Risk of falls in people with chronic kidney disease and related factors*

Objective: to identify the risk and prevalence of falls in the last year in chronic renal failure patients on hemodialysis; to associate the risk of falls with the fear of falling and socio-demographic-clinical variables. Method: association study. 131 individuals participated in the study. The Morse Falls Scale, the Fall Efficacy Scale and the Tilburg Frailty Indicator were used. The data were analyzed by linear regression, the level of significance adopted was 0.05. Results: 97.7% were at risk for falls and 37.4% had at least one fall per year, with a mean of 2.02. Extreme concern about falling was presented by women, patients with less education, amputees, and frail individuals. Diabetes, as a comorbidity, and people with difficulty or need for assistance for ambulance showed a significant increase in the occurrence of falls. Conclusion: high risk and high prevalence of falls were found in hemodialysis patients, greater in those with diabetes or mobility limitations. Fear of falling was identified especially in women and in people with less education. These findings challenge the role of preventing falls, both in hemodialysis sessions and in the adoption of strategies for activities of daily living that involve patients and their families.


Introduction
The 2019 Global Kidney Health Atlas points out that 10% of the world population is affected by chronic kidney disease (CKD) consisting of kidney damage and irreversible loss of kidney function, present for more than three months, in need of dialysis treatment (1)(2) .
CKD and hemodialysis are responsible for physical and emotional limitations with an important negative impact on the quality of life of people affected by this pathology, interfering in the performance of activities of daily living and restricting the social interaction of the individual, in addition to being associated with several comorbidities especially in elderly (1)(2)(3) .
Comorbidities related to CKD can cause functional limitations, low cardio-respiratory fitness, fatigue, disturbances of mineral metabolism, which lead to bone mineral disease, and can ultimately act as a risk factor for accidents due to falls (1)(2)(3)(4) , which are present in greater number in chronic renal patients undergoing dialysis treatment (5)(6)(7) .
Patients on hemodialysis are at a higher risk of falls, ranging from 13% to 25%, compared to the general population (6,(8)(9) . The rate of falls after hemodialysis is significantly higher compared to pre-hemodialysis, revealing a negative effect of hemodialysis on postural stability (6) .
Falls in chronic renal patients undergoing hemodialysis are also associated with polypharmacy, frailty, advanced age and a previous history of falls (10) .
However, there are still few studies that deal with this subject exactly.

Falls are defined by the World Health Organization
as inadvertently falling to the ground or at another lower level (11) .
Falls can be classified as: accidental, when caused by environmental factors (such as water on the floor for example) or by loss of the patient's balance that correspond to 14% of falls in general, anticipated physiological falls, which occur in patients classified with fall risk, that is, patients who have more than one episode of previous fall, weak or impaired pace and correspond to 78% of falls and unanticipated physiological falls, that is, those that cannot be predicted and can be associated with physiological causes such as fainting, pathological hip fractures, and correspond to 8% of falls (8)(9)11) .
Another possibility of classifying falls may also be related to complications such as: without complications, minor complications (all other complications), major complications (such as fractures) and death (8) .
In individuals with chronic kidney disease on hemodialysis (HD) falls can be classified as to temporality: fall on a day that does not perform HD, fall before the HD session or after the HD session (8) .
The study of factors related to falls in patients undergoing hemodialysis makes it possible to identify prevention and safety promotion strategies for individuals with chronic kidney disease. Thus, the objectives of this study are to identify the risk and prevalence of falls in the last year in people with chronic kidney disease undergoing hemodialysis and to associate the risk of falling with the fear of falling and socio-demographic-clinical variables.

Method
This is a quantitative, descriptive and association study. It was carried out in a nephrology service in the city of São João da Boa Vista, in the inland of the state of São Paulo, which assists patients from the Brazilian Public Health System (Sistema Único de Saúde, SUS) and from private health plans. The study site serves approximately 230 patients on hemodialysis.
The sample size was calculated considering the score obtained using the instrument that assesses the risk of falls as a dependent variable and as a set of 13 variables as independent variables: fear of falling, gender, age, education, marital status, comorbidities, time in hemodialysis, medication use, limb amputation, difficulty walking, aid in ambulance, bone mineral disease and frailty.
To perform the sample calculation, the G*Power 3.1.9.2 software was used. The level of significance was set at 5%, test power of 80%, and medium degree effect size (0.15) (12) . Thus, the sample consisted of 131 chronic renal patients undergoing hemodialysis.
To be a participant in the research, the inclusion criteria were chronic kidney patients aged 18 years old or over on Renal Replacement Therapy, in hemodialysis modality, for more than six months. Fall Scale (13) , the Fall Efficacy Scale (FEI-I -Brazil) (14) , and the Tilburg Frailty Indicator (TFI) (15) .
The activities and social participation, with the total score varying from 16 (no concern) to 64 (extreme concern) (15) .
The TFI was used to measure frailty. Although the instrument is made up of two parts, only part B, which identifies the weakness itself, was used in this study. The assessment of frailty is made up of 15 objective questions, self-reported, distributed in three domains: physical, psychological and social.
The final score ranges from 0 to 15 points, with the highest score meaning a higher level of frailty, or alternatively scores higher than five points indicate that the individual is frail (16) .
Data such as medications, comorbidities, time on hemodialysis, among others, were collected from the patients' medical records, by the first author of the study.
To study the associations between qualitative variables, the Chi-square test was applied, and for cases where the assumptions of the Chi-square test were not met, Fisher's exact test was applied.
For the comparisons involving a qualitative variable and a quantitative variable, the Mann-Whitney nonparametric test or the unpaired Student t test was applied, according to the data distribution (12) .
In a second stage of the analysis, multiple Poisson regression models were constructed with robust variance. In the results, the estimates obtained from the prevalence ratio were presented, as well as their respective confidence intervals and p-values (12) .
For all the analyses, a level of significance equal to 5% was considered.
All data were tabulated in an electronic spreadsheet and analyzed using the statistical SAS software, version 9.4.

Results
Of the 131 people who made up the sample,    concern with falling in relation to non-diabetic and non-hypertensive patients.  Table 3. As shown in Table 4, the reasons for the prevalence of falls were estimated for "the occurrence of falls in the last year", "high risk of falling" and "Very/Extremely concerned about falling" and the variables, which showed statistically significant differences for this study.

Discussion
It was found that the individuals with chronic kidney disease on hemodialysis have a high prevalence of falls, so that patients with diabetes, with difficulty or need for assistance in ambulance have a higher prevalence of falls.
In the assessment of the participants, regarding the risk of falls, it was identified that those who experienced the same clinical variables related to the high prevalence of falls, that is, people with diabetes, difficulty or need for assistance for ambulance had higher scores on the Morse scale, which represents the high risk for falls (13) .
When comparing groups of chronic kidney patients who also have diabetes mellitus, chronic kidney patients who have difficulty ambulance and those who use orthoses showed a statistically significant difference in terms of the greater number of falls in relation to the other patients who did not have these characteristics.
Hypertension as a comorbidity did not influence the results so that there was no statistically significant difference, with respect to the risk and the occurrence of falls between non-hypertensive participants and normotensive participants.
In assessing the fear of falling by the scale of fall effectiveness, women had higher scores in daily activities such as outdoor activities and social participation, which denotes extreme concern (extreme fear) of falling (14) .
Another variable that interfered with the fear of falling was the number of years of schooling, so that patients with higher education have little or no fear of falling, while patients with less education have extreme fear of falling.
The comparison of prevalence and risk of falls among the participants classified as frail in the assessment of the physical, psychological and social domains (15) in relation to patients not classified as frail found no significant differences. This finding also diverged from the literature, where frailty, described as a highly vulnerable state for adverse clinical outcomes, has been investigated as a risk factor for falls in people with kidney diseases (16) .
No statistically significant differences were identified regarding the number of falls in the last year, neither the risk nor the occurrence of falls between male participants and female participants. These findings differ from those found in a systematic review that identified in other studies that women have significant numbers for falls (16) .
Among people with a simultaneous diagnosis of In this theme, with regard to functional independence, that is, the ability to perform activities without assistance, individuals with chronic kidney disease are dependent on walking to go up and down stairs, with 10.2% of patients needing help to perform this activity; and, in relation to mobility, 18.4% of patients have some dependence (21) .
Given the impact that this fear of falling can have on quality of life by limiting activities of daily living and social activities to women and people with less education, specific support strategies for these people with chronic kidney disease arise, which can be performed by family, caregivers, nursing and interdisciplinary staff.