Risk of fall in patients with chronic kidney disease: results from the China health and retirement longitudinal study (CHARLS)

The global prevalence of chronic kidney disease (CKD) is exhibiting an upward trajectory, with a incidence estimated at approximately 8.2% in China [1, 2]. The prevalence of CKD demonstrates a linear escalation with advancing age, where the intermediate and elderly age groups constitute more than 60% of the total population affected by this condition [3]. CKD is frequently concomitant with various systemic disorders, often leading to complications such as cognitive impairment, reductions in strength, osteoporosis, muscle wasting, frailty and an increased risk to falls [4‐10].

Globally, falls stand as the second most prevalent cause of unintentional injury-related fatalities [11, 12]. Particularly accentuated in China, falls have surged to the forefront as the primary instigator of disability, functional constraints, and even mortality within the middle-aged and elderly demographic. Patients with CKD are often considered at a high risk of falling [13]., due to the frequent occurrence of bone metabolism abnormalities in CKD, these patients are more susceptible to fractures following falls, further impacting their quality of life. Therefore, previous studies have explored and identified the risk factors for falls among CKD patients, including age, History of falls, and multiple comorbid conditions [14‐16]. However, there is limited research on the increased risk of falls among CKD patients, and the risk of falls among Chinese chronic kidney disease patients remains uncertain [17]. We therefore conducted this prospective study using the data from China Health and Retirement Longitudinal Study (CHARLS) to assess the risk of fall in patients with chronic kidney disease in China.

In this retrospective propensity score-matched cohort study, participants with CKD exhibited a significantly higher risk-adjusted rate of fall accidents compared to non-CKD participants. This association remained consistent across sensitivity analysis and subgroup analysis.

To our knowledge, this is the first comprehensive examination of risk factors for falls within a substantial national sample of individuals with CKD in China. This is especially pertinent considering the growing prevalence of CKD in the country. Our findings reveal that individuals with CKD in our study tended to be older than the general population, and advanced age is a recognized pivotal risk factor for falls [11]. Falls among older individuals are of paramount concern due to their association with adverse outcomes such as fractures, diminished quality of life, loss of independence, and mortality. Despite the well-established focus on falls in the elderly, individuals with CKD often present with a constellation of comorbidities, potentially amplifying their vulnerability to falls. Therefore, our study includes middle-aged CKD patients to provide a comprehensive examination of the risk of falls within this population. In the subgroup analysis of our study, older adults with CKD did not exhibit statistically significant differences in fall rates compared to older adults without CKD. In contrast, middle-aged CKD patients showed a higher incidence of falls compared to their non-CKD counterparts. This difference may be attributed to muscle loss beginning at an earlier age among middle-aged CKD patients and age-related frailty among older non-CKD patients, which collectively contribute to a higher overall fall incidence. However, this conclusion requires further validation in larger sample sizes.

Our findings consistent with previous studies in the USA, which have reported a 20% higher risk of falls among CKD patients when compared to individuals without CKD [20, 21]. Other existing research has focused on end-stage kidney disease patients, particularly those undergoing hemodialysis, there is limited research on falls among early-stage kidney disease patients [14, 22]. However, it’s worth noting that some research has indicated that decreased renal function alone may not significantly elevate the risk of falls [23, 24]. Factors contributing to the heightened risk of falls in CKD patients may be attributed to physiological changes associated with CKD, rather than solely a decline in glomerular filtration rate.

There are numerous distinct causes for falls, including acute medical issues (e.g., postural hypotension, acute arrhythmias, transient ischemic attacks), activity or balance issues, household hazards (e.g., wet surfaces, poor lighting), and medication-related factors. Considering the cultural customs in China, people often use squat toilets rather than sitting toilets. The action of squatting and standing up can easily lead to postural hypotension, increasing the risk of falls. Additionally, flushing squat toilets can result in a wet bathroom floor, posing an environmental hazard and further elevating the risk of falls. Therefore, we hypothesize that not using sitting toilets may increase the risk of falls [9]. We have included toilet seat usage as a risk factor in our model to adjust for its potential impact.

In CKD patients, factors such as chronic inflammation, vitamin D deficiency, and proteinuria can contribute to muscle loss, compromising muscle strength and balance, thereby increasing the risk of falls [23, 25‐28]. Furthermore, studies indicate that patients with chronic kidney disease often experience cognitive decline, which aligns with our study [29, 30]. Cognitive decline may contribute to impaired balance, thereby increasing the risk of fall accidents [31].

There are several limitations to this study. Firstly, CKD was defined based on self-reported physician diagnoses. Subsequently, we validated these diagnoses during the follow-up assessment conducted in the 2015 survey to ensure data accuracy. However, it is possible that some participants may still have undiagnosed CKD. Secondly, fall accidents were defined based on self-reported incidents of falling within the past two years, which could introduce the possibility of memory bias, as incidents without injury may be overlooked or forgotten. Thirdly, all participants in this study were of Chinese ethnicity. Therefore, there may be limitations in the generalizability of our study findings to other racial or ethnic groups. Fourthly, our study focuses on self-reported falls within a community setting, leading to an inability to precisely ascertain the specific causes of these fall incidents. Factors such as acute medical issues, activity-related or balance-related aspects, household hazards, and medication-related factors contributing to falls remain unexplored. While confounding elements are commonplace in retrospective research, they introduce a degree of bias into our findings. To mitigate these limitations, we implemented rigorous statistical methodologies, including PSM, Propensity Adjustment (PA), Overweighting (OW), and doubly robust estimation. Despite these efforts, the inherent retrospective nature of our study hinders complete bias elimination. To bolster the reliability and generalizability of our findings, future research should prioritize extensive prospective studies that comprehensively explore various factors influencing falls, thereby ensuring a more thorough understanding and validation of our conclusions. Fifthly, the study outcomes are limited to self-reported falls and do not encompass long-term consequences such as hip fractures/head injuries, pain, diminished quality of life, loss of independence, and mortality. Our primary focus is on the occurrence of falls as an incidental event. While we acknowledge that non-injurious falls are also worthy of attention, considering the cost-benefit ratio, prospective research is necessary to comprehensively explore these outcomes.

Overall, our study demonstrates that population in China with CKD are at a significantly heightened risk of experiencing falls. This underscores the importance of giving heightened attention to the issue of falls within the CKD population, emphasizing the necessity for specific preventive measures and further research in this area.

d Shown is the odds ratio from a multivariable logistic regression model with the same strata and covariates, with additional adjustment for the propensity score.