to exclude subjects who did not respond to four or more postcards Because postcards were mailed every other month, this meant that subjects could miss up to months of follow-up (of a total of 36 months) and still be included in the study This final exclusion resulted in 48 subjects being dropped and gave a final sample size of 316 The subjects who dropped out or failed to respond were, on average, about years older that those who completed the 3-year follow-up, but they did not differ in terms of sex, gait abnormality, Mini-Mental State Exam score, or Body Mass Index They were, however, more likely to fail the balance test at baseline (38% vs 26% of those who completed followUP) In 1990, 267 of the 316 subjects (84.5%) were able to stand on one leg unsupported for seconds The remaining 49 subjects, who were unable to balance this way for seconds, were hypothesized to be more likely to fall or to have an injurious fall during the subsequent years Table shows baseline data by one-leg balance in 1990 As a result of many non-normal distributions, continuous variables were dichotomized as shown in the table Subjects who were unable to balance on one leg were significantly older than subjects who had normal balance They also had significantly more gait abnormalities than the comparison group There was also a difference of borderline significance ( P = 08)between the two groups with regard to MMSE score in which subjects with abnormal one-leg balance had lower scores for cognitive functions than did the comparison group Women were slightly more likely to have abnormal balance, but this was not significant There was little difference between the groups with respect to number of medications, Body Mass Index, and any of the self-reported measures Table Baseline Data from 1190 by One-Leg Standing Balance in 1990 One Leg Balance in 1990 Normal Age 573 >73 Sex Women Men Gait abnormalities 1+ Number of medications 1+ Abnormal n % n % P 150 117 56.2 43.8 11 38 22.4 77.6 OOO 156 111 58.4 33 41.6 16 67.3 32.7 242 243 24 91.0 31 9.0 18 63.3 36.7 OOO 58 208 21.8 78.2 40 18.4 81.6 150 116 56.4 21 43.6 28 42.9 57.1 129 137 48.5 26 51.5 23 53.1 46.9 MMSE score 30