In the present study, the associations between fall-related self-efficacy and speed and step length in gait parameters at maximum pace were clarified. These findings agreed with those of previous studies [12–15]; therefore, fall-related self-efficacy appears to be definitely associated with spatiotemporal gait parameters and to be an index reflecting not only gait speed, but also gait patterns for older people. In the present study, the changes in gait parameters between usual and maximum paces (Δgait parameters) were also related to fall-related self-efficacy. In a previous study, the difference in gait speed between usual and maximum paces was defined as walking speed reserve, and a smaller walking speed reserve was reported to be associated with cognitive decline in older people . Similarly, Δgait parameters as reported in the present study appear to indicate so-called gait function reserve in older people; thus, decreased gait function reserve may lead to a decline of fall-related self-efficacy. However, the clinical meanings of the Δgait parameters or gait function reserve need to be investigated in future studies.
As described above, fall-related self-efficacy and gait function were shown to have a definite association. On the other hand, the results of the present study also indicated that fall-related self-efficacy and Δdouble support time were each independent risk factors for falls. Fall-related self-efficacy has already been shown to be associated with future falls in previous studies [5–8]; the result of the present study agreed with the results of those studies. With respect to gait function, gait speed has been found to be a predictor of future falls [4, 26]. Furthermore, in addition to gait speed, it has been suggested that step length, double support time, and gait variability are associated with the occurrence of falls [4, 13, 27]. Therefore, since various gait parameters reflect on gait function and can be associated with fall risk factors, the finding that one of the Δgait parameters that may reflect gait function reserve was significantly associated with falls was not unexpected.
However, few studies have investigated the effect of the interaction of fall-related self-efficacy and gait function on the occurrence of falls. In the present study, the interaction between fall-related self-efficacy and Δgait parameters was associated with future falls, even after adjustment for confounding factors. Thus, not only fall-related self-efficacy and gait function were each independent fall risk factors, but also the interaction between both factors was found to affect future falls. In a previous study, a discrepancy between self-reported subjective physical function and test-based objective physical function was reported to be associated with future falls . Furthermore, a discrepancy between self-reported mobility and test-based mobility was reported to be associated with mortality . In addition, the interaction between subjective cognition and objective cognition was also found to have an effect on actual memory performance in previous studies . From the result of the present study, older people with a smaller Δdouble support time or Δstance time despite high self-efficacy tended to have a risk of future falls. Therefore, even if self-efficacy, which is a subjective assessment, is maintained at a high level, when gait function or gait function reserve, which is an objective assessment, is in decline, fall risk may be increased.
For prediction of future falls, spatiotemporal gait parameters and performance tests such as the TUG test, which are objective assessments of physical factors, have been shown to have insufficient predictive accuracy [31–33]. Similarly, the predictive accuracy of a scale for fall-related self-efficacy, which is a subjective assessment of psychological factors, was also suggested to be insufficient . The findings of the present study suggest that the accuracy of identification of older people with a high risk for falls may be improved by combined assessment of subjective/psychological risk factors such as fall-related self-efficacy and objective/physical risk factors such as gait function. However, in order to determine an algorithm and an accurate fall risk assessment considering the interaction between subjective/psychological and objective/physical factors, further studies are needed.
In this study, fall-related self-efficacy was evaluated as a psychological factor related to fall risk in older people. On the other hand, it has also been suggested that cognitive function, such as executive function, as one of the psychological factors, is associated with falls . As for the relationship between cognitive function and falls, older people with the combination of slow gait speed and mild cognitive impairment (MCI) were reported to have a higher fall risk than those with only slow gait speed or only MCI . Therefore, a combined assessment of cognitive function and gait function may be useful to predict falls. However, evaluation of cognitive function of older people is not easy and simple from the point of feasibility compared to fall-related self-efficacy. In fact, testing cognitive functions in multiple domains such as memory, attention, and language is necessary to assess MCI. However, the short FES-I used in this study can be assessed by just 7 questionnaire items; thus, use of this scale in local community and clinical settings is a strength.
The present study had several limitations. All of the participants of this study were independent in ADL, and about 90% were also independent in IADL. Thus, since almost all of the participants maintained good functional status, the effect of bias of the participants’ attributes on the results cannot be completely ruled out. Furthermore, about 20% of the participants could not complete the follow-up survey on the occurrence of falls. The bias caused by the missing data was estimated to be slight, but one cannot say that the missing data had absolutely no effect on the results of this study. Finally, it has been suggested that fall-related self-efficacy is affected by cultural differences . Therefore, when the results of this study are generalized to older populations other than Japanese, they must be interpreted carefully.
In conclusion, fall-related self-efficacy and spatiotemporal gait functions were associated with each other, and they were each independent risk factors for falls. Furthermore, the interaction between fall-related self-efficacy and gait function appeared to affect fall risk. Assessments that include fall-related self-efficacy and gait function may improve the accuracy of predicting the occurrence of falls.