Incidence and risk factors for hip or other bone fractures among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study

Death and Postoperative Complications After Hip Fracture Repair: Dialysis Effect

Introduction

It is unknown whether patients receiving dialysis have a higher morbidity and mortality risk after hip fracture repair conferred by their kidney failure or by the high comorbidity burden often present.

Methods

We examined associations of dialysis dependency with postoperative complications, death, and readmission in a matched cohort study of U.S. patients undergoing hip fracture repair, from January 2010 to December 2013, in the American College of Surgeons National Surgical Quality Improvement Program. Matching included sex, age, race, diabetes mellitus, operation year, primary surgery type, and anesthesia technique.

Results

Among 22,621 patients, 377 dialysis-dependent patients were matched to 1508 nondialysis patients. Median age was 78 years (interquartile range = 68−85) years, 56% were men, 70% were white, 43% had diabetes, and 47% underwent fracture fixation under mostly (80%) general anesthesia. Dialysis-dependent patients had higher physical status classification, had more heart failure and hypoalbuminemia, and were less often smokers. After adjustment, a greater risk of prolonged postoperative stays beyond 7 days (odds ratio [OR] = 1.43, 95% confidence interval [CI] = 1.09−1.89), higher in-hospital mortality (OR = 3.13, CI = 1.72−5.7), and 30-day death (OR = 2.29, CI = 1.51−3.48) but not 30-day readmission (P = 0.09) was observed with dialysis dependency. Adjusted analyses in the original cohort (n = 22,621) were similar: the dialysis group had greater risk of prolonged postoperative stay (OR = 1.77, CI = 1.42−2.21), in-hospital mortality (OR = 2.65, CI = 1.74−4.05), and 30-day death (OR = 2.03, CI = 1.48−2.80) and 30-day readmission (OR = 1.62, CI = 1.66−2.26).

Conclusion

Dialysis dependency is associated with an increased risk of death and postoperative complications after hip fracture repair. These findings have implications for case-mix adjustment and quality metrics.

Gabapentin and Pregabalin Use and Association with Adverse Outcomes among Hemodialysis Patients

Background Gabapentin and pregabalin are used to manage neuropathic pain, pruritus, and restless legs syndrome in patients on hemodialysis. These patients may be especially predisposed to complications related to these agents, which are renally cleared, but data regarding the risk thereof are lacking.Methods From the US Renal Data System, we identified 140,899 Medicare-covered adults receiving hemodialysis with Part D coverage in 2011. Using Cox regression models in which we adjusted for demographics, comorbidities, duration of exposure, number of medications, and use of potentially confounding concomitant medications, we investigated the association between gabapentin and pregabalin, modeled as separate time-varying exposures, and time to first emergency room visit or hospitalization for altered mental status, fall, and fracture. We evaluated risk according to daily dose categories: gabapentin (>0-100, >100-200, >200-300, and >300 mg) and pregabalin (>0-100 and >100 mg).Results In 2011, 19% and 4% of patients received gabapentin and pregabalin, respectively. Sixty-eight percent of gabapentin or pregabalin users had a diagnosis of neuropathic pain, pruritus, or restless legs syndrome. Gabapentin was associated with 50%, 55%, and 38% higher hazards of altered mental status, fall, and fracture, respectively, in the highest dose category, but even lower dosing was associated with a higher hazard of altered mental status (31%-41%) and fall (26%-30%). Pregabalin was associated with up to 51% and 68% higher hazards of altered mental status and fall, respectively.Conclusions Gabapentin and pregabalin should be used judiciously in patients on hemodialysis, and research to identify the most optimal dosing is warranted.

Outcomes following surgical management of femoral neck fractures in elderly dialysis-dependent patients

INTRODUCTION

Proximal femur fractures are one of the most common fractures observed in dialysis-dependent patients. Given the large comorbidity burden present in this patient population, more information is needed regarding post-operative outcomes. The goal of this study was to assess morbidity and mortality following operative fixation of femoral neck fractures in the dialysis-dependent elderly.

METHODS

The full set of medicare data from 2005 to 2014 was retrospectively analyzed. Elderly patients with femoral neck fractures were selected. Patients were stratified based on dialysis dependence. Post-operative morbidity and mortality outcomes were compared between the two populations. Adjusted odds were calculated to determine the effect of dialysis dependence on outcomes.

RESULTS

A total of 320,629 patients met the inclusion criteria. Of dialysis-dependent patients, 1504 patients underwent internal fixation and 2662 underwent arthroplasty. For both surgical cohorts, dialysis dependence was found to be associated with at least 1.9 times greater odds of mortality within 1 and 2 years post-operatively. Blood transfusions within 90 days and infections within 2 years were significantly increased in the dialysis-dependent study cohort. Dialysis dependence alone did not contribute to increased mechanical failure or major medical complications.

CONCLUSION

Regardless of the surgery performed, dialysis dependence is a significant risk factor for major post-surgical morbidity and mortality after operative treatment of femoral neck fractures in this population. Increased mechanical failure in the internal fixation group was not observed. The increased risk associated with caring for this population should be understood when considering surgical intervention and counseling patients.

Critical Governance Issue of Parathyroid Hormone Assays and its Selection in the Management of Chronic Kidney Disease Mineral and Bone Disorders

Measurement of circulating parathyroid hormone (PTH) levels is essential for optimal management of mineral and bone disorders (MBD) in chronic kidney disease (CKD) patients. There are two major types of PTH assays currently in use: intact parathyroid hormone (i-PTH) and whole PTH (w-PTH) assays. The i-PTH assay is the current standard, and considerable information regarding the management of CKD-MBD has been obtained with this method. However, several limitations have been found with the i-PTH assay. One limitation is that i-PTH assay also measures fragments other than full-length PTH (1-84). Another limitation is the existence of multiple readout methods of the i-PTH assay. The w-PTH assay is theoretically ideal because it exclusively detects full-length PTH (1-84). However, clinical data proving the advantages of w-PTH measurement are not sufficient. For uremic patients, Kidney Disease Improving Global Outcomes suggest that PTH levels should be maintained within approximately two to nine times the upper normal limit of the i-PTH assays. The most critical issue in the evaluation of PTH levels is the lack of definitive PTH assay method. Evidence-based recommendations on clinical management goals of PTH are warranted.

Opioid Analgesics and Adverse Outcomes among Hemodialysis Patients

BACKGROUND AND OBJECTIVES

Patients on hemodialysis frequently experience pain and may be particularly vulnerable to opioid-related complications. However, data evaluating the risks of opioid use in patients on hemodialysis are limited.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using the US Renal Data System, we conducted a cohort study evaluating the association between opioid use (modeled as a time-varying exposure and expressed in standardized oral morphine equivalents) and time to first emergency room visit or hospitalization for altered mental status, fall, and fracture among 140,899 Medicare-covered adults receiving hemodialysis in 2011. We evaluated risk according to average daily total opioid dose (>60 mg, ≤60 mg, and per 60-mg dose increment) and specific agents (per 60-mg dose increment).

RESULTS

The median age was 61 years old, 52% were men, and 50% were white. Sixty-four percent received opioids, and 17% had an episode of altered mental status (15,658 events), fall (7646 events), or fracture (4151 events) in 2011. Opioid use was associated with risk for all outcomes in a dose-dependent manner: altered mental status (lower dose: hazard ratio, 1.28; 95% confidence interval, 1.23 to 1.34; higher dose: hazard ratio, 1.67; 95% confidence interval, 1.56 to 1.78; hazard ratio, 1.29 per 60 mg; 95% confidence interval, 1.26 to 1.33), fall (lower dose: hazard ratio, 1.28; 95% confidence interval, 1.21 to 1.36; higher dose: hazard ratio, 1.45; 95% confidence interval, 1.31 to 1.61; hazard ratio, 1.04 per 60 mg; 95% confidence interval, 1.03 to 1.05), and fracture (lower dose: hazard ratio, 1.44; 95% confidence interval, 1.33 to 1.56; higher dose: hazard ratio, 1.65; 95% confidence interval, 1.44 to 1.89; hazard ratio, 1.04 per 60 mg; 95% confidence interval, 1.04 to 1.05). All agents were associated with a significantly higher hazard of altered mental status, and several agents were associated with a significantly higher hazard of fall and fracture.

CONCLUSIONS

Opioids were associated with adverse outcomes in patients on hemodialysis, and this risk was present even at lower dosing and for agents that guidelines have recommended for use.

The utility of FRAX® in predicting bone fractures in patients with chronic kidney disease on hemodialysis: a two-year prospective multicenter cohort study

We assessed the FRAX® method in 718 hemodialyzed patients in estimating increased risk of bone major and hip fractures. Over two prospective years, statistical analysis showed that FRAX® enables a better assessment of bone major fracture risk in these patients than any of its components and other risk factors considered in the analysis.

INTRODUCTION

Despite the generally increased risk of bone fractures among patients with end-stage renal disease, no prediction models for identifying individuals at particular risk have been developed to date. The goal of this prospective, multicenter observational study was to assess the usefulness of the FRAX® method in comparison to all its elements considered separately, selected factors associated with renal disease and the history of falls, in estimating increased risk of low-energy major bone and hip fractures in patients undergoing chronic hemodialysis.

METHODS

The study included a total of 1068 hemodialysis patients, who were followed for 2 years, and finally, 718 of them were analyzed. The risk analysis included the Polish version of the FRAX® calculator (without bone mineral density), dialysis vintage, mineral metabolism disorders (serum calcium, phosphate, and parathyroid hormone), and the number of falls during the last year before the study.

RESULTS

Over 2 years, low-energy 30 major bone fractures were diagnosed and 13 of hip fractures among them. Area under the curve for FRAX® was 0.76 (95% CI 0.69-0.84) for major fractures and 0.70 (95% CI 0.563-0.832) for hip fractures. The AUC for major bone fractures was significantly higher than for all elements of the FRAX® calculator. In logistic regression analysis FRAX® was the strongest independent risk factor of assessment of the major bone fracture risk.

CONCLUSIONS

FRAX® enables a better assessment of major bone fracture risk in ESRD patients undergoing hemodialysis than any of its components and other risk factors considered in the analysis.

A Decision-Analytic Model to Assess the Cost-Effectiveness of Etelcalcetide vs. Cinacalcet

INTRODUCTION

Etelcalcetide is a novel intravenous calcimimetic for the treatment of secondary hyperparathyroidism (SHPT) in haemodialysis patients. The clinical efficacy and safety of etelcalcetide (in addition to phosphate binders and vitamin D and/or analogues [PB/VD]) was evaluated in three phase III studies, including two placebo-controlled trials and a head-to-head study versus the oral calcimimetic cinacalcet.

OBJECTIVE

The objective of this study was to develop a decision-analytic model for economic evaluation of etelcalcetide compared with cinacalcet.

METHODS

We developed a life-time Markov model including potential treatment effects on mortality, cardiovascular events, fractures, and subjects' persistence. Long-term efficacy of etelcalcetide was extrapolated from the reduction in parathyroid hormone (PTH) in the phase III trials and the available data from the outcomes study in cinacalcet (EVOLVE trial). Etelcalcetide was compared with cinacalcet, both in addition to PB/VD. We applied unit costs averaged from five European countries and a range of potential etelcalcetide pricing options assuming parity price to weekly use of cinacalcet and varying it by a 15 or 30% increase.

RESULTS

Compared with cinacalcet, the incremental cost-effectiveness ratio of etelcalcetide was €1,355 per QALY, €24,521 per QALY, and €47,687 per QALY for the three prices explored. The results were robust across the probabilistic and deterministic sensitivity analyses.

CONCLUSIONS

Our modelling approach enabled cost-utility assessment of the novel therapy for SHPT based on the observed and extrapolated data. This model can be used for local adaptations in the context of reimbursement assessment.

Osteoporosis, bone mineral density and CKD-MBD complex (I): Diagnostic considerations

Osteoporosis (OP) and chronic kidney disease (CKD) independently influence bone and cardiovascular health. A considerable number of patients with CKD, especially those with stages 3a to 5D, have a significantly reduced bone mineral density leading to a high risk of fracture and a significant increase in associated morbidity and mortality. Independently of classic OP related to age and/or gender, the mechanical properties of bone are also affected by inherent risk factors for CKD ("uraemic OP"). In the first part of this review, we will analyse the general concepts regarding bone mineral density, OP and fractures, which have been largely undervalued until now by nephrologists due to the lack of evidence and diagnostic difficulties in the context of CKD. It has now been proven that a reduced bone mineral density is highly predictive of fracture risk in CKD patients, although it does not allow a distinction to be made between the causes which generate it (hyperparathyroidism, adynamic bone disease and/or senile osteoporosis, etc.). Therefore, in the second part, we will analyse the therapeutic indications in different CKD stages. In any case, the individual assessment of factors which represent a higher or lower risk of fracture, the quantification of this risk (i.e. using tools such as FRAX^®) and the potential indications for densitometry in patients with CKD could represent an important first step pending new clinical guidelines based on randomised studies which do not exclude CKD patients, all the while avoiding therapeutic nihilism in an area of growing importance.

Resurgence of parathyroidectomy: evidence and outcomes

PURPOSE OF REVIEW

Parathyroidectomy (PTx) is the definitive therapy for refractory secondary hyperparathyroidism (SHPT). The drastic effects of PTx on biochemical parameters of SHPT increases the possibility that this intervention will lead to a reduction in the adverse outcomes related to uncontrolled SHPT.

RECENT FINDINGS

The effect of PTx on mortality and cardiovascular outcomes among dialysis patients with severe SHPT have been evaluated in many observational studies from different regions of the world, including Asia, Europe, North America, and South America. In all but one small study, there was a significant association of PTx with lower all-cause mortality. In addition, in all studies, there was a trend in favor of PTx for cardiovascular morbidity and mortality. The effect of PTx on fractures has been evaluated in only one epidemiological study from the United States, which demonstrated a significant association of PTx and lower hip and combined fractures.

SUMMARY

Although randomized evidence is lacking, these highly consistent results may suggest a strong beneficial effect of PTx on long-term clinical outcomes and eliminate the potential concern of low parathyroid hormone after PTx.

Bone and mineral disorders in chronic kidney disease: implications for cardiovascular health and ageing in the general population

The patient with chronic kidney disease (CKD) represents an extreme model for arteriosclerosis, vascular calcification, and bone disorders, all of which are also associated with ageing in the general population. These pathological features are also relevant to other common chronic health disorders such as diabetes, and chronic inflammatory and cardiovascular diseases. Although management and interventions for these major risk factors are now incorporated into most public health guidelines (eg, smoking cessation and control of bodyweight and blood pressure, as well as glucose and cholesterol concentrations), some residual cardiovascular risk is not reduced by implementation of these interventions. CKD should be regarded as an atypical disease in which both traditional and novel cardiovascular risk factors have effects on outcomes. But CKD can also be viewed conceptually as an accelerator of traditional cardiovascular risk factors. Findings from research into mineral bone disorder associated with CKD (CKD-MBD) could help the medical community to better understand the vascular actions of certain molecules, such as phosphates, fibroblast growth factor 23, parathyroid hormone, sclerostin, or vitamin D and their relevance to the management of different pathologies in the general population. Importantly, these components, which are recognised in nephrology, could help to explain residual risk of cardiovascular events in the general population. Thus, achieving a better understanding of CKD-MBDs could provide substantial insight into future treatments for arteriosclerosis and osteoporosis, which are strongly associated with ageing and morbidity in the general population.

Long-term effects of low calcium dialysates on the serum calcium levels during maintenance hemodialysis treatments: A systematic review and meta-analysis

Hypercalcemia and hyperparathyroidism in patients receiving maintenance hemodialysis (MHD) can cause the progression of cardiovascular diseases (CVD) and mineral bone disorders (MBD). The KDIGO recommends the dialysates with a calcium (Ca) concentration of 1.25–1.5 mmol/L for MHD treatments, but the optimal concentration remains controversial. Here, we conducted a systematic review and a meta-analysis of seven randomized controlled trials examining a total of 622 patients to investigate the optimal concentration for MHD for 6 months or longer. The dialysates with a low Ca concentration (1.125 or 1.25 mmol/L) significantly lowered the serum Ca and raised the intact parathyroid hormone levels by 0.52 mg/dL (95% confidence interval, 0.20–0.85) and 39.59 pg/mL (14.80–64.38), respectively, compared with a high Ca concentration (1.50 or 1.75 mmol/L). Three studies showed that a low concentration was preferred for lowering arterial calcifications or atherosclerosis in different arteries, but one study showed that coronary arterial calcifications increased with a low concentration. Two studies showed contradictory outcomes in terms of MBD. Our meta-analysis showed that a dialysate with a low Ca concentration lowered the serum Ca levels in patients receiving long-term MHD, but further studies are needed to determine the optimal Ca concentration in terms of CVD and MBD.

Symptomatic fracture risk in the renal replacement therapy population

Background

Bone fractures are an important cause of morbidity and mortality in patients on renal replacement therapy (RRT). The aim of this multicentre observational study was to quantify the incidence of radiologically proven bone fracture by anatomical site in prevalent RRT groups and study its relationship to potential risk factors.

Methods

We performed a retrospective analysis of electronic records of all 2096 adults prevalent on RRT in the West of Scotland on 7 July 2010 across all hospitals (except one where inception was 1 August 2011) to identify all subsequent radiologically proven fractures during a median 3-year follow-up.

Results

There were 340 fractures, with an incidence of 62.8 per 1000 patient-years. The incidences were 37.6, 99.2 and 57.6 per 1000 patient-years in the transplant, haemodialysis (HD) and peritoneal dialysis (PD) groups, respectively (P < 0.05). In the multivariable model, age and HD (relative to transplant or PD) were independently associated with increased risk of fractures, while primary glomerular disease, increasing serum albumin and taking alfacalcidol or lanthanum were associated with decreased risk. In a multivariable model of only HD patients, age was independently associated with an increased risk of fractures, while glomerular disease, high serum albumin and being on alfacalcidol and lanthanum were associated with decreased risk. In a multivariable model in transplant patients, there were no significant independent predictors of fracture.

Conclusions

The risk of symptomatic bone fracture is high in RRT patients and is ∼2.5 times higher in HD than in renal transplant patients, with the increased risk being independent of baseline factors. Fracture risk increases with age and lower serum albumin and is reduced if the primary renal diagnosis is glomerular disease. The possible protective role of alfacalcidol and lanthanum in HD patients deserves further exploration.

The Effect of Parathyroidectomy on Risk of Hip Fracture in Secondary Hyperparathyroidism

Background

Secondary hyperparathyroidism increases the risk for fractures. Despite improvement in medical therapy, surgical parathyroidectomy (PTX) often becomes necessary, but its effect on risk of fractures is not clear. Our aim was to study the effect of parathyroidectomy on the risk of hip fractures in patients on dialysis or with a functioning renal graft at time of parathyroidectomy.

Design

In a cohort of 20,056 patients on dialysis or with functioning renal allograft, we identified 590 patients who underwent parathyroidectomy between 1991 and 2009. Of these, 579 were matched with 1970 non-PTX patients on age, sex, cause of renal disease and functioning renal allograft or not at the time of PTX or at the corresponding time for non-PTX patients (t). We calculated the risk for hip fracture after PTX using crude and adjusted Cox proportional hazards regressions, adjusting for time in renal replacement therapy before t, time with functioning renal allograft before and after t, comorbidity at t and a hip fracture before t.

Results

The adjusted hazard ratio (95% confidence interval) for hip fracture was 0.40 (0.18–0.88) for PTX patients, compared to non-PTX patients. When analyses were performed separately for sex, only women had a lower risk of hip fracture after PTX compared to non-PTX patients. The risk of hip fracture after PTX was similar in patients with or without functioning renal allograft at time for PTX.

Conclusion

Parathyroidectomy is associated with a lower risk of hip fracture in female patients with secondary hyperparathyroidism.

Bone biopsy practice patterns across Europe: the European renal osteodystrophy initiative-a position paper

Renal osteodystrophy (ROD) is a heterogeneous group of metabolic bone diseases complicating progressive chronic kidney disease (CKD). Bone biomarkers and bone imaging techniques may help to assess bone health and predict fractures in CKD but do have important inherent limitations. By informing on bone turnover and mineralization, a bone biopsy may help to guide prevention and treatment of ROD and its consequences. According to a recent survey conducted among European nephrologists, bone biopsies are performed rather exceptionally, both for clinical and research purposes. Obviously, clinical research in the field of ROD is threatened by vanishing clinical and pathological expertise, small patient cohorts and scientific isolation. In March 2016, the European Renal Osteodystrophy (EU-ROD) initiative was created under the umbrella of the ERA-EDTA CKD-mineral and bone disorder (MBD) Working Group to revitalize bone biopsy as a clinically useful tool in the diagnostic workup of CKD-MBD and to foster research on the epidemiology, implications and reversibility of ROD. As such, the EU-ROD initiative aims to increase the understanding of ROD and ultimately to improve outcomes in CKD patients.

Skeletal manifestations of renal disease in childhood

PURPOSE OF REVIEW

This review summarizes recent findings on musculoskeletal health in three chronic renal conditions of childhood: chronic kidney disease stages 2-5D, nephrotic syndrome, and urolithiasis. Findings with important clinical implications warranting further investigation are highlighted.

RECENT FINDINGS

Recent cohort studies have demonstrated a high burden of fracture and progressive deficits of cortical bone in children with chronic kidney disease. Lower cortical density is associated with incident fracture and may be an important therapeutic target. Parathyroid hormone and calcium are independent correlates of cortical density, and modifiable factors for fracture include parathyroid hormone and phosphate binder use. Children with nephrotic syndrome, even with normal renal function, have evidence of abnormal bone metabolism and structure, and vitamin D deficiency may be an important modifiable risk factor in this population. Urolithiasis has been associated with reduced bone mineral density and is increasingly common in children and adolescents. Population-based data found a significantly increased risk of fracture in adolescent males and young women.

SUMMARY

Recent findings substantiate concern regarding the particular vulnerability of the growing skeleton to chronic renal disease. Studies are needed to determine how to optimize assessment and management of bone health in children with these conditions, particularly in terms of calcium and vitamin D requirements, with the goal of improving childhood bone accrual for lifelong fracture prevention.

Two-year cortical and trabecular bone loss in CKD-5D: biochemical and clinical predictors

This prospective two-year study of patients on chronic dialysis measured changes in bone mineral density (BMD). Patients with higher baseline BMD and shorter dialysis vintage lost more bone. Treatment with anti-hypertensives acting on the central nervous system was protective against bone loss. Baseline serum levels of sclerostin and bone-specific alkaline phosphatase predicted bone loss.

INTRODUCTION

This prospective 2-year study of chronic kidney disease on dialysis (CKD-5D) patients assessed trabecular and cortical bone loss at the hip and spine and examined potential demographic, clinical, and serum biochemical predictors of bone loss.

METHODS

Eighty-nine CKD-5D patients had baseline, year 1, and year 2 bone mineral density (BMD) measurements using dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT); concurrent blood samples were drawn and clinical variables recorded. No study treatments occurred.

RESULTS

The 2-year total hip BMD change was - 5.9% by QCT and - 3.1% by DXA (p < 0.001). Spinal BMD was unchanged. QCT total hip cortical mass and volume decreased (- 7.3 and - 10.0%); trabecular volume increased by 5.9% (ps < 0.001). BMD changes did not vary with age, BMI, race, diabetes, smoking, or exercise. Patients with higher baseline BMD and shorter dialysis vintage lost more bone (p < 0.05). Vitamin D analogs and phosphate binders were not protective against bone loss; cinacalcet was protective by univariate but not by multivariable analysis. CNS-affecting antihypertensives were protective against loss of BMD, cortical mass, cortical volume (ps < 0.05) and trabecular mass (p = 0.007). These effects remained after adjustment. BSAP correlated with changes in BMD, cortical mass, and volume (p < 0.01) as did sclerostin (inversely).

CONCLUSIONS

There was severe cortical bone loss at the hip best recognized by QCT. Patients with shorter dialysis vintage and less pre-existing bone loss lost more bone, while treatment with CNS-acting antihypertensives was protective. BSAP and sclerostin were useful markers of bone loss.

Lesion based diagnostic performance of dual phase 99mTc-MIBI SPECT/CT imaging and ultrasonography in patients with secondary hyperparathyroidism

Background

We aimed to evaluate the diagnostic performance of ^99mTc-MIBI SPECT/CT and ultrasonography in patients with secondary hyperparathyroidism (SHPT), and explored the factors that affect the diagnostic performance.

Methods

^99mTc-MIBI SPECT/CT and ultrasonography were performed in 50 patients with SHPT within 1 month before they underwent surgery. Imaging results were confirmed by the pathology. Pearson correlation analysis was used to determine the correlation of PTH level with clinical data. The optimal cutoff value for predicting positive ^99mTc-MIBI results was evaluated by ROC analysis in lesions diameter.

Results

Forty-nine patients had a positive ^99mTc-MIBI imaging results and 39 patients had positive ultrasonography results. The sensitivities of ^99mTc-MIBI and ultrasonography were 98.00% and 78.00%, respectively. A total of 199 lesions were resected in 50 patients. Among them, 183 lesions were proved to be parathyroid hyperplasia. On per-lesion basis analysis, the sensitivity and specificity of ^99mTc-MIBI and ultrasonography were 59.34% and 75.00% vs 46.24% and 80.00%, respectively. The Pearson correlation analysis showed that the serum AKP and PTH level had a significant linear association (r = 0.699, P < 0.001). The lesion diameter was a statistically significant predictive factor in predicting positive ^99mTc-MIBI SPECT/CT. The optimal cutoff value for predicting positive ^99mTc-MIBI results evaluated by ROC analysis in lesions diameter was 8.05 mm.

Conclusion

Dual phase ^99mTc-MIBI SPECT/CT imaging had a higher sensitivity in patients with SHPT than ultrasonography. Therefore, using ^99mTc-MIBI positioning the lesion could be an effective method pre-surgical in patients with SHPT.

The frequency of bone fractures among patients with chronic kidney disease not on dialysis: two-year follow-up

INTRODUCTION

Renal osteodystrophy is a severe complication of chronic kidney disease (CKD) that increases morbidity and mortality in these patients. Mineral and bone disorder starts early in CKD and affects the incidence of bone fractures. The aim of this study was to observe the frequency of diverse bone fractures in patients with CKD not on dialysis.

METHODS

This cohort study included 68 patients that were followed during the two-year period. The patients were divided into two cohorts: one that developed bone fractures and the other that did not. There were 35 (51.5%) men and 33 (48.5%) women. The mean age of patients ranged 62.88±11.60 years. During follow-up serum values of chronic kidney disease - mineral and bone indicators were measured. The methods of descriptive and analytical statistics were used in order to analyze obtained data.

RESULTS

During this two-year follow-up seven patients developed bone fractures. Among them, females dominated (6 patients) compared to males (only 1 patient). The most common were fractures of forearm. The mean level of parathyroid hormone (PTH) at the beginning of the monitoring was higher in the group of patients with bone fractures (165.25 ± 47.69 pg/mL) in regard to another group (103.96 ± 81.55 pg/mL). After two-year follow-up, this difference became statistically significant at the level p < 0.05. Patients that developed bone fractures had higher FRAX (Fracture Risk Assessment) score compared to another group.

CONCLUSION

In our study, about 10% of patients had bone fractures in the two-year follow-up period. Patients who developed fractures had a higher PTH level and FRAX score.

Magnesium and Risk of Hip Fracture among Patients Undergoing Hemodialysis

Magnesium is an essential mineral for bone metabolism. However, little is known about the relationship between magnesium and the risk of fractures. In this cohort study, we elucidated the association between serum magnesium level and the risk of incident hip fracture among patients undergoing hemodialysis. We identified 113,683 patients undergoing hemodialysis with no history of hip fracture from a nation-wide database of patients undergoing dialysis in Japan. During a 2-year follow-up, a total of 2305 (2%) new hip fractures occurred. The crude incidence rate was significantly higher among patients in the lower quartiles of serum magnesium levels (2.63%, 2.08%, 1.76%, and 1.49% in Q1-Q4, respectively; P<0.001 for trend). The range of serum magnesium levels (in milligrams per deciliter) in each quartile was as follows: Q1, <2.3; Q2, 2.4-2.6; Q3, 2.7-2.8, and Q4, >2.9. After adjustment for demographic and clinical factors, patients in Q1 had a 1.23-fold higher risk for hip fracture than those in Q4 (95% confidence interval, 1.06 to 1.44; P<0.01). Similarly, an inverse probability weighting analysis showed an increased risk of hip fracture among patients in the lower magnesium quartiles. We did not observe significant effect modifications in subgroup analyses. The population-attributable fraction of serum magnesium level for incident hip fractures was 13.7% (95% confidence interval, 3.7% to 22.7%), which was much higher than that of serum calcium, serum phosphate, and parathyroid hormone levels. Thus, mild hypermagnesemia is associated with a lower risk of hip fracture among patients undergoing hemodialysis.

Exploring the potential value of improved care for secondary hyperparathyroidism with a novel calcimimetic therapy

AIMS

This study explored the use of a value-based pricing approach for the new calcimimetic etelcalcetide indicated for the treatment of secondary hyperparathyroidism (SHPT) in patients receiving hemodialysis. It used the US payer perspective and applied the cost-effectiveness framework. Because etelcalcetide is an intravenous therapy that can be titrated for individual patients, and because its utilization is yet to be assessed in real world settings, a range of plausible doses were estimated for etelcalcetide to define a range of prices. These were either in relation to the existing oral calcimimetic cinacalcet or compared to no calcimimetic treatment.

MATERIALS AND METHODS

The value-based price of etelcalcetide was determined via a Markov model. This model combined data from the etelcalcetide trials and previously published cost-effectiveness models in SHPT, and allowed extrapolation of treatment effects on mortality, cardiovascular events, fracture, and parathyroidectomy. Several dosing scenarios were explored covering the dose ranges of 30.0-64.18 mg per day for cinacalcet and 1.07-3.11 mg per day for etelcalcetide. These included the mean dose from the etelcalcetide trials, the preliminary defined daily dose, and the expected most common dose in real world. An acceptable price range for etelcalcetide was assessed by comparing the incremental cost-effectiveness ratios obtained with the willingness-to-pay threshold range of $100,000-$300,000/quality-adjusted life-years.

RESULTS

Cost-effectiveness analysis supported value-based prices for etelcalcetide ranging from $21.15-$49.97/mg vs cinacalcet, and $13.79-$119.45/mg vs no calcimimetics.

LIMITATIONS

There is uncertainty around what the real-world dosing will be for etelcalcetide. Another important nuance is that no studies have examined etelcalcetide effects on hard outcomes and, therefore, this modeling exercise relied on an extrapolation approach.

CONCLUSIONS

This cost-effectiveness analysis, including scenarios to address uncertainties, allowed estimation of a value-based price range to aid reimbursement decisions in the US.

Chronic kidney disease and vitamin D metabolism in human bone marrow-derived MSCs

Vitamin D that is synthesized in the skin or is ingested undergoes sequential steps of metabolic activation via a cascade of cytochrome P450 enzymatic hydroxylations in the liver and kidney to produce 1α,25-dihydroxyvitamin D (1α,25(OH)2 D). There are many tissues that are able to synthesize 1α,25(OH)2 D, but the biological significance of extrarenal hydroxylases is unresolved. Human marrow-derived mesenchymal stem cells (marrow stromal cells, hMSCs) give rise to osteoblasts, and their differentiation is stimulated by 1α,25(OH)2 D. In addition to being targets of 1α,25(OH)2 D, hMSCs can synthesize it; on the basis of those observations, we further examined the local autocrine/paracrine role of vitamin D metabolism in osteoblast differentiation. Research with hMSCs from well-characterized subjects provides an innovative opportunity to evaluate the effects of clinical attributes on the regulation of hMSCs. Like the renal 1α-hydroxylase, the enzyme in hMSCs is constitutively decreased with age and chronic kidney disease (CKD); both are regulated by PTH1-34, insulin-like growth factor 1, calcium, 1α,25(OH)2 D, 25(OH)D, and fibroblast growth factor 23. CKD is associated with impaired renal biosynthesis of 1α,25(OH)2 D, low bone mass, and increased fracture risk. Studies with hMSCs from CKD patients or aged subjects indicate that circulating 25(OH)D may have an important role in osteoblast differentiation on vitamin D metabolism and action in hMSCs.

Osteoporosis in Frail Patients: A Consensus Paper of the Belgian Bone Club

In this consensus paper, the Belgian Bone Club aims to provide a state of the art on the epidemiology, diagnosis, and management of osteoporosis in frail individuals, including patients with anorexia nervosa, patients on dialysis, cancer patients, persons with sarcopenia, and the oldest old. All these conditions may indeed induce bone loss that is superimposed on physiological bone loss and often remains under-recognized and under-treated. This is of particular concern because of the major burden of osteoporotic fractures in terms of morbidity, mortality, and economic cost. Therefore, there is an urgent need to appreciate bone loss associated with these conditions, as this may improve diagnosis and management of bone loss and fracture risk in clinical practice.

Biomarkers Predicting Bone Turnover in the Setting of CKD

PURPOSE OF THE REVIEW

Impaired bone quality contributes to the increased fracture risk in chronic kidney disease patients. Both low and high turnover bone disease may compromise bone quality. The question arises whether bone biomarkers may be additive or replace bone histormorphometry for diagnosing the extremes of bone turnover.

RECENT FINDINGS

Studies exploring the performance of established and emerging bone biomarkers against histomorphometric assessment of bone turnover are limited and overall yield inconclusive results as to their diagnostic utility. Bone biomarkers, although promising, currently fail to meet the needed diagnostic accuracy to replace bone histomorphometry and thus are not yet ready for clinical use. Bone biomarkers have not only several advantages, but also important limitations such as high biological variability, retention with kidney disease, preanalytical issues, and interassay variability. These important issues must be considered when developing and evaluating bone biomarkers. There is an urgent need for harmonization and standardization of available assays and additional bone biopsy studies.

Serum Phosphate Is Associated With Fracture Risk: The Rotterdam Study and MrOS

Extreme phosphate levels (P) have been associated with mineralization defects and increased fracture risk. Whether P within normal range is related to bone health in the general population is not well understood. To investigate the association of P with bone mineral density (BMD) and fracture risk, we assessed two population-based cohorts: the Dutch Rotterdam Study (RS-I, RS-II, RS-III; n = 6791) and the US Osteoporotic Fractures in Men (MrOS; n = 5425) study. The relationship of P with lumbar spine (LS) and femoral neck (FN) BMD was tested in all cohorts via linear models; fracture risk was tested in RS-I, RS-II, and MrOS through Cox models, after follow-up of 8.6, 6.6, and 10.9 years, respectively. Adjustments were made for age, body mass index, smoking, serum levels of calcium, potassium, 25-hydroxyvitamin D, estimated glomerular filtration rate (eGFR), FN-BMD, prevalent diabetes, and cardiovascular disease. Additional adjustments were made for phosphate intake, parathyroid hormone, and fibroblast growth factor 23 levels in MrOS. We further stratified by eGFR. Results were pooled through study-level meta-analyses. Hazard ratios (HR) and betas (β) (from meta-analyses) are expressed per 1 mg/dL P increase. P was positively associated with fracture risk in men and women from RS, and findings were replicated in MrOS (pooled HR all [95% CI]: 1.47 [1.31-1.65]). P was associated with fracture risk in subjects without chronic kidney disease (CKD): all (1.44 [1.26-1.63]) and in men with CKD (1.93 [1.42-2.62]). P was inversely related to LS-BMD in men (β: -0.06 [-0.11 to -0.02]) and not to FN-BMD in either sex. In summary, serum P was positively related to fracture risk independently from BMD and phosphate intake after adjustments for potential confounders. P and LS-BMD were negatively related in men. Our findings suggest that increased P levels even within normal range might be deleterious for bone health in the normal population. © 2017 American Society for Bone and Mineral Research.

Osteoporotic fractures in patients with systemic lupus erythematosus and end stage renal disease

Background The incidence of end stage renal disease (ESRD) in patients with systemic lupus erythematosus (SLE) is rising. However, the relationship between osteoporotic fractures and SLE in the setting of ESRD remains uninvestigated. The purpose of this study was to compare the frequency of incident osteoporotic fractures in patients with ESRD with and without SLE, to identify risk factors for fractures in patients with SLE and ESRD, and to examine the contribution of these fractures to mortality. Methods Retrospective cohort study of patients with SLE ( n = 716) and a 5% random sample of controls without SLE ( n = 4176) in the United States Renal Data System (USRDS) from years 2006-2008 enrolled in Medicare Part D. Results Fractures occurred in 10.6% ( n = 76) of patients with SLE and ESRD and 12.1% ( n = 507) of patients with ESRD without SLE ( p = 0.24). Older age (adjusted relative risk 1.02, 95% confidence interval 1.01-1.04) was associated with an increased risk for fracture in patients with SLE and ESRD. In multivariable analyses, vertebral and hip fractures more than doubled the risk for mortality. Conclusions The frequency of osteoporotic fractures in patients with SLE and ESRD is similar to the general population of patients with ESRD. Vertebral and hip fractures are significant contributors to mortality in patients with SLE and ESRD. Fracture prevention, in particular, for elderly patients with SLE and ESRD, should be considered. Summary SLE is not an independent risk factor for fractures in patients with ESRD. However, among patients with SLE and ESRD, vertebral and hip fractures are significant contributors to mortality.

Modified Creatinine Index and the Risk of Bone Fracture in Patients Undergoing Hemodialysis: The Q-Cohort Study

BACKGROUND

Hemodialysis patients are at increased risk for bone fracture and sarcopenia. There is close interplay between skeletal muscle and bone. However, it is still unclear whether lower skeletal muscle mass increases the risk for bone fracture.

STUDY DESIGN

Cross-sectional study and prospective longitudinal cohort study.

SETTING & PARTICIPANTS

An independent cohort of 78 hemodialysis patients in the cross-sectional study and 3,030 prevalent patients undergoing maintenance hemodialysis prospectively followed up for 4 years.

PREDICTOR

Skeletal muscle mass measured by bioelectrical impedance analysis (BIA) and modified creatinine index, an estimate of skeletal muscle mass based on age, sex, Kt/V for urea, and serum creatinine level.

OUTCOMES

Bone fracture at any site.

RESULTS

In the cross-sectional study, modified creatinine index was significantly correlated with skeletal muscle mass measured by BIA. During a median follow-up of 3.9 years, 140 patients had bone fracture. When patients were divided into sex-specific quartiles based on modified creatinine index, risk for bone fracture estimated by a Fine-Gray proportional subdistribution hazards model with all-cause death as a competing risk was significantly higher in the lower modified creatinine index quartiles (Q1 and Q2) compared to the highest modified creatinine index quartile (Q4) as the reference value in both sexes (multivariable-adjusted HRs for men were 7.81 [95% CI, 2.63-23.26], 5.48 [95% CI, 2.08-14.40], 2.24 [95% CI, 0.72-7.00], and 1.00 [P for trend < 0.001], and for women were 4.44 [95% CI, 1.50-13.11], 2.33 [95% CI, 0.86-6.31], 1.96 [95% CI, 0.82-4.65], and 1.00 [P for trend = 0.007] for Q1, Q2, Q3, and Q4, respectively).

LIMITATIONS

One-time assessment of modified creatinine index; no data for residual kidney function and fracture sites and causes.

CONCLUSIONS

Modified creatinine index was correlated with skeletal muscle mass measured by BIA. Lower modified creatinine index was associated with increased risk for bone fracture in male and female hemodialysis patients.

Compared effects of calcium and sodium polystyrene sulfonate on mineral and bone metabolism and volume overload in pre-dialysis patients with hyperkalemia

BACKGROUND

Hyperkalemia is prevalent in end-stage renal disease patients, being involved in life-threatening arrhythmias. Although polystyrene sulfonate (PS) is commonly used for the treatment of hyperkalemia, direct comparison of effects between calcium and sodium PS (CPS and SPS) on mineral and bone metabolism has not yet been studied.

METHODS

In a randomized and crossover design, 20 pre-dialysis patients with hyperkalemia (>5 mmol/l) received either oral CPS or SPS therapy for 4 weeks.

RESULTS

After 4-week treatments, there was no significant difference of changes in serum potassium (K) from the baseline (ΔK) between the two groups. However, SPS significantly decreased serum calcium (Ca) and magnesium (Mg) and increased intact parathyroid hormone (iPTH) values, whereas CPS reduced iPTH. ΔiPTH was inversely correlated with ΔCa and ΔMg (r = -0.53 and r = -0.50, respectively). Furthermore, sodium (Na) and atrial natriuretic peptide (ANP) levels were significantly elevated in patients with SPS, but not with CPS, whereas ΔNa and ΔANP were significantly correlated with each other in all the patients. We also found that ΔNa and Δ(Na to chloride ratio) were positively correlated with ΔHCO₃^-. In artificial colon fluid, CPS increased Ca and decreased Na. Furthermore, SPS greatly reduced K, Mg, and NH₃.

CONCLUSION

Compared with SPS, CPS may be safer for the treatment of hyperkalemia in pre-dialysis patients, because it did not induce hyperparathyroidism or volume overload.

Ensuring Patient Safety During the Transition to ESRD

Patients with chronic kidney disease (CKD) are at risk for complications both inherent to the disease and as a consequence of its treatment. The dangers that CKD patients face change across the spectrum of the disease. Providers who are well-versed in these safety threats are best poised to safeguard patients as their CKD progresses.

A comparative study of bone biopsies from the iliac crest, the tibial bone, and the lumbar spine

BACKGROUND

Patients with an impaired renal function show a high incidence of bone and mineral disturbances. These 'chronic kidney disease - mineral and bone disorders' (CKD-MBD) range from high turnover osteoporosis to adynamic bone disease. Currently, the histomorphometric analysis of a bone biopsy taken from the iliac crest is viewed as the gold standard for CKD-MBD subtype differentiation. However, the clinical relevance of such a biopsy is questionable since iliac crest fractures are an extremely rare finding. Therefore, we aimed to elucidate if the histomorphometric parameter 'trabecular bone volume (BV/TV)' from the iliac crest is representative for other biopsy locations. We chose two skeletal sites of higher fracture risk for testing, namely, the tibial bone and the lumbar spine, to examine if the current gold standard of bone biopsy is indeed golden.

METHODS

Bone biopsies were taken from 12 embalmed body donors at the iliac crest, the proximal tibia, and the lumbar vertebral body, respectively. Masson-Goldner stained sections of methyl methacrylate embedded biopsies were used for trabecular bone volume calculation. Furthermore, exemplary μ-computed tomography (XtremeCT) scans with subsequent analysis were performed.

RESULTS

Median values of trabecular bone volume were comparable between all body donors with median (interquartile range, IQR) 18.3% (10.9-22.9%) at the iliac crest, 21.5% (9.5-40.1%) at the proximal tibia, and 16.3% (11.4-25.0%) at the lumbar spine. However, single values showed extensive intra-individual variation, which were also confirmed by XtremeCT imaging.

CONCLUSIONS

Distinct intra-individual heterogeneity of trabecular bone volume elucidate why a bone biopsy from one site does not necessarily predict patient relevant endpoints like hip or spine fractures. Physicians interpreting bone biopsy results should know this limitation of the current gold standard for CKD-MBD diagnostic, especially, when systemic therapeutic decisions should be based on it.

Evaluation of fracture risk in chronic kidney disease

Chronic kidney disease (CKD) is associated with mineral and bone disorders (MBD) that are now considered as a syndrome. Bone fragility and a four to tenfold increased rate of skeletal fractures are often reported in CKD patients. The evaluation of the risk of these fractures in CKD patients should explore the same risk factors identified for the general population including low body weight, menopause, personal and familial history of osteoporosis, chronic inflammatory diseases, and corticosteroid therapy. The aim of this article is to provide a critical review of the tools used for the evaluation of bone loss and the risk of fracture in CKD patients, ranging from the measurement of bone mineral density (BMD), fracture risk assessment (Frax™), quantitative computed tomography (QCT), high-resolution peripheral quantitative computed tomography (HRpQTC), to circulating biomarkers of bone metabolism including vitamin D, parathyroid hormone (PTH), bone-specific alkaline phosphatase, osteocalcin, and some collagen type 1-related molecules indicators of bone remodeling.

Frequent monitoring of mineral metabolism in hemodialysis patients with secondary hyperparathyroidism: associations with achievement of treatment goals and with adjustments in therapy

Background

Dialysis guidelines in Japan recommend more frequent measurement of mineral metabolism markers than the Kidney Disease: Improving Global Outcomes guidelines. However, the extent to which frequent marker measurement contributes to achievement of target ranges and to therapy adjustment is unknown.

Methods

This multicenter cohort study involved 3276 hemodialysis patients with secondary hyperparathyroidism. Data on laboratory measurements and drug prescriptions were collected every 3 months. Main exposures were frequencies of measuring serum calcium and phosphorus [weekly/biweekly/monthly (reference)] and serum parathyroid hormone (PTH) [monthly/bimonthly/trimonthly (reference)] levels. Outcomes were achievement of guideline-specified ranges of mineral metabolism markers when serum levels were over, and maintenance of ranges when levels were already within, respective specified ranges, use of intravenous vitamin D receptor activator (VDRA) and initiation of cinacalcet use. Associations were examined via generalized estimating equations.

Results

When serum marker levels exceeded the target range, weekly measurement of calcium and phosphorus was positively associated with achievement of the guideline-specified calcium range [adjusted odds ratio (AOR): 1.57, 95% confidence interval (CI) 1.09-2.26] but not phosphorus range (AOR: 0.99, 95% CI 0.74-1.33). Monthly measurement of PTH was positively associated with achievement of the guideline-specified PTH range (AOR: 1.14, 95% CI 1.01-1.27). When serum marker levels were within the guideline-specified range, increased frequency of measurements was not associated with in-range maintenance of marker levels for any of the three mineral markers assessed. Regarding treatment regimen, relatively frequent measurement of serum calcium and phosphorus was positively associated with cinacalcet initiation and relatively frequent measurement of serum PTH with cinacalcet initiation and intravenous VDRA use.

Conclusions

Our results suggest that increasing frequency of measurements is helpful when serum marker levels exceed the target range, partially via adjustment in the therapeutic regimen. We found no evidence that frequent measurements are helpful when mineral levels are already within target ranges.

Osteoporosis in patients with diabetes after kidney transplantation

Preexisting diabetes increases risk of fractures after kidney transplantation (KT). However, little is known about mechanisms and prevention of increased fragility in these patients. Pathophysiology of osteoporosis after KT is complex and characterized by high prevalence of adynamic bone disease. Despite high prevalence of preexisting diabetes in KT recipients, diabetes patients were underrepresented in the studies that explored mechanisms and treatments of osteoporosis after KT. Therefore, caution should be exercised before considering conventional fracture prevention strategies in this unique group of patients. Many traditional osteoporosis medications reduce bone turnover and, hence, can be ineffective or even harmful in diabetic patients after KT. Contrary to predictions, evidence from the studies conducted in mostly non-diabetic subjects demonstrated that bisphosphonates failed to reduce fracture rates after KT. Therefore, bisphosphonates use should be limited in diabetic patients until more evidence supporting their post-transplant efficacy is available. We recommend the following strategies that may help reduce fracture risk in diabetes subjects after KT such as adequate management of calcium, parathyroid hormone, and vitamin D levels, optimization of glycemic control, use of steroid-sparing immunosuppressive regimens, and fall prevention.

Higher serum sclerostin levels and insufficiency of vitamin D are strongly associated with vertebral fractures in hemodialysis patients: a case control study

In hemodialysis patients, vertebral fractures were associated with elevated sclerostin levels, suggesting that sclerostin could reflect bone fragility in these patients.

INTRODUCTION

Fragility fractures are common in hemodialysis patients. The aims of our study were to determine the prevalence of vertebral fracture and analyze associations between sclerostin serum levels and vertebral fractures in hemodialysis patients.

METHODS

Ninety-two hemodialysis patients and 100 controls matched for age and sex were studied. Bone mineral density was measured by ultrasonography at non-dominant heel. The markers of bone turnover included serum osteocalcin, C-terminal telopeptide, and sclerostin. All participants underwent radiography of the thoracic and lumbar spine to ascertain the presence of vertebral fractures.

RESULTS

Bone ultrasound parameters at calcaneus were significantly lower in hemodialysis patients compared with controls; bone turnover markers and parathyroid hormone level were significantly higher, while serum of 25-OH-D3 was significantly lower in hemodialysis group. One or more moderate or severe vertebral fractures were found in 38 hemodialysis patients, whereas in control group, 10 patients had a vertebral fracture. In hemodialysis group, the comparison between patients with and without vertebral fractures showed that the patients with vertebral fractures had the serum sclerostin levels statistically higher than patients without vertebral, while serum levels of 25-OH-D3 was significantly lower in patients with vertebral fractures compared to the patients without vertebral fractures. Multivariate analysis disclosed that sclerostin levels were associated with an increased risk of vertebral fractures in hemodialysis patients after adjusting for multiple variables.

CONCLUSIONS

Our data shows high prevalence of vertebral fractures in hemodialysis patients and that it is associated with elevated sclerostin levels, reflecting bone fragility in these patients.

Management of secondary hyperparathyroidism: how and why?

Secondary hyperparathyroidism (SHPT) is a common complication in chronic kidney disease. Currently, various treatment options are available, including vitamin D receptor activators, cinacalcet hydrochloride, and parathyroidectomy. These treatment options have contributed to the successful control of SHPT, and recent clinical studies have provided evidence suggesting that effective treatment of SHPT leads to improved survival. Although bone disease is the most widely recognized consequence of SHPT and remains a major target for treatment of SHPT, there is increasing evidence that parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), both of which are markedly elevated in SHPT, have multiple adverse effects on extraskeletal tissues. These actions may lead to the pathological development of left ventricular hypertrophy, renal anemia, immune dysfunction, inflammation, wasting, muscle atrophy, and urate accumulation. Given that treatment of SHPT leads to decreases in both PTH and FGF23, these data provide an additional rationale for treating SHPT. However, definitive evidence is still lacking, and future research should focus on whether treatment of SHPT prevents the adverse effects of PTH and FGF23.

An update on bone imaging and markers in chronic kidney disease

Bone disorders in chronic kidney disease (CKD) are associated with heightened risks of fractures, vascular calcification, poor quality of life and mortality compared to the general population. However, diagnosis and management of these disorders in CKD are complex and appreciably limited by current diagnostic modalities. Areas covered: Bone histomorphometry remains the gold standard for diagnosis but is not widely utilised and lacks feasibility as a monitoring tool. In practice, non-invasive imaging and biochemical markers are preferred to guide therapeutic decisions. Expert commentary: This review aims to summarize the risk factors for, and spectrum of bone disease in CKD, as well as appraise the clinical utility of dual energy X-ray densitometry, peripheral quantitative computed tomography, high-resolution peripheral quantitative computed tomography, and bone turnover markers.

Chronic Kidney Disease-Mineral Bone Disorder in the Elderly Peritoneal Dialysis Patient

PURPOSE

The purpose of this paper was to review the literature concerning the treatment of chronic kidney disease-mineral bone disorder (CKD-MBD) in the elderly peritoneal dialysis (PD) patient.

RESULTS

Chronic kidney disease-mineral bone disorder is a major problem in the elderly PD patient, with its associated increased fracture risk, vascular calcification, and accelerated mortality fracture risk. Peritoneal dialysis, however, bears a lower risk than hemodialysis (HD). The approach to CKD-MBD prophylaxis and treatment in the elderly PD patient is similar to other CKD patients, with some important differences. Avoidance of hypercalcemia, hyperphosphatemia, and hyperparathyroidism is important, as in other CKD groups, and is generally easier to attain. Calcium-free phosphate binders are recommended for normocalcemic and hypercalcemic patients. Normalization of vitamin D levels to > 75 nmol/L (> 30 pg/L) and low-dose active vitamin D therapy is recommended for all patients. Hyperparathryoidism is to be avoided by using active vitamin D and cinacalcet. Particular attention should be paid to treating protein malnutrition. Fracture prophylaxis (exercise, use of walkers, dwelling modifications) are important. Hypomagnesemia is common in PD and can be treated with magnesium supplements. Vitamin K deficiency is also common and has been identified as a cause of vascular calcification. Accordingly, warfarin treatment for this age group is problematic.

CONCLUSION

While treatment principles are similar to other dialysis patient groups, physicians should be aware of the special problems of the elderly group.

Diagnosis of low bone mass in CKD-5D patients

Background and objectives: Currently, there is no consensus whether dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT) can be used to screen for osteoporosis or osteopenia in CKD-5D patients. This study uses iliac bone histology, the “gold standard” for bone volume evaluation, to determine the utility of DXA and QCT for low bone mass screening in CKD-5D patients. Patients and methods: A cross-sectional study of patients with CKD-5D employing iliac crest bone biopsies to assess bone volume by histology and comparing results to bone mineral density (BMD) measurements of the hip and spine by DXA and QCT. Pearson’s correlation, linear regression, and receiver operating characteristics curve analyses were performed. Results: 46 patients (mean age 51 years, 52% women, median dialysis vintage 46 months) had bone biopsies, DXA, and QCT scans. 37 patients (80%) had low bone volume by histology. DXA and QCT BMD values (g/cm²) were very highly correlated at the femoral neck (ρ = 0.97) and total hip (ρ = 0.97), and to a lesser degree at the spine (ρ = 0.65). DXA and QCT t-scores were also highly correlated, but QCT t-scores were systematically greater than DXA t-scores (1.1 S.D. on average at the femoral neck) leading to less recognition of osteopenia and osteoporosis by QCT. A t-score below –1 by DXA at the femoral neck (i.e., osteopenic or osteoporotic) showed 83% sensitivity and 78% specificity relative to low bone volume by histology. A QCT t-score below –1 did not reach acceptable diagnostic levels of sensitivity and specificity. Conclusions: DXA and QCT provide nearly identical areal BMD measures at the hip. However, QCT t-scores are consistently higher than DXA t-scores resulting in less diagnosis of osteoporosis or osteopenia. DXA results showed acceptable diagnostic sensitivity and specificity for low bone volume by histology and can be used for diagnosis of osteopenia and osteoporosis in patients with CKD-5D.

Geovariation in Fracture Risk among Patients Receiving Hemodialysis

BACKGROUND AND OBJECTIVES

Fractures are a major source of morbidity and mortality in patients receiving dialysis. We sought to determine whether rates of fractures and tendon ruptures vary geographically.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the US Renal Data System were used to create four yearly cohorts, 2007-2010, including all eligible prevalent patients on hemodialysis in the United States on January 1 of each year. A secondary analysis comprising patients in a large dialysis organization conducted over the same period permitted inclusion of patient-level markers of mineral metabolism. Patients were grouped into 10 regions designated by the Centers for Medicare and Medicaid Services and divided by latitude into one of three bands: south, <35°; middle, 35° to <40°; and north, ≥40°. Poisson regression was used to calculate unadjusted and adjusted region-level rate ratios for events.

RESULTS

Overall, 327,615 patients on hemodialysis were included. Mean (SD) age was 61.8 (15.0) years old, 52.7% were white, and 55.0% were men. During 716,962 person-years of follow-up, 44,014 fractures and tendon ruptures occurred, the latter being only 0.3% of overall events. Event rates ranged from 5.36 to 7.83 per 100 person-years, a 1.5-fold rate difference across regions. Unadjusted region-level rate ratios varied from 0.83 (95% confidence interval, 0.81 to 0.85) to 1.20 (95% confidence interval, 1.18 to 1.23), a 1.45-fold rate difference. After adjustment for a wide range of case mix variables, a 1.33-fold variation in rates remained. Rates were higher in north and middle bands than the south (north rate ratio, 1.18; 95% confidence interval, 1.13 to 1.23; middle rate ratio, 1.13; 95% confidence interval, 1.10 to 1.17). Latitude explained 11% of variation, independent of region. A complementary analysis of 87,013 patients from a large dialysis organization further adjusted for circulating mineral metabolic parameters and protein energy wasting yielded similar results.

CONCLUSIONS

Rates of fractures vary geographically in the United States dialysis population, even after adjustment for known patient characteristics. Latitude seems to contribute to this phenomenon, but additional analyses exploring whether other factors might influence variation are warranted.

Relationship between Fetuin A, Vascular Calcification and Fracture Risk in Dialysis Patients

Background

Fractures are a common morbidity that lead to worse outcomes in dialysis patients. Fetuin A inhibits vascular calcification (VC), potentially promotes bone mineralization and its level positively correlates with bone mineral density in the general population. On the other hand, the presence of VC is associated with low bone volume in dialysis patients. Whether the fetuin A level and VC can predict the occurrence of fractures in dialysis patients remains unknown.

Methods

We performed this prospective, observational cohort study including 685 dialysis patients (629 hemodialysis and 56 peritoneal dialysis) from a single center in Taiwan for a median follow-up period of 3.4 years. The baseline fetuin A level and status of presence of aortic arch calcification (VC) and incidence of major fractures (hip, pelvis, humerus, proximal forearm, lower leg or vertebrae) were assessed using adjusted Cox proportional hazards models, recursive partitioning analysis and competing risk models.

Results

Overall, 177 of the patients had major fractures. The incidence rate of major fractures was 3.29 per 100 person-years. In adjusted analyses, the patients with higher baseline fetuin A levels had a lower incidence of fractures (adjusted hazard ratio (HR), 0.3; 95% CI, 0.18‒0.5, fetuin A tertile 3 vs. tertile 1 and HR, 0.52; 95% CI, 0.34‒0.78, tertile 2 vs. tertile 1). The presence of aortic arch calcification (VC) independently predicted the occurrence of fractures (adjusted HR, 1.95; 95% CI, 1.34‒2.84) as well. When accounting for death as an event in competing risk models, the patients with higher baseline fetuin A levels remained to have a lower incidence of fractures (SHR, 0.31; 95% CI, 0.17‒0.56, fetuin A tertile 3 vs. tertile 1 and 0.51; 95% CI, 0.32‒0.81, tertile 2 vs. tertile 1).

Interpretations

Lower baseline fetuin A levels and the presence of VC were independently linked to higher risk of incident fractures in prevalent dialysis patients.

Clinical usefulness of bone turnover marker concentrations in osteoporosis

Current evidence continues to support the potential for bone turnover markers (BTM) to provide clinically useful information particularly for monitoring the efficacy of osteoporosis treatment. Many of the limitations identified earlier remain, principally in regard to the relationship between BTM and incident fractures. Important data are now available on reference interval values for CTX and PINP across a range of geographic regions and for individual clinical assays. An apparent lack of comparability between current clinical assays for CTX has become evident indicating the possible limitations of combining such data for meta-analyses. Harmonization of units for reporting serum/plasma CTX (ng/L) and PINP (μg/L) is recommended. The development of international collaborations continues with an important initiative to combine BTM results from clinical trials in osteoporosis in a meta-analysis and an assay harmonization program are likely to be beneficial. It is possible that knowledge derived from clinical studies can further enhance fracture risk estimation tools with inclusion of BTM together with other independent risk factors. Further data of the relationships between the clinical assays for CTX and PINP as well as physiological and pre-analytical factors contributing to variability in BTM concentrations are required.