High rates of death and hospitalization follow bone fracture among hemodialysis patients

Risk factors and clinical prediction models for osteoporosis in pre-dialysis chronic kidney disease patients

BACKGROUND

Osteoporosis in pre-dialysis chronic kidney disease (CKD) patients has been overlooked, and the risk factors of osteoporosis in these patients have not been adequately studied.

OBJECTIVE

To identify risk factors for osteoporosis in pre-dialysis CKD patients and develop predictive models to estimate the likelihood of osteoporosis.

METHODS

Dual-energy X-ray absorptiometry was used to measure bone mineral density, and clinical examination results were collected from 326 pre-dialysis CKD patients. Binary logistic regression was employed to explore the risk factors associated with osteoporosis and develop predictive models.

RESULTS

In this cohort, 53.4% (n = 174) were male, 46.6% (n = 152) were female, and 21.8% (n = 71) were diagnosed with osteoporosis. Among those diagnosed with osteoporosis, 67.6% (n = 48) were female and 32.4% (n = 23) were male. Older age and low 25-(OH)-Vitamin D levels were identified as risk factors for osteoporosis in males. For females, older age, being underweight, higher bone alkaline phosphatase (NBAP), and advanced CKD (G5) were significant risk factors, while higher iPTH was protective. Older age, being underweight, and higher NBAP were risk factors for osteoporosis in the G1-4 subgroup. In the G5 subgroup, older age and higher NBAP increased the risk, while high 25-(OH)-Vitamin D or iPTH had protective effects. Nomogram models were developed to assess osteoporosis risk in pre-dialysis patients based on gender and renal function stage.

CONCLUSION

Risk factors for osteoporosis vary by gender and renal function stages. The nomogram clinical prediction models we constructed may aid in the rapid screening of patients at high risk of osteoporosis.

Two Weeks of Continuous Opioid Treatment in an Adenine-Induced Mouse Model of Chronic Kidney Disease Exacerbates the Bone Inflammatory State and Increases Osteoclasts

Patients with chronic kidney disease (CKD) report high pain levels, but reduced renal clearance eliminates many analgesic options; therefore, 30-50% of CKD patients have chronic opioid prescriptions. Opioid use in CKD is associated with higher fracture rates. Opioids may directly alter bone turnover directly through effects on bone cells and indirectly via increasing inflammation. We hypothesized that continuous opioid exposure would exacerbate the high bone turnover state of CKD and be associated with elevated measures of inflammation. Male C57Bl/6J mice after 8 weeks of adenine-induced CKD (AD) and non-AD controls (CON) had 14-day osmotic pumps (0.25-µL/hr release) containing either saline or 50-mg/mL oxycodone (OXY) surgically implanted in the subscapular region. After 2 weeks, all AD mice had elevated blood urea nitrogen, parathyroid hormone, and serum markers of bone turnover compared to controls with no effect of OXY. Immunohistochemical staining of the distal femur showed increased numbers of osteocytes positive for the mu opioid and for toll-like receptor 4 (TLR4) due to OXY. Osteocyte protein expression of tumor necrosis factor-α (TNF-α) and RANKL were higher due to both AD and OXY so that AD + OXY mice had the highest values. Trabecular osteoclast-covered surfaces were also significantly higher due to both AD and OXY, resulting in AD + OXY mice having 4.5-fold higher osteoclast-covered surfaces than untreated CON. These data demonstrate that opioids are associated with a pro-inflammatory state in osteocytes which increases the pro-resorptive state of CKD.

Outcomes Following Surgical Fixation of Upper Extremity Fractures in Patients with Chronic Kidney Disease

Purpose

Moderate to severe (stage III-IV) chronic kidney disease (CKD) and end stage renal disease (ESRD) have been shown to be independent risk factors for sustaining a fragility fracture. High rates of complications and mortality are associated with fracture fixation in patients with CKD, but existing literature is limited. It is unknown how CKD stage III-IV or ESRD affects outcomes in upper-extremity fractures. We hypothesize that patients with CKD stage III-IV or ESRD will have high complication rates after surgical fixation of upper extremity fractures.

Methods

We identified all patients between 2008 and 2018 who underwent operative fixation of an upper extremity fracture proximal to the distal radius with a diagnosis of CKD stage III-IV or ESRD at the time of injury. Those with an acute kidney injury at the time of injury or a history of a kidney transplant were excluded. Demographics, medical complications, and surgical complications were collected retrospectively. Data on readmissions within 90 days and mortality within 1 year were also collected.

Results

Thirty-five patients were identified. Three patients had ESRD. Fractures included two clavicle, twelve proximal humerus, one humeral shaft, ten distal humerus, five olecranon, two ulnar shaft, one radial shaft, and two both-bone forearm fractures. In total, 91.4% of fractures were closed injuries. Surgical complications occurred in 40% of patients. The reoperation rate was 11.4%, and all cases of reoperation involved hardware removal. The all-cause 90-day readmission rate was 34.3%. The 1-year mortality rate was 8.6%.

Conclusions

Surgical complications occurred in 40% of patients with CKD stage III-IV or ESRD who underwent fixation for an upper extremity fracture. It is important to counsel these patients regarding their high risk for complications. Further research is needed to investigate and identify how to mitigate risk.

Type of study/level of evidence

Prognostic IV.

Outcomes Following Surgical Fixation of Distal Radius Fractures in Patients With Chronic Kidney Disease

Purpose

Moderate-to-severe chronic kidney disease (CKD, stages III-IV) and end-stage renal disease (ESRD or CKD stage V) are known to be independent risk factors for fragility fracture. Altered bone and mineral metabolism contributes to greater complications and mortality rates in the setting of fractures, although most existing literature is limited to hip fractures. We hypothesized that patients with moderate-to-severe CKD or ESRD would have greater complication rates after surgical treatment of distal radius fractures compared with those without CKD.

Methods

We retrospectively identified all patients at a level 1 trauma center between 2008 and 2018 who had a diagnosis of stage III-IV CKD or ESRD at the time of operative fixation of a distal radius fracture. We recorded demographic data, comorbidities, and surgical complications. Data for readmissions within 90 days and 1-year mortality were collected. A 2:1 sex-matched control group without CKD who underwent distal radius fixation was selected for comparison, with age-adjusted analysis.

Results

A total of 32 patients with CKD (78.1% CKD stage III/IV, 21.9% ESRD) and 62 without CKD were identified. The mean age was 67 ± 12 years in the CKD group and 55 ± 15 years in the control group. The CKD group had a higher Charlson Comorbidity Index (5.7 vs 2.0). Surgical complication rate in the CKD group was 12.5% (12.0% CKD III/IV; 14.3% ESRD). Neither early nor late surgical complication rates were statistically different from those in patients without CKD. Reoperation rate as well as 30- and 90-day readmission rates were similar between groups. Overall, 1-year mortality was greater in the CKD group (9.4% vs 0%).

Conclusions

Surgical complications and readmission rates are similar in patients with and without CKD after distal radius fracture fixation. However, 1-year mortality rate is significantly higher after distal radius fixation in patients with moderate-to-severe CKD or ESRD.

Type of study/level of evidence

Prognostic IIIa.

The Relationship Between Fracture and Mortality in a Chinese Maintenance Hemodialysis Patients Cohort

Background

Patients on maintenance hemodialysis have an increased risk of fracture. However, the relationship between fracture and poor prognosis is not clear.

Methods

A total of 182 maintenance hemodialysis patients were enrolled in the study. The relationship between fracture and poor prognosis (cardiovascular events, stroke, malignancy and 5-year all-cause mortality) were analyzed.

Results

21 of 182 patients had a history of fracture at the time of enrollment. 26 patients had a new fracture after enrollment. A total of 57 fractures occurred in 47 patients, the most common fracture site was the rib. Patients with fracture group had a higher proportion of elderly and female, higher serum phosphorus and B-type natriuretic peptide and lower hemoglobin, albumin, and potassium compared with those without fracture. Age (OR=3.809, 95% CI: 1.064-8.966, p=0.038), hemoglobin (OR=0.961, 95% CI: 0.925-0.997, p=0.035), and serum phosphorus (OR=3.325, 95% CI:1.104-10.019, p=0.033) were the independent risk factors of new fractures in MHD patients. The incidence of malignancy and 5-year all-cause mortality in patients with fracture was higher than those without fracture (p<0.05). But there was no significant difference in the incidence of acute myocardial infarction or stroke.

Conclusion

25.8% of maintenance hemodialysis patients had at least one fracture, with rib fractures accounting for the highest proportion. Age, hemoglobin and serum phosphorus were the independent risk factors of new fractures. The incidence of malignancy and 5-year all-cause mortality in patients with fracture was higher than those without fracture, but there was no significant difference in the incidence of acute myocardial infarction and stroke.

Ten tips on how to assess bone health in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) experience a several-fold increased risk of fracture. Despite the high incidence and the associated excess morbidity and premature mortality, bone fragility in CKD, or CKD-associated osteoporosis, remains a blind spot in nephrology with an immense treatment gap. Defining the bone phenotype is a prerequisite for the appropriate therapy of CKD-associated osteoporosis at the patient level. In the present review, we suggest 10 practical 'tips and tricks' for the assessment of bone health in patients with CKD. We describe the clinical, biochemical, and radiological evaluation of bone health, alongside the benefits and limitations of the available diagnostics. A bone biopsy, the gold standard for diagnosing renal bone disease, is invasive and not widely available; although useful in complex cases, we do not consider it an essential component of bone assessment in patients with CKD-associated osteoporosis. Furthermore, we advocate for the deployment of multidisciplinary expert teams at local, national, and potentially international level. Finally, we address the knowledge gaps in the diagnosis, particularly early detection, appropriate "real-time" monitoring of bone health in this highly vulnerable population, and emerging diagnostic tools, currently primarily used in research, that may be on the horizon of clinical practice.

Effectiveness of calcimimetics on fractures in dialysis patients with secondary hyperparathyroidism: meta-analysis of randomized trials

INTRODUCTION

This study aimed to assess the effectiveness of calcimimetics in reducing the risk of fractures in dialysis patients with secondary hyperparathyroidism (SHPT).

MATERIAL AND METHODS

A comprehensive literature search was conducted using PubMed, Embase, and Cochrane Library for articles published through December 9, 2023. The quality of each trial was evaluated using the Cochrane Collaboration tool. Meta-analysis was performed using a random-effects model, and effect measures across studies were synthesized. The risk ratio (RR) and 95% confidence interval (CI) were used to quantify the risk of fracture.

RESULTS

We identified seven studies involving 6481 dialysis patients with SHPT. The administration of calcimimetics reduced fracture incidence compared to placebo or conventional treatment (RR: 0.50, 95% CI 0.29-0.88, p = 0.02). Calcimimetics demonstrated a low number needed to treat (NNT) to prevent an incident fracture (NNT: 47).

CONCLUSION

The use of calcimimetics offers a significant benefit in reducing the risk of fractures in patients undergoing dialysis with SHPT.

Calcium-based phosphate binders and bone mineral density in patients undergoing hemodialysis: a retrospective cohort study

BACKGROUND

Calcium supplements are commonly prescribed to prevent fractures in patients with osteoporosis. Nonetheless, they are generally eschewed in hemodialysis patients because they increase vascular calcification and induce cardiovascular disease. This retrospective cohort study aimed to investigate the effect of calcium-based phosphate binders (CBPB) on bone mineral density (BMD) in hemodialysis patients.

METHODS

Outpatients on dialysis who underwent BMD measurement from January to December 2017, whose data on BMD trends and CBPB administration were recorded over the next 4 years, were enrolled. Patients receiving anti-osteoporotic medications were excluded. The association between the presence and duration of CBPB administration and changes in BMD was evaluated.

RESULTS

The femoral neck's BMD decreased from 0.836 g/cm2 (0.702-0.952) to 0.764 g/cm2 (0.636-0.896) (P < 0.001) in the non-CBPB group (patients who never received CBPB over 4 years, n = 32). The CBPB group (n = 56) exhibited only a minute decrease from 0.833 g/cm2 (0.736-0.965) to 0.824 g/cm2 (0.706-0.939) (P = 0.004). Multivariate linear regression analysis revealed better BMD maintenance in the CBPB group [β-coefficient (95% CI): 0.033 (0.001-0.065); P = 0.046] than in the non-CBPB group. Additionally, the prolonged-CBPB administration group showed superior BMD preservation [β-coefficient (95% CI): 0.038 (0.001-0.076); P = 0.042].

CONCLUSION

CBPB administration may be associated with BMD maintenance.

Fracture Management in Chronic Kidney Disease: Challenges and Considerations for Orthopedic Surgeons

Orthopedic surgeons treating fractures need to consider comorbidities, including chronic kidney disease (CKD), which affects millions worldwide. CKD patients are at elevated risk of fractures due to osteoporosis, especially in advanced stages. In addition, fractures in CKD patients pose challenges due to impaired bone healing and increased post-fracture complications including surgical site infection and nonunion. In this article, we will discuss factors that must be considered when treating fractures in CKD patients. Perioperative management includes careful adjustment of hemodialysis schedules, selection of anesthetic methods, and addressing bleeding tendencies. Tourniquet usage for fractures in limbs with arteriovenous fistulae should be cautious. Pain medication should be administered carefully, with opioids like hydromorphone preferred over nonsteroidal anti-inflammatory drugs. Medical management after fractures should address underlying factors and include physical rehabilitation to reduce the risk of subsequent fractures. A comprehensive approach to fracture management in CKD patients can improve outcomes.

Association of serum sodium levels with fractures and mortality in patients undergoing maintenance hemodialysis

BACKGROUND

Hyponatremia is implicated in pathological bone resorption and has been identified as a risk factor for bone fracture in the general population. However, there are limited data on the association between serum sodium levels and fracture risk in patients undergoing hemodialysis (HD).

METHODS

We analyzed a historical cohort of 2220 maintenance HD patients to examine the association between serum sodium levels and the risk of fracture and mortality. We also examined the association between serum sodium levels and osteoporosis, based on metacarpal bone mineral density, in a subcohort of 455 patients with available data. In addition, we examined the association between serum sodium levels and bone turnover markers in a separate cross-sectional cohort of 654 maintenance HD patients.

RESULTS

During a median follow-up of 5.4 years, 712 patients died, 113 experienced clinical fractures, and 64 experienced asymptomatic vertebral fractures. Lower serum sodium levels were associated with an increased risk of mortality (HR 1.06 per 1 mEq/L decrease; 95% CI 1.03-1.09) but not with the risk of clinical fracture (HR 1.04 per 1 mEq/L decrease; 95% CI 0.97-1.11). A similar lack of association was observed for asymptomatic vertebral fracture and any fracture. Serum sodium levels were also not associated with osteoporosis in a subcohort with available data (n = 455) or with bone alkaline phosphatase or tartrate-resistant acid phosphatase-5b in a separate cross-sectional cohort.

CONCLUSION

Serum sodium levels were associated with mortality but not with fracture risk, osteoporosis, or bone turnover markers in maintenance HD patients.

Long-term effects of denosumab on bone mineral density and turnover markers in patients undergoing hemodialysis

INTRODUCTION

Denosumab, a fully human anti-RANKL monoclonal antibody, is a widely used osteoporosis treatment that is increasingly being used in patients undergoing dialysis; however, its long-term efficacy and safety in these patients remain unknown.

MATERIALS AND METHODS

This observational study comprised individuals aged ≥ 20 years undergoing hemodialysis and receiving denosumab. After denosumab administration, we analyzed the long-term changes in bone mineral density (BMD) and levels of bone turnover markers (BTMs) and calcium.

RESULTS

The study included 45 patients who have been receiving denosumab for a median duration of 3.8 (interquartile range, 2.5-6.7) years. Tartrate-resistant acid phosphatase 5b (TRACP-5b) levels decreased from a median of 595 (434-778) mU/dL at baseline to 200 (141-430) mU/dL after 6 months of denosumab administration (P < 0.001) and remained low thereafter. Similarly, bone-specific alkaline phosphatase (BAP) levels decreased from a median of 18.2 (15.9-25.8) μg/L at baseline to 12.4 (9.9-15.6) μg/L after 6 months (P < 0.001) and remained low thereafter. Meanwhile, BMD, as assessed with dual energy X-ray absorptiometry and measured at the distal 1/3 of the radius, did not decrease (0.465 ± 0.112 g/cm2 at baseline vs. 0.464 ± 0.112 g/cm2 after administration; P = 0.616). Regarding hypocalcemia, corrected calcium levels reached were the lowest at 7 days after administration and normalized within 30 days.

CONCLUSION

The study showed long-term suppression of TRACP-5b and BAP levels and sustaining BMD after denosumab administration over an extended period in patients undergoing hemodialysis.

Evaluating Osteoporosis in Chronic Kidney Disease: Both Bone Quantity and Quality Matter

Bone strength is determined not only by bone quantity [bone mineral density (BMD)] but also by bone quality, including matrix composition, collagen fiber arrangement, microarchitecture, geometry, mineralization, and bone turnover, among others. These aspects influence elasticity, the load-bearing and repair capacity of bone, and microcrack propagation and are thus key to fractures and their avoidance. In chronic kidney disease (CKD)-associated osteoporosis, factors traditionally associated with a lower bone mass (advanced age or hypogonadism) often coexist with non-traditional factors specific to CKD (uremic toxins or renal osteodystrophy, among others), which will have an impact on bone quality. The gold standard for measuring BMD is dual-energy X-ray absorptiometry, which is widely accepted in the general population and is also capable of predicting fracture risk in CKD. Nevertheless, a significant number of fractures occur in the absence of densitometric World Health Organization (WHO) criteria for osteoporosis, suggesting that methods that also evaluate bone quality need to be considered in order to achieve a comprehensive assessment of fracture risk. The techniques for measuring bone quality are limited by their high cost or invasive nature, which has prevented their implementation in clinical practice. A bone biopsy, high-resolution peripheral quantitative computed tomography, and impact microindentation are some of the methods established to assess bone quality. Herein, we review the current evidence in the literature with the aim of exploring the factors that affect both bone quality and bone quantity in CKD and describing available techniques to assess them.

Proteinuria screening and risk of bone fracture: a retrospective cohort study using a nationwide population-based database

Background and hypothesis

Proteinuria is associated with an increased risk of kidney function deterioration, cardiovascular disease, or cancer. Previous reports suggesting an association between kidney dysfunction and bone fracture may be confounded by concomitant proteinuria and were inconsistent regarding the association between proteinuria and bone fracture. Therefore, we aimed to evaluate the association using a large administrative claims database in Japan.

Methods

Using the DeSC database, we retrospectively identified individuals with laboratory data including urine dipstick test between August 2014 and February 2021. We evaluated the association between proteinuria and vertebral or hip fracture using multivariable Cox regression analyses adjusted for various background factors including kidney function. We also performed subgroup analyses stratified by sex and kidney function and sensitivity analyses with Fine & Gray models considering death as a competing risk.

Results

We identified 603 766 individuals and observed 21 195 fractures. With reference to the negative proteinuria group, the hazard ratio for hip or vertebral fracture was 1.10 [95% confidence interval (CI), 1.05-1.14] and 1.16 (95%CI, 1.11-1.22) in the trace and positive proteinuria group, respectively, in the Cox regression analysis. The subgroup analyses showed similar trends. The Fine & Gray model showed a subdistribution hazard ratio of 1.09 (95%CI, 1.05-1.14) in the trace proteinuria group and 1.15 (95% CI, 1.10-1.20) in the positive proteinuria group.

Conclusions

Proteinuria was associated with an increased risk of developing hip or vertebral fractures after adjustment for kidney function. Our results highlight the clinical importance of checking proteinuria for predicting bone fractures.

Trabecular Bone Score Improves Early After Successful Kidney Transplantation Irrespective of Antiresorptive Therapy and Changes in Bone Mineral Density

Background

Trabecular bone score (TBS) is a new tool to assess trabecular bone microarchitecture based on standard dual-energy x-ray absorptiometry (DXA) of lumbar spine images. TBS may be important to assess bone quality and fracture susceptibility in kidney transplant recipients (KTRs). This study aimed to investigate the effect of different bone therapies on TBS in KTRs.

Methods

We reanalyzed DXA scans to assess TBS in 121 de novo KTRs at baseline, 10 wk, and 1 y. This cohort, between 2007 and 2009, participated in a randomized, placebo-controlled trial evaluating the effect of ibandronate versus placebo in addition to vitamin D and calcium.

Results

Although bone mineral density (BMD) Z scores showed a subtle decrease in the first weeks, TBS Z scores increased from baseline to 10 wk for both treatment groups, followed by a slight decline at 12 mo. When comparing treatment groups and adjusting for baseline TBS, there were no differences found in TBS at 12 mo (P = 0.419). Correlation between TBS and BMD at baseline was weak (Spearman's ρ = 0.234, P = 0.010), and change in TBS was not correlated with changes in lumbar spine BMD in either of the groups (ρ = 0.003, P = 0.973).

Conclusions

Treatment with ibandronate or vitamin D and calcium did not affect bone quality as measured by TBS in de novo KTRs, but TBS increased early, irrespective of intervention. Changes in TBS and BMD during the study period were not correlated, indicating that these measurements reflect different aspects of bone integrity. TBS may complement BMD assessment in identifying KTRs with a high fracture risk.

Interrelationships between sarcopenia, bone turnover markers and low bone mineral density in patients on hemodialysis

BACKGROUND

Hemodialysis (HD) patients are at risk for sarcopenia (SP) and bone loss, which may impact falls and bone fragility and lead to poor prognosis. Patients with HD and those with osteoporosis (OP) are still underdiagnosed and untreated. The aims of the present study were to evaluate the factors that affect bone mineral density (BMD) loss in HD patients, and explore traditional and novel approaches to manage chronic kidney disease-mineral-bone disorder (CKD-MBD).

METHODS

Patients who underwent regular HD at the First Affiliated Hospital of Soochow University were retrospectively evaluated. According to the WHO osteoporosis criteria, patients were categorized into three groups: normal BMD, osteopenia, and osteoporosis. Demographic and clinical data, skeletal muscle mass, and bone turnover markers(BTM) were compared between the three groups. The correlation between bone density and muscle mass was calculated, and related risk factors were analyzed.

RESULTS

This study enrolled 130 HD patients, 36 patients were diagnosed with sarcopenia (27.7%), 44 patients were diagnosed with osteopenia (33.8%), 19 patients were diagnosed with osteoporosis (14.6%), and 23 patients were diagnosed with osteosarcopenia (17.7%). The SMI was positively correlated with the BMD of the lumbar spine (r = 0.23, p < 0.01) and femoral neck (r = 0.22, p < 0.05). In ordinal logistic regression analysis, the odds ratio (OR) for low BMD was high for patients with sarcopenia (OR = 5.894, 95% CI 1.592-21.830, p < 0.01), older age (OR = 1.095, 95% CI 1.041-1.153, p < 0.001), higher TRACP-5b levels (OR = 1.597, 95% CI 1.230-2.072, p < 0.01), and lower 25-OH vitamin D levels (OR = 0.631, 95% CI 0.544-0.733, p < 0.001).

CONCLUSION

The preservation of skeletal muscle mass could be important to prevent a BMD decrease in HD patients. Adequate intake of vitamin D and control of TRACP-5b levels will help reduce the occurrence and progression of osteopenia/sarcopenia in HD patients.

Vitamin D Therapy in Adults With CKD: A Systematic Review and Meta-analysis

RATIONALE & OBJECTIVE

Vitamin D is widely used to manage chronic kidney disease-mineral and bone disorder (CKD-MBD). We evaluated the effects of vitamin D therapy on mortality, cardiovascular, bone, and kidney outcomes in adults with CKD.

STUDY DESIGN

Systematic review of randomized controlled trials (RCT) with highly sensitive searching of MEDLINE, Embase, and CENTRAL, through February 25, 2023.

SETTING & STUDY POPULATIONS

Adults with stage 3, 4, or 5 CKD, including kidney failure treated with dialysis. Recipients of a kidney transplant were excluded.

SELECTION CRITERIA FOR STUDIES

RCTs with≥3 months of follow-up evaluating a vitamin D compound.

DATA EXTRACTION

Data were extracted independently by three investigators.

ANALYTICAL APPROACH

Treatment estimates were summarized using random effects meta-analysis. Primary review endpoints were all-cause death, cardiovascular death, and fracture. Secondary outcomes were major adverse cardiovascular events, hospitalization, bone mineral density, parathyroidectomy, progression to kidney failure, proteinuria, estimated glomerular filtration rate, hypercalcemia, hyperphosphatemia, biochemical markers of CKD-MBD, and various intermediate outcome measures of cardiovascular disease. Risk of bias was assessed using the Cochrane Risk of Bias (RoB) 2 tool. Evidence certainty was adjudicated using GRADE.

RESULTS

Overall, 128 studies involving 11,270 participants were included. Compared with placebo, vitamin D therapy probably had no effect on all-cause death (relative risk [RR], 1.04; 95% CI, 0.84-1.24); and uncertain effects on fracture (RR, 0.68; 95% CI, 0.37-1.23) and cardiovascular death (RR, 0.73; 95% CI, 0.31-1.71). Compared with placebo, vitamin D therapy lowered serum parathyroid hormone and alkaline phosphatase, but increased serum calcium.

LIMITATIONS

Data were limited by trials with short-term follow-up periods, small sample size, and the suboptimal quality.

CONCLUSIONS

Vitamin D therapy did not reduce the risk of all-cause death in people with CKD. Effects on fracture and cardiovascular and kidney outcomes were uncertain.

TRIAL REGISTRATION

Registered at PROSPERO with study number CRD42017057691.

PLAIN-LANGUAGE SUMMARY

Chronic kidney disease (CKD) is associated with increased risk of death, cardiovascular disease, and fractures. This excess risk is thought to be related to changes in bone and mineral metabolism, leading to the development of CKD-mineral and bone disorder (CKD-MBD) which is characterized by vascular calcification and reduced bone quality. Vitamin D is commonly used in the treatment of this condition. We reviewed randomized controlled trials examining the effect of vitamin D therapy in CKD. We found that vitamin D therapy affects serum biomarkers, including an increase in serum calcium. However, it probably has no effect on risk of all-cause death in CKD, and the effects on other clinical bone, cardiovascular, and kidney outcomes are uncertain.

Active Vitamin D Use and Fractures in Hemodialysis Patients: Results from the International DOPPS

Active vitamin D is commonly used to control secondary hyperparathyroidism in dialysis patients, but it is unknown whether active vitamin D directly improves bone strength, independently of its ability to suppress parathyroid hormone (PTH). We analyzed the association between the prescription of active vitamin D and incidence of any fracture and hip fracture in 41,677 in-center hemodialysis patients from 21 countries in phases 3 to 6 (2005 to 2018) of the Dialysis Outcomes and Practice Patterns Study (DOPPS). We used Cox regression, adjusted for PTH and other potential confounders, and used a per-protocol approach to censor patients at treatment switch during follow-up. We also used a facility preference approach to minimize confounding by indication. Overall, 55% of patients were prescribed active vitamin D at study enrollment. Event rates (per patient-year) were 0.024 for any fracture and 0.010 for hip fracture. The adjusted hazard ratio (95% confidence interval) comparing patients prescribed versus not prescribed active vitamin D was 1.02 (0.90 to 1.17) for any fracture and 1.00 (0.81 to 1.23) for hip fracture. In the facility preference approach, there was no difference in fracture rate between facilities with higher versus lower active vitamin D prescriptions. Thus, our results do not suggest a PTH-independent benefit of active vitamin D in fracture prevention and support the current KDIGO guideline suggesting the use of active vitamin D only in subjects with elevated or rising PTH. Further research is needed to determine the role of active vitamin D beyond PTH control. © 2023 American Society for Bone and Mineral Research (ASBMR).

Mortality After Hip and Spine Fractures in Patients With End-Stage Kidney Disease: A Systematic Review and Meta-Analysis

Fractures represent a major cause of disability in the elderly, and patients with fractures exhibit a higher mortality rate than those without. Fractures are also an important health problem among patients with end-stage kidney disease (ESKD) requiring hemodialysis, peritoneal dialysis, or kidney transplantation. To the best of our knowledge, no study in the literature has yet quantitatively summarized the mortality rates, and a summary of evidence on post-hip and spine fracture mortality in patients with ESKD is lacking. The purpose of this study is to quantitatively evaluate the mortality rate, one-year mortality rate, and five-year mortality rate after hip and spine fractures in patients with ESKD receiving kidney replacement therapy. The MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and ClinicalTrials.gov databases were comprehensively searched for reports on mortality rate and time-period mortality in patients with ESKD after hip or spine fractures up to June 2022. Prospective and retrospective cohort studies, as well as case series involving four or more patients, were included. Pooled mortality rate, one-year rate, and five-year mortality rate with 95% confidence intervals (CIs) were examined using a random-effects model. The risk of bias was assessed using the Joanna Briggs Institute (JBI) Prevalence Critical Appraisal Tool. Additionally, heterogeneity between studies was evaluated. A total of 26 studies were included in this meta-analysis. The one-year and five-year mortality rates after hip and spine fractures were 215.35-774.0 per 1,000 person-year and 148-194.1 per 1,000 person-year, respectively. After hip fractures, the one-year mortality rate was 27% (95% CI: 18-38%, I2 = 98%), whereas the five-year mortality rate was 56% (95% CI: 41-71%, I2 = 99%). After spine fractures, the one-year mortality rate was 10% (95% CI: 4-17%, I2 = 70%), whereas the five-year mortality rate was 48.3%. The post-fracture mortality rate was high in patients with ESKD, particularly within one year after the occurrence of fractures. Additionally, the five-year mortality rate after hip femoral or spine fractures was high at approximately 50%.

Association between CKD-MBD and mortality in older patients with advanced CKD-results from the EQUAL study

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication of CKD; it is associated with higher mortality in dialysis patients, while its impact in non-dialysis patients remains mostly unknown. We investigated the associations between parathyroid hormone (PTH), phosphate and calcium (and their interactions), and all-cause, cardiovascular (CV) and non-CV mortality in older non-dialysis patients with advanced CKD.

METHODS

We used data from the European Quality study, which includes patients aged ≥65 years with estimated glomerular filtration rate ≤20 mL/min/1.73 m2 from six European countries. Sequentially adjusted Cox models were used to assess the association between baseline and time-dependent CKD-MBD biomarkers and all-cause, CV and non-CV mortality. Effect modification between biomarkers was also assessed.

RESULTS

In 1294 patients, the prevalence of CKD-MBD at baseline was 94%. Both PTH [adjusted hazard ratio (aHR) 1.12, 95% confidence interval (CI) 1.03-1.23, P = .01] and phosphate (aHR 1.35, 95% CI 1.00-1.84, P = .05), but not calcium (aHR 1.11, 95% CI 0.57-2.17, P = .76), were associated with all-cause mortality. Calcium was not independently associated with mortality, but modified the effect of phosphate, with the highest mortality risk found in patients with both hypercalcemia and hyperphosphatemia. PTH level was associated with CV mortality, but not with non-CV mortality, whereas phosphate was associated with both CV and non-CV mortality in most models.

CONCLUSIONS

CKD-MBD is very common in older non-dialysis patients with advanced CKD. PTH and phosphate are independently associated with all-cause mortality in this population. While PTH level is only associated with CV mortality, phosphate seems to be associated with both CV and non-CV mortality.

The Effect of Antihypertensive Therapy on Skeletal Muscle Mass and Bone Mineral Density in Patients With End-Stage Kidney Disease

OBJECTIVE

Sarcopenia and osteoporosis substantially influence health and lifespan. However, the variables affecting skeletal muscle mass (SMM) or bone mineral density (BMD) remain unknown.

DESIGN AND METHODS

From August 1, 2018 to July 31, 2019, we conducted a single-center, observational cohort study with 291 Japanese adult patients on maintenance hemodialysis due to end-stage kidney disease, who had their femoral neck BMD measured using dual-energy X-ray absorptiometry. After 1-year follow-up, we measured annual changes of BMD (ΔBMD) and SMM (ΔSMM), which were calculated through a modified creatinine index (mg/kg/day) using age, sex, serum creatinine, and single-pooled Kt/V for urea. The factors associated with ΔSMM/ΔBMD or progressive loss of SMM/BMD, defined as ΔSMM/ΔBMD < 0 per year, respectively, were analyzed with multivariable, linear regression or logistic regression models.

RESULTS

The median age of the patients was 66 years and 33% were female. Dialysis vintage and β-blocker-use were inversely correlated to ΔSMM. In comparison to nonusers, β-blockers users had 2.5-fold higher SMM loss odd ratios [95% confidence interval, 1.3-4.8]. The risk for SMM loss caused by β-blockers was not increased in users of renin-angiotensin system inhibitors. The ΔBMD was negatively correlated to the usage of calcium channel blockers. The risk of developing osteosarcopenia, which was defined as annual loss of both SMM and BMD, increased in calcium channel blockers users.

CONCLUSIONS

The use of β-blockers is associated with an elevated risk of developing sarcopenia, whereas renin-angiotensin system inhibitors may minimize this effect in patients with end-stage kidney disease. Use of calcium channel blocker therapy was associated with a faster decline of BMD.

Efficacy and safety of medications for osteoporosis in kidney transplant recipients or patients with chronic kidney disease: A meta-analysis

This study conducted a meta-analysis to analyze the efficacy and safety of osteoporosis medications in kidney transplant recipients and patients with chronic kidney disease (CKD). PubMed, Embase, the Cochrane Central Register of Controlled Trials were searched from the date of their inception through October 21, 2022. We performed a meta-analysis of the efficacy and safety of osteoporosis medications in adult patients with stage 3-5 CKD or kidney transplant recipients enrolled in randomized clinical trials (RCTs). We calculated the standard mean deviations with 95% confidence intervals (CI) for bone mineral density (BMD) and T scores after 6 and 12 months treatment, pooled odds ratio and 95% CI for fracture risk, and summarized adverse events. The inclusion criteria were met by 27 studies. Out of this, 19 studies were included for the meta-analysis. In stage 3-4 CKD patients, alendronate increased lumbar spine BMD. In patients at stage 5 CKD and undergoing hemodialysis, alendronate and raloxifene increased lumbar spine BMD. After 6 months, the BMD of kidney transplant recipients was seen to be significantly increased; however, there was no difference after 12 months, and the risk of fracture did not reduce. Thus, there is no evidence that these medications reduce the risk of fracture, and their effect on BMD and fracture remains unproven. These medications may increase the incidence of adverse events and their safety needs to be further evaluated. Therefore, we cannot draw a definitive conclusion about the efficacy and safety of osteoporosis medications in the above group of patients.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Current Status of Mineral and Bone Disorders in Transplant Recipients

Most patients with end-stage kidney disease undergoing kidney transplantation are affected by the chronic kidney disease-mineral and bone disorder. This entity encompasses laboratory abnormalities, calcification of soft tissues, and the bone abnormalities of renal osteodystrophy that together result in an increased risk of fracture, cardiovascular events, and mortality. Although many biochemical disturbances associated with end-stage kidney disease improve in the first year after transplantation, hyperparathyroidism commonly persists, and residual changes of renal osteodystrophy are slow to resolve. When superimposed on common, traditional risk factors, post-transplant glucocorticoid treatment, the possibility of tubular disturbances and post-transplant chronic kidney disease, rates of incident fracture remain high. This review examines hormonal and biochemical changes before and after kidney transplantation, fracture risk assessment tools and imaging modalities, a staged approach to management and concerns associated with antiresorptive and anabolic therapies. A multidisciplinary approach is proposed as the best means to improve patient-level outcomes.

Vitamin K supplementation and bone mineral density in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial

BACKGROUND

Vitamin K deficiency is highly prevalent in patients on dialysis and may contribute to their low bone mineral density (BMD) and increased risk of fracture. This study investigated the effect of menaquinone-7 (MK-7) supplementation on BMD in patients on chronic dialysis.

METHODS

In a multicentre, double-blind, placebo-controlled intervention trial, 123 patients on chronic dialysis were randomised to a daily oral supplement of either MK-7 360 µg or placebo for 2 years. BMD of the distal radius (1/3, mid, ultradistal and total), femoral neck, lumbar spine (L1-L4) and whole body was assessed by dual-energy X-ray absorptiometry. Serum levels of vitamin K1 and MK-7 and plasma levels of total osteocalcin, dephosphorylated-uncarboxylated matrix Gla protein and protein induced by vitamin K absence II were measured to assess vitamin K status.

RESULTS

After 2 years, an accelerated BMD loss of the 1/3 distal radius was found with MK-7 supplementation {mean difference of changes relative to placebo -0.023 g/cm2 [95% confidence interval (CI) -0.039 to -0.008]}, whereas the decrease in lumbar spine BMD seen in the placebo group was prevented [mean difference of changes between groups 0.050 g/cm2 (95% CI 0.015-0.085)]. No significant effects were observed at the remaining skeletal sites. Vitamin K status strongly improved in MK-7-supplemented participants.

CONCLUSION

Compared with placebo, an accelerated BMD loss of the 1/3 distal radius was found after 2 years of MK-7 supplementation, whereas a decline in lumbar spine BMD was prevented. As such, MK-7 supplementation might modify BMD site-specifically in patients on dialysis. In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.

Postoperative Outcomes Among Dialysis Patients Undergoing Hip Fracture Repair

Background

Geriatric hip fractures are strongly correlated with increased morbidity. Even so, postoperative outcomes following surgical repair of hip fractures for patients with end stage renal disease lack extensive investigation. Chronic kidney disease (CKD) poses unique risks for surgical procedures as it has been associated with several complications. Little information is available regarding the outcomes of patients whose renal function decline necessitates dialysis usage. The purpose of this study was to compare post-surgical outcomes based on dialysis usage among CKD patients requiring hip fracture repair.

Materials and Methods

We used the PearlDiver database to identify hip fracture repair patients diagnosed with stages 3, 4, and 5 CKD. We matched the populations according to patient characteristics and comorbidities. We then compared patient complication rates among dialyzed and non-dialyzed CKD patients following hip fracture repair at 30 days, 90 days, and 1 year following the procedure.

Results

Dialyzed patients were more likely to experience myocardial infarction within 30 days (P = .02) and 90 days (P = .002). Dialyzed patients suffered cardiac arrest at higher rates within the same time intervals (P = .02; P = .002). Furthermore, dialysis patients developed sepsis (P = .005) and pneumonia (P = .005) at higher rates within 30 days of operation. Dialysis patients did not have increased risk of blood transfusion within 30 days of the operation (P = .07).

Discussion

We found significant increases in myocardial infarction, cardiac arrest, pneumonia, and sepsis risk among dialyzed CKD patients. Blood transfusion risk failed to reach statistical significance. Our findings are consistent with previous research regarding CKD pathophysiology and associated perioperative outcomes.

Conclusion

Given the drastic decline of renal function among patients on dialysis, our findings may be attributable to decreased glomerular filtration rate in CKD as well as dialysis itself. Regardless, multidisciplinary collaboration should be employed when performing hip fracture repair on a patient who is actively undergoing hemodialysis.

Design and methodology of the SARCopenia trajectories and associations with adverse clinical outcomes in patients on HemoDialysis: the SARC-HD study

BACKGROUND

Sarcopenia has been associated with adverse outcomes in patients with chronic kidney disease (CKD), particularly in those undergoing hemodialysis (HD). However, the trajectories across sarcopenia stages, their determinants, and associations with adverse clinical outcomes have yet to be comprehensively examined.

METHODS

The SARC-HD is a multicenter, observational prospective cohort study designed to comprehensively investigate sarcopenia in patients on HD. Eligibility criteria include adult patients undergoing HD for ≥ 3 months. The primary objective is to investigate the trajectories of sarcopenia stages and their potential determinants. Secondary objectives include evaluating the association between sarcopenia and adverse clinical outcomes (i.e., falls, hospitalization, and mortality). Sarcopenia risk will be assessed by the SARC-F and SARC-CalF questionnaire. Sarcopenia traits (i.e., low muscle strength, low muscle mass, and low physical performance) will be defined according to the revised European Working Group on Sarcopenia in Older People and will be assessed at baseline and after 12 follow-up months. Patients will be followed-up at 3 monthly intervals for adverse clinical outcomes during 24 months.

DISCUSSION

Collectively, we expect to provide relevant clinical findings for healthcare professionals from nephrology on the association between sarcopenia screening tools (i.e., SARC-F and SARC-CalF) with objective sarcopenia measurements, as well as to investigate predictors of trajectories across sarcopenia stages, and the impact of sarcopenia on adverse clinical outcomes. Hence, our ambition is that the data acquired from SARC-HD study will provide novel and valuable evidence to support an adequate screening and management of sarcopenia in patients on HD.

Role of Chronic Kidney Disease (CKD)-Mineral and Bone Disorder (MBD) in the Pathogenesis of Cardiovascular Disease in CKD

Cardiovascular disease (CVD) is the leading cause of death in patients with chronic kidney disease (CKD). Multiple factors account for the increased incidence of cardiovascular morbidity and mortality in patients with CKD. Traditional risk factors for atherosclerosis and arteriosclerosis, including age, hypertension, dyslipidemia, diabetes mellitus, and smoking, are also risk factors for CKD. Non-traditional risk factors specific for CKD are also involved in CVD pathogenesis in patients with CKD. Recently, CKD-mineral and bone disorder (CKD-MBD) has emerged as a key player in CVD pathogenesis in the context of CKD. CKD-MBD manifests as hypocalcemia and hyperphosphatemia in the later stages of CKD; however, it initially develops much earlier in disease course. The initial step in CKD-MBD involves decreased phosphate excretion in the urine, followed by increased circulating concentrations of fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH), which increase urinary phosphate excretion. Simultaneously, the serum calcitriol concentration decreases as a result of FGF23 elevation. Importantly, FGF23 and PTH cause left ventricular hypertrophy, arrhythmia, and cardiovascular calcification. More recently, calciprotein particles, which are nanoparticles composed of calcium, phosphate, and fetuin-A, among other components, have been reported to cause inflammation, cardiovascular calcification, and other clinically relevant outcomes. CKD-MBD has become one of the critical therapeutic targets for the prevention of cardiovascular events and is another link between cardiology and nephrology. In this review, we describe the role of CKD-MBD in the pathogenesis of cardiovascular disorders and present the current treatment strategies for CKD-MBD.

The levels of bone turnover markers and parathyroid hormone and their relationship in chronic kidney disease

BACKGROUND

Chronic kidney disease-mineral bone disease (CKD-MBD) is a major complication of CKD. Bone turnover markers (BTMs) are important for clinicians to evaluate and manage patients with CKD-MBD. This study aimed to assess BTMs in patients with CKD and their correlation with parathyroid hormone (PTH) and other clinical characteristics of CKD.

METHODS

A total of 408 subjects were included in this study. The serum BTMs including N-terminal midfragment osteocalcin (N-MID OC), β-isomerized C-terminal telopeptides (β-CTX), and total procollagen type 1 amino-terminal propeptide (tPINP) were measured. Spearman correlation and multiple stepwise regression models were used to investigate the association of N-MID OC, β-CTX, and tPINP with the clinical characteristics of CKD patients.

RESULTS

BTMs was no significant difference between non-CKD and CKD stages 1, 2, and 3. However, N-MID OC, β-CTX were significantly increased in patients with CKD stage 4 compared to non-CKD patients and patients with CKD stages 1, 2, and 3. Compared with non-dialysis dependent (NDD)-CKD stage 5, BTMs were significantly higher in dialysis patients. The estimated glomerular filtration rate was negatively associated with N-MID OC (r = -0.479, P < 0.001), β-CTX (r = -0.474, P < 0.001), and tPINP (r = -0.375, P < 0.001). Multiple analysis showed that N-MID OC (β = 0.67, P < 0.001), β-CTX (β = 0.64, P < 0.001), and tPINP (β = 0.81, P < 0.001) were independently associated with PTH. CKD patients with secondary hyperparathyroidism (SHPT) have higher β-CTX (P < 0.05), and N-MID OC (P < 0.05) than patients with non-SHPT.

CONCLUSIONS

BTMs in advanced CKD stages were significantly higher than in the early disease stages. PTH level was independently and positively associated with the BTM levels in patients with CKD. In the advanced stage of CKD, β-CTX and N-MID OC levels were significantly higher in those with SHPT than those with non-SHPT.

The implication of calf circumference and grip strength in osteoporosis and bone mineral density among hemodialysis patients

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD), nutritional status, and uremia management have been emphasized for bone management in hemodialysis patients. Nevertheless, valuable data on the importance of muscle mass in bone management are limited, including whether conventional management alone can prevent osteoporosis. Thus, the importance of muscle mass and strength, independent of the conventional management in osteoporosis prevention among hemodialysis patients, was evaluated.

METHODS

Patients with a history of hemodialysis 6 months or longer were selected. We assessed the risk for osteoporosis associated with calf circumference or grip strength using multivariable adjustment for indices of CKD-MBD, nutrition, and dialysis adequacy. Moreover, the associations between bone mineral density (BMD), calf circumference, grip strength, and bone metabolic markers were also evaluated.

RESULTS

A total of 136 patients were included. The odds ratios (95% confidence interval) for osteoporosis at the femoral neck were 1.25 (1.04-1.54, P < 0.05) and 1.08 (1.00-1.18, P < 0.05) per 1 cm shorter calf circumference or 1 kg weaker grip strength, respectively. Shorter calf circumference was significantly associated with a lower BMD at the femoral neck and lumbar spine (P < 0.001). Weaker grip strength was also associated with lower BMD at the femoral neck (P < 0.01). Calf circumference or grip strength was negatively correlated with bone metabolic marker values.

CONCLUSION

Shorter calf circumference or weaker grip strength was associated with osteoporosis risk and lower BMD among hemodialysis patients, independent of the conventional therapies.

Roles of PTH and FGF23 in kidney failure: a focus on nonclassical effects

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) each play a central role in the pathogenesis of chronic kidney disease-mineral and bone disorder (CKD-MBD). Both hormones increase as kidney function declines, presumably as a response to maintain normal phosphate balance, but when patients reach kidney failure, PTH and FGF23 fail to exert their phosphaturic effects, leading to hyperphosphatemia and further elevations in PTH and FGF23. In patients with kidney failure, the major target organ for PTH is the bone, but elevated PTH is also associated with mortality presumably through skeletal and nonskeletal mechanisms. Indeed, accumulated evidence suggests improved survival with PTH-lowering therapies, and a more recent study comparing parathyroidectomy and calcimimetic treatment further suggests a notion of "the lower, the better" for PTH control. Emerging data suggest that the link between SHPT and mortality could in part be explained by the action of PTH to induce adipose tissue browning and wasting. In the absence of a functioning kidney, the classical target organ for FGF23 is the parathyroid gland, but FGF23 loses its hormonal effect to suppress PTH secretion owing to the depressed expression of parathyroid Klotho. In this setting, experimental data suggest that FGF23 exerts adverse nontarget effects, but it remains to be confirmed whether FGF23 directly contributes to multiple organ injury in patients with kidney failure and whether targeting FGF23 can improve patient outcomes. Further efforts should be made to determine whether intensive control of SHPT improves clinical outcomes and whether nephrologists should aim at controlling FGF23 levels just as with PTH levels.

Impaired renal function is an independent risk factor for complications after surgery for femoral neck fracture

BACKGROUND

The metabolic abnormalities that occur secondary to chronic kidney disease (CKD) increase the risk of femoral neck fractures compared to the general population. The purpose of this study is to determine whether impaired renal function is an independent risk factor for complications after surgery for femoral neck fracture.

METHODS

The ACS-NSQIP database was reviewed for patients who underwent total hip arthroplasty, hemiarthroplasty and open reduction internal fixation (ORIF) for femoral neck fractures between 2007 and 2018. Patients were split into cohorts based on calculated estimated glomerular filtration rate. Demographic information, comorbidities, and 30-day complications were analysed with univariate and multivariate analyses using chi-square, Fischer's exact and analysis of variance testing.

RESULTS

The total number of patients for the study was 163,717. Patients with CKD stage 4 and 5 had an increased rate of any complication (39.1 and 36.7% respectively) compared with higher eGFRs (p < 0.001). Similarly, 30-day mortality was increased at 6.0% and 6.7% for both stage 4 and 5 (p < 0.001). By multivariate regression, those with CKD Stage 4 and 5 were at increased risk for any complication compared to patients with a normal preoperative eGFR of 90-120 (p < 0.001).

CONCLUSIONS

This study demonstrated that patients with CKD Stage 4 and 5 are at increased risks of all complications, including death, renal, pulmonary and thromboembolic disease. Therefore, these patients should be cared for from a multidisciplinary approach with close attention to postoperative medications and fall prevention to help mitigate the risk of complications in the immediate postoperative period.

Bone Mineral Density and All-Cause Mortality in Patients with Nondialysis Chronic Kidney Disease: Results from KNOW-CKD Study

Despite the clear association between low BMD and all-cause mortality in the general population, the association has not been validated in patients with nondialysis CKD. To investigate the association of low BMD with all-cause mortality in this population, a total of 2089 patients with nondialysis CKD at stages 1 to predialysis 5 were categorized into normal BMD (T-score ≥ -1.0), osteopenia (-2.5 < T-score < -1.0), and osteoporosis (T-score ≤ - 2.5) by the BMD at femoral neck. The study outcome was all-cause mortality. Kaplan-Meier curve depicted a significantly increased number of all-cause death events in the subjects with osteopenia or osteoporosis during the follow-up period compared with subjects with normal BMD. Cox regression models demonstrated that osteoporosis, but not osteopenia, was significantly associated with an increased risk of all-cause mortality (adjusted hazard ratio 2.963, 95% confidence interval 1.655 to 5.307). Smoothing curve fitting model visualized a clear inverse correlation between BMD T-score and the risk of all-cause mortality. Even after recategorizing the subjects by BMD T-scores at total hip or lumbar spine, the result was similar to the primary analyses. Subgroup analyses revealed that the association was not significantly modified by clinical contexts, such as age, gender, body mass index, estimated glomerular filtration rate, and albuminuria. In conclusion, low BMD is associated with an increased risk of all-cause mortality in patients with nondialysis CKD. This emphasizes that the routine measurement of BMD by DXA may confer an additional benefit beyond the prediction of fracture risk in this population.

Comparison of the association between six different frailty scales and clinical events in patients on hemodialysis

BACKGROUND

Frailty is associated with adverse outcomes in patients undergoing hemodialysis (HD). However, no study has used various frailty assessments in patients on HD to examine their association with clinical events. In this study, we investigated the association between clinical events and six frailty scales.

METHODS

Outpatients who underwent HD between 2018 and 2020 were retrospectively enrolled. Frailty was defined using the Fried Frailty Phenotype, Study of Osteoporotic Fractures (SOF) Index, Short Physical Performance Battery (SPPB), Frail Screening Index, FRAIL scale and Clinical Frailty Scale. Outcomes were clinical events, including a composite of multiple (i.e. recurrent) all-cause hospitalizations, fractures and/or all-cause mortality. The association of clinical events and the frailty scales were investigated using negative binomial regression analysis.

RESULTS

Fried Frailty Phenotype [incident rate ratio (IRR), 1.62; 95% confidence interval (CI), 1.49-1.76], SOF Index (IRR, 1.42; 95% CI, 1.10-1.83), SPPB (IRR, 1.79; 95% CI, 1.11-2.88) and Clinical Frailty Scale (IRR, 1.65; 95% CI, 1.04-2.61) were significantly associated with clinical events. However, Frail Screening Index (IRR, 1.38; 95% CI, 0.60-3.18) and FRAIL scale (IRR, 1.30; 95% CI, 0.88-1.92) showed no significant association with clinical events.

CONCLUSIONS

Objective frailty assessments (SPPB) and medical staff impression-based frailty (Clinical Frailty Scale) may be useful prognostic predictors for patients on HD. Questionnaire-based frailty assessment should be carefully considered when used as a measurement of frailty.

Radiofrequency echographic multi-spectrometry and DXA for the evaluation of bone mineral density in a peritoneal dialysis setting

BACKGROUND

The aim of this real-life cross-sectional explorative study was to compare radiofrequency echographic multi-spectrometry (REMS) with dual-energy X-rays absorptiometry (DXA) in the BMD assessment of patients receiving peritoneal dialysis (PD). Furthermore, we investigated the relationship between lumbar aortic calcifications (AOCs) and the DXA lumbar measurements.

METHODS

Consecutive patients referring to the PD clinic of our hospital were included. Lumbar spine and femur scans were acquired with both techniques (including lumbar laterolateral DXA scans). The risk assessment of two fracture risk algorithms (FRAX^® and DeFRA^®) were compared. Cohen's k coefficients were used to assess the inter-technique agreement in the classification of patients as osteoporotic. Lumbar AOCs were estimated semi-quantitatively on laterolateral DXA scans.

RESULTS

41 patients were enrolled. No significant differences were documented between the BMD T-scores measured through DXA or REMS at the femur. At the lumbar spine, the DXA anteroposterior mean T-score (- 0.49 ± 1.98) was significantly higher than both the laterolateral DXA (- 1.66 ± 0.99) and the REMS (- 2.00 ± 1.94) measurements (p < 0.01 vs both). No significant differences were found between the DXA and REMS fracture risk estimates with both algorithms. The inter-technique Cohen's k coefficient (for the worst T-score, any site) was 0.421, p < 0.001. The discrepancy between the DXA laterolateral and anteroposterior lumbar T-score was positively associated with the AOCs extent and severity (r = 0.402, p < 0.01).

CONCLUSIONS

Our data showed a promising agreement, in a real-life PD setting, between DXA and REMS BMD assessment and in the consequent fracture risk estimation and confirm the AOCs interference on the diagnostic accuracy of lumbar DXA.

One-Year Romosozumab Treatment Followed by One-Year Denosumab Treatment for Osteoporosis in Patients on Hemodialysis: An Observational Study

There is limited evidence on the use of romosozumab (ROMO) in the treatment of osteoporosis in patients on hemodialysis (HD); thus, we aimed to investigate this topic. This prospective, observational, single-center cohort study included 13 prior osteoporosis treatment-naïve patients on HD with osteoporosis. They first received ROMO once monthly for 12 months (210 mg; subcutaneously once every month). Thereafter, they received denosumab (DENO) for an additional 12 months (60 mg; subcutaneously once every 6 months). We examined the incidence of new fractures; treatment safety; and temporal changes in the bone mineral density (BMD), bone metabolism markers, and vascular calcification. No new cases of fractures were noted. The median one-year percentage changes (from the baseline) in the BMDs at the lumbar spine (LS), total hip (TH), and femoral neck (FN) were + 9.0%, + 2.5%, and + 4.7%, respectively. These changes were maintained for 24 months. The corresponding relative changes from the baseline to 24 months thereafter were + 14.9%, + 5.4%, and + 6.5%, respectively. The percentage changes in TH BMD and FN BMD were negatively correlated with baseline BMD. Coronary artery and thoracic aorta calcification scores increased slightly from baseline to 12 months thereafter. However, fatal events (cardiovascular disease-associated and all-cause deaths) did not occur during ROMO treatment. Effectiveness of ROMO was better in patients who had severe osteoporosis with low TH BMD, low FN BMD, and high tartrate-resistant acid phosphatase 5b level at ROMO initiation.

Bone Disease in Chronic Kidney Disease and Kidney Transplant

Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) comprises alterations in calcium, phosphorus, parathyroid hormone (PTH), Vitamin D, and fibroblast growth factor-23 (FGF-23) metabolism, abnormalities in bone turnover, mineralization, volume, linear growth or strength, and vascular calcification leading to an increase in bone fractures and vascular disease, which ultimately result in high morbidity and mortality. The bone component of CKD-MBD, referred to as renal osteodystrophy, starts early during the course of CKD as a result of the effects of progressive reduction in kidney function which modify the tight interaction between mineral, hormonal, and other biochemical mediators of cell function that ultimately lead to bone disease. In addition, other factors, such as osteoporosis not apparently dependent on the typical pathophysiologic abnormalities resulting from altered kidney function, may accompany the different varieties of renal osteodystrophy leading to an increment in the risk of bone fracture. After kidney transplantation, these bone alterations and others directly associated or not with changes in kidney function may persist, progress or transform into a different entity due to new pathogenetic mechanisms. With time, these alterations may improve or worsen depending to a large extent on the restoration of kidney function and correction of the metabolic abnormalities developed during the course of CKD. In this paper, we review the bone lesions that occur during both CKD progression and after kidney transplant and analyze the factors involved in their pathogenesis as a means to raise awareness of their complexity and interrelationship.

Skeletal Outcomes in Children and Young Adults with Glomerular Disease

BACKGROUND

Children with glomerular disease have unique risk factors for compromised bone health. Studies addressing skeletal complications in this population are lacking.

METHODS

This retrospective cohort study utilized data from PEDSnet, a national network of pediatric health systems with standardized electronic health record data for more than 6.5 million patients from 2009 to 2021. Incidence rates (per 10,000 person-years) of fracture, slipped capital femoral epiphysis (SCFE), and avascular necrosis/osteonecrosis (AVN) in 4598 children and young adults with glomerular disease were compared with those among 553,624 general pediatric patients using Poisson regression analysis. The glomerular disease cohort was identified using a published computable phenotype. Inclusion criteria for the general pediatric cohort were two or more primary care visits 1 year or more apart between 1 and 21 years of age, one visit or more every 18 months if followed >3 years, and no chronic progressive conditions defined by the Pediatric Medical Complexity Algorithm. Fracture, SCFE, and AVN were identified using SNOMED-CT diagnosis codes; fracture required an associated x-ray or splinting/casting procedure within 48 hours.

RESULTS

We found a higher risk of fracture for the glomerular disease cohort compared with the general pediatric cohort in girls only (incidence rate ratio [IRR], 1.6; 95% CI, 1.3 to 1.9). Hip/femur and vertebral fracture risk were increased in the glomerular disease cohort: adjusted IRR was 2.2 (95% CI, 1.3 to 3.7) and 5 (95% CI, 3.2 to 7.6), respectively. For SCFE, the adjusted IRR was 3.4 (95% CI, 1.9 to 5.9). For AVN, the adjusted IRR was 56.2 (95% CI, 40.7 to 77.5).

CONCLUSIONS

Children and young adults with glomerular disease have significantly higher burden of skeletal complications than the general pediatric population.

Cortical porosity occurs at varying degrees throughout the skeleton in rats with chronic kidney disease

Cortical porosity develops in chronic kidney disease (CKD) and increases with progressing disease. Cortical porosity is likely a prominent contributor to skeletal fragility/fracture. The degree to which cortical porosity occurs throughout the skeleton is not fully known. In this study, we assessed cortical bone porosity via micro-computed tomography at multiple skeletal sites in rats with progressive chronic kidney disease. We hypothesized that cortical porosity would occur in long bones throughout the body, but to a lesser degree in flat bones and irregular bones. Porosity was measured, using micro-CT, at 17 different skeletal sites in 6 male rats with CKD. Varying degrees of porosity were seen throughout the skeleton with higher porosity in flat and irregular bone (i.e. parietal bone, mandible) vs. long bones (p = 0.01) and in non-weightbearing bones vs. weightbearing bones (p = 0.01). Porosity was also higher in proximal sites vs. distal sites in long bones (p < 0.01 in all comparisons). There was large heterogeneity in porosity within skeletal sites across rats and within the same rat across skeletal sites. Correlations showed cortical porosity of the proximal tibia was positively associated with porosity at the other sites with the strongest correlation to the parietal bone and the weakest to the ulna. Overall, our data demonstrates varying and significant cortical bone porosity across the skeleton of animals with chronic kidney disease. These data point to careful selection of skeletal sites to assess porosity in pre-clinical studies and the potential for fractures at multiple skeletal sites in patients with CKD.

Lower Bone Turnover and Skeletal PTH Responsiveness in Japanese Compared to European Patients on Hemodialysis

CONTEXT

Parathyroid hormone (PTH) treatment targets for patients receiving hemodialysis (HD) are lower in Japan than in Europe. Whether this translates to lower bone turnover is unknown and could depend on skeletal PTH responsiveness.

OBJECTIVE

This study investigates whether skeletal PTH responsiveness is better preserved in Japanese vs European patients receiving HD.

METHODS

This is a post hoc analysis of data from 2 prospective cohort studies, using a case-control design. Patients receiving chronic intermittent HD therapy were eligible for inclusion. Participating Belgian and Japanese patients (n = 374) were matched 1:1 by age (59 ± 12 years), sex (66% male), diabetes (34%), and dialysis duration (39 months [22-63 months]). PTH, bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b) were measured centrally in Liège, Belgium.

RESULTS

Japanese patients had lower levels of iPTH (207 vs 268 pg/mL; P < .001), BALP (15.3 vs 24.5 μg/L; P < .001), and TRAP5b (3.35 vs 5.79 U/L; P < .001). Linear regression analyses revealed lower levels of bone turnover markers for any given level of PTH in Japanese vs Belgian patients, indicating lower skeletal PTH responsiveness. Consistently, bone turnover markers were significantly lower in Japanese vs Belgian patients when stratifying or matching according to PTH levels. Male sex, obesity, and hyperphosphatemia were the main determinants of the bone turnover marker/PTH ratios.

CONCLUSION

Japanese patients receiving HD have lower bone turnover than their European counterparts, even at similar PTH levels. The rationale for the current regional differences in PTH treatment targets remains obscure and deserves further attention.

The impact of chronic kidney disease and dialysis therapy on outcomes of elderly patients with hip fractures: A systematic review and meta-analysis

BACKGROUND AND AIMS

Hip fractures are a commonly occurring comorbidity in patients with chronic kidney disease. To evaluate the comparative rates of post-operative complications, revision surgery, and mortality after hip fracture surgery in chronic kidney disease patients undergoing hemodialysis.

METHODS

A systematic search of the academic literature was performed according to the PRISMA guidelines across five databases: Web of Science, EMBASE, CENTRAL, Scopus, and MEDLINE. A random-effect meta-analysis was conducted to evaluate the overall comparative risks of post-operative complications in chronic kidney disease patients.

RESULTS

Out of 993 studies, 11 eligible studies were included in the review, with a total of 72618 chronic kidney disease patients (mean age: 75.3  ±  3.0 years), and 50566 healthy controls (75.3  ±  2.6 years). Meta-analysis revealed a higher risk of post-operative complications (Odd's ratio: 1.76), revision surgeries (1.69), and mortality-related outcomes (2.47) after hip fracture surgery in chronic kidney disease patients undergoing hemodialysis as compared to chronic kidney disease patients not undergoing hemodialysis.

CONCLUSION

We report higher risks of post-operative complications, revision surgery, and mortality in chronic kidney disease patients undergoing hemodialysis as compared to chronic kidney disease patients not undergoing hemodialysis.

MicroRNAs: emerging biomarkers and therapeutic targets of bone fragility in chronic kidney disease

Bone fragility is highly prevalent, yet underdiagnosed in patients with chronic kidney disease. Incomplete understanding of the pathophysiology and limitations of current diagnostics contribute to therapeutic hesitation, if not nihilism. This narrative review addresses the question of whether microRNAs (miRNAs) may improve therapeutic decision making in osteoporosis and renal osteodystrophy. miRNAs are key epigenetic regulators of bone homeostasis and show promise as both therapeutic targets and as biomarkers, primarily of bone turnover. Experimental studies show that miRNAs are involved in several osteogenic pathways. Clinical studies exploring the usefulness of circulating miRNAs for fracture risk stratification and for guiding and monitoring therapy are few and, so far, provide inconclusive results. Likely, (pre)analytical heterogeneity contributes to these equivocal results. In conclusion, miRNAs are promising in metabolic bone disease, both as a diagnostic tool and as therapeutic targets, but not yet ready for clinical prime time.

Performance Status Modifies the Association Between Vitamin D Receptor Activator and Mortality or Fracture: A Prospective Cohort Study on the Japanese Society for Dialysis Therapy (JSDT) Renal Data Registry

Immobilization osteoporosis is characterized by excess bone resorption. Vitamin D receptor activators (VDRA) might have adverse effects in immobilized patients. The objective of this study was to elucidate the impact of performance status (PS) on the associations between VDRA use and outcomes among hemodialysis patients. This is a prospective cohort study. Adults on hemodialysis in the Japanese Society for Dialysis Therapy (JSDT) Renal Data Registry were included. Exposure of interest was the use of VDRA. Outcomes were all-cause mortality and hip fracture. Associations between VDRA use and mortality or hip fractures were examined by Cox and Poisson regression analyses, respectively. Among 208,512 subjects, 128,535 were on VDRA. Poor PS was associated with higher calcium (Ca), lower parathyroid hormone, and higher alkaline phosphatase levels. The association between higher Ca levels and VDRA use was stronger among those with poor PS (p interaction 0.007). Adjusted hazard ratio (HR) (95% confidence interval [CI]) for mortality and incidence rate ratio (IRR) for hip fracture was 1.02 (95% CI, 0.99-1.05) and 0.93 (0.86-1.00) among users of VDRA, respectively. The VDRA use was associated with lower mortality and incidence of hip fractures among subjects with good PS but not among subjects with poor PS (p interaction 0.03 and 0.05). Effect modification by PS was observed for cardiovascular (CV) mortality but not for non-CV mortality. In conclusion, VDRA use was associated with better outcomes only among those with good PS. These results suggest that bone and mineral disorders among hemodialysis patients should be treated differently, depending on their performance status. © 2022 American Society for Bone and Mineral Research (ASBMR).

Clinical utility of bone turnover markers in patients with chronic kidney disease

PURPOSE OF REVIEW

The burden of fractures is very high in patients with chronic kidney disease (CKD). It is increasingly recognized that knowledge of bone turnover is of paramount importance in guiding mineral metabolism and osteoporosis therapy in CKD. Bone histomorphometry is the gold standard to assess bone turnover, but is seldomly performed in clinical practice. Bone turnover markers (BTMs) may be the long awaited noninvasive diagnostic that may help to close the therapeutic gap in patients with advanced CKD presenting with bone fragility.

RECENT FINDINGS

Mounting evidence indicates that BTMs may be useful in skeletal and nonskeletal risk stratification, in guiding mineral metabolism and osteoporosis therapy, and in monitoring the therapeutic response.

SUMMARY

BTMs provide information that is complementary to other clinical tests. It may be envisioned that in the near future, the assessment of nonkidney cleared BTMs may become part of routine clinical evaluation and monitoring of bone health in CKD patients, integrated with clinical risk factors, imaging data and, eventually, bone histomorphometry. Panels of BTMs will likely be more informative than single markers, and the same might hold true for trends as opposed to single time point data.

Circadian rhythm of markers of bone turnover in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have a high risk of bone fractures. A circadian rhythmicity in turnover and mineralization of bone appears to be of importance for bone health. In CKD disturbances in the circadian rhythm of various functions has been demonstrated and indeed the circadian rhythm in the mineral metabolism is disturbed. The aim of the present study was to compare the circadian rhythm of bone turnover markers in ten patients with CKD to ten healthy controls. Bone turnover markers (C-terminal telopeptide of type I collagen, tartrate-resistant acid phosphatase 5b, N-terminal propeptide of type I procollagen, bone alkaline phosphatase and osteocalcin) were measured every third hour for 24 h. All bone turnover markers displayed a significant circadian rhythm in both groups and there were no significant differences in the rhythmicity between the two groups (no group*time interaction). As expected, due to the reduced renal clearance, the overall level of C-terminal telopeptide of type I collagen and osteocalcin was higher in CKD compared to the healthy controls. The present study suggests that disturbances in the circadian rhythm of bone turnover do not explain the metabolic bone disease and increased risk of fractures in CKD.

Cortical porosity is elevated after a single dose of zoledronate in two rodent models of chronic kidney disease

PURPOSE

Patients with chronic kidney disease (CKD) have high risk of fracture in part due to cortical bone deterioration. The goal of this study was to assess the impact of two different bisphosphonates and dosing regimens on cortical microstructure (porosity, thickness, area) and bone mechanical properties in animal models of CKD.

METHODS

In experiment 1, Male Cy/+ (CKD) rats were treated with either a single dose or ten fractionated doses of zoledronate at 18 weeks of age. Fractionated animals received 1/10th of single dose given weekly for 10 weeks, with study endpoint at 28 weeks of age. In experiment 2, male C57Bl/6 J mice were given dietary adenine (0.2%) to induce CKD. Bisphosphonate treated groups were given either a single dose of zoledronate or weekly risedronate injections for 4 weeks. Cortical microstructure was assessed via μCT and mechanical parameters evaluated by monotonic bending tests.

RESULTS

Exp 1: CKD rats had higher blood urea nitrogen (BUN) and parathyroid hormone (PTH) compared to NL littermate controls. Single dose zoledronate had significantly higher cortical porosity in CKD S.Zol (2.29%) compared to NL control (0.04%) and untreated CKD (0.14%) (p = 0.004). Exp 2: All adenine groups had significantly higher BUN and PTH compared to control mice. Mice treated with single dose zoledronate (Ad + Zol) had the highest porosity (~6%), which was significantly higher compared to either Ad or Ad + Ris (~3%; p < 0.0001) and control mice had the lowest cortical porosity (0.35%). In both experiments, mechanics were minimally affected by any bisphosphonate dosing regimen.

CONCLUSION

A single dose of zoledronate leads to higher cortical porosity compared to more frequent dosing of bisphosphonates (fractionated zoledronate or risedronate). Bisphosphonate treatment demonstrated limited effectiveness in preventing cortical bone microstructure deterioration with mechanical parameters remaining compromised due to CKD and/or secondary hyperparathyroidism irrespective of bisphosphonate treatment.

Effects of bone turnover status on the efficacy and safety of denosumab among haemodialysis patients

Denosumab is reported to increase bone mineral density (BMD) among haemodialysis patients; however, hypocalcaemia is a serious adverse effect among chronic kidney disease (CKD) patients. Identifying which patients will show greater improvement in BMD is important. We enrolled 84 haemodialysis patients with osteoporosis in our study. 28 patients initiated denosumab treatment between October 2019 and October 2020. We assessed BMD changes and investigated the association between baseline bone turnover marker (BTM) levels and 6-month changes in BMD after denosumab treatment. BMD was increased at 6 months in denosumab-treated patients compared with patients not treated with denosumab (lumbar spine: 5.34% vs. - 0.49%; total hip: 2.43% vs. - 0.47%). Bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase-5b (TRACP-5b) at baseline were independently associated with increased BMD in the total hip (BAP: β = 0.472, p value = 0.004; TRACP-5b: β = 0.433, p value = 0.008) and lumbar spine (BAP: β = 0.591, p value = 0.001; TRACP-5b: β = 0.613, p value = 0.0008). BAP and TRACP-5b were also independent predictors of hypocalcaemic events (OR [95% CI] 1.747 [1.084-4.604] and 1.006 [1.000-1.015], respectively). BTMs may be associated with increased BMD and hypocalcaemic events after denosumab treatment. BTM measurement may be useful for assessing the effect of denosumab on BMD; however, careful monitoring of serum calcium levels is needed.

Role of Vitamin K in Chronic Kidney Disease: A Focus on Bone and Cardiovascular Health

Chronic kidney disease (CKD) is commonly associated with vitamin K deficiency. Some of the serious complications of CKD are represented by cardiovascular disease (CVD) and skeletal fragility with an increased risk of morbidity and mortality. A complex pathogenetic link between hormonal and ionic disturbances, bone tissue and metabolism alterations, and vascular calcification (VC) exists and has been defined as chronic kidney disease–mineral and bone disorder (CKD-MBD). Poor vitamin K status seems to have a key role in the progression of CKD, but also in the onset and advance of both bone and cardiovascular complications. Three forms of vitamin K are currently known: vitamin K1 (phylloquinone), vitamin K2 (menaquinone), and vitamin K3 (menadione). Vitamin K plays different roles, including in activating vitamin K-dependent proteins (VKDPs) and in modulating bone metabolism and contributing to the inhibition of VC. This review focuses on the biochemical and functional characteristics of vitamin K vitamers, suggesting this nutrient as a possible marker of kidney, CV, and bone damage in the CKD population and exploring its potential use for promoting health in this clinical setting. Treatment strategies for CKD-associated osteoporosis and CV disease should include vitamin K supplementation. However, further randomized clinical studies are needed to assess the safety and the adequate dosage to prevent these CKD complications.

Role of Fracture Risk Assessment Tool and Bone Turnover Markers in Predicting All-Cause and Cardiovascular Mortality in Hemodialysis Patients

Background

Fracture Risk Assessment Tool (FRAX) and bone turnover markers (BTMs) predict fractures in the general population. However, the role of FRAX and BTMs in predicting mortality remains uncertain in hemodialysis (HD) patients.

Methods

One hundred and sixty-four HD patients stratified by low or high risk of 10-year fracture probability using FRAX. High risk of fracture was defined as 10-year probability of hip fracture ≥3% or major osteoporotic fracture ≥20%. The association of high risk of fracture and BTMs with all-cause mortality and cardiovascular (CV) mortality were evaluated using multivariate-adjusted Cox regression analysis.

Results

Eighty-five (51.8%) patients were classified as high risk of fracture based on FRAX among 164 HD patients. During a mean follow-up period of 3.5 ± 1.0 years, there were 39 all-cause deaths and 23 CV deaths. In multivariate-adjusted Cox regression, high risk of fracture based on FRAX was independently associated with all-cause mortality [hazard ratio (HR): 2.493, 95% confidence interval (CI): 1.026–6.056, p = 0.044) but not with CV mortality (HR: 2.129, 95% CI: 0.677–6.700, p = 0.196). There were no associations between BTMs and mortality risk. Furthermore, lower geriatric nutritional risk index (GNRI) was significantly associated with increased CV mortality (HR: 0.888, 95% CI: 0.802–0.983, p = 0.022) after adjusting by confounding variables.

Conclusion

High risk of fracture using FRAX was an independent predictor of all-cause mortality in patients undergoing HD. FRAX, rather than BTMs, has an important role of prognostic significance in HD patients.