THE PREVALENCE OF FEAR of falling is high in community-dwelling

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1 ORIGINAL ARTICLE What is the Relationship Between Fear of Falling and Gait in Well-Functioning Older Persons Aged 65 to 70 Years? Stephane Rochat, MM (Clin Epi), Christophe J. Büla, MD, Estelle Martin, PhD, Laurence Seematter-Bagnoud, MPH, Athanassia Karmaniola, PhD, Kamiar Aminian, PhD, Chantal Piot-Ziegler, PhD, Brigitte Santos-Eggimann, DrPH 879 ABSTRACT. Rochat S, Büla CJ, Martin E, Seematter- Bagnoud L, Karmaniola A, Aminian K, Piot-Ziegler C, Santos- Eggimann B. What is the relationship between fear of falling and gait in well-functioning older persons aged 65 to 70 years? Arch Phys Med Rehabil 2010;91: Objective: To investigate the association between fear of falling and gait performance in well-functioning older persons. Design: Survey. Setting: Community. Participants: Subjects (N 860, aged 65 70y) were a subsample of participants enrolled in a cohort study who underwent gait measurements. Interventions: Not applicable. Main Outcome Measures: Fear of falling and its severity were assessed by 2 questions about fear and related activity restriction. Gait performance, including gait variability, was measured using body-fixed sensors. Results: Overall, 29.6% (210/860) of the participants reported fear of falling, with 5.2% (45/860) reporting activity restriction. Fear of falling was associated with reduced gait performance, including increased gait variability. A gradient in gait performance was observed from participants without fear to those reporting fear without activity restriction and those reporting both fear and activity restriction. For instance, stride velocity decreased from to to m/s (P.001) in participants without fear, with fear but no activity restriction and with fear and activity restriction, respectively. In multivariate analysis, fear of falling with activity restriction remained associated with reduced gait performance, independent of sex, comorbidity, functional status, falls history, and depressive symptoms. Conclusions: In these well-functioning older people, those reporting fear of falling with activity restriction had reduced gait performance and increased gait variability, independent of health and functional status. These relationships suggest that early interventions targeting fear of falling might potentially From the Service of Geriatric Medicine and Geriatric Rehabilitation (Rochat, Büla, Martin, Seematter-Bagnoud) and Institute of Social and Preventive Medicine (Seematter-Bagnoud, Karmaniola, Santos-Eggimann), University of Lausanne Hospital Center; Laboratory of Movement Analysis and Measurements, Ecole Polytechnique Federale de Lausanne (Aminian); and Institute of Psychology, CerPsa, Social and Political Sciences Faculty, University of Lausanne (Piot-Ziegler), Lausanne Switzerland. Presented in part to the Gerontological Society of America, November 21 25, 2008, National Harbor, MD. Supported by the Swiss National Scientific Foundation (grant nos and 32473B ), the Leenaards Foundation, the Loterie Romande. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. Reprint requests to Stephane Rochat, MM (Clin Epi), Service of Geriatric Medicine & Geriatric Rehabilitation, CUTR Sylvana, 1066 Epalinges, Switzerland, stephane.rochat@chuv.ch /10/ $36.00/0 doi: /j.apmr help to prevent its adverse consequences on mobility and function in similar populations. Key Word: Rehabilitation by the American Congress of Rehabilitation Medicine THE PREVALENCE OF FEAR of falling is high in community-dwelling older people, ranging up to 60% in some studies. 1-4 Fear of falling has been related to several adverse outcomes, including activity restriction, functional decline, falls, and reduced quality of life In prospective studies, fear of falling has also been associated with incident mobility impairment, in particular in older people reporting activity restriction related to fear of falling. 3,12 The complex relationship between fear of falling and gait performance is not completely understood. Several studies showed that reduced gait speed is associated with higher levels of fear. 9,13,14 However, the causality and the direction in the relationship between fear of falling and gait is uncertain and possibly reciprocal. Some studies suggest that gait modifications associated with fear of falling could primarily be gait adaptations to improve stability and therefore reduce the risk of falling Overall, the relationship between fear of falling and specific gait parameters has not been widely investigated. While fear of falling has been associated with reduced stride length and increased double support time in selected small samples of frail older people, conflicting results have been found regarding the relationship between fear of falling and variability in gait parameters, an important risk factor for falling. 15,17-19 An additional limitation of several previous studies is the relatively small set of variables that were accounted for in the multivariate analyses. In particular, adjustment for potential confounders such as muscular strength, comorbidity, and falls history was not always performed. Finally, most previous studies were conducted in already frail and disabled older people. Younger and well-functioning older people might actually be better candidates to benefit from early preventative interventions specifically targeting fear of falling and mobility. In order to design such interventions and to monitor their effect, it is necessary to better understand the intricate relationship between fear of falling and gait performance in this population. The aim of this study was to evaluate the cross-sectional relationship between self-reported fear of falling, with or with- CI CV FES-I Lc65 List of Abbreviations confidence interval coefficient of variation Falls Efficacy Scale-International Lausanne cohort 65

2 880 FEAR OF FALLING AND GAIT PERFORMANCE, Rochat out activity restriction, and specific gait parameters assessed at baseline in a cohort of young (65 70y) and well-functioning community-dwelling older people. The hypothesis was that, in this population, fear of falling would be associated with gait performance independent of comorbidity, previous falls, and muscular strength. Secondary hypothesis was that gait performance would be more impaired as the severity of fear of falling increased. METHODS Study Design and Population Participants were a subsample of subjects enrolled in the Lc65. The recruitment of the cohort has been described in detail elsewhere. 20 Briefly, a random sample of 3056 community-dwelling persons born between 1934 and 1938 was contacted. From the 1310 subjects who completed baseline data collection during an in-person visit, 861 had gait parameters recorded. Main reasons for missing gait parameters were unavailability of the recording device (24.9%, n 326), inability to walk because of health and/or safety problems (5.3%, n 69), inability to travel to examination site (2.8%, n 36), and gait evaluation refusal (1.4%, n 18). Data concerning fear of falling were missing for 1 subject. A total of 860 (860/1310, 65.6%) participants were included in this analysis. Compared with participants who did not undergo gait recording, those who did were more frequently men and married and had higher education, had better functional status, and less frequently reported one or more previous falls (data not shown). Data Collection Self-reported data about socioeconomic status, education, comorbidity (out of a list of 12 chronic diseases), vision impairment (difficulty reading a newspaper), previous falls (last 12mo), depressive symptoms, as well as difficulty or requiring help to perform basic and instrumental activities of daily living were collected using a postal questionnaire. 21 Data collected during the in-person visit included measures of height, weight, and cognitive performance using the Mini- Mental State Examination. 22 Maximal grip strength in the right hand (best performance of 3 trials) was measured using a BASELINE hand-held dynamometer, a and the time to perform 5 chair stands was used to evaluate leg strength. 23 Gait assessment. Gait was assessed over 20m, on a welllighted walkway with participants walking with their own shoes at self-selected speed. Gait parameters were measured using the Physilog system, b a device that includes 4 body-fixed sensors on lower limbs and a data logger carried on the waist. 24,25 Stride velocity (m/s), stride length (m), total double support (% of the gait cycle with both feet on the ground), and step cadence (steps/min) were estimated from the angular velocity recorded by the Physilog system. In addition, gait variability was assessed using CV of each gait parameter (CV in %, defined as the SD divided by the mean value of the parameter for each stride). Fear of falling assessment. Fear of falling and related activity restriction were assessed using as a first step the single question: Are you afraid of falling? Three levels of fear were considered: no fear, moderately fearful, very fearful. The variable was dichotomized in afraid of falling yes/no by combining the last 2 levels of fear, because very few people reported being very fearful (n 16). Participants reporting fear of falling were then asked a second question: Because of your fear of falling, have you restricted any activities? Participants were classified into 3 groups according to their answers: not afraid of falling, afraid of falling without activity restriction, and afraid of falling with activity restriction. In addition, falls efficacy was measured using the FES-I. 26,27 The FES-I is based on self-reported concern about falling while performing 16 activities of daily living. FES-I scoring was reversed and standardized to provide a score ranging from 0 to 100, higher scores indicating higher falls efficacy. 28 Data collection was performed by trained research assistants, using a standardized protocol. The ethics committee from the Faculty of Biology and Medicine, University of Lausanne, approved the project, and written consent was obtained during the in-person visit. Statistical Analyses Characteristics of participants (including gait parameters) were compared across the 3 groups of participants (without fear, with fear but no activity restriction, and with both fear and activity restriction), using chi-square test for categorical variables, Kruskal-Wallis test for continuous variables, and tests for trend (nonparametric Cuzick test). The Kruskal-Wallis test was used because of heteroscedasticity in the continuous variables and the presence of outliers in the 3 groups. Bivariate and multivariate robust linear regression analyses were performed to examine the association between fear of falling and gait performance. The following adjustment variables were included in the analyses: age, sex, living alone, education, falls in the last 12 months, depressive symptoms, visual impairment, comorbidity, and functional impairment. Cognitive impairment and height were not included as covariates in the models because of collinearity with other covariates. Finally, to further investigate the effect of muscular strength on the relationship between fear of falling and gait performance, multivariate analyses were repeated after adding grip strength and time to perform 5 chair stands as covariates into the full model. Analyses were conducted using Stata, version c RESULTS Overall, 70.3% (605/860) of the participants reported no fear of falling, 24.4% (210/860) reported fear of falling without activity restriction, and 5.2% (45/860) reported fear of falling with activity restriction. Table 1 provides the baseline characteristics of the population and compares these characteristics across the 3 groups. Significant gradients were observed from participants without fear of falling to those with fear but no activity restriction and to those reporting both fear and activity restriction in the proportions of women and participants living alone and those with 2 or more chronic diseases, depressive symptoms, and impairment in basic as well as instrumental activities of daily living. Falls efficacy (reversed and standardized FES-I) significantly decreased as the severity of fear of falling increased across the 3 groups. Decreased muscular strength (decreased grip strength and increased time to perform 5 chair stands) was also associated with levels of fear of falling. Comparisons of gait parameters across categories of fear of falling are presented in figure 1. Differences were observed across the 3 groups, with gradual decrease in stride velocity and stride length, as well as a gradual increase in total double support from participants reporting no fear of falling to those reporting fear but no restriction and those reporting both fear and activity restriction. In contrast, only this latter group had a significantly reduced step cadence compared with those without fear (see fig 1D). Comparisons of CV revealed similar trends with a small increase in the CV of stride velocity, stride length, and cadence

3 FEAR OF FALLING AND GAIT PERFORMANCE, Rochat 881 Table 1: Baseline Characteristics of the Study Population and Bivariate Comparisons According to the Presence of Fear of Falling and Activity Restriction Variables Total Population No Fear of Falling? Yes Activity Restriction? (N 860) (n 605, 70.4%) No (n 210, 24.4%) Yes (n 45, 5.2%) P* P Age (y) Women (%) Higher education (%) Living alone (%) Comorbidity (2 chronic diseases, %) Depressive symptoms (%) Cognitive impairment (%) Visual impairment (%) Basic ADLs impairment (%) # Instrumental ADLs impairment (%)** Falls in the last 12 months (%) None One Two or more rsfes-i score Grip strength (pounds) Time to perform 5 chair stands (s) NOTE. Values are mean SD unless otherwise specified. Abbreviation: ADLs, activities of daily living; rsfes-i, reversed and standardized FES-I. *Kruskal-Wallis test for continuous variables; chi-square test for categorical variables. Nonparametrical Cuzick test for trend. Defined as 12 or more years of education. Defined as at least 1 positive answer to 2 screening questions for depression. Defined as a score 24/30 on Folstein s Mini-Mental State Examination. Defined as difficulty reading a newspaper. # Defined as difficulty or help received in at least one basic ADLs. **Defined as difficulty or help received in instrumental ADLs. in participants with fear of falling. Variability in double support was actually slightly decreased among participants reporting fear with activity restriction. This result was not statistically significant. Table 2 presents results from analyses investigating the association between fear of falling and gait performance. In bivariate analyses, fear of falling with activity restriction was associated with significantly worse performance in all gait parameters, including increased variability. Although weaker, these associations were also present for most gait parameters in participants reporting fear of falling but no activity restriction. In multivariate analyses, compared with participants without fear of falling, only those reporting fear of falling with activity restriction remained with significantly decreased stride velocity (.10 m/s, P.001) and stride length (.06m, P.005), increased stride velocity CV (.39%, P.042) and total double support (1.41%, P.028), and reduced step cadence ( 5.05 steps/min, P.001). Adding grip strength and time to perform 5 chair stands to the multivariate models reduced but did not cancel these relationships, because fear of falling with activity restriction remained associated with decreased stride velocity (.05 m/s, 95% CI.10 to.00, P.034). A weaker association was also found between fear of falling with activity restriction and step cadence ( 2.59 steps/min, 95% CI 5.32 to.14, P.063). DISCUSSION This study shows that fear of falling was independently associated with reduced gait performance in a population of community-dwelling, well-functioning elderly persons aged 65 to 70 years. Results provide original and detailed information on gait performance across levels of fear of falling in this population and show evidence of a gradual and significant deterioration in most gait parameters across levels of fear of falling and activity restriction, despite the overall favorable health and functional status of these participants. Although relatively small, these differences can be considered as clinically significant, as suggested in a study about significant changes in physical performance. 29 In particular, these results suggest that, even in relatively young older persons, selfreported activity restriction because of fear of falling is likely to be a useful prognostic marker because gait performance, especially gait speed, is a strong predictor of adverse events such as future falls and functional decline, as well as mortality. This will need to be further investigated in this cohort. Results from the current study also add to current knowledge in suggesting that different mechanisms might be at work in subjects who report and in those who do not report fear-related activity restriction. In the former, the significant relationship between fear and gait alteration persisted after adjustment for multiple covariates including age, previous falls, comorbidity, depressive symptoms, and functional impairment. In contrast, in the latter group that did not report fear-related activity restriction, this relationship did not remain significant once adjusted for covariates. Although cross-sectional, these results suggest that when fear of falling is not accompanied by activity restriction, its association with reduced gait performance is mainly mediated by the effect of confounders such as comorbidity and functional impairment.

4 882 FEAR OF FALLING AND GAIT PERFORMANCE, Rochat Fig 1. Comparison of gait performance among subjects reporting no fear of falling, fear without activity restriction, and fear with activity restriction (mean and 95% CIs). (A) Stride velocity and stride velocity CV. (B) Stride length and stride length CV. (C) Total double support and total double support CV. (D) Cadence and cadence CV. NOTE. Values are mean SD. Squares represent mean values; bars represent 95% CIs. CV: coefficient of variation, where CV (SD/mean) 100. *Kruskal-Wallis test for continuous variables. Nonparametrical Cuzick test for trend. The lower level of falls efficacy in participants reporting activity restriction because of fear of falling, compared with those reporting fear only, highlights the specific importance of self-reported activity restriction as a marker of fear of falling s severity, a finding that has not been yet reported in similar, well-functioning populations. These results also extend previous observations in providing new insights about the possible pathway linking activity restriction caused by fear of falling and adverse events. Overall, several previous studies suggested that the effect of activity restriction on these outcomes was mostly mediated by a reduction in muscular strength and postural control. 6,12,30 For instance, a previous study in an older and more heterogeneous population than the current one found that fear-related avoidance of activities was a predictor of falls at 1 year and was strongly associated with reduced upperand lower-body maximal strength. 30 In another study, activity restriction was independently associated with reduced performance on a timed composite mobility score. 31 In contrast, our results show that, even after adjusting for upper- and lower-body strength (grip strength and time to perform 5 chair stands), fear of falling with activity restriction remained independently associated with reduced gait speed. Although residual confounding is always possible, this strongly suggests that fear by itself, when severe enough to cause activity restriction, might have a direct effect on gait, independent of physical performance. These findings support the hypothesis that the relationship between gait performance and fear of falling could be reciprocal rather than unidirectional (gait impairment leading to fear of falling and fear of falling also directly causing gait impairment through attentional interference). This kind of reciprocal relationship has been found previously in

5 FEAR OF FALLING AND GAIT PERFORMANCE, Rochat 883 Table 2: Unadjusted and Adjusted Beta Coefficients from Linear Regression Analysis Investigating the Association Between Fear of Falling and Gait Parameters Gait Parameters Fear of Falling Unadjusted Coefficient (95% CI) P Adjusted Coefficient* (95% CI) P Stride velocity (m/s) No fear Reference Reference Fear without activity restriction 0.04 ( 0.07 to 0.02) ( 0.04 to 0.02).435 Fear with activity restriction 0.15 ( 0.20 to 0.11) ( 0.15 to 0.05).001 Stride velocity CV (%) No fear Reference Reference Fear without activity restriction 0.20 (0.01 to 0.38) ( 0.07 to 0.34).182 Fear with activity restriction 0.46 (0.10 to 0.83) (0.01 to 0.76).042 Stride length (m) No fear Reference Reference Fear without activity restriction 0.05 ( 0.08 to 0.03) ( 0.04 to 0.01).194 Fear with activity restriction 0.12 ( 0.16 to 0.08) ( 0.10 to 0.02).005 Stride length CV (%) No fear Reference Reference Fear without activity restriction 0.15 (0.01 to 0.29) ( 0.02 to 0.27).097 Fear with activity restriction 0.32 (0.06 to 0.59) ( 0.05 to 0.52).106 Total double support (%) Total double support CV (%) Step cadence (steps/ min) No fear Reference Reference Fear without activity restriction 1.24 (0.59 to 1.89) ( 0.20 to 1.13).168 Fear with activity restriction 2.77 (1.51 to 4.02) (0.15 to 2.68).028 No fear Reference Reference Fear without activity restriction 0.20 ( 0.64 to 1.04) ( 0.34 to 1.48).217 Fear with activity restriction 1.65 ( 3.26 to 0.04) ( 2.90 to 0.40).138 No fear Reference Reference Fear without activity restriction 0.20 ( 1.17 to 1.74) ( 1.99 to 0.84).429 Fear with activity restriction 5.20 ( 8.00 to 2.39) ( 7.73 to 2.37).001 Step cadence CV (%) No fear Reference Reference Fear without activity restriction 0.07 ( 0.04 to 0.18) ( 0.13 to 0.10).806 Fear with activity restriction 0.28 (0.06 to 0.50) ( 0.03 to 0.40).087 CV: coefficient of variation, where CV (SD/mean) 100. *Adjusted for covariates including age, sex, living alone, education, falls in the last 12 months, depressive symptoms, visual impairment, comorbidity, and functional impairment. the association between fear of falling and falls in a prospective study in community-dwelling elderly people. 8 The cross-sectional design of this study, nevertheless, prevents any conclusion about the chronology as well as the causality in the observed relationships between fear of falling, activity restriction, and gait performance. This will be tested prospectively with follow-up data from the current study. This study also contributes to a better understanding of the relationship between fear of falling and gait variability. While this association has been previously shown in a small sample of selected older adults with higher level gait disorders of unknown origin, 19 this study is the first, to our knowledge, to demonstrate this association in relatively young elderly persons without specific gait impairment. This result is intriguing and raises several hypotheses. Gait variability might directly cause or worsen fear of falling by increasing gait unsteadiness and the perceived risk of falling. Hence, gait variability would lead to fear of falling. On the other hand, the consequences of activity restriction caused by fear of falling could be severe enough to have a global effect on the gait process, reducing gait performance and also disrupting its rhythm and regularity, resulting in increased variability. 16 Again, both effects could be present and result in a vicious circle of fear of falling and gait impairment. Study Limitations A limitation of the study is the fact that gait performance was recorded only in a subsample of the initial cohort. However, the main reason for missing data (ie, unavailability of gait measuring device) occurred randomly. Moreover, despite this potential selection bias, the prevalence of fear of falling in participants with recorded gait tests was consistent with the results of a recent national survey in the United States, in which 28.9% of community-dwelling older adults aged 65 to 74 years reported having experienced fear of falling, a proportion similar to this study. 5 This study has several strengths, including the large number of participants with a narrow age range, making it a homogeneous cohort of well-functioning individuals. A unique feature is also the detailed assessment of gait parameters, which were recorded over a longer distance than usual, an important factor to adequately measure gait variability. 32,33 Finally, an extensive set of potential confounders, including performance-based measures, was collected and adjusted for in the analyses. The findings of this study might contribute to better designing fear of falling intervention programs in several ways. Although gait training and strengthening exercise are likely to be beneficial in all fearful subjects, independent of their reporting of activity restriction, 34 the weakening in the relationship between fear of falling and gait performance observed once controlling for comorbidity suggests that interventions should also emphasize optimal comorbidity management. In addition, in subjects reporting activity restriction, the persistence of an independent association between fear of falling and gait impairment after multivariate adjustment suggests that interventions in these subjects should ideally also include a psychologic component specifically targeting this factor. CONCLUSIONS This study provides new evidence of an independent association between fear of falling and gait performance, including increased gait variability. Even in well-functioning older people, fear of falling appears as an important prognostic marker, to be confirmed in longitudinal data. As such, it could be a specific target for interventions aimed at preventing or delaying functional decline and disability.

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