Fracture risk and mortality post-kidney transplantation

Vertebral fractures in patients with CKD and the general population: a call for diagnosis and action

Vertebral fractures (VFs) are the most common osteoporotic fractures in the general population, and they have been associated with high mortality, decreased quality of life, and high risk of subsequent fractures, especially when recent, multiple, or severe. Currently, VF diagnosis and classification determine fracture risk and the most appropriate anti-osteoporotic treatment. However, VFs are clearly underdiagnosed, especially in patients with chronic kidney disease (CKD), and CKD-associated osteoporosis has been disregarded until recently. VFs are associated with higher morbidity and mortality, and their prevalence and incidence differ depending on the grade of renal dysfunction (CKD G1-G5) and/or the type of renal replacement therapy (dialysis or transplantation). In addition to classical risk factors [such as higher age, female sex, reduced bone mineral density, diabetes and steroid use], various other factors have been associated with an increased risk of VFs in CKD, including CKD grade, haemodialysis vintage, time since renal transplantation, low or high intact parathyroid hormone and phosphate levels, and/or vitamin D and K1 deficiencies. Importantly, several clinical societies have recently modified their algorithms according to the fracture risk classification (including the presence of VFs) and determined the most appropriate anti-osteoporotic treatment for the general population. However, there are no specific guidelines addressing this topic in patients with CKD despite an important paradigm shift regarding the prognostic value of bone mineral density in 2017 after the publication of the CKD-Mineral and Bone Disorder Kidney Disease: Improving Global Outcomes guidelines. A proactive attitude towards diagnosis, treatment, and research is proposed to avoid therapeutic nihilism.

Association of physical activity with fractures in kidney transplant recipients: A Korean nationwide cohort study

Kidney transplant recipients are at high risk for fractures, primarily due to post-transplant bone disease. This retrospective cohort study analyzed data from the Korean National Health Insurance Service, including 10 083 kidney transplant recipients examined from 2009 to 2017. We assessed fracture incidence, emphasizing vertebral and hip fractures, and the association of physical activity and traditional risk factors with fracture risk. Kidney transplant recipients were categorized into three groups according to physical activity levels: non-activity, metabolic equivalent of task (MET) 1-499, and MET ≥500. Physical activity was associated with a decreased risk of all types of fractures: any (MET 1-499: adjusted hazard ratio (aHR) .75; 95% confidence interval (CI) .62-.92, MET ≥500: aHR .84; 95% CI .70-1.00), vertebral (MET 1-499: aHR .69; 95% CI .49-.98, MET ≥500: aHR .67; 95% CI .49-.91), and hip (MET 1-499: aHR .43; 95% CI .23-.81) fractures. Additionally, older age, female sex, and diabetes were associated with an increased fracture risk. The assessment of physical activity and traditional risk factors could improve fracture risk prediction. Our findings emphasize the need for further research to establish optimal physical activity recommendations for fracture prevention in kidney transplant recipients.

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%.

Kidney Transplantation, Immunosuppression and the Risk of Fracture: Clinical and Economic Implications

Rationale & Objective

Disorders of bone and mineral metabolism frequently develop with advanced kidney disease, may be exacerbated by immunosuppression after kidney transplantation, and increase the risk of fractures.

Study Design

Retrospective database study.

Setting & Participants

Kidney-only transplant recipients aged ≥18 years from 2005 to 2016 in the United States captured in US Renal Data System records, which integrate Organ Procurement and Transplantation Network/United Network for Organ Sharing records with Medicare billing claims.

Exposures

Various immunosuppression regimens in the first 3 months after kidney transplantation.

Outcomes

The development of fractures, as ascertained using diagnostic codes on Medicare billing claims.

Analytical Approach

We used multivariable Cox regression with inverse propensity weighting to compare the incidence of fractures >3 months-to-3 years after kidney transplantation associated with various immunosuppression regimens compared to a reference regimen of antithymocyte globulin (TMG) or alemtuzumab (ALEM) with tacrolimus + mycophenolic acid + prednisone using inverse probability treatment weighting.

Results

Overall, fractures were identified in 7.5% of kidney transplant recipients (women, 8.8%; men, 6.7%; age < 55 years, 5.9%; age ≥ 55 years, 9.3%). In time-varying regression, experiencing a fracture was associated with a substantially increased risk of subsequent death within 3 months (adjusted hazard ratio [aHR], 3.06; 95% confidence interval [CI], 2.45-3.81). Fractures were also associated with increased Medicare spending (first year: $5,122; second year: $10,890; third year: $11,083; [P < 0.001]). Induction with TMG or ALEM and the avoidance or early withdrawal of steroids significantly reduced the risk of fractures in younger (aHR, 0.63; 95% CI, 0.54-0.73) and older (aHR, 0.83; 95% CI, 0.74-0.94) patients. The avoidance or early withdrawal of steroids with any induction was associated with a reduced risk of fractures in women.

Limitations

This was a retrospective study which lacked data on immunosuppression levels.

Conclusions

Fractures after kidney transplantation are associated with significantly increased mortality risk and costs. The early avoidance or early withdrawal of steroids after induction with TMG or ALEM reduces the risk of fractures after kidney transplantation and should be considered for patients at high-risk of this complication, including older adults and women.

Cholecalciferol Supplementation Attenuates Bone Loss in Incident Kidney Transplant Recipients: A Prespecified Secondary Endpoint Analysis of a Randomized Controlled Trial

Vitamin D deficiency, persistent hyperparathyroidism, and bone loss are common after kidney transplantation (KTx). However, limited evidence exists regarding the effects of cholecalciferol supplementation on parathyroid hormone (PTH) and bone loss after KTx. In this prespecified secondary endpoint analysis of a randomized controlled trial, we evaluated changes in PTH, bone metabolic markers, and bone mineral density (BMD). At 1 month post-transplant, we randomized 193 patients to an 11-month intervention with cholecalciferol (4000 IU/d) or placebo. The median baseline 25-hydroxyvitamin D (25[OH]D) level was 10 ng/mL and 44% of participants had osteopenia or osteoporosis. At the end of the study, the median 25(OH)D level was increased to 40 ng/mL in the cholecalciferol group and substantially unchanged in the placebo group. Compared with placebo, cholecalciferol significantly reduced whole PTH concentrations (between-group difference of -15%; 95% confidence interval [CI] -25 to -3), with greater treatment effects in subgroups with lower 25(OH)D, lower serum calcium, or higher estimated glomerular filtration rate (p_int  < 0.05). The percent change in lumbar spine (LS) BMD from before KTx to 12 months post-transplant was -0.2% (95% CI -1.4 to 0.9) in the cholecalciferol group and -1.9% (95% CI -3.0 to -0.8) in the placebo group, with a significant between-group difference (1.7%; 95% CI 0.1 to 3.3). The beneficial effect of cholecalciferol on LS BMD was prominent in patients with low bone mass p_int  < 0.05). Changes in serum calcium, phosphate, bone metabolic markers, and BMD at the distal radius were not different between groups. In mediation analyses, change in whole PTH levels explained 39% of treatment effects on BMD change. In conclusion, 4000 IU/d cholecalciferol significantly reduced PTH levels and attenuated LS BMD loss after KTx. This regimen has the potential to eliminate vitamin D deficiency and provides beneficial effects on bone health even under glucocorticoid treatment. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Diabetes increases the risk of bone fractures in patients on kidney replacement therapy: A Danish national cohort study

BACKGROUND

Patients treated with dialysis or living with a kidney transplant (kidney replacement therapy, KRT) have an increased risk of bone fracture. Patients with diabetes also have an increased risk of fracture. The aim of this study was to investigate whether the presence of diabetes in patients on KRT aggravates the risk of fracture.

METHODS

Nationwide Danish registries were used in this retrospective cohort study. All prevalent adult patients on hemodialysis (HD) or peritoneal dialysis (PD) on 1st of January 2000 and all incident patients starting KRT (HD, PD, kidney transplanted (KTX)) until 31st of December 2011 were included in the KRT group. Adult persons not on KRT and without diabetes on 1st of January 2000 were used as a reference group. Patients were separated in groups with and without (+/-) diabetes. They were followed until first fracture, emigration, death, or end-of-study on 31st of December 2016.

RESULTS

A total of 4,074,085 not on KRT +/- diabetes and 9053 patients on KRT +/- diabetes were included. Comparing the different groups with diabetes to the corresponding group without diabetes, the unadjusted HR (95% CI) for any first fracture were 1.2 (1.0-1.3) in the HD population, 1.4 (1.1-1.7) in the PD population, and 1.7 (1.4-2.2) in the KTX population. Further adjustments for age, sex, prior fractures, comorbidity and medication did not change these results significantly.

CONCLUSIONS

Diabetes increases the risk of fracture in patients on KRT.

Health claims databases used for kidney research around the world

Health claims databases offer opportunities for studies on large populations of patients with kidney disease and health outcomes in a non-experimental setting. Among others, their unique features enable studies on healthcare costs or on longitudinal, epidemiological data with nationwide coverage. However, health claims databases also have several limitations. Because clinical data and information on renal function are often lacking, the identification of patients with kidney disease depends on the actual presence of diagnosis codes only. Investigating the validity of these data is therefore crucial to assess whether outcomes derived from health claims data are truly meaningful. Also, one should take into account the coverage and content of a health claims database, especially when making international comparisons. In this article, an overview is provided of international health claims databases and their main publications in the area of nephrology. The structure and contents of the Dutch health claims database will be described, as well as an initiative to use the outcomes for research and the development of the Dutch Kidney Atlas. Finally, we will discuss to what extent one might be able to identify patients with kidney disease using health claims databases, as well as their strengths and limitations.

Understanding Bone Disease in Patients with Diabetic Kidney Disease: a Narrative Review

PURPOSE OF REVIEW

Both diabetes and kidney disease associate with the development of bone disease and an increased risk of fragility fractures. The etiologies of bone disease in patients with diabetic kidney disease (DKD) are multiple and complex. This review explores the association between DKD and bone disease and discusses how the presence of both diabetes and kidney disease may impair bone quality and increase fracture risk. Diagnostic tools as well as future research areas are also discussed.

RECENT FINDINGS

Patients with DKD have an increased risk of fragility fracture, most pronounced in patients with type 1 diabetes, and in DKD a high prevalence of adynamic bone disease is found. Recent studies have demonstrated disturbances in the interplay between bone regulating factors in DKD, such as relative hypoparathyroidism and alterations of bone-derived hormones including fibroblast growth factor-23 (FGF-23), sclerostin and klotho, which lead to bone disease. This review examines the current knowledge on bone disease in patients with DKD, clinical considerations for patient care, as well as subjects for future research.

Fractures after kidney transplantation: Incidence, predictors, and association with mortality

BACKGROUND

Major fractures (MF) are associated with increased mortality in the general population and represent an even higher risk in patients with chronic kidney disease. We investigated incidence, predictors and clinical outcomes associated with first MF (MF_first) following kidney transplantation (KT).

METHODS

We used the Swedish National Renal Registry of 3992 first KT recipients (2005-2016) (median age 53 years, 65% men) and identified all MF_first in hip, spine, humerus and forearm following KT. We estimated incidence rates and predictors of MF_first using flexible parametric hazard models and Fine-Gray analysis accounting for competing risk of death, and risk of all-cause mortality following MF_first using Cox proportional hazards models with fracture as time-varying exposure.

RESULTS

During median follow-up of 4.8 years (IQR 2.2-7.9 years), there were 279 fractures of which 139 were forearm fractures. The crude incidence rate of MF_first (n = 279) was 13.5/1000 patient-years and that of hip fractures (n = 69) 3.4/1000 patient-years. The multivariate-adjusted fracture incidence rates were highest during the first 6 months following KT, and 86% higher in women than in men. High age, female sex, previous history of MF, diabetes nephropathy, pretransplant dialysis therapy and acute rejection were associated with increased risk for MF_first, whereas pre-emptive KT was associated with lower risk of MF_first. Spline curves showed markedly higher impact of higher age on risk of MF_first in women than in men. MF_first (n = 279) independently predicted increased all-cause mortality risk (hazard ratio, HR, 1.78(95%CI 1.35-2.36)). Among MF_first, with humerus fracture as reference, hip fracture (HR, 4.68(95%CI 1.56-14.06)) and spine fracture (HR, 4.02(95%CI 1.19-13.54)), but not forearm fracture (HR, 1.17 (95%CI 0.38-3.53)), were associated with increased all-cause mortality risk.

CONCLUSIONS

The initial 6 months following kidney transplantation is a high-risk period for MF. Among MF, hip fracture and spine fracture associate with substantially increased all-cause mortality risk.

Perioperative Dexmedetomidine Improves Outcomes of Kidney Transplant

Graft function is crucial for successful kidney transplantation. Many factors may affect graft function or cause delayed graft function (DGF), which decreases the prognosis for graft survival. This study was designed to evaluate whether the perioperative use of dexmedetomidine (Dex) could improve the incidence of function of graft kidney and complications after kidney transplantation. A total of 780 patients underwent kidney transplantations, 315 received intravenous Dex infusion during surgery, and 465 did not. Data were adjusted with propensity scores and multivariate logistic regression was used. The primary outcomes are major adverse complications, including DGF and acute rejection in the early post‐transplantation phase. The secondary outcomes included length of hospital stay (LOS), infection, overall complication, graft functional status, post‐transplantation serum creatinine values, and estimated glomerular filtration rate (eGFR). Dex use significantly decreased DGF (19.37% vs. 23.66%; adjusted odds ratio, 0.744; 95% confidence interval, 0.564–0.981; P = 0.036), risk of infection, risk of acute rejection in the early post‐transplantation phase, the risk of overall complications, and LOS. However, there were no statistical differences in 90‐day graft functional status or 7‐day, 30‐day, and 90‐day eGFR. Perioperative Dex use reduced incidence of DGF, risk of infection, risk of acute rejection, overall complications, and LOS in patients who underwent kidney transplantation.

Fractures and Subsequent Graft Loss and Mortality among Older Kidney Transplant Recipients

OBJECTIVES

Older adults who undergo kidney transplantation (KT) are living longer with a functioning graft and are at risk for age-related adverse events including fractures. Understanding recipient, transplant, and donor factors and the outcomes associated with fractures may help identify older KT recipients at increased risk. We determined incidence of hip, vertebral, and extremity fractures; assessed factors associated with incident fractures; and estimated associations between fractures and subsequent death-censored graft loss (DCGL) and mortality.

DESIGN

This was a prospective cohort study of patients who underwent their first KT between January 1, 1999, and December 31, 2014.

SETTING

We linked data from the Scientific Registry of Transplant Recipients to Medicare claims through the US Renal Data System.

PARTICIPANTS

The analytic population included 47 815 KT recipients aged 55 years or older.

MEASUREMENTS

We assessed the cumulative incidence of and factors associated with post-KT fractures (hip, vertebral, or extremity) using competing risks models. We estimated risk of DCGL and mortality after fracture using adjusted Cox proportional hazards models.

RESULTS

The 5-year incidence of post-KT hip, vertebral, and extremity fracture for those aged 65 to 69 years was 2.2%, 1.0%, and 1.7%, respectively. Increasing age was associated with higher hip (adjusted hazard ratio [aHR] = 1.37 per 5-y increase; 95% confidence interval [CI] = 1.30-1.45) and vertebral (aHR = 1.31; 95% CI = 1.20-1.42) but not extremity (aHR = .97; 95% CI = .91-1.04) fracture risk. DCGL risk was higher after hip (aHR = 1.34; 95% CI = 1.12-1.60) and extremity (aHR = 1.30; 95% CI = 1.08-1.57) fracture. Mortality risk was higher after hip (aHR = 2.31; 95% CI = 2.11-2.52), vertebral (aHR = 2.80; 95% CI = 2.44-3.21), and extremity (aHR = 1.85; 95% CI = 1.64-2.10) fracture.

CONCLUSION

Our findings suggest that older KT recipients are at higher risk for hip and vertebral fracture but not extremity fracture; and those with hip, vertebral, or extremity fracture are more likely to experience subsequent graft loss or mortality. These findings underscore that different fracture types may have different underlying etiologies and risks, and they should be approached accordingly. J Am Geriatr Soc 67:1680-1688, 2019.

Association between malnutrition-inflammation score and risk of subsequent self-reported bone fractures in prevalent kidney transplant recipients

Chronic inflammation and protein energy wasting (PEW) syndrome are common in kidney transplant recipients (KTR). The presence of inflammation and PEW syndrome can directly affect bone resorption and bone formation, leading to bone loss and fractures. We showed PEW is independently associated with new clinically detected bone fractures in prevalent KTR.

INTRODUCTION

Kidney transplant recipients (KTR) have a 4-fold higher risk of fracture compared to the general population. Chronic inflammation and PEW syndrome are common in KTR and are associated with poor outcomes. We hypothesized that the Malnutrition-Inflammation Score (MIS), a validated measure of PEW, is associated with higher risk of bone fractures in KTR.

METHODS

This prospective cohort study included 839 prevalent KTR from a Central European academic center. MIS, a semiquantitative instrument of PEW, was calculated at the study entry. Self-reported history of fractures was recorded during the 2-year follow-up period. The association between MIS and bone fractures was examined in logistic regression analyses with adjustment for age, gender, eGFR, smoking habits, history of pre-transplant bone fractures, and acute rejection.

RESULTS

Mean age was 51 ± 13 years, and 56% of patients were males with median (interquartile range) transplant vintage 69 (38-112) months, estimated glomerular filtration rate 55 ± 21 ml/min/1.73 m², and calculated MIS 3 (2-4) at enrollment. Fifty-five (7%) patients experienced self-reported bone fractures during the 2-year follow-up period. Higher MIS score showed linear association with increased risk of fracture. Each one-point higher MIS was associated with 23% higher risk of bone fractures (odds ratio (OR) and 95% CI 1.23, 1.12-1.34), which remained significant after multivariable adjustments (OR 1.17, 95% CI 1.06-1.29).

CONCLUSION

The MIS is independently associated with new clinically detected bone fractures in prevalent KTR.

Fracture Risk in Dialysis and Kidney Transplanted Patients: A Systematic Review

Chronic kidney disease is associated with an increased risk of fracture and cardiovascular mortality. The risk of fracture in hemodialysis (HD), peritoneal dialysis (PD) and kidney transplant (KT) patients is higher when compared with the general population. However, there exists a knowledge gap concerning which group has the highest risk of fracture. We aimed to compare the risk of fracture in HD, PD, and KT populations. We conducted a systematic review of observational studies evaluating the risk of fracture in HD, PD, or KT patients. Eligible studies were searched using MEDLINE, Embase, Web of Science, and Cochrane Library from their inception to January 2016, and in grey literature. Incidences (cumulative and rate) of fracture were described together using the median, according to fracture sites, the data source (administrative database or cohort and clinical registry), and fracture diagnosis method. Prevalence estimates were described separately. We included 47 studies evaluating the risk of fracture in HD, PD, and KT populations. In administrative database studies, incidence of hip fracture in HD (median 11.45 per 1000 person-years [p-y]), range: 9.3 to 13.6 was higher than in KT (median 2.6 per 1000 p-y; range 1.5 to 3.8) or in PD (median 5.2 per 1000 p-y; range 4.1 to 6.3). In dialysis (HD+PD), three studies reported a higher incidence of hip fracture than in KT. Prevalent vertebral fracture (assessed by X-rays or questionnaire) reported in HD was in a similar range as that reported in KT. Incidence of overall fracture was similar in HD and KT, from administrative databases studies, but lower in HD compared with KT, from cohorts or clinical registry studies. This systematic review suggests an important difference in fracture risk between HD, PD, and KT population, which vary according to the diagnosis method for fracture identification. © 2018 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Mineral and Bone Disease in Kidney Transplant Recipients

PURPOSE OF REVIEW

Despite metabolic improvements following kidney transplantation, transplant recipients still often suffer from complex mineral and bone disease after transplantation.

RECENT FINDINGS

The pathophysiology of post-transplant disease is unique, secondary to underlying pre-transplant mineral and bone disease, immunosuppression, and changing kidney function. Changes in modern immunosuppression regimens continue to alter the clinical picture. Modern management includes reducing cumulative steroid exposure and correcting the biochemical abnormalities in mineral metabolism. While bone mineral density screening appears to help predict fracture risk and anti-osteoporotic therapy appears to have a positive effect on bone mineral density, more data regarding specific treatment is necessary. Patients with mineral and bone disease after kidney transplantation require special care in order to properly manage and mitigate their mineral and bone disease. Recent changes in clinical management of transplant patients may also be changing the implications on patients' mineral and bone disease.

Risk of hip fracture in patients on dialysis or kidney transplant: a meta-analysis of 14 cohort studies

Purpose

We aimed to conduct a meta-analysis of published cohort studies to evaluate the risk of hip fracture in patients undergoing dialysis or kidney transplantation (KT).

Methods

We identified relevant studies by searching PubMed, EMBASE and Google Scholar databases from their inception to December 31, 2017. Cohort studies evaluating risk of hip fractures in patients undergoing dialysis or KT were considered included. The methodological quality of the cohort studies was assessed using the modified Newcastle-Ottawa scale.

Results

In our meta-analysis of 14 retrospective cohort studies, a total of more than 1.5 million patients undergoing dialysis or KT were included, of whom more than 30,000 had hip fractures. After the merger, the proportion of hip fractures was 1.92% (95% CI, 1.38%−2.46%) with significant heterogeneity (I²=99.9%, P=0.000) in all patients, and the incidence rate of hip fractures (per 1,000 person-years) was 8.95 (95% CI, 4.05–13.85) with significant heterogeneity (I²=99.9%, P=0.000). The pooled relative risks (RR) value for dialysis patients compared with the general population were 6.35 (95% CI, 4.53–8.88) for male and 5.57 (95% CI, 4.44–6.99) for female. The pooled RR value for hemodialysis (HD) patients compared with peritoneal dialysis (PD) patients was 1.39 (95% CI, 1.13–1.70) with no heterogeneity (I²=0.0%, P=0.763).

Conclusion

In conclusion, the present meta-analysis reveals that about 2% of dialysis or KT patients go on to sustain a hip fracture during follow-up, with the overall hip fracture incidence rates being 8.95 per 1,000 person-years. The overall risk of hip fracture was more than 5-fold higher in dialysis patients than in the general population. Among patients on PD, HD, and KT, HD and KT patients had the highest and the lowest risk of hip fractures, respectively.

Fractures in Kidney Transplant Recipients: A Comparative Study Between England and New York State

OBJECTIVES

Fractures are associated with high morbidity and are a major concern for kidney transplant recipients. No comparative analysis has yet been conducted between countries in the contemporary era to inform future international prevention trials.

MATERIALS AND METHODS

Data were obtained from the Hospital Episode Statistics and the Statewide Planning and Research Cooperative databases on all adult kidney transplants performed in England and New York State from 2003 to 2013, respectively, and on posttransplant fracture-related hospitalization from 2003 to 2014.

RESULTS

Our analysis included 18 493 English and 11 602 New York State kidney transplant recipients. Overall, 637 English recipients (3.4%) and 398 New York State recipients (3.4%) sustained a fracture, giving an unadjusted event rate of 7.0 and 5.9 per 1000 years, respectively (P = .948). Of these, 147 English (0.8%) and 101 New York State recipients (0.9%) sustained a hip fracture, giving an unadjusted event rate of 1.6 and 1.5 per 1000 years, respectively (P = .480). There were no differences in the cumulative incidence of all fractures or hip fractures. One-year mortality rates after any fracture (9% and 11%) or after a hip fracture (15% and 17%) were not different between cohorts.

CONCLUSIONS

Contemporaneous English and New York State kidney transplant recipients have similar fracture rates and mortality rates postfracture.

Advances in the evaluation of bone health in kidney transplant patients

Bone disease related to chronic kidney disease and, particularly, to kidney transplant patients is a common cause or morbidity and mortality, especially due to a higher risk of osteoporotic fractures. Despite the fact that this has been known for decades, to date, an appropriate diagnostic strategy has yet to be established. Apart from bone biopsy, which is invasive and scarcely used, no other technique is available to accurately establish the risk of fracture in kidney patients. Techniques applied to the general population, such as bone densitometry, have not been subjected to sufficient external validation and their use is not systematic. This means that the identification of patients at risk of fracture and therefore those who are candidates for preventive strategies is an unmet need. Bone strength, defined as the ability of the bone to resist fracture, is determined by bone mineral density (measured by bone densitometry), trabecular architecture and bone tissue quality. The trabecular bone score estimates bone microarchitecture, and low values have been described as an independent predictor of increased fracture risk. Bone microindentation is a minimally invasive technique that measures resistance of the bone to micro-cracks (microscopic separation of mineralised collagen fibres), and therefore bone tissue biomechanical properties. The superiority over bone densitometry of the correlation between the parameters measured by trabecular bone score and microindentation with the risk of fracture in diverse populations led us to test its feasibility in chronic kidney disease and kidney transplant patients.

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.

Proton Pump Inhibitor Use and Risk of Hip Fracture in Kidney Transplant Recipients

BACKGROUND

Posttransplantation bone disease is a significant problem, with few well-evidenced therapeutic options. Proton pump inhibitors (PPIs) are associated with hip fracture in the general population and are widely prescribed for kidney transplant recipients.

STUDY DESIGN

A case-control study.

SETTING & PARTICIPANTS

From the US Renal Data System, we identified from diagnoses and procedures 231 kidney transplant recipients with a first hip fracture. Cases were matched at the hip fracture index date with 15,575 controls on age, sex, race, and transplantation year.

PREDICTOR

PPI use.

OUTCOMES

First hip fracture.

RESULTS

In the year prior to the index date, a PPI was prescribed to 65.4% of cases and 57.4% of controls. Additionally, in 34.6% of cases and 28.9% of controls, a PPI was prescribed for >80% of the year preceding the index date (higher PPI users). Unadjusted ORs of hip fracture associated with any and higher PPI use were 1.55 (95% CI, 1.18-2.05) and 1.65 (95% CI, 1.2-2.27), respectively. When adjusted for baseline demographic, clinical, and pharmacologic covariables, any and higher PPI use remained associated with hip fracture, with ORs of 1.39 (95% CI, 1.04-1.84) and 1.41 (95% CI, 1.02-1.95), respectively.

LIMITATIONS

Potential residual confounding through either incorrectly ascertained or unavailable confounders; cohort limited to Medicare beneficiaries receiving low-income subsidy.

CONCLUSIONS

In summary, PPI use was associated with hip fracture risk in the US kidney transplant population.

Bone Disease after Kidney Transplantation

Bone and mineral disorders occur frequently in kidney transplant recipients and are associated with a high risk of fracture, morbidity, and mortality. There is a broad spectrum of often overlapping bone diseases seen after transplantation, including osteoporosis as well as persisting high- or low-turnover bone disease. The pathophysiology underlying bone disorders after transplantation results from a complex interplay of factors, including preexisting renal osteodystrophy and bone loss related to a variety of causes, such as immunosuppression and alterations in the parathyroid hormone-vitamin D-fibroblast growth factor 23 axis as well as changes in mineral metabolism. Management is complex, because noninvasive tools, such as imaging and bone biomarkers, do not have sufficient sensitivity and specificity to detect these abnormalities in bone structure and function, whereas bone biopsy is not a widely available diagnostic tool. In this review, we focus on recent data that highlight improvements in our understanding of the prevalence, pathophysiology, and diagnostic and therapeutic strategies of mineral and bone disorders in kidney transplant recipients.

Risk factors for fracture in adult kidney transplant recipients

AIM: To determine the general and transplant-specific risk factors for fractures in kidney transplant recipients.

METHODS: We conducted a cohort study of all adults who received a kidney-only transplant (n = 2723) in Ontario, Canada between 2002 and 2009. We used multivariable Cox proportional hazards regression to determine general and transplant-specific risk factors for major fractures (proximal humerus, forearm, hip, and clinical vertebral). The final model was established using the backward elimination strategy, selecting risk factors with a P-value ≤ 0.2 and forcing recipient age and sex into the model. We also assessed risk factors for other fracture locations (excluding major fractures, and fractures involving the skull, hands or feet).

RESULTS: There were 132 major fractures in the follow-up (8.1 fractures per 1000 person-years). General risk factors associated with a greater risk of major fracture were older recipient age [adjusted hazard ratio (aHR) per 5-year increase 1.11, 95%CI: 1.03-1.19] and female sex (aHR = 1.81, 95%CI: 1.28-2.57). Transplant-specific risk factors associated with a greater risk of fracture included older donor age (5-year increase) (aHR = 1.09, 95%CI: 1.02-1.17) and end-stage renal disease (ESRD) caused by diabetes (aHR = 1.72, 95%CI: 1.09-2.72) or cystic kidney disease (aHR = 1.73, 95%CI: 1.08-2.78) (compared to glomerulonephritis as the reference cause). Risk factors across the two fracture locations were not consistent (major fracture locations vs other). Specifically, general risk factors associated with an increased risk of other fractures were diabetes and a fall with hospitalization prior to transplantation, while length of time on dialysis, and renal vascular disease and other causes of ESRD were the transplant-specific risk factors associated with a greater risk of other fractures.

CONCLUSION: Both general and transplant-specific risk factors were associated with a higher risk of fractures in kidney transplant recipients. Results can be used for clinical prognostication.

Efficacy and Safety of Bisphosphonates for Low Bone Mineral Density After Kidney Transplantation: A Meta-Analysis

In patients with low bone mineral density (BMD) after kidney transplantation, the role of bisphosphonates remains unclear. We performed a systematic review and meta-analysis to investigate the efficacy and safety of bisphosphonates.We retrieved trials from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception through May 2015. Only randomized controlled trials that compared bisphosphonate-treated and control groups of patients with low bone mineral density after kidney transplantation were included. The primary outcomes were the percent change in BMD, the absolute change in BMD, and the BMD at the end of study at the lumbar spine. The results were expressed as the mean difference (MD) or relative risk (RR) with the 95% confidence interval (CI). We used a random-effects model to pool the outcomes.We included 17 randomized controlled trials with 1067 patients. Only 1 included trial was found to be at low risk of bias. The rest of the included studies were found to have high to uncertain risk of bias. Compared with the control group, those who received bisphosphonates had a significant increase in percent change in BMD (mean difference [MD] = 5.51, 95% confidence interval [CI] 3.22-7.79, P < 0.00001) and absolute change in BMD (MD = 0.05, 95% CI 0.04-0.05, P < 0.00001), but a nonsignificant increase in BMD at the end of the study (MD = 0.02, 95% CI -0.01 to 0.05, P = 0.25) at the lumbar spine. Bisphosphonates resulted in a significant improvement in percent change in BMD (MD = 4.95, 95% CI 2.57-7.33, P < 0.0001), but a nonsignificant improvement in absolute change in BMD (MD = 0.03, 95% CI -0.00 to 0.06, P = 0.07) and BMD at the end of the study (MD = -0.01, 95% CI -0.04 to 0.02, P = 0.40) at the femoral neck. No significant differences were found in vertebral fractures, nonvertebral fractures, adverse events, and gastrointestinal adverse events.Bisphosphonates appear to have a beneficial effect on BMD at the lumbar spine and do not significantly decrease fracture events in recipients. However, the results should be interpreted cautiously due to the lack of robustness and the heterogeneity among studies.