This study assessed predictive factors of recurrent falls by age group in young-old and old-old elderlies. First, 8.8% and 12.3% of young–old and old–old elderlies fell only once in the past year, respectively, whereas 4.5% of young–old and 6.7% of old–old elderlies fell more than twice. Thus, both single and recurrent fall rates were higher in the old–old elderly, which was consistent with a previous study reporting an increased rate of falls with age . Additionally, half of those who experienced a single fall also experienced recurrent falls, which was consistent with the results reported by Kabeshova et al .
In both young–old and old–old elderlies, factors that affected recurrent falls were limitations in ADL, visual aid, suicidal ideations, and the number of chronic diseases. The young–old and old–old elderlies with limitations in ADL were 2.25 and 1.98 times more likely to experience recurrent falls, respectively, which is consistent with the results of a previous study  showing that the risk of falls increased as the ability to perform ADL decreased. The elderly have difficulties in balance with sitting to standing and surface-to-surface transfer . Decreased body function likely leads to an increase in the rate of falls; thus, the physical functions of the elderly must be assessed to propose measures to prevent falls.
The young–old and old–old elderlies with visual aids experienced 1.56 and 1.54 times more recurrent falls, respectively, than those without visual aids. The WHO also suggested poor balance and limited vision as risk factors of falls. Therefore, creating an appropriate environment and developing auxiliary devices to complement for decreased sensory functions may be necessary .
The young–old and old–old elderlies with suicidal ideations experienced recurrent falls 1.69 and 1.63 times more than those without suicidal ideations, respectively. In a study using large-scale national data , depression, along with the fear of falling, was identified as a risk factor for falls in the elderly. However, although both depression and suicidal ideations were assessed in our study, only suicidal ideations were shown to significantly affect falls. A previous study noted that depression affected single falls whereas recurrent falls were affected not only by depression but by multiple factors including sleep disturbance and subjective stress . Since suicidal ideations reflect both family structures and social activities, multi-dimensional approaches at individual, family, and community levels are necessary to prevent recurrent falls.
In our study, young–old and old–old elderlies were 1.22 and 1.18 times more likely to experience recurrent falls, respectively, as the number of chronic diseases increased by one. This was consistent with the findings of studies showing that the number of chronic diseases was related to falls . In a previous study , the elderly with chronic diseases believed that their subjective health was bad, which led to a vicious cycle of increased fear and falls. Therefore, interventions that consider the physical health and psychological aspects in the elderly are necessary.
There were some differences in the factors that affected recurrent falls in young–old and old–old elderlies. In the young–old, cognitive function and number of prescribed medications were predictors of recurrent falls. It was consistent with the finding that decreased cognitive function increased the risk of falls . In young–old elderlies, as cognitive function starts to decline, there are also differences in the level of decrease in cognitive function, which are believed to have affected the differences observed in the results of this study.
As the number of prescribed medications increased by 1, the odds of recurrent falls increased by 1.06 times, which was consistent with the finding that medications increase the risk of falls in the elderly . Since medications increase the likelihood of adverse drug reactions and drug interactions in the elderly, more medications can cause greater side effects from drug interactions . Therefore, physicians must provide explanations for medications that greatly increase the risk of falls to the elderly, and education on behavior guidelines may be necessary to prevent falls.
Unique predictive factors of recurrent falls in the old–old were spouse status, NBLSS beneficiaries, exercise, and Parkinson's disease. As noted in a study reporting that spouse is a factor affecting falls , our finding suggests that having a spouse affects both single and recurrent falls. The old–old are less influenced by their spouse at home because they participate less in work or social life. Thus, support systems that can continue to provide support, such as spouses, can prevent recurrent falls in those with reduced body functions.
Furthermore, NBLSS beneficiaries were 1.53 times more likely to experience recurrent falls, which supported a WHO report that included socioeconomic factors, such as poverty, as risk factors for falls . This finding suggests that NBLSS beneficiaries are socially and economically vulnerable, which may also indicate that the risk of falls in the residential environment is high. In the elderly, the risks of fall-related injuries and death are high because of aging-related physical, sensory, and cognitive changes and unsafe environments . Since forming a safe environment is an important factor for preventing falls, NBLSS beneficiaries would require support for assessment and improvement of the residential environment for a safe living environment.
Those who did not exercise were 1.48 times more likely to experience recurrent falls. This finding was not consistent with the results of a previous study indicating that lack of exercise was a main risk factor of falls in the elderly over the age of 80 . Our study defined exercise as 10 minutes or more once a week whereas the definitions and classifications of exercise varied in previous studies, and mixed results were reported. One previous study reported exercise time as a risk factor for falls in those over the age of 85. The risk of falls was higher in those who exercised for a short period of 10–20 minutes than in those who exercised for 30 minutes or more , suggesting that the type, intensity, and duration of exercise affect the risk of falls. Therefore, safety must be prioritized in exercise programs for the elderly, particularly the old–old. Because exercise is important for the elderly with weak physical functions, interventions that are safe for the elderly must be created.
Lastly, those with Parkinson's disease were more likely to experience recurrent falls than those without, which is consistent with previous results indicating that Parkinson's disease is closely related to falls since it affects motor function . Moreover, falls are the most important factor causing disability in Parkinson's patients . Therefore, those with Parkinson’s disease must be considered a high-risk group, and appropriate measures to prevent falls are necessary.
This study observed differences in factors related to recurrent falls between young–old and old–old elderlies. Risk assessments that reflect the characteristics of different age groups of the elderly must be developed to screen for recurrent falls in the community. Additionally, further studies that evaluate the effects of interventions and strategies that can prevent re-falls in high-risk groups are required. However, the cross-sectional design of this study limits the assessment of causality of the relationship between the variables. Longitudinal studies that include causal variables to assess the cause-and-effect relationship should be conducted in the future.