Impaired muscle strength is associated with fractures in hemodialysis patients

Determination of bone architecture and strength in men and women with stage 5 chronic kidney disease

Fractures are common in men and women with dialysis-dependent chronic kidney disease (stage 5D CKD) and are associated with substantial morbidity and mortality. The clinical utility of dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), noninvasive measures of bone mass and architecture that reflect fracture risk in healthy men and women, is uncertain in patients with stage 5D CKD. This review will outline the epidemiology and etiology of fractures and will summarize the published data that describe the association between fractures, bone mass, and bone strength in stage 5D CKD. Fracture risk assessment in stage 5D CKD is complicated as the etiology of fractures is multifactorial and includes impairments in bone quantity and quality. Cross-sectional data suggest that bone density by DXA is lower among stage 5D CKD patients with fractures compared with those without, and that this may be particularly true at cortical sites. However, DXA does not capture bone microarchitecture and cannot differentiate between cortical and trabecular bone. Some, but not all studies, that measure cortical and trabecular bone by pQCT in stage 5D CKD, demonstrate a preferential decrease in cortical bone; however, these studies are limited by small sample sizes and cross-sectional study design. No studies have reported on longitudinal relationships between bone architecture, strength, and incident fractures in patients with stage 5D CKD. Further research is needed to identify noninvasive measures of bone strength that can be used for fracture risk assessment in stage 5D CKD.

Fracture risk assessment in patients with chronic kidney disease

Fractures are common in patients with chronic kidney disease (CKD) and associated with substantially high morbidity and mortality. Bone mass measurements are commonly used to assess fracture risk in the general population, but the utility of these measurements in patients with CKD, and specifically among those on hemodialysis, is unclear. This review will outline the epidemiology and etiology of fractures in patients with CKD with a particular emphasis on men and women on hemodialysis. As well, we will summarize the published data, which describes the association between risk factors for fracture (including bone mass measurements, biochemical markers of mineral metabolism, and muscle strength) and fractures in patients with CKD. Patients with CKD suffer from fractures due to impairments in bone quantity, bone quality, and abnormalities of neuromuscular function. There is a paucity of evidence on the associations between bone quality, bone turnover markers, neuromuscular function, and fractures in patients with CKD. Furthermore, the complex etiology of fractures combined with the technical limitations of bone mineral density testing, both by dual energy X-ray absorptiometry (DXA) and by peripheral quantitative tomography (pQCT), limits the clinical utility of bone mass measurements for fracture prediction in CKD; this is particularly true among patients with stages 4 and 5 CKD. Further prospective studies to identify noninvasive measures of bone strength that can be used for fracture risk assessment are needed.

Vitamin K(2) improves renal function and increases femoral bone strength in rats with renal insufficiency

Renal insufficiency induces cortical bone loss in rats. The present study examined the influence of vitamin K(2) on renal function, cortical bone mass, and bone strength in rats with renal insufficiency. Thirty male Sprague-Dawley rats (8 weeks old) were randomized by the stratified weight method to the following three groups of 10 animals each: sham operation (control), 5/6 nephrectomy, and 5/6 nephrectomy + oral vitamin K(2) (menaquinone-4, menatetrenone, 30 mg/kg, 5 days/week). Treatment was initiated 10 days after surgery. After 6 weeks of treatment, samples of serum, urine, and bone (femur and tibia) were obtained. Renal function was evaluated, bone histomorphometric analysis was performed on the tibial diaphysis, and the bone mineral density (BMD) and mechanical strength of the femoral diaphysis were determined by peripheral quantitative computed tomography and a three-point bending test, respectively. Nephrectomy induced renal dysfunction, as indicated by increased levels of serum creatinine and urea nitrogen along with a decrease of creatinine clearance; and it also decreased BMD without significantly affecting bone strength at the femoral diaphysis. Vitamin K(2) improved renal function parameters but did not significantly influence BMD at the femoral diaphysis. However, vitamin K(2) decreased the bone marrow area of the tibial diaphysis and increased the stiffness of the femoral diaphysis. These findings suggest that administration of vitamin K(2) improves renal function and increases cortical bone strength without altering BMD in rats with renal insufficiency.

[Is there a place for the physical activity in the prevention of the fractures of chronic kidney disease patients?]

The risk of non-traumatic fractures is greatly increased in kidney disease patients and well demonstrated in dialysis patients. If osteoporosis plays a major role in the general population, in chronic kidney disease renal osteodystrophy is associated with neurological and muscular disorders, which probably worsen the risk. The decrease in physical activity is a factor contributing to the loss of bone mass and the initiation of a rehabilitation program improves the prognosis. Despite the association between chronic renal disease and sedentary lifestyle, the relationship between physical inactivity and bones in dialysis patients and the effect of increased activity programs, are not well documented in the literature.

Tests of neuromuscular function are associated with fractures in patients with chronic kidney disease

BACKGROUND

Fractures are common in individuals with chronic kidney disease (CKD), and tests of neuromuscular function (NMT) discriminate well among fractured and non-fractured patients with Stage 5 CKD on dialysis. The ability of NMT to discriminate fracture status in patients with Stages 3-5 CKD is unknown.

METHODS

In this cross-sectional study, we sought to determine in adult patients with Stages 3-5 CKD (eGFR by the Modification of Diet in Renal Disease equation) if NMT [timed up and go (TUG), 6-min walk (6MW) and grip strength] could discriminate fracture status (self-reported low-trauma fractures since age 40 and/or vertebral fractures by morphometry). We conducted logistic regression and receiver-operating characteristic (ROC) curves for each predictor [expressed as area under the ROC curves (AUROC) with 95% confidence intervals (CI)].

RESULTS

Data was available for 125 men and 86 women. The mean age was 63.3 ± 15.5 years, duration of CKD was 96.7 ± 125.3 months and one-third had diabetes. Patients with fractures were older and fell more frequently (P < 0.05). After adjusting for age, weight and sex, for every standard deviation increase in TUG and 6MW, the risk of fracture increased [odds ratio (OR): 1.68; 95% CI: 1.40-2.02] and decreased (OR: 0.53; 95% CI: 0.52-0.54), respectively. Both the TUG and 6MW could discriminate among those with and without fractures (AUROC: 0.90; 95% CI:0.84-0.95, AUROC: 0.87; 95% CI: 0.80-0.94, respectively).

CONCLUSIONS

The TUG and 6MW are able to discriminate fracture status in patients with Stages 3-5 CKD. These tests do not require specialized expertise/equipment and are an inexpensive method to assess for the presence of fractures.

Bone mass measurements in men and women with chronic kidney disease

PURPOSE OF REVIEW

Fractures are common in patients with chronic kidney disease (CKD) and are associated with substantial morbidity and mortality. Bone mass measurements are commonly used to assess fracture risk in the general population, but the utility of these measurements in patients with CKD is unclear.

RECENT FINDINGS

This review will outline the epidemiology and etiology of fractures in patients with CKD. Also, we will summarize the published data that describe the association between bone mass measurements and fracture in patients with CKD.

SUMMARY

Patients with CKD suffer from fractures due to impairments in bone quantity, bone quality, and abnormalities of neuromuscular function. The complex etiology of fractures combined with the technical limitations of bone mineral density testing, both by dual energy X-ray absorptiometry and by peripheral quantitative computed tomography, limits the clinical utility of bone mass measurements for fracture prediction in CKD; this is particularly true among patients with stages 4 and 5 CKD. As such, clinicians should not routinely order bone mineral density testing in patients with CKD. Further research, to determine whether bone mineral density together with other noninvasive measures to assess bone strength can predict fracture, is needed.

Fracture Risk Assessment in Chronic Kidney Disease, Prospective Testing Under Real World Environments (FRACTURE): a prospective study

Background

Chronic kidney disease (CKD) is associated with an increased risk of fracture. Decreased bone mass and disruption of microarchitecture occur early in the course of CKD and worsens with the progressive decline in renal function so that at the time of initiation of dialysis at least 50% of patients have had a fracture. Despite the excess fracture risk, and the associated increases in morbidity and mortality, little is known about the factors that are associated with an increase in fracture risk. Our study aims to identify prognostic factors for bone loss and fractures in patients with stages 3 to 5 CKD.

Methods

This prospective study aims to enroll two hundred and sixty men and women with stages 3 to 5 CKD. Subjects will be followed for 24 months and we will examine the ability of: 1) bone mineral density by dual x-ray absorptiometry at the spine, hip, and radius; 2) volumetric bone density by high resolution peripheral quantitated computed tomography at the radius and tibia; 3) serum markers of bone turnover; 4) bone formation rate by bone biopsy; and 5) muscle strength and balance to predict spine and non-spine fractures, identified by self-report and/or vertebral morphometry. All measurements will be obtained at baseline, at 12 and at 24 months with the exception of bone biopsy, which will be measured once at 12 months. Subjects will be contacted every 4 months to determine if there have been incident fractures or falls.

Discussion

This study is one of the first that aims to identify risk factors for fracture in early stage CKD patients. Ultimately, by identifying risk factors for fracture and targeting treatments in this group-before the initiation of renal replacement therapy - we will reduce the burden of disease due to fractures among patients with CKD.

Use of handgrip strength in the assessment of the muscle function of chronic kidney disease patients on dialysis: a systematic review

BACKGROUND

Even though handgrip strength (HGS) is considered a simple and reliable method to evaluate muscle function and, indirectly, the nutritional status in clinical settings, there is still no consensus concerning its use in patients with chronic kidney disease (CKD) undergoing dialysis. This study presents a systematic review of the literature on the use of HGS as a parameter for nutritional assessment and a prognostic marker in patients on dialysis.

METHODS

The MEDLINE database (1966 to October 2009) was consulted for this systematic review by using the search terms hand strength or muscle strength dynamometer and dialysis. Eighteen articles were identified and included in the analysis.

RESULTS

Similar to the general population, HGS values were associated with age and gender. The analysed studies showed correlation between muscle function estimated by HGS and variables used in the assessment of muscle mass and nutritional status, as well as the prediction of clinical complications.

CONCLUSIONS

The analysis indicates that HGS is a useful tool for continuous and systematic assessment of muscle mass related to nutritional status in patients on dialysis. However, it is still necessary to standardize the techniques used for HGS, especially with respect to the position of measurement, the evaluation period, the choice of arm side and the diagnostic criterion.

Effect of intradialytic versus home-based aerobic exercise training on physical function and vascular parameters in hemodialysis patients: a randomized pilot study

BACKGROUND

Hemodialysis patients show reduced physical function and greater risk of increased arterial stiffness because of hypertension, metabolic disturbances, and vascular calcification. Exercise interventions potentially could improve their vascular risk profile.

STUDY DESIGN

Randomized controlled pilot clinical study comparing the effects of 6 months of supervised intradialytic exercise training versus home-based exercise training or usual care on physical function and arterial stiffness in hemodialysis patients.

SETTING & PARTICIPANTS

70 hemodialysis patients from 3 renal units.

INTERVENTION

Intradialytic-exercise patients trained 3 times/wk for 6 months on a cycle ergometer and home-based-exercise patients followed a walking program to achieve the same weekly physical activity. Usual-care patients received no specific intervention.

OUTCOMES & MEASUREMENTS

Primary outcome measures were distance traveled during a 6-minute walk test and aortic pulse wave velocity. Secondary outcome measures included augmentation index (augmentation pressure as a percentage of central pulse pressure), peripheral (brachial) and central blood pressures (measured noninvasively using radial tonometry), physical activity, and self-reported physical functioning. Measurements were made at baseline and 6 months.

RESULTS

At 6 months, there were no significant differences between changes in 6-minute walk test distance (intradialytic exercise, +14%; home-based exercise, +11%; usual care, +5%), pulse wave velocity (intradialytic exercise, -4%; home-based exercise, -2%; usual care, +5%), or any secondary outcome measure.

LIMITATIONS

Lack of medication data limited the analysis of vascular parameters in this study.

CONCLUSION

There were no differences between intradialytic or home-based exercise training and usual care for either physical function or vascular parameters.

A structural approach to skeletal fragility in chronic kidney disease

Renal osteodystrophy is a multifactorial disorder of bone metabolism in chronic kidney disease (CKD). As CKD progresses, ensuing abnormalities in mineral metabolism result in distortions in trabecular microarchitecture, thinning of the cortical shell, and increased cortical porosity. Recent studies have shown significantly increased hip fracture rates in CKD stages 3 and 4, in dialysis patients, and in transplant recipients. The majority of studies of bone loss in CKD relied on dual-energy x-ray absorptiometry (DXA) measures of bone mineral density. However, DXA summarizes the total bone mass within the projected bone area, concealing distinct structural alterations in trabecular and cortical bone. Recent data have confirmed that peripheral quantitative computed tomography (pQCT) measures of cortical density and thickness provide substantially better fracture discrimination in dialysis patients, compared with hip or spine DXA. This review summarizes the growing evidence for bone fragility in CKD stages 3 through 5, considers the effects of CKD on trabecular and cortical bone structure as it relates to fracture risk, and details the potential advantages and disadvantages of DXA and alternative measures of bone density, geometry, and microarchitecture, including pQCT, high-resolution pQCT, and micro-magnetic resonance imaging for fracture risk assessment in CKD.

Geriatric hemodialysis rehabilitation care

The 2 objectives of this review are to provide background information about functional status in older dialysis patients and to discuss the utility of geriatric dialysis rehabilitation. We performed a literature search using PubMed and MedLine. All relevant texts were reviewed for information on functional status and disability in the renal population and in the general population. Data pertaining to geriatric rehabilitation and geriatric dialysis rehabilitation were also reviewed. We show how disability and functional limitations are more prevalent in populations with advanced stages of chronic kidney disease (CKD) compared with those with only mild stages of CKD. We describe data showing that dedicated geriatric dialysis rehabilitation units, using interdisciplinary care models, result in more than 70% of patients meeting their rehabilitation goals and being successfully discharged home. Nephrologists increasingly will be faced with problems arising from functional decline. We conclude by offering suggestions for future changes that may help to stem the rising tide of dialysis disability.

Quality improvement through the introduction of interdisciplinary geriatric hemodialysis rehabilitation care

Background

Provision of rehabilitation with the aim of restoring personal independence in elderly hemodialysis patients faces several challenges.

Design

Quality improvement report.

Setting & Participants

First 3 years of experience of an inpatient geriatric hemodialysis rehabilitation program in Toronto. Patients with new-onset disability from prolonged illness or an acute event rendering them incapable of living independently.

Quality Improvement Plan

Provision of in-patient rehabilitation with on-site dialysis; a simplified referral system; preferential admission of elderly dialysis patients; short daily dialysis sessions; integrated multidisciplinary care by experts in rehabilitation, geriatric medicine, and nephrology; and reciprocal continued medical education among staff.

Measures

Outcome measures were percentage of patients discharged home, score on the Functional Independence Measure, and attainment of rehabilitation goals.

Results

In the first 36 months, 164 dialysis patients aged 74.5 ± 7.8 years were admitted. On admission, patients had a mean Charlson comorbidity score of 7.8 ± 2.5, 98% had difficulty walking, and 84% required help with bed-to-chair transfers. After a median of 48.5 days, 111 patients (69%) were discharged home; 15 patients (9%), to an assisted-living setting; 20 patients (12%), to a long-term care facility; and 18 patients (11%), to other facilities for acute or palliative care. Of those completing therapy, 82% met some or all of their rehabilitation goals.

Limitations

The program relied on the leadership and drive of key personnel. Discharge disposition as an outcome can be affected by many factors, and definition of attainment of rehabilitation goals is arbitrary.

Conclusion

The introduction of an integrated dialysis rehabilitation service can help older dialysis patients with new-onset functional decline return to their home. Am J Kidney Dis 00:00-00