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Calf Circumference Predicts Falls in Older Adults on Hemodialysis

Published:September 22, 2022DOI:https://doi.org/10.1053/j.jrn.2022.08.003

      Objective

      Older patients with chronic kidney disease (CKD) undergoing maintenance hemodialysis are at a higher risk of falling. However, there is no standard method to screen patients at higher risk. We have evaluated whether calf circumference (CC) measurement would be able to predict falls in this population.

      Methods

      This is a prospective study that enrolled patients aged ≥65 years on conventional hemodialysis, followed for 6 months. The presence of falls was associated with demographical, clinical, and biochemical data. Reduced CC was set at <34 cm for men and <33 cm for women. We evaluated physical status using Duke activity status index (DASI) and hand grip strength (HGS).

      Results

      Ninety-one patients were included (age 73.7 ± 5.4 years, 69.2% men, 56% with diabetes). Mean CC was 32.6 ± 3.7 cm, with a high prevalence of reduced CC (61.5%). During the follow-up, 13 falls were identified (1 had a fracture and died). These patients were older and heavier (P = .017 and P = .025, respectively). Most falls occurred in patients with sarcopenic obesity (BMI >27 kg/m2 plus reduced HGS or reduced CC). In a logistic regression model, reduced CC (hazard ratio (HR) 7.81, confidence interval (CI): 1.13-53.86, P = .037), higher age (HR 1.19, CI: 1.04-1.36, P = .011), and higher body weight (relative risk (RR) 1.13, CI: 1.04-1.22, P = .003) were independently associated with falls in a fully adjusted model.

      Conclusion

      CC measurement, an easy and nonexpensive tool, was able to predict falls in older patients on HD. Further studies should test the inclusion of CC in a fall risk assessment in older patients on hemodialysis.

      Keywords

      Introduction

      Chronic kidney disease (CKD) affects the worldwide population and is considered a public health problem. With the aging population, there has been an increase in older patients initiating hemodialysis.
      • Saran R.
      • Robinson B.
      • Abbott K.C.
      • et al.
      US Renal data System 2019 Annual data report: epidemiology of kidney disease in the United States.
      This population is characterized by frailty, loss of muscle mass, reduced functional capacity, and polypharmacy, factors associated with an increased risk of falls.
      • Chantanachai T.
      • Sturnieks D.L.
      • Lord S.R.
      • Payne N.
      • Webster L.
      • Taylor M.E.
      Risk factors for falls in older people with cognitive impairment living in the community: systematic review and meta-analysis.
      About 30% to 40% of elderly people aged ≥65 years fall at least once a year, and these rates tend to increase with advancing age.
      Organization WH
      Falls 2021.
      Falls and fractures, which are considered devastating events in older individuals, lead to high morbidity and mortality rates, reduced functional capacity, institutionalization, and death.
      • Berry S.D.
      • Miller R.R.
      Falls: epidemiology, pathophysiology, and relationship to fracture.
      Several tools have been developed to assess the risk of falls in the elderly. However, a standardized tool for use in hemodialysis services, and particularly for older individuals, has not been clearly defined. Calf circumference (CC) measurement is considered a simple and inexpensive way to check muscle mass and has been already used in studies as a simplified way to assess the presence of sarcopenia,
      • Gonzalez M.C.
      • Mehrnezhad A.
      • Razaviarab N.
      • Barbosa-Silva T.G.
      • Heymsfield S.B.
      Calf circumference: cutoff values from the NHANES 1999-2006.
      which has been associated with falls in the general population.
      • Veronese N.
      • Smith L.
      • Barbagallo M.
      • et al.
      Sarcopenia and fall-related injury among older adults in five low- and middle-income countries.
      However, so far, CC, as an isolate measurement, has not been applied to evaluate falls in patients on hemodialysis.
      The ability to precisely estimate falls risk is critical for patients on hemodialysis, a population with a high risk of fracture. In this regard, even the fracture risk assessment tool (FRAX),
      • Kanis J.A.
      • Johansson H.
      • Harvey N.C.
      • McCloskey E.V.
      A brief history of FRAX.
      a well-validated instrument, does not incorporate falls. Therefore, the aim of the present study was to verify whether elderly patients on hemodialysis with a reduced CC would have a higher risk of falls.

      Methods

      This is a prospective study with a 6-month followed that included older patients (age higher or equal to 65 years) on maintenance hemodialysis. Patients were recruited from 2 dialysis centers in Sao Paulo, Brazil, in the period between June 1st, 2019 and June 30th, 2020. Inclusion criteria were age ≥65 years, on hemodialysis for at least 1 month, ability to read, understand and sign the consent form. Exclusion criteria were current treatment for cancer, amputation, or restriction to bed.
      Baseline clinical, demographic, and biochemical data were collected at the first contact and included age, sex, race, body weight, body mass index (BMI), and presence of comorbidities such as diabetes, hypertension, congestive heart failure, and coronary disease. History of previous fall or fracture in the past 6 months was assessed by interview and chart registration. We defined polypharmacy as the use of five or more medications.
      • Masnoon N.
      • Shakib S.
      • Kalisch-Ellett L.
      • Caughey G.E.
      What is polypharmacy? A systematic review of definitions.
      Laboratory parameters evaluated were hemogram, serum albumin, total calcium, phosphate, 25(OH)-vitamin D, parathyroid hormone (PTH), cholesterol, and creatinine. Secondary hyperparathyroidism was defined as PTH >300 pg/mL, hypovitaminosis D was considered if 25(OH)-vitamin D was below 30 ng/dL.
      The Local Research Ethics Boards has approved the protocol, and written consent was obtained from all patients.

      Dependent Variable

      The main outcome was fall, considered any situation in which the subject suffered an unintentional change in his position to a lower plane. The same researcher followed all patients, by visiting the clinics and contacting patients by phone in a maximal interval of 2 months, for 6 months.

      Independent Variable

      Calf circumference (CC) was measured by the same trained researcher, using an inelastic measuring tape. Patients were seated, with feet flat on the floor, and knee and ankle at a 90-degree angle. The measurement was taken on the most protruding part of left leg, except for left-handed elderly, where the measurement was carried out on the right leg. Two consecutive measurements were taken, and the average was used for statistical purposes. The time to measure CC was around 2 minutes. The tape zero value was placed below the measured value, the measured values were immediately recorded without rounding. We considered a reduced CC if <34 cm for men and <33 cm for women, as previously described.
      • Gonzalez M.C.
      • Mehrnezhad A.
      • Razaviarab N.
      • Barbosa-Silva T.G.
      • Heymsfield S.B.
      Calf circumference: cutoff values from the NHANES 1999-2006.

      Potential Confounders

      Hand grip strength (HGS) was evaluated using a portable digital dynamometer (Instrutherm®, Sao Paulo, Brazil). Patients remained seated, the upper limb chosen to be evaluated was positioned at the side of the body with the elbow at a 90° angle, the contralateral limb remained relaxed on the chair arm or on the thigh, the test was performed on the limb without fistula. All adornments present on the hand and wrist of the evaluated limb were removed. With the wrist in a neutral position, thumb facing up, the subject was instructed to feel the instrument well adapted and comfortable in his hand. The participant was encouraged to squeeze as much as possible, when the force value was fixed, the participant was instructed to stop squeezing and the value obtained was recorded immediately. Participant dominance was also recorded. A single measure was taken to avoid the participant’s wear and/or stress. We considered normal values >27 kgf for men and >16 kgf for women, as previously described.
      • Dodds R.M.
      • Syddall H.E.
      • Cooper R.
      • et al.
      Grip strength across the life course: normative data from twelve British studies.
      Patients were classified into 4 groups according to HGS and body mass index (BMI): normal (normal BMI and HGS), obesity (BMI >27 kg/m2 and normal HGS), sarcopenia (normal BMI and altered HGS), and sarcopenic obesity (BMI >27 kg/m2 and altered HGS).
      Duke activity status index (DASI) is a 12-item scale that estimates the functional capacity of patients.
      • Hlatky M.A.
      • Boineau R.E.
      • Higginbotham M.B.
      • et al.
      A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index).
      Each of the 12 items has a specific weight based on the metabolic equivalent of task (MET). Positive responses are summed to get a total score, which ranges from 0 and 58.2. Results correlated with peak oxygen uptake, with higher scores indicating better functional capacity.

      Statistical Analysis

      Data are presented as mean SD or median (25, 75), as appropriate. The Kolmogorov–Smirnov test was used to determine the normality of data. Associations between 2 categorical variables were verified using the Chi-Square test, or alternatively, Fisher’s exact test. Linear associations between numerical variables were assessed using Pearson’s correlation. Comparison of means between 2 groups was performed using Student’s t-test for independent samples or, alternatively, the nonparametric Mann–Whitney test. To assess the variable effects that predict the occurrence of falls, a multivariate logistic regression was performed, and independent variables included were selected from univariate analysis (P < .01). Therefore, we included as independent variables age, history of falls, weight, hypertension, and CC (categorized as normal or reduced) in a final model. Diabetes was also modeled since this is a known risk factor for fall.
      For all statistical tests, a significance level of 5% was used. Statistical analyzes were performed using SPSS 20.0 statistical software.

      Results

      During the follow-up, there were 13 falls, which occurred at home (N = 10), in the street (N = 1), and at the hemodialysis unit (N = 2). One fall was associated with fracture and death and all others had no severe consequences. Characteristics of patients and according to the occurrence of falls are shown in Table 1. Most patients were non-White men. Diabetes and hypertension were observed in more than half of the patients. Polypharmacy was found in 68.9% of the samples. Altered CC and HGS were found in 61.5% and 70.3% of patients, respectively. Al least 1/3rd of the samples had previous history of falls. Patients with a reduced CC distinguished from those with a normal CC by presenting lower weight (58.7 ± 8.4 vs. 76.8 ± 9.7 kg, P < .001), lower DASI scores (15.7 ± 12.1 vs. 28.5 ± 17.6, P < .001), and lower HGS (16.7 ± 8.3 vs. 22.7 ± 8.1, P < .001).
      Table 1Characteristics of patients
      ParameterEntire cohort N = 91Non-fallers N = 78Fallers N = 13P
      Age, years74 ± 573 ± 577 ± 4.017
      Male gender, n (%)63 (69.2)52 (66.7)11 (84.6).194
      Non-White, n (%)69 (75.9)61 (78.2)8 (61.5).407
      Assistive device, n (%)30 (33.0)27 (34.6)3 (23.1).533
      Comorbidities, n (%)
       Hypertension68 (74.7)61 (78.2)7 (53.8).061
       Diabetes51 (56.0)43 (55.1)8 (61.5).666
       Congestive heart failure7 (7.7)6 (7.7)1 (7.7).999
       Coronary artery disease23 (25.3)18 (23.1)5 (38.5).237
      Current drinking, n (%)3 (3.3)2 (2.6)1 (7.7).338
      Polypharmacy, n (%)62 (68.9)53 (68.8)9 (69.2).977
      Weight, kg65.6 ± 12.564.4 ± 12.072.8 ± 14.0.025
      DASI, sores20.6 ± 15.721.7 ± 15.123.8 ± 16.2.655
      Calf circumference, cm32.6 ± 3.732.5 ± 3.833.2 ± 2.9.519
      Altered calf circumference, n (%)56 (61.5)48 (61.5)8 (61.5).999
      HGS, kg19.1 ± 8.718.7 ± 8.921.2 ± 7.2.346
      Altered HGS, n (%)64 (70.3)53 (67.9)11 (84.6).223
      History of previous fall, n (%)28 (30.8)21 (26.9)7 (53.8).052
      Creatinine, mg/dL8.4 ± 2.48.5 ± 2.48.1 ± 2.5.621
      Albumin, g/dL4.0 ± 0.34.0 ± 0.34.1 ± 0.2.699
      Cholesterol, mg/dL148 ± 40148 ± 38150 ± 50.861
      Ionized calcium, mg/dL5.32 ± 1.605.32 ± 1.565.28 ± 1.68.956
      Phosphate, mg/dL5.8 ± 1.75.8 ± 1.75.8 ± 1.2.875
      PTH, pg/mL388 (234, 614)383 (238, 615)405 (198, 581).937
      Hyperparathyroidism, n (%)58 (63.7)50 (64.1)8 (61.5).859
      25(OH)-vitamin D27.0 ± 11.027.6 ± 11.022.8 ± 9.7.172
      Hemoglobin, g/dL12.8 ± 11.611.7 ± 1.511.2 ± 1.4.315
      DASI, duke activity status index; HGS, hand grip strength; PTH, parathyroid hormone.
      Values are expressed as mean ± SD, median (25,75) or percentage.
      BMI was <22 kg/m2, 22-27 kg/m2, and >27 kg/m2 in 44.4%, 32.3%, and 23.3% of patients, respectively. Falls occurred in 50% of patients with sarcopenic-obesity, none of the patients with obesity, 9.8% of patients with sarcopenia, and 11.1% of patients with normal BMI and HGS (P = .002), as shown in Figure 1. Same results were obtained using reduced CC instead of HGS (data not shown).
      Figure thumbnail gr1
      Figure 1Incidence of falls according to body mass index (BMI) and calf circumference (CC) that classified patients into 4 groups: 1. non-obese and nonsarcopenic, 2. obese, 3. sarcopenic and obese, and 4. sarcopenic. Bars represent the number of patients.
      Patients identified as fallers to be older and heavier than non-faller patients. Logistic regression analysis identified that reduced CC (OR 7.81, CI: 1.13-53.86, P = .037), higher age (OR 1.19, CI: 1.04-1.36, P = .011), and higher body weight (OR 1.13, CI: 1.04-1.22, P = .003) were independently associated with falls in a model adjusted for history of falls and hypertension (Figure 2). Inclusion of diabetes in the model did not change the results. HGS and DASI scores were not independently associated with falls.
      Figure thumbnail gr2
      Figure 2Odds ratio for the risk of falls. Symbols and lines represent hazard ratio and confidence interval.

      Discussion

      The present study investigated whether CC could predict falls in older patients on hemodialysis. The results indicate that CC, higher weight, and age were the main determinants of falls for these patients. Higher body weight as a predictor of falls might reflect sarcopenic obesity.
      We found a 14.3% frequency of falls, a rate of 1.7 fall/1,000 patients/year, which agrees with literature data.
      • Kono K.
      • Nishida Y.
      • Yabe H.
      • et al.
      Development and validation of a fall risk assessment index for dialysis patients.
      Higher age, weight, and a reduced CC were independently associated with falls. Of note, these falls occurred in patients classified as sarcopenic obese. Sarcopenia is already recognized as a risk factor for falls. Only one previous study has tested CC to predict falls in elderly patients from the general population.
      • Dargent-Molina P.
      • Favier F.
      • Grandjean H.
      • et al.
      Fall-related factors and risk of hip fracture: the EPIDOS prospective study.
      However, to our knowledge, there is no study testing CC measurement as a fall predictor in a hemodialysis setting.
      CC is a relatively simple measurement that can be easily performed before the dialysis initiation, and it is not time-consuming. This study proposes the use of this measurement in a greater number of patients so that CC can indeed configure as a tool to predict the risk of falling in patients on dialysis. An additional advantage is to perform CC measurement with patients seated, right before the dialysis initiation. CC measurement is well-validated in older individuals from the general population.
      • Rolland Y.
      • Lauwers-Cances V.
      • Cournot M.
      • et al.
      Sarcopenia, calf circumference, and physical function of elderly women: a cross-sectional study.
      For patients on dialysis, CC can add information on health status and allow a more accurate assessment of the nutritional status.
      • Rodrigues J.
      • Cuppari L.
      • Campbell K.L.
      • Avesani C.M.
      Nutritional assessment of elderly patients on dialysis: pitfalls and potentials for practice.
      Questions on the longitudinal value of this measurement are yet to be answered. Important to mention that, in the presence of pedal edema, the result should be reduced by 2 cm, as previously recommended,
      • Ishida Y.
      • Maeda K.
      • Nonogaki T.
      • et al.
      Impact of edema on length of calf circumference in older adults.
      although this has not been tested in a population on dialysis.
      Sarcopenia and obesity are common situations in patients with CKD.
      • Johansen K.L.
      • Lee C.
      Body composition in chronic kidney disease.
      Whereas sarcopenia yields bad outcomes in patients on dialysis,
      • Zamboni M.
      • Rubele S.
      • Rossi A.P.
      Sarcopenia and obesity.
      obesity might confer survival advantage in patients with CKD.
      • Kalantar-Zadeh K.
      • Rhee C.M.
      • Chou J.
      • et al.
      The obesity paradox in kidney disease: How to Reconcile it with obesity Management.
      However, body mass index, although the most widely used tool to assess obesity, is far from being a perfect measure of adiposity. Sarcopenic obesity is a combination of high body fat with muscle depletion and contribute to bad outcomes more than either of these conditions alone,
      • Zamboni M.
      • Rubele S.
      • Rossi A.P.
      Sarcopenia and obesity.
      which was also true for the risk of falls in the current study.
      There are some limitations to our study. First, selection bias was inevitable as we did not include patients with severe disabilities. Second, the sample size is small. Third, we had no information about environmental hazards (including hypotension during hemodialysis) and caregiver factors for each patient. Fourth, patients were followed for a short period of time. This study, however, is the first that has tested the CC measurement as a tool to predict falls among patients on hemodialysis.
      Further studies are necessary to test whether the measurement of CC, an easy and inexpensive tool, should be incorporated into the clinical practice as a predictor of falls for patients on hemodialysis.

      Practical Application

      The measurement of CC is an easy and inexpensive tool that should be incorporate as a screening assay to prevent falls in older individuals on hemodialysis.
      Patients with reduced CC (particularly those with high body mass index) should be closely monitored for the risk of falls. Actions should include stimulating regular strength exercises, avoiding hypotensive episodes (adjust medications and ultrafiltration rate during dialysis), avoiding environmental hazards at home (do not use slip shoes, ask for help during baths or when moving positions) and at the dialysis clinic (after dialysis do not go out unaccompanied after dialysis and do not get out of the chair quickly).

      Credit Authorship Contribution Statement

      Renata G. Rodrigues: Conceptualization, Investigation, Data acquisition, Formal analysis, Writing – original draft, Writing – review & editing. Maria Aparecida Dalboni: Writing – review & editing. Marilia de A. Correia: Writing – review & editing, Visualization. Luciene M. dos Reis: Writing – review & editing. Rosa M.A. Moyses: Writing – review & editing, Formal analysis. Rosilene M. Elias: Formal analysis, Supervision, Project administration.

      Acknowledgments

      The authors thank Soraia Stael Drumont for gently allowing recruit patients in a dialysis unit.

      References

        • Saran R.
        • Robinson B.
        • Abbott K.C.
        • et al.
        US Renal data System 2019 Annual data report: epidemiology of kidney disease in the United States.
        Am J kidney Dis : official J Natl Kidney Found. 2020; 75: A6-A7
        • Chantanachai T.
        • Sturnieks D.L.
        • Lord S.R.
        • Payne N.
        • Webster L.
        • Taylor M.E.
        Risk factors for falls in older people with cognitive impairment living in the community: systematic review and meta-analysis.
        Ageing Res Rev. 2021; 71: 101452
        • Organization WH
        Falls 2021.
        • Berry S.D.
        • Miller R.R.
        Falls: epidemiology, pathophysiology, and relationship to fracture.
        Curr Osteoporos Rep. 2008; 6: 149-154
        • Gonzalez M.C.
        • Mehrnezhad A.
        • Razaviarab N.
        • Barbosa-Silva T.G.
        • Heymsfield S.B.
        Calf circumference: cutoff values from the NHANES 1999-2006.
        The Am J Clin Nutr. 2021; 113: 1679-1687
        • Veronese N.
        • Smith L.
        • Barbagallo M.
        • et al.
        Sarcopenia and fall-related injury among older adults in five low- and middle-income countries.
        Exp Gerontol. 2021; 147: 111262
        • Kanis J.A.
        • Johansson H.
        • Harvey N.C.
        • McCloskey E.V.
        A brief history of FRAX.
        Arch Osteoporos. 2018; 13: 118
        • Masnoon N.
        • Shakib S.
        • Kalisch-Ellett L.
        • Caughey G.E.
        What is polypharmacy? A systematic review of definitions.
        BMC Geriatr. 2017; 17: 230
        • Dodds R.M.
        • Syddall H.E.
        • Cooper R.
        • et al.
        Grip strength across the life course: normative data from twelve British studies.
        PloS one. 2014; 9: e113637
        • Hlatky M.A.
        • Boineau R.E.
        • Higginbotham M.B.
        • et al.
        A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index).
        The Am J Cardiol. 1989; 64: 651-654
        • Kono K.
        • Nishida Y.
        • Yabe H.
        • et al.
        Development and validation of a fall risk assessment index for dialysis patients.
        Clin Exp Nephrol. 2018; 22: 167-172
        • Dargent-Molina P.
        • Favier F.
        • Grandjean H.
        • et al.
        Fall-related factors and risk of hip fracture: the EPIDOS prospective study.
        Lancet. 1996; 348: 145-149
        • Rolland Y.
        • Lauwers-Cances V.
        • Cournot M.
        • et al.
        Sarcopenia, calf circumference, and physical function of elderly women: a cross-sectional study.
        J Am Geriatr Soc. 2003; 51: 1120-1124
        • Rodrigues J.
        • Cuppari L.
        • Campbell K.L.
        • Avesani C.M.
        Nutritional assessment of elderly patients on dialysis: pitfalls and potentials for practice.
        Nephrology, Dialysis, Transplantation : Official Publication Eur Dial Transpl Assoc - Eur Ren Assoc. 2017; 32: 1780-1789
        • Ishida Y.
        • Maeda K.
        • Nonogaki T.
        • et al.
        Impact of edema on length of calf circumference in older adults.
        Geriatr Gerontol Int. 2019; 19: 993-998
        • Johansen K.L.
        • Lee C.
        Body composition in chronic kidney disease.
        Curr Opin Nephrol Hypertens. 2015; 24: 268-275
        • Zamboni M.
        • Rubele S.
        • Rossi A.P.
        Sarcopenia and obesity.
        Curr Opin Clin Nutr Metab Care. 2019; 22: 13-19
        • Kalantar-Zadeh K.
        • Rhee C.M.
        • Chou J.
        • et al.
        The obesity paradox in kidney disease: How to Reconcile it with obesity Management.
        Kidney Int Rep. 2017; 2: 271-281