Geovariation in Fracture Risk among Patients Receiving Hemodialysis

Association of Nondihydropyridine Calcium Channel Blockers Versus β-Adrenergic Receptor Blockers With Risk of Heart Failure Hospitalization

Heart failure (HF) with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) are interrelated and often coexisting conditions in older adults. Although equally recommended, nondihydropyridine calcium channel blockers (non-DHP CCBs), such as diltiazem and verapamil, are less often used than β blockers. Because recent studies suggested that β-blocker use in both HFpEF and AF may increase the risk for HF, we tested whether non-DHP CCBs were associated with lower HF hospitalization risk than β blockers. We examined fee-for-service Medicare beneficiaries who were aged ≥66 years, had HFpEF or AF, and newly initiated a β blocker (n = 83,458) or non-DHP CCB (n = 18,924) from 2014 to 2018. The outcomes of HF hospitalization and all-cause mortality were analyzed using multivariable-adjusted Cox regression in the full cohort and, separately, in the subset without a recent hospital or skilled nursing discharge. Follow-up was analyzed using 2 frameworks: intention-to-treat and censored-at-drug-switch-or-discontinuation. There was a modestly protective association of non-DHP CCBs for the risk of HF hospitalization. Before drug switch or discontinuation, the use of diltiazem or verapamil was associated with decreased risk of HF hospitalization in the full cohort (hazard ratio [HR] 0.90, 95% confidence interval [CI] 0.81 to 1.00, p = 0.05) and in the subgroup (HR 0.70, 95% CI 0.56 to 0.89, p = 0.003). However, the association with all-cause mortality tended to favor β blockers, including in the intention-to-treat analysis (HR 1.21, 95% CI 1.17 to 1.25, p <0.001). In conclusion, compared with β blockers, the initiation of diltiazem or verapamil in patients with HFpEF or AF may be associated with fewer HF hospitalization events but also with more all-cause deaths.

Association between cause of kidney failure and fracture incidence in a national US dialysis population cohort study

Background

Whether fracture rates, overall and by fracture site, vary by cause of kidney failure in patients receiving dialysis is unknown.

Methods

Using the US Renal Data System, we compared fracture rates across seven causes of kidney failure in patients who started dialysis between 1997 and 2014. We computed unadjusted and multivariable adjusted proportional sub-distribution hazard models, with fracture events (overall, and by site) as the outcome and immunoglobulin A nephropathy as the reference group. Kidney transplantation and death were competing events.

Results

Among 491 496 individuals, with a median follow-up of 2.0 (25%, 75% range 0.9–3.9) years, 62 954 (12.8%) experienced at least one fracture. Patients with diabetic nephropathy, vasculitis or autosomal polycystic kidney disease (ADPKD) had the highest (50, 46 and 40 per 1000 person-years, respectively), and patient with lupus nephritis had the lowest (20 per 1000 person-years) fracture rates. After multivariable adjustment, diabetic nephropathy [hazard ratio (HR) 1.43, 95% confidence interval 1.33–1.53], ADPKD (HR 1.37, 1.26–1.48), vasculitis (HR 1.22, 1.09–1.34), membranous nephropathy (HR 1.16, 1.02–1.30) and focal segmental glomerulosclerosis (FSGS) (HR 1.13, 1.02–1.24) were associated with a significantly higher, and lupus nephritis with a significantly lower (HR 0.85, 0.71–0.98) fracture hazard. The hazards for upper extremity and lower leg fractures were significantly higher in diabetic nephropathy, ADPKD, FSGS and membranous nephropathy, while the hazard for vertebral fracture was significantly higher in vasculitis. Our findings were limited by the lack of data on medication use and whether fractures were traumatic or non-traumatic, among other factors.

Conclusions

Fracture risk, overall and by fracture site, varies by cause of end-stage kidney disease. Future work to determine underlying pathogenic mechanisms contributing to differential risks might inform more tailored treatment strategies. Our study was limited by lack of data regarding numerous potential confounders or mediators including medications and measures or bone biomarkers.

Prescribing Patterns of Direct-Acting Oral Anticoagulants in Patients With Atrial Fibrillation and Chronic Kidney Disease: A Retrospective Cohort Analysis

BACKGROUND

The association of patient and prescriber characteristics with use of warfarin versus direct-acting oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) and chronic kidney disease (CKD) is not well studied.

METHODS

The 20% Centers for Medicare & Medicaid Services Parts A, B, and D claims data from 2010 to 2017 were used to identify patients with stage 3, 4, or 5 CKD and AF who received a DOAC (apixaban, dabigatran, rivaroxaban) or warfarin. Prescribers were categorized as cardiologists, primary care providers (PCPs), and others. Using logistic regression, we estimated odds ratios (ORs) for the association of baseline characteristics and prescriber specialty with first use of a DOAC, relative to warfarin.

RESULTS

We identified 22,739 individuals with CKD who were newly initiated on oral anticoagulation for AF. New DOAC prescriptions increased from 490 in 2011 to 3261 in 2017, and displaced warfarin over time (1849, 2011; 945, 2017). By Q4 of 2014, cardiologists prescribed DOACs as initial treatment more frequently than warfarin, but non-cardiologists did not do so until 2015. As of 2017, apixaban was the most widely prescribed anticoagulant, comprising 56% and 50% of prescriptions by cardiologists and non-cardiologists, respectively. PCPs (OR 0.54, 0.51-0.58) and other providers (OR 0.55, 0.51-0.59) were less likely than cardiologists to prescribe DOACs.

CONCLUSIONS

DOAC prescriptions, particularly apixaban, increased over time and gradually displaced warfarin. The total number of patients with AF and CKD receiving anticoagulation increased over time. Cardiologists increased DOAC prescriptions more rapidly than non-cardiologists.

Adverse Outcomes Associated With Off-Label Agents Used to Treat Dementia Patients With Psychosis: A Case-Control Medicare Database Study

INTRODUCTION

Currently, there are no Food and Drug Administration-approved therapies to treat dementia-related psychosis (DRP). This study investigated the association between using antipsychotics and the anticonvulsant divalproex (sodium valproate) to manage DRP and adverse outcomes.

METHODS

A retrospective case/control matching study evaluated the risk of mortality, extrapyramidal symptoms (EPS), ischemic stroke, and cardiac arrest/ventricular arrhythmia (CA/VA) with ever-use of antipsychotics/divalproex in patients with DRP vs never-use.

RESULTS

49 509 patients were included; 76.8% used an antipsychotic/divalproex. Treatment ever-use was associated with an increased risk of all-cause mortality (odds ratio, 1.14; 95% CI, 1.10-1.18) and a smaller increase in the risk of EPS (1.10; 1.00-1.19) relative to never-use (adjusted for matching demographic variables, comorbid conditions, and disability).

CONCLUSIONS

Current agents used for DRP were associated with increased risk of death and adverse outcomes. An increased risk of death was evident within 3 months of antipsychotic/divalproex initiation and persisted with long-term use.

Smoking and risk of fractures requiring hospitalization in hemodialysis patients: a nationwide cohort study in Japan

BACKGROUND

Smoking is a well-established lifestyle risk factor for fractures in the general population, but evidence specific to hemodialysis populations is lacking. This nationwide cohort study used data from the Japanese Society for Dialysis Therapy Renal Data Registry to examine the association between smoking status and fractures.

METHODS

A total of 154,077 patients (64.2% men; mean age, 68 years) aged ≥20 years undergoing maintenance hemodialysis thrice a week at the end of 2016 were followed for 1 year. Among these, 19,004 (12.3%) patients were current smokers. Standardized incidence rate ratios of hospitalization due to any fracture were calculated and analyzed by multivariable logistic regression analysis, controlling for potential confounders. Propensity score matching and subgroup analyses were also performed as sensitivity analyses.

RESULTS

During the 1-year follow-up period, 3,337 fractures requiring hospitalization (1,201 hip, 479 vertebral, and 1,657 other fractures) occurred in 3,291 patients. The age- and sex-standardized incidence ratio for current smokers was 1.24 (95% confidence interval, 1.12-1.39) relative to non-smokers. Standardized incidence ratios were similar after stratification by age group and sex. Multivariable logistic regression analysis revealed a 1.25-fold higher risk of any fracture requiring hospitalization (95% confidence interval, 1.10-1.42) in current smokers relative to non-smokers in a fully adjusted model. Propensity score matching showed similar results (odds ratio, 1.25; 95% confidence interval, 1.05-1.48). Subgroup analyses for baseline covariates revealed no significant interactions.

CONCLUSIONS

Smoking is a significant risk factor for any fracture requiring hospitalization in hemodialysis patients.

Erythropoietin treatment and the risk of hip fractures in hemodialysis patients

Erythropoietin (EPO) is the primary regulator of bone marrow erythropoiesis. Mouse models have provided evidence that EPO also promotes bone remodeling and that EPO-stimulated erythropoiesis is accompanied by bone loss independent of increased red blood cell production. EPO has been used clinically for three decades to treat anemia in end-stage renal disease, and notably, although the incidence of hip fractures decreased in the United States generally after 1990, it rose among hemodialysis patients coincident with the introduction and subsequent dose escalation of EPO treatment. Given this clinical paradox and findings from studies in mice that elevated EPO affects bone health, we examined EPO treatment as a risk factor for fractures in hemodialysis patients. Relationships between EPO treatment and hip fractures were analyzed using United States Renal Data System (USRDS) datasets from 1997 to 2013 and Consolidated Renal Operations in a Web-enabled Network (CROWNWeb) datasets for 2013. Fracture risks for patients treated with <50 units of EPO/kg/week were compared to those receiving higher doses by multivariable Cox regression. Hip fracture rates for 747,832 patients in USRDS datasets (1997-2013) increased from 12.0 per 1000 patient years in 1997 to 18.9 in 2004, then decreased to 13.1 by 2013. Concomitantly, average EPO doses increased from 11,900 units/week in 1997 to 18,300 in 2004, then decreased to 8,800 by 2013. During this time, adjusted hazard ratios for hip fractures with EPO doses of 50-149, 150-299, and ≥ 300 units/kg/week compared to <50 units/kg/week were 1.08 (95% confidence interval [CI], 1.01-1.15), 1.22 (95% CI, 1.14-1.31), and 1.41 (95% CI, 1.31-1.52), respectively. Multivariable analyses of 128,941 patients in CROWNWeb datasets (2013) replicated these findings. This study implicates EPO treatment as an independent risk factor for hip fractures in hemodialysis patients and supports the conclusion that EPO treatment may have contributed to changing trends in fracture incidence for these patients during recent decades. Published 2021. This article is a U.S. Government work and is in the public domain in the USA. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Secular trends in hip fracture incidence and subsequent mortality in dialysis patients and the general population in Sweden

BACKGROUND

Declining trends of hip fracture incidence in dialysis patients were reported from USA and Japan while studies from Europe are lacking. We investigated trends in hip fracture incidence and subsequent mortality in Swedish dialysis patients, comparing with the Swedish general population.

METHODS

We used the population-based Swedish national database of fractures and the Swedish National Renal Registry to retrieve data on hip fractures incidence and subsequent mortality for years 2007-2016. Trends for age-standardized hip fracture incidence rate (ASR_{hip fracture}) and age-standardized 30-day (ASMR_30day) and 180-day (ASMR_180day) post-hip fracture mortality rate in Swedish general population were evaluated by joinpoint regression analysis. Standardized incidence ratios of hip fracture (SIR) and standardized mortality ratios (SMR) were calculated for Swedish dialysis patients.

RESULTS

In the general population, ASR_{hip fracture} declined significantly: in women from 2007 and in men from 2009. In dialysis patients, SIR was 3-5 times higher compared to the general population and declined over time in women but not in men. In general population, mortality (ASMR_30day and ASMR_180day) declined significantly in women and men. In dialysis patients, post-fracture mortality (SMR, mainly for 180-day mortality) remained two-fold higher than in general population with no consistent trend towards improvement.

CONCLUSIONS

Hip fracture incidence and subsequent mortality fell among women and men in the Swedish general population. In dialysis patients, hip fracture incidence declined in women but not in men while post-fracture mortality did not improve, and the incidence and subsequent mortality remained 3 to 5-fold and 2-fold higher than in the general population.

CKD Progression in Medicare Beneficiaries With Nonvalvular Atrial Fibrillation Treated With Apixaban Versus Warfarin

RATIONALE & OBJECTIVE

Comparing kidney disease progression among patients treated with direct oral anticoagulants (DOACs) versus warfarin has not been well studied. We hypothesized that apixaban would be associated with lower risks of progression of chronic kidney disease (CKD) and progression to incident kidney failure than warfarin in patients with atrial fibrillation (AF).

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Medicare recipients with stage 3, 4, or 5 CKD and incident AF who received a new prescription for apixaban or warfarin from 2013 through 2017.

EXPOSURE

Apixaban or warfarin.

OUTCOMES

Progression to incident kidney failure or, separately, to a more advanced stage of CKD.

ANALYTICAL APPROACH

Marginal structural cause-specific proportional hazards models with inverse probability weighting to estimate marginal hazard ratios (HRs) for each outcome. HRs compared apixaban to warfarin in intention-to-treat and censored-at-drug-switch analyses.

RESULTS

12,816 individuals met inclusion criteria (50.3% received apixaban; 49.7% received warfarin). After weighting, the mean age of the cohort was 80 ± 7 years, 51% were women, and 88% were White. Approximately 84% had stage 3, 15% had stage 4, and 1% had stage 5 CKD. In the intention-to-treat analysis, apixaban, relative to warfarin, was associated with an HR of developing incident kidney failure of 0.98 (95% confidence interval [CI], 0.79-1.22) and of CKD stage progression of 0.90 (95% CI, 0.82-0.99). Corresponding HRs for censored-at-drug-switch analyses were 0.81 (95% CI, 0.56-1.17) and 0.81 (95% CI, 0.70-0.92). Results were similar for a series of subgroup and sensitivity analyses.

LIMITATIONS

CKD was defined based on diagnosis codes from claims; findings may not be generalizable to non-Medicare CKD populations.

CONCLUSIONS

Apixaban, compared with warfarin, was associated with lower risk of CKD stage progression, but not with incident kidney failure.

Outcomes Following Ischemic Stroke in Older Patients With CKD Stages 4 and 5: A Retrospective Cohort Study

RATIONALE & OBJECTIVE

The associations between ischemic stroke and time to dialysis initiation and/or death in adults with late-stage chronic kidney disease (CKD) have not been explored. We sought to measure the rate and factors associated with stroke in CKD stages 4 and 5 (CKD4-5) and assess the association of stroke with initiation of dialysis and death.

STUDY DESIGN

Retrospective cohort.

SETTING & PARTICIPANTS

Patients with CKD4-5 in Medicare 2007 to 2014.

EXPOSURE OR PREDICTOR

Ischemic stroke in CKD4-5.

OUTCOMES

Initiation of maintenance dialysis or death.

ANALYTICAL APPROACH

Cox proportional hazard modeling assessed factors associated with ischemic stroke. A matched analysis (stroke/no stroke) estimated the cumulative incidence of incident kidney failure and death, treated as competing events. Simulations using a state transition model determined differences in expected time to kidney failure or death and death alone for patients with and without stroke with CKD5.

RESULTS

123,251 patients with CKD4 and 22,054 with CKD5 were identified. Mean ages were 81.0 and 79.2 years, respectively. Female sex (HRs of 1.21 [95% CI, 1.12-1.31] and 1.39 [95% CI, 1.04-1.86] for CKD4 and CKD5, respectively) and black race (HRs of 1.25 [95% CI, 1.12-1.39] and 1.12 [95% CI, 0.80-1.58] for CKD4 and CKD5, respectively) were factors associated with ischemic stroke. Rates for 30-day mortality were 13.3% and 18.8%, and for 1-year mortality, 40.0% and 38.2%. For patients with CKD5, kidney failure or death occurred an average of 3.6 months sooner for patients with an ischemic stroke, and death (irrespective of kidney failure), a mean of 24.3 months sooner.

LIMITATIONS

Study design cannot determine causality; lack of data for stroke severity.

CONCLUSIONS

Female sex and black race were associated with increased risk for stroke in CKD4 and CKD5. In CKD5, stroke was associated with a shorter time to kidney failure or death by nearly 4 months, and to death, by more than 2 years.

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.

Direct-Acting Oral Anticoagulants Versus Warfarin in Medicare Patients With Chronic Kidney Disease and Atrial Fibrillation

Background and Purpose:

The comparative effectiveness of direct-acting oral anticoagulants, compared with warfarin, for risks of stroke/systemic embolism, major bleeding, or death have not been studied in Medicare beneficiaries with atrial fibrillation and nondialysis-dependent chronic kidney disease.

Methods:

Medicare data from 2011 to 2017 were used to identify patients with stages 3, 4, or 5 chronic kidney disease and new atrial fibrillation who received a new prescription for warfarin, apixaban, rivaroxaban, or dabigatran. We estimated marginal hazard ratios with 95% CIs for the association of each direct-acting oral anticoagulant, compared with warfarin, for the outcomes of interest using inverse-probability-of-treatment weighted Cox proportional hazards models in as-treated and intention-to-treat analyses.

Results:

A total of 22 739 individuals met criteria (46.3% warfarin, 29.6% apixaban, 17.2% rivaroxaban, 6.9% dabigatran). Across the groups of anticoagulant users, mean age was 78.4 to 79.0 years; 50.3% to 51.4% were women, and 80.3% to 82.8% had stage 3 chronic kidney disease. In the as-treated analysis, for stroke/systemic embolism, hazard ratios, all compared with warfarin, were 0.70 (0.51–0.96) for apixaban, 0.80 (0.54–1.17) for rivaroxaban, and 1.15 (0.69–1.94) for dabigatran. For major bleeding, analogous hazard ratios were 0.47 (0.37–0.59) for apixaban, 1.05 (0.85–1.30) for rivaroxaban, and 0.95 (0.70–1.31) for dabigatran. There was no difference in the risk of all-cause mortality between the direct-acting oral anticoagulants and warfarin. Results of the intention-to-treat analysis were similar.

Conclusions:

Apixaban, compared with warfarin, was associated with decreased risk of stroke/systemic embolism and major bleeding; risks for both outcomes with rivaroxaban and dabigatran did not differ from risks with warfarin.

Early withdrawal and non-withdrawal death in the months following hemodialysis initiation: A retrospective cohort analysis

INTRODUCTION

Whether and how factors associated with elective hemodialysis withdrawal differ from those associated with non-withdrawal death soon after maintenance hemodialysis initiation have not been well studied.

METHODS

A retrospective cohort analysis was performed using USRDS data from 2011 to 2014. Patients were randomly categorized 2:1 into training and validation samples. Elective withdrawal deaths were identified using the Death Notification form. Multinomial logistic regression was used to fit a prediction model for three outcome categories (withdrawal, non-withdrawal death, survival at 6 months) as a function of demographic, comorbidity, and functional status.

FINDINGS

The training sample comprised 80,284 hemodialysis patients. Mean age was 71.7 ± 11.4 years, 44.9% were female, 72.9% were white, and 22.8% were black. Within 6 months, 19.1% died, of whom 2099 (2.6%) withdrew and 13,223 (16.5%) died of a non-withdrawal cause; 13.7% of all deaths were withdrawals. Baseline characteristics and event rates were similar among the 40,142 patients in the validation sample. The model was calibrated adequately and could discriminate moderately well between withdrawal and survival (area under ROC curve [AUC]: 0.77) and between non-withdrawal death and survival (AUC: 0.73). However, discrimination between withdrawal and non-withdrawal death was relatively low (AUC: 0.62). Older age and white, compared with non-white, race were each associated with greater odds of death, and these associations were stronger for withdrawal than for non-withdrawal death.

DISCUSSION

Advanced age and white, as opposed to black, race were most strongly associated with early elective hemodialysis withdrawal compared with non-withdrawal death. However, it is difficult to differentiate between patients who will experience early withdrawal vs. non-withdrawal death, as many factors are similarly associated with both outcomes.

Relation of Race, Apparent Disability, and Stroke Risk With Warfarin Prescribing for Atrial Fibrillation in Patients Receiving Maintenance Hemodialysis

Little is known about how warfarin is prescribed for stroke prevention in maintenance dialysis patients with chronic atrial fibrillation (AF). We examined patterns of warfarin use, and associated factors, after AF diagnosis. This retrospective cohort analysis studied US Medicare patients receiving maintenance dialysis January 1, 2008, to June 30, 2010. Demographics, co-morbidity, and a durable medical equipment claims-based disability proxy score predicted warfarin prescription after AF diagnosis. The analysis included 8,964 patients with nonvalvular AF. Compared with nonusers, warfarin users were younger (age 65.4 ± 12.1 vs 67.0 ± 12.9 years) and more likely to be men (54.3% vs 52.8%) and of white race (64.0% vs 59.6%). After adjustment for other factors, nonwhite, versus white, race was associated with significantly less warfarin use within 30 days: odds ratios (ORs), 95% confidence intervals (CIs), were 0.80, 0.71 to 91, for black patients; 0.57, 0.43 to 0.76, for Asians; and 0.74, 0.49 to 1.12, for members of other races. Percentages of patients receiving warfarin decreased as Hypertension Abnormal renal and liver function Stroke-Bleeding Labile INR Elderly Drugs or alcohol (HAS-BLED) bleeding risk score increased (OR 0.82, 95% CI 0.73 to 0.92, HAS-BLED score 3 to 4 versus 2; 0.38, 0.26 to 0.57, score ≥ 5 vs 2). However, as CHA2DS2-Vasc stroke-risk score increased, warfarin use tended to decrease (OR 0.90, 95% CI 0.78 to 1.03, p = 0.13, CHA2DS2-Vasc score 4 versus 1 to 3; 0.69, 0.61 to 0.78, p < 0.0001, score 5 vs 1 to 3). In conclusion, providers appear to weigh bleeding risk more heavily than stroke-prevention potential when prescribing warfarin for maintenance dialysis patients. Racial minorities received warfarin substantially less often than whites, even after accounting for other factors.

Predictors of bone fractures in a single-centre cohort of hemodialysis patients: a 2-year follow-up study

PURPOSE

Bone involvement represents one of the complications of end-stage chronic kidney disease, with fractures being its major risk. The aim of our study was to assess the frequency and predictors of low-trauma fractures in a cohort of maintenance hemodialysis patients followed-up on for 2 years.

METHODS

59 patients (67.6 ± 13.1 years, 43 males) treated with hemodiafiltration underwent initially laboratory (markers of calcium-phosphate metabolism and bone turnover markers) and densitometry examination with TBS assessment (Lunar Prodigy, TBS software 2.1.2). During 24-month follow-up, the frequency of low-trauma fractures was assessed and possible predictors of increased fracture risk were identified using product-moment correlation matrices.

RESULTS

Altogether 7 (11.9%) low-trauma fractures were observed. In the whole group, age (P = 0.047), T-score in proximal femur (P = 0.04), low vitamin D, low BMI (P = 0.03 for both), and higher FRAX for major osteoporotic fracture (P = 0.01) were connected with fractures, but in multi-variate analysis only BMI remained significantly negatively associated with fractures (P = 0.047). TBS and bone turnover markers failed to predict fractures. However, women with fractures had significantly lower serum phosphate (P = 0.03) and higher parathyroid hormone (P = 0.04). Parameters of hip structure analysis significantly correlated with FRAX, but not with fractures.

CONCLUSIONS

In a group of hemodialysis patients from one centre, T-score in proximal femur, low vitamin D, low BMI, and high FRAX for major osteoporotic fracture were associated with low-trauma fractures, however, in multi-variate analysis only low BMI remained a significant predictor of fracture risk.

Factors Associated With Withdrawal From Maintenance Dialysis: A Case-Control Analysis

BACKGROUND

Little is known about differences in the clinical course between patients receiving maintenance dialysis who do and do not withdraw from dialysis therapy.

STUDY DESIGN

Case-control analysis.

SETTING & PARTICIPANTS

US patients with Medicare coverage who received maintenance hemodialysis for 1 year or longer in 2008 through 2011.

PREDICTORS

Comorbid conditions, hospitalizations, skilled nursing facility stays, and a morbidity score based on durable medical equipment claims.

OUTCOME

Withdrawal from dialysis therapy.

MEASUREMENTS

Rates of medical events, hospitalizations, skilled nursing facility stays, and a morbidity score.

RESULTS

The analysis included 18,367 (7.7%) patients who withdrew and 220,443 (92.3%) who did not. Patients who withdrew were older (mean age, 75.3±11.5 [SD] vs 66.2±14.1 years) and more likely to be women and of white race, and had higher comorbid condition burdens. The odds of withdrawal among women were 7% (95% CI, 4%-11%) higher than among men. Compared to age 65 to 74 years, age 85 years or older was associated with higher adjusted odds of withdrawal (adjusted OR, 1.61; 95% CI, 1.54-1.68), and age 18 to 44 years with lower adjusted odds (adjusted OR, 0.36; 95% CI, 0.32-0.40). Blacks, Asians, and Hispanics were less likely to withdraw than whites (adjusted ORs of 0.36 [95% CI, 0.35-0.38], 0.47 [95% CI, 0.42-0.53], and 0.46 [95% CI, 0.44-0.49], respectively). A higher durable medical equipment claims-based morbidity score was associated with withdrawal, even after adjustment for traditional comorbid conditions and hospitalization; compared to a score of 0 (lowest presumed morbidity), adjusted ORs of withdrawal were 3.48 (95% CI, 3.29-3.67) for a score of 3 to 4 and 12.10 (95% CI, 11.37-12.87) for a score ≥7. Rates of medical events and institutionalization tended to increase in the months preceding withdrawal, as did morbidity score.

LIMITATIONS

Results may not be generalizable beyond US Medicare patients; people who withdrew less than 1 year after dialysis therapy initiation were not studied.

CONCLUSIONS

Women, older patients, and those of white race were more likely to withdraw from dialysis therapy. The period before withdrawal was characterized by higher rates of medical events and higher levels of morbidity.

Molecular Abnormalities Underlying Bone Fragility in Chronic Kidney Disease

Prevention of bone fractures is one goal of therapy for patients with chronic kidney disease-mineral and bone disorder (CKD-MBD), as indicated by the Kidney Disease: Improving Global Outcomes guidelines. CKD patients, including those on hemodialysis, are at higher risk for fractures and fracture-related death compared to people with normal kidney function. However, few clinicians focus on this issue as it is very difficult to estimate bone fragility. Additionally, uremia-related bone fragility has a more complicated pathological process compared to osteoporosis. There are many uremia-associated factors that contribute to bone fragility, including severe secondary hyperparathyroidism, skeletal resistance to parathyroid hormone, and bone mineralization disorders. Uremia also aggravates bone volume loss, disarranges microarchitecture, and increases the deterioration of material properties of bone through abnormal bone cells or excess oxidative stress. In this review, we outline the prevalence of fractures, the interaction of CKD-MBD with osteoporosis in CKD patients, and discuss possible factors that exacerbate the mechanical properties of bone.

Chronic kidney disease and fragility fracture

Osteoporosis is defined simply as "a skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. Thus, any bone lesion that causes fragility fracture is osteoporosis, which has quite heterogeneous backgrounds. Chronic kidney disease-related bone and mineral disease (CKD-MBD) is defined as "a systemic disorder of mineral and bone metabolism due to CKD, which is manifested by abnormalities in bone and mineral metabolism and/or extra-skeletal calcification". Although CKD-MBD is one of the possible causes of osteoporosis, we do not have evidences that CKD-MBD is the only or crucial determinant of bone mechanical strength in CKD patients. The risk of hip fracture is considerably high in CKD patients. Drugs that intervene in systemic mineral metabolism, indeed, lead to the improvement on bone histology in CKD patients. However, it remains unclear whether the intervention in systemic mineral metabolism also improves bone strength, today. Thus, the use of drugs that directly act on bone and the introduction of fracture liaison concept are promising strategies for fragility fracture prevention among CKD patients, as well as treatment for CKD-MBD.