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

Components of Residential Neighborhood Deprivation and Their Impact on the Likelihood of Live-Donor and Preemptive Kidney Transplantation

INTRODUCTION

Adults residing in deprived neighborhoods face various socioeconomic stressors, hindering their likelihood of receiving live-donor kidney transplantation (LDKT) and preemptive kidney transplantation (KT). We quantified the association between residential neighborhood deprivation index (NDI) and the likelihood of LDKT/preemptive KT, testing for a differential impact by race and ethnicity.

METHODS

We studied 403 937 adults (age ≥ 18) KT candidates (national transplant registry; 2006-2021). NDI and its 10 components were averaged at the ZIP-code level. Cause-specific hazards models were used to quantify the adjusted hazard ratio (aHR) of LDKT and preemptive KT across tertiles of NDI and its 10 components.

RESULTS

Candidates residing in high-deprivation neighborhoods were more likely to be female (40.1% vs. 36.2%) and Black (41.9% vs. 17.7%), and were less likely to receive both LDKT (aHR = 0.66, 95% confidence interval [CI]: 0.64-0.67) and preemptive KT (aHR = 0.60, 95% CI: 0.59-0.62) than those in low-deprivation neighborhoods. These associations differedby race and ethnicity (Black: aHRLDKT = 0.58, 95% CI: 0.55-0.62; aHRpreemptive KT = 0.68, 95% CI: 0.63-0.73; Pinteractions: LDKT < 0.001; Preemptive KT = 0.002). All deprivation components were associated with the likelihood of both LDKT and preemptive KT (except median home value): for example, higher median household income (LDKT: aHR = 1.08, 95% CI: 1.07-1.09; Preemptive KT: aHR = 1.10, 95% CI: 1.08-1.11) and educational attainments (≥high school [LDKT: aHR = 1.17, 95% CI: 1.15-1.18; Preemptive KT: aHR = 1.23, 95% CI: 1.21-1.25]).

CONCLUSION

Residence in socioeconomically deprived neighborhoods is associated with a lower likelihood of LDKT and preemptive KT, differentially impacting minority candidates. Identifying and understanding which neighborhood-level socioeconomic status contributes to these racial disparities can be instrumental in tailoring interventions to achieve health equity in LDKT and preemptive KT.

Postoperative Care and Outcomes in Solid-Organ Transplant Patients Undergoing Lower Extremity Fracture Treatment

OBJECTIVES

To determine the postoperative outcomes in solid-organ transplant (SOT) patients undergoing operative treatment of lower extremity fractures.

METHODS

DESIGN

Retrospective comparative study.

SETTING

Academic Level 1 trauma center.

PATIENT SELECTION CRITERIA

Patients who underwent SOT and operative treatment of lower extremity fracture from 2013 to 2021 were identified, excluding pathologic fractures.

OUTCOME MEASURES AND COMPARISONS

Postoperative complications, length of stay, time to death, 90-day and 1-year readmission rates, readmission causes, discharge location, and immunosuppressive regiments.

RESULTS

Sixty-one patients with an average age of 67 years (range 29-88) were included. The mortality rate was 37.7%. The average follow-up was 15.2 months (range of 2 weeks-10 years). The majority of patients (32.8%) had received a liver transplant, and femoral neck fractures constituted the largest fracture group. The average length of stay was 10 days, with the shortest being 1 day and the longest being 126 days (SD 18). The majority of patients (57.3%) were not discharged home. Only 2 suffered from a postoperative complication requiring another procedure: hardware removal and liner exchange for periprosthetic joint infection, respectively. There was a 27.9% 90-day readmission rate with 2 deaths within that period with the most common being altered mental status (29.4%), genitourinary infections (17.6%), repeat falls (11.8%), and low hemoglobin requiring transfusion (11.8%). The longest average time to death analyzed by transplant type was found among lung transplant patients (1076 days, 62.5% mortality), followed by liver transplant patients (949 days, 35.0% mortality), and then kidney transplant patients (834 days, 38.9% mortality). The shortest time to death was 71 days from index procedure.

CONCLUSIONS

Family members of SOT patients undergoing operative treatment of lower extremity fractures should be made aware of the high risk for 90-day readmission postoperatively (27.9%) and overall mortality (12.5%). Providers should be aware of the need for multidisciplinary involvement for inpatient care, monitoring postoperative complications, and facilitating discharge planning.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bone health and fracture prevention after kidney transplantation

Changes in bone health and strength are common after kidney transplantation and can lead to an increased risk of fracture. This has implications for morbidity, mortality and renal allograft survival. This review will focus on the changes that occur in bone health and fracture risk after kidney transplantation and examine the evidence available to guide diagnostic and therapeutic decisions with the aim of fracture prevention.

The comprehensive incidence and risk factors of fracture in kidney transplant recipients: A meta-analysis

AIM

Kidney transplant recipients are at high risk of fracture due to many factors such as nutritional status, hyperparathyroidism, acidosis and steroid administration. The current meta-analysis aimed to comprehensively analyse the incidence and risk factors of fracture in kidney transplant recipients.

METHODS

A systematic search on Embase, Web of Science, PubMed and Cochrane Library until November 2023 was performed. RStudio software was used to analyse data.

RESULTS

Twenty-eight eligible studies containing 310 530 kidney transplant recipients were included in the analysis. The pooled incidence of fracture was 10% (95% confidence interval [CI]: 7%-13%) generally. When divided by regions, it was further observed that the pooled incidence of fracture was 13% (95% CI: 9%-17%) in Europe, 11% (95% CI: 6%-16%) in North America, 7% (95% CI: 3%-11%) in Asia. Regarding the risk factors, pooled analysis revealed that age of recipient (hazard ratio [HR] = 1.50, 95% CI: 1.17-1.91), female sex (HR = 1.45, 95% CI: 1.36-1.53), pretransplantation diabetes (HR = 1.76, 95% CI: 1.58-1.97), pretransplantation fracture history (HR = 2.28, 95% CI: 1.86-2.78), dialysis duration (HR = 1.09, 95% CI: 1.01-1.17) and deceased donor (HR = 1.21, 95% CI: 1.05-1.39) related to higher risk of fracture. The general quality of included studies was acceptable, and no publication bias existed except for the analysis between age of recipient and fracture incidence; further trim and fill method indicated age of recipient showed a correlation trend with the fracture incidence without the statistical significance.

CONCLUSION

The pooled incidence of fracture reaches 10% in kidney transplant recipients, which relates to age of recipient, female sex, pretransplantation diabetes or fracture history, dialysis duration and decease donor.

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.

Current Status of Mineral and Bone Disorders in Transplant Recipients

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

Non-Traditional Non-Immunological Risk Factors for Kidney Allograft Loss-Opinion

Rates of late allograft loss have improved slowly in the last decades. Well described traditional risk factors that influence allograft survival include cardiovascular events, rejection, infections and post-transplant neoplasia. Here, we critically evaluate the influence of several non-immunological, non-traditional risk factors and describe their impact on allograft survival and cardiovascular health of kidney transplant recipients. We assessed the following risk factors: arterial stiffness, persistent arteriovenous access, mineral bone disease, immunosuppressive drugs residual levels variability, hypomagnesemia, glomerular pathological alterations not included in Banff criteria, persistent inflammation and metabolic acidosis.

Time-Varying Risk Factors for Incident Fractures in Kidney Transplant Recipients: A Nationwide Cohort Study in South Korea

Little is known about the time-varying risk factors for fractures in kidney transplant recipients (KTRs). Using the Korea Organ Transplantation Registry, a nationwide cohort study of KTRs, the incidence, locations, and time-varying predictors of fractures were analyzed, including at baseline and post-transplant 6-month variables in KTRs who underwent KT between January 2014 and June 2019. Among 4134 KTRs, with a median follow-up of 2.94 years (12,441.04 person-years), 63 patients developed fractures. The cumulative 5-year incidence was 2.10%. The most frequent locations were leg (25.40%) and foot/ankle (22.22%). In multivariable analysis, older recipient age at baseline (hazard ratio [HR], 1.035; 95% confidence interval [CI], 1.007–1.064; p = 0.013) and higher tacrolimus trough level (HR, 1.112; 95% CI, 1.029–1.202; p = 0.029) were associated with higher risks for fractures. Pretransplant diabetes mellitus had a time-dependent impact on fractures, with increasing risk as time elapses (HR for diabetes mellitus 1.115; 95% CI, 0.439–2.832; HR for diabetes mellitus × time, 1.049; 95% CI, 1.007–1.094; p = 0.022). In conclusion, KTRs had a high risk of peripheral skeletal fractures in the first 5 years. At baseline recipient age, pretransplant diabetes mellitus and tacrolimus trough level after KT were responsible for the fractures in KTRs.

Risk Factors for First and Recurrent Fractures among Kidney Transplant Recipients

Introduction: Kidney transplantation is associated with increased risk of bone fracture. Current literature reports widely variable fracture burden and contains limited data on risk factors for recurrent fractures. Methods: The incidence of all and major osteoporotic fractures (hip, forearm, thoracolumbar, and proximal humerus) were assessed. The risk factors for first and recurrent fractures among 1285 Canadian kidney transplant recipients transplanted between January 1, 2004, and December 31, 2013 were also identified. Results: The 10-year cumulative incidence of all fractures and major osteoporotic fractures in this population was 27.1% (95% CI: 22.5, 32.4) and 17.8% (95% CI: 13.4, 23.5), respectively. On multivariable analysis, female sex (HR = 1.64 [95% CI: 1.20, 2.26]), history of fracture (HR = 1.54 [95% CI: 1.12, 2.11]), and pretransplant diabetes (HR = 1.85 [95% CI: 1.29, 2.65]) were recipient factors found to increase the risk for any first fracture posttransplant. These risk factors persist in analysis with the time origin 3-months posttransplant, where transplant age (HR = 1.01 [95% CI: 1.00, 1.03]) and increased time on pretransplant dialysis (HR = 1.06 [95% CI: 1.00, 1.12]) also emerge as risk factors for first fracture. On multivariable shared frailty model analysis, increased risk of recurrent fractures was associated with recipient female sex (HR = 1.74 [95% CI: 1.21, 2.51]) and history of diabetes (HR = 1.76 [95% CI: 1.17, 2.66]). Discussion: The results suggested that some risk factors for first fracture may not inform risk of recurrent fractures. As such, fracture risk should be assessed accordingly to optimize long-term care and implement preventive measures.

Risk factors for graft loss and death among kidney transplant recipients: A competing risk analysis

INTRODUCTION

Kidney transplantation is the best therapeutical option for CKD patients. Graft loss risk factors are usually estimated with the cox method. Competing risk analysis could be useful to determine the impact of different events affecting graft survival, the occurrence of an outcome of interest can be precluded by another. We aimed to determine the risk factors for graft loss in the presence of mortality as a competing event.

METHODS

A retrospective cohort of 1454 kidney transplant recipients who were transplanted between July 1, 2008, to May 31, 2019, in Colombiana de Trasplantes, were analyzed to determine risk factors of graft loss and mortality at 5 years post-transplantation. Kidney and patient survival probabilities were estimated by the competing risk analysis. The Fine and Gray method was used to fit a multivariable model for each outcome. Three variable selection methods were compared, and the bootstrapping technique was used for internal validation as split method for resample. The performance of the final model was assessed calculating the prediction error, brier score, c-index and calibration plot.

RESULTS

Graft loss occurred in 169 patients (11.6%) and death in 137 (9.4%). Cumulative incidence for graft loss and death was 15.8% and 13.8% respectively. In a multivariable analysis, we found that BKV nephropathy, serum creatinine and increased number of renal biopsies were significant risk factors for graft loss. On the other hand, recipient age, acute cellular rejection, CMV disease were risk factors for death, and recipients with living donor had better survival compared to deceased-donor transplant and coronary stent. The c-index were 0.6 and 0.72 for graft loss and death model respectively.

CONCLUSION

We developed two prediction models for graft loss and death 5 years post-transplantation by a unique transplant program in Colombia. Using a competing risk multivariable analysis, we were able to identify 3 significant risk factors for graft loss and 5 significant risk factors for death. This contributes to have a better understanding of risk factors for graft loss in a Latin-American population. The predictive performance of the models was mild.

Natural History of Bone Disease following Kidney Transplantation

BACKGROUND

Knowledge of the effect of kidney transplantation on bone is limited and fragmentary. The aim of this study was to characterize the evolution of bone disease in the first post-transplant year.

METHODS

We performed a prospective, observational cohort study in patients referred for kidney transplantation under a steroid-sparing immunosuppressive protocol. Bone phenotyping was done before, or at the time of, kidney transplantation, and repeated at 12 months post-transplant. The phenotyping included bone histomorphometry, bone densitometry by dual-energy x-ray absorptiometry, and biochemical parameters of bone and mineral metabolism.

RESULTS

Paired data were obtained for 97 patients (median age 55 years; 72% male; 21% of patients had diabetes). Bone turnover remained normal or improved in the majority of patients (65%). Bone histomorphometry revealed decreases in bone resorption (eroded perimeter, mean 4.6% pre- to 2.3% post-transplant; P<0.001) and disordered bone formation (fibrosis, 27% pre- versus 2% post-transplant; P<0.001). Whereas bone mineralization was normal in all but one patient pretransplant, delayed mineralization was seen in 15% of patients at 1 year post-transplant. Hypophosphatemia was associated with deterioration in histomorphometric parameters of bone mineralization. Changes in bone mineral density were highly variable, ranging from -18% to +17% per year. Cumulative steroid dose was related to bone loss at the hip, whereas resolution of hyperparathyroidism was related to bone gain at both spine and hip.

CONCLUSIONS

Changes in bone turnover, mineralization, and volume post-transplant are related both to steroid exposure and ongoing disturbances of mineral metabolism. Optimal control of mineral metabolism may be key to improving bone quality in kidney transplant recipients.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Evolution of Bone Histomorphometry and Vascular Calcification Before and After Renal Transplantation, NCT01886950.

Bone and Mineral Disease in Kidney Transplant Recipients

After kidney transplantation, mineral and bone disorders are associated with higher risk of fractures and consequent morbidity and mortality. Disorders of calcium and phosphorus, vitamin D deficiency, and hyperparathyroidism are also common. The epidemiology of bone disease has evolved over the past several decades due to changes in immunosuppressive regimens, mainly glucocorticoid minimization or avoidance. The assessment of bone disease in kidney transplant recipients relies on risk factor recognition and bone mineral density assessment. Several drugs have been trialed for the treatment of post-transplant mineral and bone disorders. This review will focus on the epidemiology, effect, and treatment of metabolic and skeletal derangements in the transplant recipient.

Competing Risk Analysis in Renal Allograft Survival: A New Perspective to an Old Problem

BACKGROUND

Graft survival after kidney transplant (KTX) is often estimated by the Kaplan-Meier (KM) method censoring for competing endpoints, primarily death. This method overestimates the incidence of graft loss.

METHODS

In 3157 adult KTX recipients followed for a mean of 79.2 months, we compared kidney and patient survival probabilities by KM versus competing risk analysis (CRA). These methods are extended to comparing different regression methods.

RESULTS

Compared with CRA, the probabilities of death and graft loss (censored for the other outcome) were substantially higher by KM. These differences increased with increasing follow-up time. Importantly, differences in graft losses were magnified in subgroups with greater probabilities of death. Among recipients with diabetes, the probabilities of graft loss at 20 years were 57% by KM and 32% by CRA, while for non-diabetes mellitus corresponding values were 44% and 35%. Similar results are noted when comparing older versus younger recipients. Finally, we find that the Fine-Gray method assumptions are violated when using age and gender as covariates and that the alternative method of Aalen-Johansen may be more appropriate.

CONCLUSIONS

CRA provides more accurate estimates of long-term graft survival and death, particularly in subgroups of recipients with higher rates of the competing event. Overestimation of risk by KM leads to both quantitative and qualitative misinterpretations of long-term KTX outcomes. When using regression analyses, care should be taken to check assumptions to guide the choice of appropriate method.

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.

Frailty and Long-Term Post-Kidney Transplant Outcomes

PURPOSE OF REVIEW

To highlight recent research about frailty and its role as a predictor of adverse, long-term post-kidney transplant (KT) outcomes.

RECENT FINDINGS

Frailty is easily measured using the physical frailty phenotype (PFP) developed by gerontologist Dr. Linda Fried and colleagues. In recent studies, >50% of KT recipients were frail (20%) or intermediately frail (32%) at KT admission. Frail recipients were at 1.3-times higher risk of immunosuppression intolerance and 2.2-times higher risk of mortality, even after accounting for recipient, donor, and transplant factors; these findings were consistent with those on short-term post-KT outcomes. Pilot data suggests that prehabilitation may be an intervention that increases physiologic reserve in frail KT recipients.

SUMMARY

The PFP is a effective tool to measure frailty in ESRD that improves risk stratification for short-term and long-term post-KT outcomes. Interventions to improve physiologic reserve and prevent adverse KT outcomes, particularly among frail KT recipients, are needed.