Abstract

Background

The fear of falling is a common issue among older adults that negatively affects physical and psychological aspects of health-related quality of life, regardless of actual fall events. Interventions aimed at reducing fear of falling, independent of falls, may improve older adults鈥� quality of life. This study examined the moderated mediation effect of physical activity in how fear of falling affects health-related quality of life through depression in community-dwelling older adults.

Methods

This study used secondary data from the Korea Centers for Disease Control and Prevention鈥檚 2019 Community Health Survey. The study included 73,738 adults aged 65 years or older. The researchers used the fear of falling scale, International Physical Activity Questionnaire, Patient Health Questionnaire-9, and EuroQol 5 Dimension as research tools, and performed descriptive statistics, Pearson鈥檚 correlation coefficient, and SPSS PROCESS macro analysis. The study used the bootstrapping method to assess the adjusted mediating effect by resampling 5,000 times, and determined statistical significance with a 95% confidence interval.

Results

In the model in which fear of falling affects health-related quality of life by mediating depression, the moderated mediation effect of physical activity was statistically significant, as the bootstrapping result did not include 0 in the 95% confidence interval (Index of moderated mediation [95% CI]鈥�=鈥�0.006 [0.004鈥�0.007], 0.008 [0.006鈥�0.009]). Depression and health-related quality of life impairment decreased as the level of physical activity increased through inactivity, minimal activity, and health promotion activities, as the negative mediating effects decreased.

Conclusion

Physical activity reduces depression and improves health-related quality of life by influencing older adults鈥� fear of falling. Community-based programs are needed to encourage and support older adults in maintaining moderate physical activity to manage the depression caused by fear of falling, which is common among older adults, and to improve their health-related quality of life.

Introduction

The world population is aging; spending on age-related United Nations projects will increase from 761 million in 2021 to 1.6 billion in 2050 [1]. In 2021, Japan had the world鈥檚 highest population of older adults at 29.8%, followed by Italy with 23.7% [1]. South Korea has already become an aged society, with older adults accounting for 17.5% of the population in 2020鈥攅xpected to increase to 46.4% by 2070, giving South Korea the highest proportion of older adults globally [2]. Life expectancy in the Organization for Economic Co-operation and Development (OECD) is 83.5 years; South Korea鈥檚 average is 2.6 years longer for men and 3.3 years longer for women than the OECD average. Healthy life expectancy, excluding childhood illnesses, is 66.3 years鈥攁 significant gap [3]. Health-related quality of life (HRQOL) is an important issue for the growing older adult population, as people spend more time in their later years in poor health.

Older adults are at increased risk for falls due to age-related functional decline, disability, and serious injury [4]. Because a fall can be fatal, many older adults experience fear of falling (FOF) regardless of whether they have ever fallen [5]. FOF is a fall-related psychological concern affecting community-dwelling older adults鈥� health [6]. Experiencing relatives or friends of similar age who have fallen may also trigger FOF [7]. In Japan, the prevalence of FOF is as high as 86.48% [8]; Italy also found that a high percentage of older adults suffer from FOF [9]. In South Korea, a study using nationwide survey data found that the prevalence of FOF among community-dwelling adults aged 65 years and older was 75.6% [10], with 96.7% of older adults who had experienced a fall and 75.1% of those who had not experienced a fall experiencing FOF. Importantly, the interaction between FOF and fall history was not significant [11]. FOF is a common health problem among community-dwelling older adults, regardless if they experienced a fall. It is multifactorial and is associated with negative consequences for physical and psychosocial functioning [5, 12, 13]. A systematic review found a negative association between FOF in older people and their quality of life. This association was independent of fall events and more impactful than actual falls [14]. Consequently, scholars suggested that interventions to reduce FOF independent of falls may improve HRQOL in older adults [14].

Research commonly considers HRQOL dynamic, subjective, and multidimensional, and the dimensions often include physical, social, psychological, and spiritual factors [15, 16]. A recent study [13] examined the association between FOF and HRQOL among community-dwelling older adults in five European countries and found that, compared to those who reported low FOF, older adults who reported moderate or high FOF experienced lower physical and psychological HRQOL. In addition, studies found a strong association between FOF among community-dwelling older adults and physical components of quality of life, including physical function [17,18,19,20,21], physical role functioning [18], general health [17, 18], physical independence [22], and activity engagement [23], even after controlling for covariates. FOF strongly influenced the physical and mental health components of quality of life [17, 18, 21].

A recent study [24] reported that depression independently and serially with frailty mediated the relationship between FOF and psychological HRQOL, but the mediation effect was not significant in the relationship between FOF and physical HRQOL. Therefore, it is necessary to consider other factors affecting the association between FOF and physical HRQOL. Another study reported the relationship between self-concept of health and physical activity [25] and function and disability [26] mediated the association between FOF and HRQOL in community-dwelling older adults.

Physical activity has been a widely used intervention to improve the quality of life in older adults [27,28,29]. A systematic review and meta-analysis of the consequences of physical inactivity in older adults [30] found that physically active older adults had a reduced risk of all-cause mortality, fractures, recurrent falls, activities of daily living and functional limitations, cognitive decline, and depression, and improved quality of life. Researchers have found that in community-dwelling older adults, higher physical function, such as increased physical activity and reduced physical dependence, have an inverse association with FOF [20, 31, 32] and influences HRQOL [33,34,35]. A study examining the role of physical activity among nursing home residents found that physical activity was a full mediator in the pathway between FOF and depression and a moderator depending on activity level, suggesting that increasing activity is a beneficial intervention to prevent depression due to FOF [36]. Another study found that physical activity in older adults had a moderating effect on the relationship between depression and HRQOL [37].

Given these associations between physical activity and physical and mental health outcomes, it is likely that physical activity acts as a mediator or moderator in the relationship between FOF, depression, and HRQOL. However, few studies have examined physical activity as a moderator in the relationship between FOF and HRQOL in older adults. A better understanding of the relationship between these variables [38] is important for developing health interventions for older adults. Therefore, this study hypothesizes that physical activity in older adults moderates the pathways between FOF and depression and FOF and HRQOL. Using data from the Korea Centers for Disease Control and Prevention鈥檚 2019 Community Health Survey, we tested the moderated mediation effect of physical activity in the pathway through which FOF mediates depression to affect HRQOL.

Materials and methods

Design

This study used a descriptive cross-sectional survey design.

Study population

This study used data from the Korea Centers for Disease Control and Prevention鈥檚 2019 Community Health Survey, conducted among adults aged 19 and older throughout South Korea. We extracted the primary sample points using the probability proportional cluster sampling method and selected secondary sample households using the cluster sampling method [39]. From a total of 229,099 participants in the 2019 Community Health Survey, we selected data from participants who were adults aged 65 or older (n鈥�=鈥�74,547) for this study. After excluding subjects with FOF (n鈥�=鈥�52), PHQ-9 (n鈥�=鈥�634), physical activity (n鈥�=鈥�102), and EQ-5 (N鈥�=鈥�21) non-response, we had 73,738 samples for the final analysis (Fig. 1).

Fig. 1

Study population: a flow diagram of exclusions

Instrument

Fear of falling

We used a single question in the Community Health Survey [40], 鈥淒o you usually feel afraid of falling?鈥� to assess FOF. The question scoring was 1 for 鈥渘ot at all afraid,鈥� 2 for 鈥渁 little afraid,鈥� and 3 for 鈥渧ery afraid.鈥�

Physical activity

We measured physical activity using the Korean version of the International Physical Activity Questionnaire (IPAQ) [41]. The IPAQ captures the extent of comprehensive physical activity in daily life; participants indicate the number of days and average minutes of vigorous activity, moderate activity, and walking for at least 10 min each in the past week. To calculate the IPAQ score, we assign weights of 8.0 metabolic equivalents (METs) per minute for vigorous activity, 4.0 METs per minute for moderate activity, and 3.3 METs per minute for walking. Then, we calculate and sum the score using the formula: number of times per week 脳 duration of activity (minutes) 脳 intensity (MET level), resulting in MET-min/week. The score has three levels: inactivity (Level 1, less than 600 MET-min/week of physical activity), minimal activity (Level 2, at least 600 MET-min/week of physical activity), and health-promoting activity (Level 3, at least 3,000 MET-min/week of physical activity).

Depression

We measured depression using scores from the Patient Health Questionnaire-9 (PHQ-9), which consists of nine questions asking about depressive symptoms, scored on a four-point Likert scale with 0 for 鈥渘ot at all,鈥� 1 for 鈥渕any days,鈥� 2 for 鈥渕ore than a week,鈥� and 3 for 鈥渁lmost every day.鈥� The total score ranges from 0 to 27, with higher scores indicating more severe depressive symptoms [42].

Health-related quality of life

We used the EuroQol 5 Dimension (EQ-5D) to measure health-related quality of life (HRQOL). The EQ-5D comprises five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Ratings for each dimension are Level 1 (no problems), Level 2 (some problems), or Level 3 (extreme problems) [43]. To calculate the EQ-5D index, we apply value weights to the measures of each dimension of the EQ-5D. We derived these weights using the model from a weight estimation study conducted in South Korea [44].

Covariates

The study鈥檚 control variables were gender, age, education level, household monthly income level, number of chronic diseases, and fall experience. We categorized education level into elementary school or less, middle school, high school, and college or higher, and household monthly income level into lower (less than 1 million won), lower middle (less than 1 million to 300 million won), upper middle (less than 300 to 500 million won), and upper (more than 500 million won). The number of chronic diseases was 0, 1, or 2, according to the presence of physician-diagnosed hypertension and diabetes. Categories of fall experience comprised 鈥渙ne-time fall鈥� and 鈥渞epeated falls鈥� (two or more falls). We converted all variables except age into dummy variables.

Data collection and ethical considerations

A trained researcher collected data from the 2019 Community Health Survey [44] through one-on-one interviews who visited adults aged 19 and older living in sample households in 17 provinces nationwide. The researcher obtained informed consent before data collection. The current study obtained the raw data from the 2019 Community Health Survey through the Community Health Survey website after approval from the Korean Centers for Disease Control and Prevention. The researcher received data labeled with unique, non-identifiable numbers. The Institutional Review Board of the researcher鈥檚 institution approved this research (IRB No: GIRB-D23-NX-0064).

Data analysis

The researchers analyzed data using SPSS Statistics 27.0 and PROCESS Macro 4.1. Data analysis included descriptive statistics of frequencies and percentages for general characteristics and means and standard deviations for measured variables, and Pearson鈥檚 correlations between FOF, depression (PHQ-9 scores), and HRQOL (EQ-5D scores). We performed regression analyses using PROCESS Macro Model 4 and Model 8 to examine mediating and moderated mediation effects [45]. First, we examined the mediating effect of depression on the relationship between FOF and HRQOL. Second, we examined the moderating effect of physical activity on the relationship between FOF and depression. Third, we examined the moderated mediation effect of physical activity on the effect of FOF on HRQOL via depression.

To determine statistical significance, researchers resampled the moderated mediation effect 5,000 times using the bootstrapping method and set 95% confidence intervals. The control variables were gender, age, education, monthly household income, number of chronic diseases, and fall experience; we converted all to dummy variables except for age. We mean-centered continuous variables and reported figures as raw data for easy interpretation.

Results

Sample characteristics

The mean age of the subjects was 74.5 years, with 41.6% male and 58.4% female. The educational level was 59.8% with elementary school or less. Monthly household income was less than one million won (USD 1,000) for 36.9% of the participants, and one鈥�300 million won for 42.9%. The number of diagnosed chronic diseases was one (46.3%), and the proportion of participants experiencing falls in the past year was 82.6%. Physical activity levels were 46.7% in the inactive group (Table 1).

Table 1 Characteristics of subjects (N鈥�=鈥�73,738)

Descriptive statistics and correlation coefficients

The mean and standard deviation of each variable and the correlation between variables are in Table 2. FOF was positively correlated with depression (r鈥�=鈥�0.29, p鈥�<鈥�.001) and negatively correlated with HRQOL (r鈥�=鈥夆垝鈥�0.46, p鈥�<鈥�.001), and depression was negatively correlated with HRQOL (r鈥�=鈥夆垝鈥�0.47, p鈥�<鈥�.001). As FOF increased, depression increased and HRQOL decreased, and as depression increased, HRQOL decreased.

Table 2 Descriptive statistics and correlation between variables (N鈥�=鈥�73,738)

Mediating effect of depression on the relationship between FOF and HRQOL

The results of the PROCESS analysis (Model 4) to test the effect of FOF on HRQOL through the mediation of depression are in Fig. 2. The total effect of FOF on HRQOL through the mediation of depression was 鈭掆��0.073, of which the direct effect was 鈭掆��0.057, and the indirect effect through the mediation of depression was 鈭掆��0.016. The indirect effect was statistically significant because the bootstrapped 95% confidence interval did not include zero (Boot 95% CI鈥�=鈥夆垝鈥�0.017鈭�鈭�0.015). This result suggests an association between an increased FOF and depression and decreased HRQOL.

Fig. 2

Result of mediational analysis in research model.  Controlling for age, gender (dummy), educational level (dummy), economic level (dummy), number of chronic diseases (dummy), fall experiences (dummy); ** p&苍产蝉辫;&濒迟;鈥�.001

Examination of Moderated Mediation effects

To test the moderated mediation effects of physical activity on the effects of FOF and depression on HRQOL, we analyzed with PROCESS macro (Model 8).

Moderating effect of physical activity on the effect of fear of falling on depression

The results of the moderating effect of physical activity on the relationship between FOF and depression are in Table 3. FOF had a positive effect on depression, while minimal activity and health promotion activities negatively affected depression, and the interactions between FOF and physical activity were all statistically significant and negative. In other words, higher FOF increased depression, but minimal activity and health promotion activities offset this effect. When we compared the conditional effect of FOF on depression by the level of physical activity (moderator variable), we found that the effect of FOF on depression was statistically significant at all three levels of physical activity and decreased as the level of physical activity increased from inactivity to minimal activity and health-promoting activity.

Table 3 Moderating effect of physical activity on the effect of FOF on depression

Moderating effect of physical activity on the effects of fear of falling and depression on health-related quality of life

The results of the moderating effect of physical activity on the effects of FOF and depression on HRQOL are in Table 4. FOF and depression had an inverse effect on HRQOL; minimal activity and health promotion activities positively affected HRQOL, and the interactions between FOF and minimal activity and health promotion activities were all statistically significant. When comparing the conditional effect of physical activity on the relationship between fear of falling and HRQOL, all three levels of physical activity were statistically significant, and the negative effect of FOF on HRQOL decreased with increasing levels of physical activity (inactivity, minimal activity, and health-promoting activity).

Table 4 Moderating effects of physical activity in the fear of falling and depression on health-related quality of life

Moderated mediation effect of physical activity in the fear of falling鈥揹epression鈥揾ealth-related quality of life mediation pathway

In the model where FOF mediated the effect of depression on HRQOL, the moderated mediation effect of physical activity was statistically significant. The bootstrapped 95% confidence interval did not include zero (Index of moderated mediation [95% CI]鈥�=鈥�0.006 [0.004鈥�0.007], 0.008 [0.006鈥�0.009]) (Table 5). When we tested the mediation effect adjusted for physical activity level, all three levels of physical activity were statistically significant, with bootstrapped 95% confidence intervals that did not include zero, meaning that the mediating effect of FOF on HRQOL through depression was significant at all three levels of physical activity. The negative effect of the mediation effect decreased as the level of physical activity increased from inactivity to minimal activity to health-promoting activity.

Table 5 Moderated mediation and conditional indirect effects of physical activity levels

Discussion

This study sought a basis for developing programs to manage the fear of falling (FOF) and improve health-related quality of life (HRQOL) in community-dwelling older adults. Using nationwide data, it identified the moderated mediation effect of physical activity on the relationship between FOF, depression, and HRQOL.

First, we found that in community-dwelling older adults, FOF negatively affected HRQOL directly and indirectly through depression. Systematic reviews that determined the impact of FOF on quality of life in older adults also found an inverse relationship between FOF and quality of life [14], and lower levels of FOF were consistently associated with better quality of life [18, 46,47,48]. Depression was also negatively associated with FOF [11, 19, 23, 49,50,51,52,53] and was a factor influencing HRQOL [21, 33, 53,54,55,56]. In a simple test of the correlation between FOF, depression, and quality of life in older adults, the correlations between FOF and depression and depression and quality of life were significant [56]; we tested the mediating effect of depression on the relationship between FOF and HRQOL based on the correlation between the variables and found a partial mediating effect. This result is consistent with a recent study that found depression to be an independent and serial mediator of the relationship between FOF and psychological quality of life [57] and partially consistent with another recent study [24, 25] that found depression to be a mediator of the relationship between FOF and psychological quality of life independently and serially with frailty.

The previous studies [24, 25] focused on a high-risk group of community-dwelling older adults participating in an all-inclusive care program. In contrast, the present study is a population-based analysis of community-dwelling older adults aged 65 and older. It identifies the mediating effect of depression on the relationship between FOF and HRQOL, supporting the generalizability of these findings. The results suggest that FOF in older adults significantly reduces HRQOL independently and contributes to HRQOL decline through the psychological factor of depression. This finding suggests that interventions focused on reducing FOF in combination with depression interventions may be an effective strategy for improving HRQOL in older adults.

Second, physical activity among community-dwelling older adults moderated the relationship between FOF and depression, with higher levels of physical activity offsetting the static effect of FOF on depression. In a previous study [36] that examined the moderated moderation effects of physical activity on the pathway between FOF and depression in nursing home residents, those with higher levels of physical activity had a lower impact of FOF on depression than those with lower levels of physical activity, indicating the moderating effect of physical activity on the relationship between FOF and depression. This finding is consistent with the present study, in which the results show an association between FOF and significantly higher depression in inactive older adults. However, we found the static effect of FOF on depression offset in the minimally active and health-promoting older adults, providing additional support for the moderating effect of physical activity. A study of the effects of FOF and activity restriction on depression in Korean adults aged 60 and older [50] also found higher odds ratios for depressive symptoms in participants with FOF and FOF plus activity restriction compared with those without FOF. These results suggest implementing preventive and mitigating measures to address FOF and its negative health effects.

Third, physical activity in community-dwelling older adults also had a moderating effect on the pathway from FOF and depression to HRQOL. Specifically, we found a strong association between FOF and lower HRQOL in the inactive group. However, in the minimally active and health-promoting activity groups, physical activity in the minimally active and health-promoting activity groups moderated this negative effect. Although few studies have tested the moderating effect of physical activity on the relationship between FOF and HRQOL, some have tested the mediating effect. In one study, participation in physical activity partially mediated the pathway through which FOF affected the quality of life in Taiwanese and German older adult populations [25]. Function and disability mediated the association between FOF and HRQOL (EQ-5D) in community-dwelling older adults [26]. A meta-analysis of the effectiveness of exercise programs in preventing falls in older adults [57, 58] found that these interventions improved psychological variables, including fall prevention efficacy and fear of falling. Additionally, the exercise interventions鈥� effectiveness increased with the program鈥檚 frequency. The evidence suggests it is important to include interventions to improve physical function, such as physical activity and exercise, to reduce FOF in older adults and mitigate the HRQOL impairment caused by FOF.

Depression is another important factor in these relationships. In a path analysis study of factors influencing HRQOL in community-dwelling older adults [33], depression acted as a mediator in the pathway through which physical function and regular exercise influenced HRQOL. In a structural modeling study of the relationship between functional ability, mental health, and quality of life in older people living alone, mental health (depression and loneliness) had a direct effect on quality of life, and physical function and participation in social activities were mediators in the pathway to quality of life [21]. These studies suggest that strategies to screen for and mitigate depression and loneliness are needed to improve older adults鈥� quality of life. Therefore, future studies should compare physical activity鈥檚 moderated mediation effects on the relationship between FOF, depression, and HRQOL in community-dwelling older adults.

Fourth, in community-dwelling adults, physical activity showed a moderated mediation effect on the pathway where FOF influences HRQOL through depression. Specifically, the mediating effect of FOF on HRQOL via depression was significant at all three levels of physical activity. The negative effect of the moderated mediation effect decreased as the level of physical activity increased from inactivity to minimal activity to health-promoting activity. In particular, physical activity at the level of minimal activity and health-promoting activity moderated the effects of FOF on depression and HRQOL. In a previous study, the physical activity intensity of community-dwelling older adults showed a significant linear trend with the severity of FOF, indicating that as the severity of FOF increased, physical activity decreased, and the association between physical activity and FOF varied by physical activity intensity level [31]. Therefore, interventions that promote physical activity levels above the minimum level may effectively prevent HRQOL impairment due to FOF in community-dwelling older adults. World Health Organization (WHO) guidelines for physical activity recommend that all adults should engage in 150鈥�300 min of moderate-intensity physical activity, 75鈥�150 min of vigorous-intensity physical activity, or an equivalent combination of the two per week, and perform muscle strengthening exercises at least two days per week [58].

In addition, scholars recommend reducing sedentary behavior for all age groups [58]. This recommendation may be particularly urgent in South Korea, where the prevalence of insufficient physical activity among adults was 54.4% in 2020, exceeding the global average of 28% and showing particularly high rates among older adults (鈮モ��65 years) [59]. In this study, the prevalence of physical inactivity among community-dwelling older adults was 46.7%, and we found exacerbated FOF-induced depression and HRQOL impairment in these inactive individuals.

Studies have demonstrated an association between the fear of falling and physical and cognitive decline, including psychological, social, and cultural factors [60,61,62]. One study found a significant increase in the risk of falling when physical and cognitive decline are present, raising the need for interventions that address both aspects [60]. Another study emphasized the need to manage physical and cognitive health in older adults with chronic conditions [61]. Additionally, social and cultural factors, such as race and marital status, impact fear of falling [62]. These studies suggest that a comprehensive approach that includes physical, cognitive, and sociocultural factors is essential to reduce older adults鈥� fear of falling. Therefore, to prevent adverse health outcomes due to FOF in community-dwelling older adults, it is necessary to assess, educate, and intervene to promote at least minimal physical activity. It is also important to screen and manage depression as such an integrated approach is more likely to be effective in improving mental and physical HRQOL.

This study is subject to some limitations. First, we did not exclude individuals with a history of depression or dementia from the study population. Consequently, the research findings may include potential biases due to these factors influencing responses. Therefore, when interpreting the study results, it is important to consider the impact of these factors on generalization and interpretation. Second, as this is a cross-sectional study using secondary data, it is not possible to establish causality between the examined variables. Future longitudinal or intervention studies should confirm the causal model. Third, we used a single-item instrument to measure FOF, which may affect the interpretation and relationship of the results. Future studies could improve the study鈥檚 internal validity by using FOF measures with confirmed reliability and validity.

Conclusion

This study demonstrated the moderated mediation effect of physical activity on the relationship between the FOF and HRQOL, with depression as a mediator. The results showed that depression and impaired HRQOL decreased as physical activity levels increased. Specifically, the negative mediating effect of inactivity, minimal activity, and health-promoting activities decreased as physical activity levels increased. This finding suggests that physical activity is important in reducing depression due to FOF in older adults, which in turn improves HRQOL. Therefore, there is a need to encourage and support older adults to maintain adequate physical activity through community-based programs. Such programs could make an important contribution to reducing older adults鈥� depression due to the fear of falling and improving their health-related quality of life.