Kidney Function and Fracture Risk: The Atherosclerosis Risk in Communities (ARIC) Study

Rapid decline of kidney function increases fracture risk in the general population: Insights from TLGS

BACKGROUND

Although the association between Chronic Kidney Disease (CKD) and all-cause fractures was addressed in previous studies, the association between estimated glomerular filtration rate (eGFR) decline and fractures was poorly addressed. For the first time we examined the association between rapid kidney function decline (RKFD) and fracture incidence among Iranian general population.

METHODS

In a Tehranian community-based cohort, RKFD was defined as a 30 % decline in eGFR over 2-3 years. Cox proportional hazards models, adjusted for age, sex, current eGFR, diabetes mellitus, hypertension, dyslipidemia, current smoking, obesity status, waist circumference, prevalent cardiovascular diseases, aspirin, steroid use, education level, and marital status, were used to examine the association of RKFD with different fracture outcomes.

RESULTS

Among 5305 (3031 women) individuals aged ≥30 years, during the median follow-up of 9.62 years, 226 fracture events were observed. The multivariable hazard ratio of RKFD for any-fracture events, lower-extremity, and major osteoporotic fractures were 2.18 (95 % CI, 1.24-3.85), 2.32 (1.15-4.71), and 2.91 (1.29-6.58), respectively. These associations remained significant after accounting for the competing risk of death. The impact of RKFD on the development of incident all-cause fractures was not modified by gender [men: 2.64 (1.11-6.25) vs. women: 2.11 (1.00-4.47)] and according to current CKD status [without CKD: 2.34 (1.00-5.52) vs. with CKD: 2.59 (1.04-6.44)] (all P for interaction >0.5).

CONCLUSIONS

RKFD can increase the incidence of fractures among general population, the issue that was equally important among non-CKD individuals, emphasizing the need for early identification and management in those with rapidly declining eGFR.

Association of estimated glomerular filtration rate with prostate cancer risk in a cross-ethnic population: a Mendelian randomization study

OBJECTIVE

To investigate whether a causal relationship exists between the estimated glomerular filtration rate (EGFR) and the occurrence of prostate cancer in East Asian and European populations and to determine if genetic factors influence the association between the EGFR and prostate cancer risk.

METHODS

In this Mendelian randomization study, the existence of a causal relationship between the EGFR and prostate cancer occurrence was assessed using five analytical techniques, including Mendelian randomization-Egger regression (MR-Egger), calculation of the weighted median estimator (WME), the maximum likelihood ratio method, the linear median weighting method and the random-effects inverse-variance weighting (IVW) method.

RESULTS

In the IVW model, no causal relationship was observed between the EGFR and prostate cancer in either the East Asian or European populations.

CONCLUSIONS

After excluding confounding factors and reverse causal associations using two-sample Mendelian randomization, unbiased estimates were obtained, and there was no causal relationship between prostate cancer and the EGFR in the East Asian or European populations. Therefore, for patients with suspected prostate cancer, it is considered unnecessary to improve the detection of glomerular filtration rate, which will effectively reduce the economic burden of patients.

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

Background and hypothesis

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

Methods

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

Results

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

Conclusions

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

Degree of Albuminuria is Associated With Increased Risk of Fragility Fractures Independent of Estimated GFR

Introduction

Fragility fractures are common in persons with chronic kidney disease (CKD); however, the association between fragility fractures and albuminuria is not well-studied. The primary objective of this study is to determine the association of albuminuria with incident risk of fragility fractures. The secondary objective is to examine the risk of fragility fracture by estimated glomerular filtration rate (eGFR) and Kidney Disease Improving Global Outcomes (KDIGO) risk categories.

Methods

Community dwelling adults residing in Alberta, Canada who had at least 1 creatinine and albuminuria measurement between April 1, 2008 and March 31, 2019 participated in the study (N = 2.72 million). Incident fragility fractures were identified using Canadian Chronic Disease Surveillance Systems Osteoporosis Working Group algorithms. Albuminuria was categorized as none/mild (albumin-to-creatinine ratio [ACR] <30 mg/g, protein-to-creatinine ratio [PCR] <150 mg/g, trace/negative dipstick); moderate (ACR 30-300 mg/g, PCR 150-500 mg/g, 1+ dipstick) or severe (ACR >300 mg/g, PCR >500 mg/g, ≥2+ dipstick). Multivariable analysis controlled for 42 variables.

Results

Patients with severe albuminuria had an increased risk of hip fracture (odds ratio [OR] = 1.37; 95% confidence interval [CI] 1.28, 1.47]), vertebral fracture (OR = 1.31; 95% CI 1.21, 1.41) and any-type fracture (OR = 1.22; 95% CI 1.17, 1.28) compared with patients with none/mild albuminuria. Patients in the most severe KDIGO risk category had an increased risk of hip fracture (OR = 1.22; 95% CI 1.16, 1.29), vertebral fracture (OR = 1.18; 95% CI 1.09, 1.26) and any type of fracture (OR = 1.25; 95% CI 1.21, 1.30).

Conclusion

This study demonstrates the important role of albuminuria as a risk factor for fragility fractures in CKD and may help inform risk stratification and prevention strategies in this high-risk population category.

Incident vertebral fracture and longitudinal BMD change in Chinese postmenopausal women with early CKD: Peking Vertebral Fracture Study

Early chronic kidney disease (CKD) and non-CKD individuals had similar morphometric vertebral fracture (mVF) incidence and longitudinal bone mineral density (BMD) change. CKD did not modify the association between BMD and incident mVF status. Patients with a higher baseline BMD had a higher longitudinal BMD loss in early CKD.

PURPOSE

The aim of this 5-year longitudinal cohort study was to compare the risk of incident morphometric vertebral fracture (mVF) and longitudinal bone mineral density (BMD) change between individuals with early chronic kidney disease (CKD) and those without CKD.

METHODS

A total of 869 Chinese postmenopausal women were enrolled in the study. Serum creatinine levels were assessed using standard methods, and estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. Incident mVF was confirmed through lateral radiographs of the thoracolumbar spine. BMDs at the lumbar spine (LS) and femoral neck (FN) were measured using dual-energy X-ray absorptiometry. CKD was defined based on eGFR values: 60-89 mL/min/1.73m2 for stage 2 (n = 511) and 30-59 mL/min/1.73m2 for stage 3 (n = 92). The non-CKD group included individuals with an eGFR greater than or equal to 90 mL/min/1.73m2.

RESULTS

The incidence of mVF was not statistically different between individuals with early CKD and those without CKD (4.1% in non-CKD, 6.3% in CKD stage 2, and 7.6% in CKD stage 3; p = 0.348). Neither eGFR nor CKD status was significantly associated with incident mVF in the multivariate logistic regression analysis. Baseline BMD T-scores were negatively associated with incident mVF (LS T-score, OR = 0.603, 95% CI = 0.468-0.777; FN T-score, OR = 0.511, 95% CI = 0.350-0.746). No evidence of interaction between BMD T-scores and CKD status were identified (p = 0.284-0.785) . The differences in longitudinal BMD changes between non-CKD and CKD groups were comparable (FN BMD: -6.31 ± 7.20% in non-CKD, -5.07 ± 8.20% in CKD stage 2, and -4.49 ± 8.40% in CKD stage 3, p = 0.556; LS BMD: -1.38 ± 8.18% in non-CKD, -0.32 ± 7.14% in CKD stage 2, and 1.5 ± 6.97% in CKD stage 3, p = 0.406). Individuals with a higher baseline FN BMD showed a greater longitudinal FN BMD loss (r = -0.185, p < 0.001) .

CONCLUSIONS

Our study revealed that early CKD was not associated with an increased risk of incident mVF or greater longitudinal BMD loss. Moreover, CKD did not modify the association between BMD and the risk of incident mVF, suggesting that the management and prevention of fractures in early CKD should be approached similarly to those without CKD. Measurement of BMD appears to be crucial for predicting incident mVF risk and longitudinal bone loss in early CKD.

Cardiorenal outcomes, kidney function, and other safety outcomes with ertugliflozin in older adults with type 2 diabetes (VERTIS CV): secondary analyses from a randomised, double-blind trial

BACKGROUND

VERTIS CV was a randomised, double-blind, placebo-controlled, parallel-group, multicentre cardiovascular outcomes trial that evaluated the cardiovascular efficacy and safety of ertugliflozin in adults with type 2 diabetes and atherosclerotic cardiovascular disease. The primary objective of VERTIS CV was to show non-inferiority of ertugliflozin to placebo with respect to the primary outcome, major adverse cardiovascular events (a composite of death from cardiovascular causes, non-fatal myocardial infarction, or non-fatal stroke). The analyses reported here aimed to assess cardiorenal outcomes, kidney function, and other safety outcomes with ertugliflozin in older adults with type 2 diabetes and atherosclerotic cardiovascular disease compared with younger participants.

METHODS

VERTIS CV was done at 567 centres in 34 countries. Participants (aged ≥40 years) with type 2 diabetes and atherosclerotic cardiovascular disease were randomly assigned (1:1:1) to once-daily ertugliflozin 5 mg, ertugliflozin 15 mg, or placebo in addition to background standard-of-care treatment. Random assignment was done with the use of an interactive voice-response system. The study outcomes were major adverse cardiovascular events, hospitalisation for heart failure or cardiovascular death, cardiovascular death, hospitalisation for heart failure, prespecified kidney composite outcomes, kidney function, and other assessments of safety. Cardiorenal outcomes, kidney function, and safety outcomes were evaluated by baseline age (≥65 years and <65 years [prespecified] and ≥75 years and <75 years [post hoc]). The study is registered with ClinicalTrials.gov, NCT01986881.

FINDINGS

Between Dec 13, 2013, and July 31, 2015, and between June 1, 2016, and April 14, 2017, 8246 adults with type 2 diabetes and atherosclerotic cardiovascular disease were recruited to the study and randomly assigned. 2752 patients were assigned to ertugliflozin 5 mg, 2747 patients to ertugliflozin 15 mg, and 2747 patients to placebo. 8238 participants received at least one dose of ertugliflozin 5 mg, ertugliflozin 15 mg, or placebo. 4145 (50·3%) of 8238 participants were aged 65 years and older, including 903 (11·0%) participants aged 75 years and older. 5764 (70·0%) of 8238 participants were male and 2474 (30·0%) were female, and 7233 (87·8%) of 8238 participants were White, 497 (6·0%) were Asian, 235 (2·9%) were Black, and 273 (3·3%) were classified as other. The mean estimated glomerular filtration rate (eGFR) was lower and the type 2 diabetes duration longer for those aged 65 years and older versus those younger than 65 years, and for those aged 75 years and older versus those younger than 75 years. Cardiovascular outcomes were more common in the older age subgroups than in the younger age subgroups. Similar to the overall VERTIS CV cohort, ertugliflozin did not increase the risk of major adverse cardiovascular events, cardiovascular death or hospitalisation for heart failure, cardiovascular death alone, or the kidney composite outcome (using doubling of serum creatinine, dialysis or transplantation, or kidney death), and reduced the risk of hospitalisation for heart failure and the exploratory kidney composite outcome (using a 40% sustained eGFR decrease, dialysis or transplantation, or kidney death) in the older age subgroups (p_interaction>0·05 for outcomes assessed). A slower decline in eGFR and a smaller increase in the urine albumin-to-creatinine ratio were observed over time in all age subgroups taking ertugliflozin compared with placebo. Across age subgroups, safety outcomes were consistent with the known profile of ertugliflozin.

INTERPRETATION

The effects of ertugliflozin on cardiorenal outcomes, kidney function, and safety outcomes were generally similar across age subgroups. These results have the potential to help clinical decision making by providing a longer-term evaluation of the cardiorenal safety and overall tolerability of ertugliflozin in a large population of older adults.

FUNDING

Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ, USA in collaboration with Pfizer Inc, New York, NY, USA.

Association between prevalence of laxative use and history of bone fractures and cardiovascular diseases in patients with chronic kidney disease: the Fukuoka Kidney disease Registry (FKR) study

BACKGROUND

Constipation is a common complication in patients with chronic kidney disease (CKD) and is involved in the pathogenesis of dysbiosis and progression of CKD. However, little is known about its association with disorders of the bone-cardiovascular axis in patients with CKD.

METHODS

We performed a cross-sectional analysis of 3878 patients with CKD using the baseline dataset of the Fukuoka Kidney disease Registry study, as a multicenter, prospective cohort study of pre-dialysis CKD patients. The main exposure of interest was constipation defined as use of at least one type of laxative. The main outcomes were the histories of bone fractures and cardiovascular diseases (CVDs) as manifestations of disorders of the bone-cardiovascular axis.

RESULTS

The prevalences of laxative use and histories of bone fractures and CVDs increased as kidney function declined. Among the 3878 patients, 532 (13.7%) patients used laxatives, 235 (6.1%) patients had prior bone fractures, and 1001 (25.8%) patients had prior CVDs. Histories of bone fractures and CVDs were significantly more prevalent among laxative users (P < 0.05). Multivariable-adjusted logistic regression analysis revealed that patients with laxatives had a significantly higher odds ratios for histories of bone fractures and CVDs than those without laxatives [adjusted odds ratios (95% confidence intervals) 1.67 (1.20-2.31) and 1.70 (1.30-2.22), respectively, P < 0.05].

CONCLUSIONS

These results suggest that constipation indicated by laxative use is associated with increased prevalences of historical bone fractures and CVDs in pre-dialysis patients with CKD.

Type 2 diabetes and bone fragility in children and adults

Type 2 diabetes (T2D) is a global epidemic disease. The prevalence of T2D in adolescents and young adults is increasing alarmingly. The mechanisms leading to T2D in young people are similar to those in older patients. However, the severity of onset, reduced insulin sensitivity and defective insulin secretion can be different in subjects who develop the disease at a younger age. T2D is associated with different complications, including bone fragility with consequent susceptibility to fractures. The purpose of this systematic review was to describe T2D bone fragility together with all the possible involved pathways. Numerous studies have reported that patients with T2D show preserved, or even increased, bone mineral density compared with controls. This apparent paradox can be explained by the altered bone quality with increased cortical bone porosity and compr-omised mechanical properties. Furthermore, reduced bone turnover has been described in T2D with reduced markers of bone formation and resorption. These findings prompted different researchers to highlight the mechanisms leading to bone fragility, and numerous critical altered pathways have been identified and studied. In detail, we focused our attention on the role of microvascular disease, advanced glycation end products, the senescence pathway, the Wnt/β-catenin pathway, the osteoprotegerin/receptor-activator of nuclear factor kappa B ligand, osteonectin and fibroblast growth factor 23. The understanding of type 2 myeloid bone fragility is an important issue as it could suggest possible interventions for the prevention of poor bone quality in T2D and/or how to target these pathways when bone disease is clearly evident.

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.

Testosterone Deficiency as One of the Major Endocrine Disorders in Chronic Kidney Disease

Reduced testosterone concentration is nowadays thought to be one of the main endocrine disorders in chronic kidney disease (CKD). It is caused by the dysfunction of the hypothalamic-pituitary-gonadal axis. The role of testosterone is multifactorial. Testosterone is responsible not only for reproductive processes, but it is a hormone which increases bone and muscle mass, improves lipid profile, insulin sensitivity, erythropoiesis, reduces blood pressure, and ameliorates mood and perception. The implications of hypogonadism in CKD are infertility and loss of libido, reduction of muscle mass and strength, disorders in bone mineralization, the development of sarcopenia and protein energy wasting (PEW), progression of atherosclerosis, increased visceral adiposity, insulin resistance, and anaemia. Reduced testosterone serum concentrations in CKD are associated with increased mortality rate. Testosterone supplementation improves sexual functions, reduces the level of inflammatory markers and blood pressure, stimulates muscle protein synthesis, improves insulin sensitivity and lipid profile, and increases muscle mass, bone mineral density, and haemoglobin concentration. It positively affects mood and well-being. The modes of testosterone supplementation are intramuscular injections, subcutaneous pellets, and percutaneous methods—patches and gels. Successful kidney transplantation may improve gonadal function and testosterone production, however, half of men with low testosterone concentrations before kidney transplantation do not restore hormonal function.

Height-adjusted lean body mass and its associations with physical activity and kidney function in pediatric kidney transplantation

BACKGROUND

Although LBM is positively associated with health outcomes, studies assessing determinants for the accrual of ht-LBM, such as physical activity, are limited. This study aimed to assess ht-LBM levels in pediatric kidney transplant recipients and test its association with baseline and contemporaneous variables, including physical activity.

METHODS

A retrospective cross-sectional review was performed on 46 pediatric kidney transplant recipients, and a longitudinal review was performed on a subset of recipients with serial post-transplant (n = 21) and pre/post-transplant (n = 11) ht-LBM measurements. Ht-LBM measurements were obtained using DXA scans.

RESULTS

This cohort was 16.0 (IQR 12.3, 17.7) years old, 56.5% male and 46 ± 45 months post-transplant with a mean ht-LBM of 15.1 ± 2.5 kg/m² . A median ht-LBM increase of 1.6 kg/m² (IQR - 0.1, 2.6 kg/m² ; p < .01) was observed, over 29.2 ± 12.0 months from the earliest post-transplant scan obtained at 46 ± 25 months post-transplant until the most recent post-transplant scan. A 1.7 ± 1.4 kg/m² (p < .01) increase was observed between pre- and post-transplant DXA scans which were taken at 12 ± 11 months pre-transplant and 13 ± 6 months post-transplant, respectively. In separate adjusted models, lower physical activity questionnaire scores (n = 17, beta = 1.55, p = .02), faster rate of estimated glomerular filtration rate decline (beta = 0.05, p < .048) adjusted for annualized change in BSA, and younger age at scan (beta = 0.32, p < .01) were each significant predictors of lower ht-LBM.

CONCLUSIONS

Physical activity and kidney function may influence ht-LBM in the pediatric kidney transplant population.

Risk Factors for Fracture in Patients with Coexisting Chronic Kidney Disease and Type 2 Diabetes: An Observational Analysis from the CREDENCE Trial

BACKGROUND

The fracture pathophysiology associated with type 2 diabetes and chronic kidney disease (CKD) is incompletely understood. We examined individual fracture predictors and prediction sets based on different pathophysiological hypotheses, testing whether any of the sets improved prediction beyond that based on traditional osteoporotic risk factors.

METHODS

Within the CREDENCE cohort with adjudicated fracture outcomes, we assessed the association of individual factors with fracture using Cox regression models. We used the Akaike information criteria (AIC) and Schwartz Bayes Criterion (SBC) to assess six separate variable sets based on hypothesized associations with fracture, namely, traditional osteoporosis, exploratory general population findings, cardiovascular risk, CKD-mineral and bone disorder, diabetic osteodystrophy, and an all-inclusive set containing all variables.

RESULTS

Fracture occurred in 135 (3.1%) participants over a median 2.35 [1.88-2.93] years. Independent fracture predictors were older age (hazard ratio [HR] 1.04, confidence interval [CI] 1.01-1.06), female sex (HR 2.49, CI 1.70-3.65), previous fracture (HR 2.30, CI 1.58-3.34), Asian race (HR 1.74, CI 1.09-2.78), vitamin D therapy requirement (HR 2.05, CI 1.31-3.21), HbA1c (HR 1.14, CI 1.00-1.32), prior cardiovascular event (HR 1.60, CI 1.10-2.33), and serum albumin (HR 0.41, CI 0.23-0.74) (lower albumin associated with greater risk). The goodness of fit of the various hypothesis sets was similar (AIC range 1870.92-1849.51, SBC range 1875.60-1948.04).

CONCLUSION

Independent predictors of fracture were identified in the CREDENCE participants with type 2 diabetes and CKD. Fracture prediction was not improved by models built on alternative pathophysiology hypotheses compared with traditional osteoporosis predictors.

Ankle-Brachial Index and Subsequent Risk of Severe Ischemic Leg Outcomes: The ARIC Study

Background Ankle-brachial index (ABI) is used to identify lower-extremity peripheral artery disease (PAD). However, its association with severe ischemic leg outcomes (eg, amputation) has not been investigated in the general population. Methods and Results Among 13 735 ARIC (Atherosclerosis Risk in Communities) study participants without clinical manifestations of PAD (mean age, 54 [SD, 5.8] years; 44.4% men; and 73.6% White) at baseline (1987-1989), we quantified the prospective association between ABI and subsequent severe ischemic leg outcomes, critical limb ischemia (PAD with rest pain or tissue loss) and ischemic leg amputation (PAD requiring amputation) according to discharge diagnosis. Over a median follow-up of ≈28 years, there were 221 and 129 events of critical limb ischemia and ischemic leg amputation, respectively. After adjusting for demographics, ABI ≤0.90 versus 1.11 to 1.20 had a ≈4-fold higher risk of critical limb ischemia and ischemic leg amputation (hazard ratios, 3.85 [95% CI, 2.09-7.11] and 4.39 [95% CI, 2.08-9.27]). The magnitude of the association was modestly attenuated after multivariable adjustment (hazard ratios, 2.44 [95% CI, 1.29-4.61] and 2.72 [95% CI, 1.25-5.91], respectively). ABI 0.91 to 1.00 and 1.01 to 1.10 were also associated with these severe leg outcomes, with hazard ratios ranging from 1.7 to 2.0 after accounting for potential clinical and demographic confounders. The associations were largely consistent across various subgroups. Conclusions In a middle-aged community-based cohort, lower ABI was independently and robustly associated with increased risk of severe ischemic leg outcomes. Our results further support ABI ≤0.90 as a threshold diagnosing PAD and also suggest the importance of recognizing the prognostic value of ABI 0.91 to 1.10 for limb prognosis.

Estimated Glomerular Filtration Rate (eGFR) based on cystatin C was associated with increased risk of hip and proximal humerus fractures in women and decreased risk of hip fracture in men, whereas eGFR based on creatinine was not associated with fracture risk in both sexes: The Tromsø Study

PURPOSE

Patients with end-stage kidney disease have an increased fracture risk. Whether mild to moderate reductions in kidney function is associated with increased fracture risk is uncertain. Results from previous studies may be confounded by muscle mass because of the use of creatinine-based estimates of the glomerular filtration rate (eGFRcre). We tested the hypothesis that lower eGFR within the normal range of kidney function based on serum cystatin C (eGFRcys) or both cystatin C and creatinine (eGFRcrecys) predict fractures better than eGFR based on creatinine (eGFRcre).

METHODS

In the Tromsø Study 1994-95, a cohort of 3016 women and 2836 men aged 50-84 years had eGFRcre, eGFRcys and eGFRcrecys estimated using the Chronic Kidney Disease Epidemiology Collaboration equations. Hazard ratios (HRs) (95% confidence intervals) for fracture were calculated in Cox's proportional hazards models and adjusted for age, height, body mass index, bone mineral density, diastolic blood pressure, smoking, physical activity, previous fracture, diabetes and cardiovascular disease.

RESULTS

During a median of 14.6 years follow-up, 232, 135 and 394 women and 118, 35 and 65 men suffered incident hip, proximal humerus and wrist fractures. In women, lower eGFRcre did not predict fracture, but the risk for hip and proximal humerus fracture increased per standard deviation (SD) lower eGFRcys (HRs 1.36 (1.16-1.60) and 1.33 (1.08-1.63)) and per SD lower eGFRcrecys (HRs 1.25 (1.08-1.45) and 1.30 (1.07-1.57)). In men, none of the eGFR estimates were related to increased fracture risk. In contrast, eGFRcys and eGFRcrecys were inversely associated with hip fracture risk (HRs 0.85 (0.73-0.99) and 0.82 (0.68-0.98)).

CONCLUSIONS

In women, each SD lower eGFRcys and eGFRcrecys increased the risk of hip and proximal humerus fracture by 25-36%, whereas eGFRcre did not. In men, none of the estimates of eGFR were related to increased fracture risk, and each SD lower eGFRcys and eGFRcrecys decreased the risk of hip fracture by 15-18%. The findings particularly apply to a cohort of generally healthy individuals with a normal kidney function. In future studies, the association of measured GFR using the gold standard method of iohexol clearance with fractures risk should be examined for causal inference. More clinical research is needed before robust clinical inferences can be made.

The Role of Bone Biopsy in the Management of CKD-MBD

A bone biopsy is still considered the gold standard for diagnosis of renal osteodystrophy. It allows to measure both static and dynamic parameters of bone remodeling and is the only method able to evaluate mineralization and allows analysis of both cortical and trabecular bone. Although bone volume can be measured indirectly by dual-energy X-ray absorptiometry, mineralization defects, bone metal deposits, cellular number/activity, and even turnover abnormalities are difficult to determine by techniques other than qualitative bone histomorphometry. In this review, we evaluate the role of bone biopsy in the clinical practice.

Incidence of fractures in middle-aged individuals with early chronic kidney disease: a population-based analysis of CARTaGENE

BACKGROUND

Previous studies evaluating fractures in chronic kidney disease (CKD) have mostly focused on hip or major fractures in aged populations with moderate to advanced CKD. We aimed at evaluating the association between early CKD and fracture incidence at all sites across age and sex in middle-aged individuals.

METHODS

We analyzed CARTaGENE, a prospective population-based survey of 40- to 69-year-old individuals from Quebec (Canada). Estimated glomerular filtration rate (eGFR) at baseline was evaluated categorically or continuously using restricted cubic splines. Fractures at any site (except toes, hand and craniofacial) for up to 7 years of follow-up were identified through administrative databases using a validated algorithm. Adjusted Cox models were used to evaluate the association of CKD with fracture. Interaction terms for age and sex were also added.

RESULTS

A total of 19 391 individuals (756 CKD Stage 3; 9114 Stage 2; 9521 non-CKD) were included and 829 fractures occurred during a median follow-up of 70 months. Compared with the median eGFR of 90 mL/min/1.73 m2, eGFRs of ≤60 mL/min/1.73 m2 were associated with increased fracture incidence in unadjusted and adjusted models [adjusted hazard ratio (HR) = 1.25 (95% confidence interval 1.05-1.49) for 60 mL/min/1.73 m2; 1.65 (1.14-2.37) for 45 mL/min/1.73 m2]. The eGFR was linearly associated with fracture incidence <75 mL/min/1.73 m2 [HR = 1.18 (1.04-1.34) per 10 mL/min/1.73 m2 decrease] but not above [HR = 0.98 (0.91-1.06) per 10 mL/min/1.73 m2 decrease). The effect of decreased eGFR on fracture incidence was more pronounced in younger individuals [HR = 2.45 (1.28-4.67) at 45 years; 1.11 (0.73-1.67) at 65 years] and in men.

CONCLUSIONS

Even early CKD increases fracture incidence, especially in younger individuals and in men.

Dietary Patterns and Progression of Impaired Kidney Function in Japanese Adults: A Longitudinal Analysis for the Fukushima Health Management Survey, 2011-2015

To investigate associations between dietary patterns and the risk of impaired kidney function, we analyzed data from 14,732 participants (40–89 years) who completed the baseline diet questionnaire of The Fukushima Health Management Survey in 2011. The incidence of chronic kidney disease (CKD) (estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² or proteinuria (≥1+ by dipstick test)) and annual changes in eGFR were assessed from 2012 to 2015. Three major dietary patterns were identified. The adjusted cumulative incidence ratio of the highest vs. lowest tertile of a vegetable diet scores was 0.90 (95% confidence interval (CI): 0.82, 1.00) for eGFR < 60 mL/min/1.73 m², 0.68 (95% CI: 0.52, 0.90) for proteinuria, and 0.88 (95% CI: 0.80, 0.97) for CKD (P for trend = 0.031, 0.007, and 0.005, respectively). The incident risk of CKD in the highest tertile of juice diet scores was 18% higher than the lowest tertile. The odds ratio of the highest vs. lowest tertile of vegetable diet scores was 0.85 (95% CI: 0.75, 0.98) in the rapidly decreasing eGFR group (P for trend = 0.009). We did not observe significant associations for the meat dietary pattern. A Japanese vegetable diet could reduce the risk of developing impaired kidney function and CKD.

Albuminuria, Kidney Function, and Cancer Risk in the Community

Few studies have comprehensively investigated the association of 2 key kidney disease measures, estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (ACR), with cancer incidence. In 8,935 participants at the baseline (1996-1998) from the Atherosclerosis Risk in Communities study, we quantified the associations of eGFR (based on creatinine and cystatin C) and ACR with cancer risk using Cox regression models adjusted for potential confounders. Due to changing guidelines for prostate cancer screening during the follow-up period, we investigated overall cancer, overall nonprostate cancer, and site-specific cancer. During a median follow-up of 14.7 years, 2,030 incident cancer cases occurred. In demographically adjusted models, low eGFR and high ACR were associated with cancer incidence (both overall and overall nonprostate cancer). These associations were attenuated after adjusting for other shared risk factors, with a significant association remaining only for ACR (≥103 compared with 5 mg/g) and overall nonprostate cancer. For site-specific cancer, only high ACR showed a significant association with lung and urinary tract cancers. Of these, the association between ACR and lung cancer appeared most robust in several sensitivity analyses. Kidney disease measures, particularly high ACR, were independently associated with cancer risk. The association between ACR and lung cancer was uniquely robust, warranting future studies to explore potential mechanisms.

Risk of fracture incidence in prostate cancer survivors: a nationwide cohort study in South Korea

PURPOSE

We analyzed the risk of fracture in prostate cancer (PC) survivors compared to that in the general population in South Korea and according to the primary treatment.

METHODS

From 2007 to 2013, a total of 41,733 PC survivors newly diagnosed with PC in South Korea were identified and matched to non-cancer controls. Cox proportional hazards regression analysis was performed to determine the relative risk of fracture.

RESULTS

Compared to the matched controls, PC survivors had a higher risk of fracture (adjusted hazard ratio (aHR) 1.39; 95% confidence interval (CI) 1.33-1.45). Compared to the matched controls, the active surveillance/watchful waiting and radiotherapy group showed a similar risk of fracture (aHR 1.08; 95% CI 0.98-1.20, and aHR 1.04; 95% CI 0.63-1.73, respectively). PC survivors who underwent surgery showed a lower risk of fracture (aHR 0.89; 95% CI 0.82-0.96), while those who underwent surgery + androgen deprivation therapy (ADT) (aHR 1.41; 95% CI 1.26-1.57), radiotherapy + ADT (aHR 1.86; 95% CI 1.50-2.32), and only ADT (aHR 1.92; 95% CI 1.82-2.02) showed a higher risk of fracture than the control group.

CONCLUSION

The risk of fracture differed according to the primary treatment method for PC; survivors who underwent surgery had a lower risk of fracture compared to that of the general population. However, PC survivors treated with ADT showed a higher risk of fracture than the other PC treatment groups or the general population. Therefore, more attention and preventive bone care are required for PC survivors who receive ADT.

Chronic Kidney Disease Increases the Risk of Hip Fracture: A Prospective Cohort Study in Korean Adults

This study was conducted to examine the association between renal function and hip fracture. We followed up 352,624 Korean adults, who participated in health examinations during 2009-2010 until 2013. Kidney function was assessed by creatinine-based estimated glomerular filtration rate (eGFR) and albuminuria using urine reagent strip results. The incidence of hip fracture was examined by hospital discharge records. Hazard ratios (HRs) for hip fracture were calculated using Cox proportional hazard models after adjusting for multiple confounders. During a mean follow-up of 4.0 years, 1177 participants suffered a hip fracture. Lower eGFR and more severe albuminuria were associated with a higher risk of hip fracture. The HRs for hip fracture were 1.89 (95% confidence interval [CI] 1.47-2.43) and 3.75 (95% CI 2.30-6.11) among participants with eGFRs of 30 to 44 and 15 to 29 mL/min/1.73m² relative to those with an eGFR ≥60 mL/min/1.73m² , respectively. The HRs were 1.30 (95% CI 1.02-1.65) for moderate albuminuria and 1.58 (95% CI 1.07-2.35) for severe albuminuria (p for trend = 0.002). Participants with albuminuria had a higher risk of hip fracture than those without albuminuria, even when they belonged to the same eGFR category (HR = 1.75 versus 3.30 for an eGFR of 30 to 44 mL/min/1.73m² ; HR = 2.72 versus 7.84 for an eGFR of 15 to 29 mL/min/1.73m² ). The effects of each 10 mL/min/1.73m² decrease in eGFR were stronger with advancing albuminuria severity (p_interaction = 0.016). In conclusion, both low eGFR and albuminuria were risk factors for incident hip fracture in Korean adults. Moreover, these factors exerted a synergistic effect on the risk of hip fracture. © 2020 American Society for Bone and Mineral Research.

Comparison of Fracture Prediction Tools in Individuals Without and With Early Chronic Kidney Disease: A Population-Based Analysis of CARTaGENE

Whether fracture prediction tools developed for the management of osteoporosis can be used in chronic kidney disease (CKD) is poorly known. We aimed to compare the performance of fracture prediction tools in non-CKD and CKD. We analyzed CARTaGENE, a population-based survey of 40-year-old to 69-year-old individuals recruited between 2009 and 2010. Renal function was assessed using baseline creatinine and categorized according to Kidney Disease Improving Global Outcomes (KDIGO) guidelines (non-CKD, stage 2, stage 3). Individuals without creatinine measurements or with advanced CKD (stage 4 or 5; prevalence <0.25%) were excluded. Predicted 5-year fracture probabilities (using Fracture Risk Assessment Tool [FRAX], QFracture, and Garvan) were computed at baseline. Fracture incidence (major fracture [MOF] or any fracture) was evaluated in administrative databases from recruitment to March 2016. Discrimination (hazard ratios [HRs] per standard deviation [SD] increase in Cox models; c-statistics) and calibration (standardized incidence ratios [SIRs] before and after recalibration) were assessed in each CKD strata. We included 19,393 individuals (9522 non-CKD; 9114 stage 2; 757 stage 3). A total of 830 patients had any fracture during follow-up, including 352 MOF. FRAX (HR = 1.89 [1.63-2.20] non-CKD; 1.64 [1.41-1.91] stage 2; 1.76 [1.10-2.82] stage 3) and QFracture (HR = 1.90 [1.62-2.22] non-CKD; 1.57 [1.35-1.82] stage 2; 1.86 [1.19-2.91] stage 3) discriminated MOF similarly in non-CKD and CKD. In contrast, the discrimination of Garvan for any fracture tended to be lower in CKD stage 3 compared to non-CKD and CKD stage 2 (HR = 1.36 [1.22-1.52] non-CKD; 1.34 [1.20-1.50] stage 2; 1.11 [0.79-1.55] stage 3). Before recalibration, FRAX globally overestimated fracture risk while QFracture and Garvan globally underestimated fracture risk. After recalibration, FRAX and QFracture were adequately calibrated for MOF in all CKD strata whereas Garvan tended to underestimate any fracture risk in CKD stage 3 (SIR = 1.31 [0.95-1.81]). In conclusion, the discrimination and calibration of FRAX and QFracture is similar in non-CKD and CKD. Garvan may have a lower discrimination in CKD stage 3 and underestimate fracture risk in these patients. © 2020 American Society for Bone and Mineral Research.

Dipstick proteinuria and cancer incidence: a nationwide population-based study

BACKGROUND

The association between proteinuria and malignancy has been frequently reported, but the issue is matter of controversy. Thus, in order to shed light on the association, we evaluated proteinuria as a risk factor for malignancy using the dataset from the Korean National Health Insurance System (NHIS).

METHODS

The subjects had undergone a medical examination in 2009 (index year) among the entire Korean adult population. From a pool of 10,505,818 participants, we excluded subjects who were younger than 19 years (15,327), had a previous diagnosis of cancer (152,095), had missing data for at least one variable (544,508), and were diagnosed with cancer within 1 year from the index year (79,501). Proteinuria was examined by a single dipstick urinalysis.

RESULTS

A total of 9,714,387 subjects were included in this study and tracked until December 31, 2017. The participants were divided into three groups; no (95.2%), trace (2.3%), and overt (2.5%) proteinuria. Over the duration of this study, we observed that overt proteinuria was associated with an increased risk of cancer development (all cancers) (adjusted HR 1.154, 95% CI 1.134-1.173) and the long-term risk of cancer incidence increased proportionally according to the changes in proteinuria over a four-year period.

LIMITATIONS

Our study population consisted of Korean adults. Therefore, the results of this study may not be generalized to other ethnicities.

CONCLUSIONS

We found a significant relationship between proteinuria and the risk of overall and site-specific cancer development. Further studies are needed to find an explanation of these findings.

Predictive value of quantitative ultrasound parameters in individuals with chronic kidney disease: A population-based analysis of CARTaGENE

BACKGROUND

The use of calcaneal quantitative ultrasound (QUS) to predict fractures has not been well studied in early CKD populations. We compared the association of QUS with incidental fractures and its predictive properties in non-CKD and CKD individuals.

METHODS

Analysis of a prospective population-based survey of 40- to 69-year-old individuals recruited between 2009 and 2010. QUS parameters (stiffness index [SI], speed of sound [SOS], broadband attenuation [BUA]) were measured at baseline. Renal function was measured using baseline creatinine and was classified into CKD stages (non-CKD, stage 2, stage 3). Fracture incidence at any site or at major osteoporotic fracture sites for up to 7 years of follow-up was identified in administrative databases using a validated algorithm. The association (age-adjusted hazard ratio per standard deviation decrease in Cox models), discrimination (c-statistic) and calibration (standardized incidence ratio [SIR]) of QUS parameters with fracture outcomes was computed in each CKD stratum.

RESULTS

We included 18,306 individuals (9,011 non-CKD; 8,595 CKD stage 2; 700 CKD stage 3). During a median follow-up of 70 months, we identified 782 fractures at any site and 326 major osteoporotic fractures. Although all QUS parameters (SI, SOS and BUA) were associated with any or major fracture incidence in non-CKD and CKD patients, the magnitude of these associations was lower for any fracture and for BUA. QUS parameters moderately discriminated incidental fractures across CKD strata but underestimated fracture incidence in CKD stage 3 even after adjustment for demographics and clinical risk factors. At a given QUS value, CKD stage 3 patients had higher fracture risk than non-CKD and CKD stage 2 patients.

CONCLUSIONS

QUS parameters are associated with fracture incidence in both non-CKD and CKD but underestimate fracture incidence in individuals with early CKD.

FGF23-klotho axis as predictive factors of fractures in type 2 diabetics with early chronic kidney disease

BACKGROUND

The aim of our study was to evaluate the relevance of FGF23-klotho axis in the predisposition for bone fractures in type 2 diabetic patients with early chronic kidney disease.

METHODS

In a prospective study we included 126 type 2 diabetic patients with CKD stages 2-3 (from 2010 to 2017). We used descriptive statistics, ANOVA and chi-square test. Our population was divided into two groups according to the occurrence of a bone fracture event or not, and the groups were compared considering several biological and laboratorial parameters. We employed a multiple regression model to identify risk factors for bone fracture events and hazard ratios (HR) were calculated using a backward stepwise likelihood ratio (LR) Cox regression.

RESULTS

Patients with a fracture event displayed higher levels of FGF-23, Phosphorus, PTH, TNF-α, OxLDL, HOMA-IR, calcium × phosphorus product and ACR and lower levels of Osteocalcin, α-Klotho, 25(OH)D3 and eGFR compared with patients without a fracture event (p < 0.001). The number of patients with a fracture event was higher than expected within inclining CKD stages (χ2, p = 0.06). The occurrence of fracture and the levels of TNF- α, klotho, 25(OH)D3 and OxLDL were found to predict patient entry into RRT (p < 0.05). Age, osteocalcin, α-Klotho and FGF-23 independently influenced the occurrence of bone fracture (p < 0.05).

CONCLUSIONS

α-Klotho and FGF-23 levels may have a good clinical use as biomarkers to predict the occurrence of fracture events.

The association between chronic kidney disease, falls, and fractures: a systematic review and meta-analysis

Patients with chronic kidney disease (CKD) are more likely to experience falls and fractures due to renal osteodystrophy and the high prevalence of risk factors for falls. However, it is not well established how great the risk is for falls and fractures for the different stages of CKD compared to the general population. The objective of this systematic review and meta-analysis was to assess whether, and in which degree, CKD was associated with falls and fractures in adults. A systematic search in PubMed, Embase, CINAHL, and The Cochrane Library was performed on 7 September 2018. All retrospective, cross-sectional, and longitudinal studies of adults (18 years of older) that studied the association between CKD, fractures, and falls were included. Additional studies were identified by cross-referencing. A total of 39 publications were included, of which two publications assessed three types of outcome and four publications assessed two types of outcome. Ten studies focused on accidental falling; seventeen studies focused on hip, femur, and pelvis fractures; seven studies focused on vertebral fractures; and thirteen studies focused on any type of fracture without further specification. Generally, the risk of fractures increased when kidney function worsened, with the highest risks in the patients with stage 5 CKD or dialysis. This effect was most pronounced for hip fractures and any type of fractures. Furthermore, results on the association between CKD and accidental falling were contradictory. Compared to the general population, fractures are highly prevalent in patients with CKD. Besides more awareness of timely fracture risk assessment, there also should be more focus on fall prevention.

Efficacy and safety of empagliflozin in older patients in the EMPA-REG OUTCOME® trial

OBJECTIVE

The risks of cardio-renal complications of diabetes increase with age. In the EMPA-REG OUTCOME® trial, empagliflozin reduced cardiovascular (CV) mortality by 38% in patients with type 2 diabetes (T2D) and CV disease. Here we compare outcomes with empagliflozin in older patients in EMPA-REG OUTCOME.

METHODS

Patients with T2D and CV disease were randomised to empagliflozin 10 or 25 mg, or placebo plus standard of care. In post hoc analyses, risks of 3-point major adverse CV events (3P-MACE: composite of CV death, non-fatal myocardial infarction (MI) or non-fatal stroke), CV death, hospitalisation for heart failure, all-cause mortality, all-cause hospitalisation and incident/worsening nephropathy were evaluated for empagliflozin versus placebo by baseline age (<65, 65 to <75, ≥75 years). Adverse events (AEs) were analysed descriptively.

RESULTS

Effect of empagliflozin on all outcomes was consistent across age categories (P ≥ 0.05 for interactions) except 3P-MACE. The 3P-MACE hazard ratios (HRs) were 1.04 (95% confidence interval [CI] 0.84, 1.29), 0.74 (0.58, 0.93) and 0.68 (0.46, 1.00) in patients aged <65, 65 to <75, and ≥75 years, respectively (P = 0.047 for treatment-by-age group interaction). Corresponding CV death HRs were 0.72 (95% CI 0.52, 1.01), 0.54 (0.37, 0.79) and 0.55 (0.32, 0.94), respectively (P = 0.484 for treatment-by-age group interaction). Across age categories, empagliflozin AEs reflected its known safety profile. Rates of bone fractures, renal AEs and diabetic ketoacidosis were similar between empagliflozin and placebo across age categories.

CONCLUSIONS

In the EMPA-REG OUTCOME trial, empagliflozin reduced risks of CV mortality, heart failure and renal outcomes, supporting its cardio-renal benefits in older patients.

Assessing risk factors of non-fatal outcomes amid a competing risk of mortality: the example of hip fracture

The Fine-Gray method is often used instead of Cox regression to account for competing risks of death in time-to-event analyses for non-fatal outcomes. A series of examples using well-known risk factors of hip fracture in an older cohort with substantial competing mortality demonstrates that the Fine-Gray approach can yield estimates that implausibly contradict long-established associations, while Cox regression preserves them. Cox regression is generally preferred for risk factor-outcome associations even in the presence of competing risk of death.

INTRODUCTION

Factors like age, sex, and race are associated not only with risk of hip fracture but also with mortality. Substantial misunderstanding remains regarding the appropriate statistical approach to account for the competing risk of mortality.

METHODS

In the Cardiovascular Health Study, an ongoing cohort study of 5888 older adults, we followed participants for incident hip fracture from their 1992-1993 visit through June 2014. We contrasted the conventional cause-specific Cox analysis, which censors individuals at the time of death, with the Fine-Gray (FG) approach, which extends participant follow-up even after death, to estimate the association of well-established demographic and clinical factors with incident hip fracture.

RESULTS

For age, current smoking and sex, Cox and FG methods yielded directionally concordant but quantitatively different strengths of association. For example, the Cox hazard ratio (HR) for a 5-year increment in age was 1.74 (95% CI, 1.61-1.87), while the corresponding FG HR was 1.16 (1.09-1.24). In contrast, the FG approach estimated a stronger association of hip fracture with sex. The two approaches yielded nearly identical results for race. For diabetes and kidney function, the estimates were discordant in direction, and the FG HRs suggested effects that were in the opposite direction of well-understood and widely accepted associations.

CONCLUSIONS

Cause-specific Cox models provide appropriate estimates of hazard for non-fatal outcomes like hip fracture even in the presence of competing risk of mortality. The Cox approach estimates hazard in the population of individuals who have not yet had an incident hip fracture and remain alive, which is typically the group of clinical interest. The Fine-Gray method estimates hazard in a hypothetical population that can yield misleading inferences about risk factors in populations of clinical interest.

Association of Bone Mineral Density With Fractures Across the Spectrum of Chronic Kidney Disease: The Regina CKD-MBD Study

Background:

Recent studies have demonstrated that measurement of areal bone mineral density by dual-energy x-ray absorptiometry (DXA) predicts fractures in patients with chronic kidney disease (CKD). However, whether fracture risk prediction through bone mineral density (BMD) is enhanced due to the assessment of biochemical markers of chronic kidney disease and mineral and bone disease (CKD-MBD) or clinical risk factors is not clear. We hypothesized that in a select cohort of patients managed in a CKD clinic, that combining T-Scores with biochemical markers would optimize fracture discrimination than using DXA alone.

Objective:

To examine the relationships among BMD, biochemical markers of CKD-MBD, and fracture risk across Kidney Disease Improving Global Outcomes (KDIGO) glomerular filtration rate (GFR) categories G3a to G5.

Design:

Retrospective study.

Setting:

Patients were recruited from the multidisciplinary CKD clinic, Regina General Hospital, Canada.

Patients:

A total of 374 patients who received a DXA scan upon initial referral to Regina Multidisciplinary CKD Program from January 31, 2001 to January 31, 2010, were included in this study. The patients were followed for a total of 5 years.

Methods:

We conducted a retrospective review of 374 consecutive patients who underwent DXA imaging at the point of entry into our multidisciplinary CKD program. Areal BMD, T- and Z-Scores were obtained at the lumbar spine, total hip, mean of left and right femoral neck, and the one-third radius. We collected data on demographic, cross-sectional biochemical markers of mineral metabolism and fractures (identified through self-reported questionnaires, hospital electronic medical records, and physician billing records). We were able to gather data on 8/11 variables of Fracture Risk Assessment (FRAX) tool.

Results:

In our cohort, 14.3% of GFR categories G3a and G3b, 15.7% of GFR category G4, and 19.7% of GFR category G5 experienced a clinical fracture during the study period. On multivariate analysis, each decline of 1.0 SD in total hip BMD T-Score was associated with a significant increase in the risk of fracture (OR = 1.46, 95% confidence interval [CI], 1.12-1.89). Adding CKD-MBD markers and clinical risk factors did not further contribute to the model. Low BMD was the only independent risk factor for fracture in patients with CKD.

Limitations:

Self-reporting by patients and administrative records were used to identify fractures. We did not perform spine imaging to ascertain morphometric vertebral fractures. We were unable to gather all 11 variables of FRAX score and information on ethnicity. We were unable to capture site of fracture (hips, spine, etc) from billing records. Albumin excretion rates were not collected at baseline. Treatment of the underlying bone disease with pharmacotherapeutic agents may have attenuated patients’ fracture risk and thus underestimated the association between BMD and future fracture.

Conclusions:

Our findings confirm that BMD predicts fracture. The addition of cross-sectional CKD-MBD parameters and clinical risk factors to BMD did not add to fracture prediction. Prospective studies should investigate the utility of longitudinal biochemical markers on improving fracture risk assessment.

Proteinuria Is Associated With Increased Risk of Fragility Fracture in Men With or at Risk of HIV Infection

BACKGROUND

Proteinuria has been associated with bone loss and fractures in general population, but data in HIV-infected population are lacking.

SETTING

Prospective, multicenter cohort study of men with or at risk of HIV infection.

METHODS

Between 2006 and 2015, urine protein measurements and bone fracture histories were ascertained semiannually in 947 HIV-infected (HIV+) and 969 HIV-uninfected (HIV-) men aged 40 years or older. Proteinuria was defined as protein-to-creatinine ratio ≥200 mg/g at ≥2 consecutive visits. Outcome measures (1) all fractures (excluding fractures of skull, face, and digits) and (2) fragility fractures (fractures of vertebral column, femur, wrist, and humerus). Multivariable Cox proportional hazards models assessed the association between proteinuria and fracture after adjusting for additional risk factors.

RESULTS

The overall period prevalence of proteinuria was higher among HIV+ than HIV- (29% vs 6%, P < 0.001). Men with proteinuria had a significantly higher risk of fragility fracture compared with men without proteinuria [adjusted hazard ratio (aHR) = 2.29 (1.12-4.66)] and did not differ by HIV serostatus (p-interaction = 0.83). The risk of all fractures was not statistically different between men with or without proteinuria [aHR = 1.31 (0.84-2.05)]. Among HIV+ men, the association between confirmed proteinuria and fragility fracture was attenuated [aHR = 2.12 (0.95-4.73)] after additional adjustment for CD4 T-cell count/mm, history of AIDS, the presence of detectable plasma HIV-1 RNA, and cumulative exposure to tenofovir disoproxil fumarate.

CONCLUSIONS

Proteinuria was more common in HIV+ than in HIV- men and was a strong independent risk factor for fragility fracture regardless of HIV serostatus. Proteinuria should prompt consideration of a thorough evaluation for bone disease among HIV+ persons.

Estimated Glomerular Filtration Rate and the Risk of Cancer

BACKGROUND AND OBJECTIVES

Community-based reports regarding eGFR and the risk of cancer are conflicting. We here explore plausible links between kidney function and cancer incidence in a large Scandinavian population-based cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the Stockholm Creatinine Measurements project, we quantified the associations of baseline eGFR with the incidence of cancer among 719,033 Swedes ages ≥40 years old with no prior history of cancer. Study outcomes were any type and site-specific cancer incidence rates on the basis of International Classification of Diseases-10 codes over a median follow-up of 5 years. To explore the possibility of detection bias and reverse causation, we divided the follow-up time into different time periods (≤12 and >12 months) and estimated risks for each of these intervals.

RESULTS

In total, 64,319 cases of cancer (affecting 9% of participants) were detected throughout 3,338,226 person-years. The relationship between eGFR and cancer incidence was U shaped. Compared with eGFR of 90-104 ml/min, lower eGFR strata associated with higher cancer risk (adjusted hazard ratio, 1.08; 95% confidence interval, 1.05 to 1.11 for eGFR=30-59 ml/min and adjusted hazard ratio, 1.24; 95% confidence interval, 1.15 to 1.35 for eGFR<30 ml/min). Lower eGFR strata were significantly associated with higher risk of skin, urogenital, prostate, and hematologic cancers. Any cancer risk as well as skin (nonmelanoma) and urogenital cancer risks were significantly elevated throughout follow-up time, but they were higher in the first 12 months postregistration. Associations with hematologic and prostate cancers abrogated after the first 12 months of observation, suggesting the presence of detection bias and/or reverse causation.

CONCLUSIONS

There is a modestly higher cancer risk in individuals with mild to severe CKD driven primarily by skin and urogenital cancers, and this is only partially explained by bias.

Fracture status in middle-aged individuals with early CKD: cross-sectional analysis of the CARTaGENE survey

Whether early chronic kidney disease (CKD) is associated with fracture in middle-aged adults is unclear. In a cross-sectional analysis of the CARTaGENE survey, we observed that early CKD was not associated with increased fracture, did not modify the association between calcaneal QUS and fracture, but modified the association between clinical, pharmacological parameters and fracture.

INTRODUCTION

The association between advanced CKD and increased fracture risk is well described. However, whether early CKD is associated with increased fractures, especially in middle-aged adults, is unclear. We aimed to assess if early CKD is associated with increased fracture status and whether early CKD status modifies the association between calcaneal quantitative ultrasound parameters, clinical, pharmacological parameters, and fractures.

METHODS

Cross-sectional analysis of CARTaGENE, a population-based survey of 40- to 69-year-old individuals. Individuals with CKD (stage 2, estimated glomerular filtration rate [eGFR] 60-89 ml/min/1.73 m²; stage 3, eGFR 30-59) were compared to non-CKD individuals (eGFR > 90). Fracture status (excluding face, toe, hand, and patella) was identified through a questionnaire at baseline. Calcaneal quantitative ultrasound (QUS) was measured in each participant.

RESULTS

A total of 17,608 individuals (656 CKD stage 3; 8227 stage 2; 8725 non-CKD) were included. CKD stage 2 and 3 individuals (mean eGFR 78 and 53 ml/min/1.73 m²) were older and had more diabetes, cardiovascular disease, and hypertension. Fracture status prevalence was 14.9% in CKD stage 3, 10.8% in CKD stage 2, and 9.0% in non-CKD individuals. Fracture status prevalence was similar between CKD and non-CKD individuals when stratified by age or after adjustment for demographic and clinical parameters. QUS stiffness index was associated with fracture status in both CKD stage 3 (standardized odds ratio [sOR] = 1.525 [1.200 to 1.939] per 1 SD decrease), stage 2 (sOR = 1.415 [1.310 to 1.530]), and non-CKD individuals (sOR = 1.477 [1.361 to 1.602]). The associations between blood pressure, antihypertensive, and fracture status followed a U-shape throughout the progression of CKD.

CONCLUSIONS

CKD stage 3 was not associated with an increase in fracture status. QUS parameters were similarly associated with fracture status in patients with and without CKD.

Mineral bone disorders in chronic kidney disease

As the GFR loss aggravates, the disturbed mineral metabolism worsens the bone microstructure and remodelling - scenario, which is known as CKD-mineral bone disease (MBD). CKD-MBD is characterized by : (i) abnormal metabolism of calcium, phosphorus, parathyroid hormone (PTH), or vitamin D; (ii) abnormalities in bone turnover, mineralization, volume linear growth or strength; (iii) soft-tissue calcifications, either vascular or extra-osseous. Uremic vascular calcification and osteoporosis are the most common complications related to CKD-MBD. Disregulated bone turnover by uremic toxin or secondary hyperparathyroidism disturbed bone mineralization and makes it difficult for calcium and inorganic phosphate to enter into bone, resulting in increased serum calcium and inorganic phosphate. Vascular calcification worsens by hyperphosphatemia and systemic inflammation. Since vitamin D deficiency plays an important role in renal osteodystrophy, supplement of nutritional vitamin D is important in treating uremic osteoporosis and vascular calcification at the same time. Its pleotropic effect improves the bone remodeling initiated by osteoblast and alleviates the risk factors for vascular calcification with less hypercalcemia than vitamin D receptor analogs. Therefore, nutritional vitamin D should be considered in managing CKDMBD.

Clinical epidemiology of infectious disease among patients with chronic kidney disease

Infectious disease is recognized as an important complication among patients with end-stage renal disease, contributing to excess morbidity and health care costs. However, recent epidemiological studies have revealed that even mild to moderate stages of chronic kidney disease (CKD) substantially increase risk of infection. Regarding underlying mechanisms, evidence suggests various aspects of altered immune response in patients with CKD including impaired function of T cells, B cells and neutrophil. Multiple conditions surrounding CKD, such as older age, diabetes, and cardiovascular disease are important contributors in the increased susceptibility to infection in this population. In addition, several mechanisms impairing immune function have been hypothesized including accumulated uremic toxins, increased oxidative stress, endothelial dysfunction, low-grade inflammation, and mineral and bone disorders. In terms of prevention strategies, influenza and pneumococcal vaccines are most feasible and important. Nevertheless, the extent of vaccine utilization in CKD has not been well documented. In addition, antibody response to vaccination may be reduced in CKD patients, and thus a vaccine delivery strategy (e.g., dose and frequency) may need to be optimized among patients with CKD. Through this review, we demonstrate that infection is a major but underrecognized complication of CKD. As CKD is recognized as a serious public health issue, dedicated research is needed to better characterize the burden of infectious disease associated with CKD, understand the pathophysiology of infection in patients with CKD, and develop effective strategies to prevent infection and its sequela in this high risk population.

Chronic kidney disease and cause-specific hospitalisation: a matched cohort study using primary and secondary care patient data

BACKGROUND

Although chronic kidney disease (CKD) is associated with various outcomes, the burden of each condition for hospital admission is unknown.

AIM

To quantify the association between CKD and cause-specific hospitalisation.

DESIGN AND SETTING

A matched cohort study in primary care using Clinical Practice Research Datalink linked to Hospital Episode Statistics in England.

METHOD

Patients with CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2 for ≥3 months) and a comparison group of patients without known CKD (matched for age, sex, GP, and calendar time) were identified, 2004-2014. Outcomes were hospitalisations with 10 common conditions as the primary admission diagnosis: heart failure; urinary tract infection; pneumonia; acute kidney injury (AKI); myocardial infarction; cerebral infarction; gastrointestinal bleeding; hip fracture; venous thromboembolism; and intracranial bleeding. A difference in the incidence rate of first hospitalisation for each condition was estimated between matched patients with and without CKD. Multivariable Cox regression was used to estimate a relative risk for each outcome.

RESULTS

In a cohort of 242 349 pairs of patients, with and without CKD, the rate difference was largest for heart failure at 6.6/1000 person-years (9.7/1000 versus 3.1/1000 person-years in patients with and without CKD, respectively), followed by urinary tract infection at 5.2, pneumonia at 4.4, and AKI at 4.1/1000 person-years. The relative risk was highest for AKI with a fully adjusted hazard ratio of 4.90, 95% confidence interval (CI) = 4.47 to 5.38, followed by heart failure with 1.66, 95% CI = 1.59 to 1.75.

CONCLUSION

Hospitalisations for heart failure, infection, and AKI showed strong associations with CKD in absolute and(or) relative terms, suggesting targets for improved preventive care.

Analysis of Fractures in Patients With Type 2 Diabetes Treated With Empagliflozin in Pooled Data From Placebo-Controlled Trials and a Head-to-Head Study Versus Glimepiride

OBJECTIVE

To assess the effect of empagliflozin on bone fractures and bone mineral density in patients with type 2 diabetes in pooled placebo-controlled trial data and a head-to-head study versus glimepiride.

RESEARCH DESIGN AND METHODS

Pooled data were analyzed from patients who were randomized 1:1:1 to empagliflozin 10 mg, empagliflozin 25 mg, or placebo in phase I-III clinical trials. Data were also analyzed from the EMPA-REG H2H-SU trial in which patients received empagliflozin 25 mg or glimepiride as an add-on to metformin for 104 weeks with a 104-week extension. Bone fracture adverse events (AEs) were evaluated through a search of investigator-reported (nonadjudicated) events.

RESULTS

In the pooled analysis, bone fracture AEs were reported in 119 of 4,221 (2.8%), 105 of 4,196 (2.5%), and 123 of 4,203 (2.9%) patients in the empagliflozin 10 mg, empagliflozin 25 mg, and placebo groups, respectively (rates of 1.55, 1.36, and 1.69/100 patient-years, respectively). In the EMPA-REG H2H-SU trial, bone fracture AEs were reported in 31 of 765 (4.1%) patients receiving empagliflozin 25 mg and in 33 of 780 (4.2%) patients receiving glimepiride (rates of 1.28 and 1.40/100 patient-years, respectively).

CONCLUSIONS

Empagliflozin did not increase the risk of bone fracture compared with placebo in a pooled analysis of >12,000 patients or compared with glimepiride in a 4-year head-to-head study.

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

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

Hip fracture incidence and mortality in chronic kidney disease: the GLOMMS-II record linkage cohort study

BACKGROUND

Individuals on renal replacement therapy (RRT) have increased fracture risk, but risk in less advanced chronic kidney disease (CKD) is unclear.

OBJECTIVE

To investigate CKD associations with hip fracture incidence and mortality.

DESIGN

Record linkage cohort study Grampian Laboratory Outcomes Mortality and Morbidity Study II.

SETTING

Single health region in Scotland.

PARTICIPANTS

All individuals (≥15 years) with sustained CKD stages 3-5 and those on RRT, and a 20% random sample of those with normal renal function, in the resident population in 2003.

OUTCOME MEASURES

Outcomes were (1) incident hip fracture measured with (A) admissions or (B) deaths, with at least 5.5 years follow-up and (2) post-hip fracture mortality. Unadjusted and adjusted, incident rate ratios (IRRs) and mortality rate ratios were calculated using Poisson regression.

RESULTS

Of 39 630 individuals identified in 2003 (41% males, mean age 63.3 years), 19 537 had CKD stages 3-5, 345 were on RRT and 19 748 had normal estimated glomerular filtration rate (eGFR). Hip fracture incidence, measured by admissions, was increased in CKD stages 3-5 (compared with normal eGFR), both overall (adjusted IRR 1.49 (95% CI 1.24 to 1.79)) and for individual CKD stages 3a, 3b and 4. Hip fracture incidence, measured using deaths, was increased in those with CKD stages 3b and 4. Post-hip fracture mortality was only increased in CKD stage 4. There was only a small number of individuals and events for CKD stage 5, resulting in insufficient statistical power.

CONCLUSION

Hip fracture incidence was higher in CKD stages 3-5 compared with normal eGFR. Post-hip fracture mortality was only increased in CKD stage 4. Reducing hip fracture incidence in CKD through regular fall and fracture risk review should reduce overall deaths after hip fracture in the population.

Frailty and chronic kidney disease: current evidence and continuing uncertainties

Frailty, the state of increased vulnerability to physical stressors as a result of progressive and sustained degeneration in multiple physiological systems, is common in those with chronic kidney disease (CKD). In fact, the prevalence of frailty in the older adult population is reported to be 11%, whereas the prevalence of frailty has been reported to be greater than 60% in dialysis-dependent CKD patients. Frailty is independently linked with adverse clinical outcomes in all stages of CKD and has been repeatedly shown to be associated with an increased risk of mortality and hospitalization. In recent years there have been efforts to create an operationalized definition of frailty to aid its diagnosis and to categorize its severity. Two principal concepts are described, namely the Fried Phenotype Model of Physical Frailty and the Cumulative Deficit Model of Frailty. There is no agreement on which frailty assessment approach is superior, therefore, for the time being, emphasis should be placed on any efforts to identify frailty. Recognizing frailty should prompt a holistic assessment of the patient to address risk factors that may exacerbate its progression and to ensure that the patient has appropriate psychological and social support. Adequate nutritional intake is essential and individualized exercise programmes should be offered. The acknowledgement of frailty should prompt discussions that explore the future care wishes of these vulnerable patients. With further study, nephrologists may be able to use frailty assessments to inform discussions with patients about the initiation of renal replacement therapy.

The epidemiology of wrist fractures in older men: the Osteoporotic Fractures in Men (MrOS) study

There is limited wrist fracture information on men. Our goal was to calculate frequency and identify risk factors for wrist fracture in the Osteoporotic Fractures in Men (MrOS) study. We confirmed that fracture history and certain medications are predictors, and identified novel predictors including markers of kidney function and physical performance.

INTRODUCTION

To calculate the incidence of wrist fractures and their risk factors in older community-dwelling men from the US Osteoporotic Fractures in Men (MrOS) study.

METHODS

Using triannual postcards, we identified incident wrist fractures (centrally confirmed by radiology) in men aged ≥ 65. Potential risk factors included the following: demographics, lifestyle, bone mineral density (BMD), selected medications, biomarkers, and physical function and performance measures. Both baseline and time-varying models were adjusted for age, race/ethnicity, MrOS geographic location, and competing mortality risks.

RESULTS

We observed 97 incident wrist fractures among 5875 men followed for an average of 10.8 years. The incidence of wrist fracture was 1.6 per 1000 person-years overall and ranged from 1.0 among men aged 65-69 to 2.4 among men age ≥ 80. Significant predictors included the following: fracture history after age 50 [hazard ratio (95% CI): 2.48 (1.65, 3.73)], high serum phosphate [1.25 (1.02, 1.53)], use of selective serotonin receptor inhibitor (SSRI) [3.60 (1.96, 6.63), decreased right arm BMD [0.49 (0.37, 0.65) per SD increase], and inability to perform the grip strength test [3.38 (1.24, 9.25)]. We did not find associations with factors commonly associated with wrist and other osteoporosis fractures like falls, diabetes, calcium and vitamin D intake, and alcohol intake.

CONCLUSIONS

Among these older, community-dwelling men, we confirmed that fracture history is a strong predictor of wrist fractures in men. Medications such as SSRIs and corticosteroids also play a role in wrist fracture risk. We identified novel risk factors including kidney function and the inability to perform the grip strength test.

Enhancing the Infrastructure of the Atherosclerosis Risk in Communities (ARIC) Study for Cancer Epidemiology Research: ARIC Cancer

Background: We describe the expansion of the Atherosclerosis Risk in Communities (ARIC) Study into a cancer cohort. In 1987 to 1989, ARIC recruited 15,792 participants 45 to 64 years old to be sex (55% female), race (27% black), and geographically diverse. ARIC has exceptional data collected during 6 clinical visits and calls every 6 months, repeated biospecimens, and linkage to Medicare claims data.Methods: We established a Cancer Coordinating Center to implement infrastructure activities, convened a Working Group for data use, leveraged ARIC staff and procedures, and developed protocols. We initiated a cancer-specific participant contact, added questions to existing contacts, obtained permission to collect medical records and tissue, abstracted records, linked with state cancer registries, and adjudicated cases and characterizing data.Results: Through 2012, we ascertained and characterized 4,743 incident invasive, first, and subsequent primary cancers among 4,107 participants and 1,660 cancer-related deaths. We generated a total cancer incidence and mortality analytic case file, and analytic case files for bladder, breast, colorectal, liver, lung, pancreas, and prostate cancer incidence, mortality, and case fatality. Adjudication of multiple data sources improved case records and identified cancers not identified via registries. From 2013 onward, we ascertain cases from self-report coupled with medical records. Additional cancer registry linkages are planned.Conclusions: Compared with starting a new cohort, expanding a cardiovascular cohort into ARIC Cancer was an efficient strategy. Our efforts yielded enhanced case files with 25 years of follow-up.Impact: Now that the cancer infrastructure is established, ARIC is contributing its unique features to modern cancer epidemiology research. Cancer Epidemiol Biomarkers Prev; 27(3); 295-305. ©2017 AACR.

Kidney Function, Proteinuria, and Cancer Incidence: The Korean Heart Study

BACKGROUND

Reported associations of estimated glomerular filtration rate (eGFR) with cancer risk are inconsistent, and data for the proteinuria-cancer relationship are sparse. We sought to quantify the associations of cancer incidence with eGFR and with proteinuria in a large population-based cohort.

STUDY DESIGN

A prospective cohort study.

SETTING & PARTICIPANTS

242,583 adults (30-74 years old) without a diagnosis of cancer at baseline in the Korean Heart Study, based on health checkups in 1996 to 2004 with follow-up until 2012.

PREDICTORS

Creatinine-based eGFR (≥90, 60-89, 45-59, and <45mL/min/1.73m²) and dipstick proteinuria (undetectable/trace, 1+, 2+, and ≥3+).

OUTCOMES

Overall and site-specific cancer incidence based on ICD-10 codes.

RESULTS

15,165 cases of cancer were detected. The relationship between eGFR and incidence of any cancer was J shaped, with the lowest risk at 45 to 59mL/min/1.73m². There was 44% higher risk for any cancer among those with eGFRs<45mL/min/1.73m² compared with those with eGFRs≥90mL/min/1.73m² (HR, 1.44; 95% CI, 1.11-1.87). High proteinuria was also associated with cancer risk, showing a dose-response relationship (HRs of 1.24 [95% CI, 1.13-1.35], 1.38 [95% CI, 1.17-1.63], and 1.66 [95% CI, 1.30-2.12] for 1+, 2+, and ≥3+ vs undetectable/trace). Examining site-specific cancer, eGFR<45 (vs ≥45) mL/min/1.73m² was significantly associated with kidney and ureteral cancer, multiple myeloma, and leukemia, whereas proteinuria ≥ 1+ (vs undetectable/trace) was related to a broader set of cancers (ie, stomach, rectal, liver, lung, ovarian, kidney, bladder, and multiple myeloma). After excluding study participants with follow-up less than 3 years, the associations remained consistent for kidney cancer and myeloma with eGFR and for rectal, liver, lung, and ovarian cancer with proteinuria.

LIMITATIONS

Relatively small number of participants with severely reduced eGFR or 70 years or older.

CONCLUSIONS

Kidney measures, particularly proteinuria, were associated with increased incidence of cancer. Future studies are needed to better understand the pathophysiologic mechanisms underlying these associations.

Vitamin D and osteoporosis in chronic kidney disease

Osteoporotic fractures are common in patients with chronic kidney disease (CKD). Morbidity and mortality are higher in CKD patients with a fracture than in the general population. The assessment of bone mineral density for fracture prediction may be useful at all CKD stages. It should be considered when this influences treatment decisions. Vitamin D deficiency is common in patients with CKD, particularly in patients with proteinuria, due to loss of 25-hydroxyvitamin D and its binding protein. Vitamin D supplementation should be prescribed early in the course of renal disease. For treatment and prevention of vitamin D deficiency in CKD patients cholecalciferol 800 IU/day or the equivalent per month is recommended just as in the general population.

Rediscovering Beta-2 Microglobulin As a Biomarker across the Spectrum of Kidney Diseases

There is currently an unmet need for better biomarkers across the spectrum of renal diseases. In this paper, we revisit the role of beta-2 microglobulin (β₂M) as a biomarker in patients with chronic kidney disease and end-stage renal disease. Prior to reviewing the numerous clinical studies in the area, we describe the basic biology of β₂M, focusing in particular on its role in maintaining the serum albumin levels and reclaiming the albumin in tubular fluid through the actions of the neonatal Fc receptor. Disorders of abnormal β₂M function arise as a result of altered binding of β₂M to its protein cofactors and the clinical manifestations are exemplified by rare human genetic conditions and mice knockouts. We highlight the utility of β₂M as a predictor of renal function and clinical outcomes in recent large database studies against predictions made by recently developed whole body population kinetic models. Furthermore, we discuss recent animal data suggesting that contrary to textbook dogma urinary β₂M may be a marker for glomerular rather than tubular pathology. We review the existing literature about β₂M as a biomarker in patients receiving renal replacement therapy, with particular emphasis on large outcome trials. We note emerging proteomic data suggesting that β₂M is a promising marker of chronic allograft nephropathy. Finally, we present data about the role of β₂M as a biomarker in a number of non-renal diseases. The goal of this comprehensive review is to direct attention to the multifaceted role of β₂M as a biomarker, and its exciting biology in order to propose the next steps required to bring this recently rediscovered biomarker into the twenty-first century.

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

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

Association of Increased Urinary Albumin With Risk of Incident Clinical Fracture and Rate of Hip Bone Loss: the Osteoporotic Fractures in Men Study

Prior studies suggest that increased urine albumin is associated with a heightened fracture risk in women, but results in men are unclear. We used data from Osteoporotic Fractures in Men (MrOS), a prospective cohort study of community-dwelling men aged ≥65 years, to evaluate the association of increased urine albumin with subsequent fractures and annualized rate of hip bone loss. We calculated albumin/creatinine ratio (ACR) from urine collected at the 2003-2005 visit. Subsequent clinical fractures were ascertained from triannual questionnaires and centrally adjudicated by review of radiographic reports. Total hip BMD was measured by DXA at the 2003-2005 visit and again an average of 3.5 years later. We estimated risk of incident clinical fracture using Cox proportional hazards models, and annualized BMD change using ANCOVA. Of 2982 men with calculable ACR, 9.4% had ACR ≥30 mg/g (albuminuria) and 1.0% had ACR ≥300 mg/g (macroalbuminuria). During a mean of 8.7 years of follow-up, 20.0% of men had an incident clinical fracture. In multivariate-adjusted models, neither higher ACR quintile (p for trend 0.75) nor albuminuria (HR versus no albuminuria, 0.89; 95% CI, 0.65 to 1.20) was associated with increased risk of incident clinical fracture. Increased urine albumin had a borderline significant, multivariate-adjusted, positive association with rate of total hip bone loss when modeled in ACR quintiles (p = 0.06), but not when modeled as albuminuria versus no albuminuria. Macroalbuminuria was associated with a higher rate of annualized hip bone loss compared to no albuminuria (-1.8% more annualized loss than in men with ACR <30 mg/g; p < 0.001), but the limited prevalence of macroalbuminuria precluded reliable estimates of its fracture associations. In these community-dwelling older men, we found no association between urine albumin levels and risk of incident clinical fracture, but found a borderline significant, positive association with rate of hip bone loss. © 2016 American Society for Bone and Mineral Research.

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

BACKGROUND

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

STUDY DESIGN

Cross-sectional study and prospective longitudinal cohort study.

SETTING & PARTICIPANTS

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

PREDICTOR

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

OUTCOMES

Bone fracture at any site.

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Frailty, Kidney Function, and Polypharmacy: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Frail individuals are at increased risk for poor outcomes, including adverse drug events. Kidney function is often compromised in frailty and is a key consideration in medication choice and dosing; however, creatinine-based measures of kidney function may be biased in frail individuals.

STUDY DESIGN

Observational study.

SETTING & PARTICIPANTS

4,987 community-dwelling older men and women with complete data who participated in visit 5 of the Atherosclerosis Risk in Communities (ARIC) Study (2011-2013).

PREDICTORS

Kidney measures included glomerular filtration rate (GFR) estimated using serum creatinine (eGFRcr) and serum cystatin C level (eGFRcys) and urine albumin-creatinine ratio.

OUTCOME

Frailty, defined using established criteria of 3 or more frailty characteristics (weight loss, slowness, exhaustion, weakness, and low physical activity).

RESULTS

341 (7%) participants were classified as frail, 1,475 (30%) had eGFRcr<60mL/min/1.73m2, 2,480 (50%) had eGFRcys<60mL/min/1.73m2, and 1,006 (20%) had albuminuria with albumin excretion ≥ 30mg/g. Among frail participants, prevalences of eGFRcr and eGFRcys<60mL/min/1.73m2 were 45% and 77%, respectively. Adjusted for covariates, frailty showed a moderate association with eGFRcr and a strong association with eGFRcys and albumin-creatinine ratio. Frail individuals with eGFRcr of 60 to <75mL/min/1.73m2 were frequently reclassified to lower eGFR categories using eGFRcys (49% to 45-<60, 32% to 30-<45, and 3% to <30mL/min/1.73m2). Hyperpolypharmacy (taking ≥10 classes of medications) was more common in frail individuals (54% vs 38% of nonfrail), including classes requiring kidney clearance (eg, digoxin) and associated with falls and subsequent complications (eg, hypnotic/sedatives and anticoagulants).

LIMITATIONS

Cross-sectional study design.

CONCLUSIONS

Frail individuals had a high prevalence of reduced kidney function, with large discrepancies when reduced kidney function was classified by eGFRcys versus eGFRcr. Given the substantial medication burden and uncertainty in chronic kidney disease classification, confirmation of kidney function with alternative biomarkers may be warranted to ensure careful prescribing practices in this vulnerable population.

CKD and Risk for Hospitalization With Infection: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Individuals on dialysis therapy have a high risk for infection, but risk for infection in earlier stages of chronic kidney disease has not been comprehensively described.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

9,697 participants (aged 53-75 years) in the Atherosclerosis Risk in Communities (ARIC) Study. Participants were followed up from 1996 to 1998 through 2011.

PREDICTORS

Estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (ACR).

OUTCOMES

Risk for hospitalization with infection and death during or within 30 days of hospitalization with infection.

RESULTS

During follow-up (median, 13.6 years), there were 2,701 incident hospitalizations with infection (incidence rate, 23.6/1,000 person-years) and 523 infection-related deaths. In multivariable analysis, HRs of incident hospitalization with infection as compared to eGFRs≥90mL/min/1.73m² were 2.55 (95% CI, 1.43-4.55), 1.48 (95% CI, 1.28-1.71), and 1.07 (95% CI, 0.98-1.16) for eGFRs of 15 to 29, 30 to 59, and 60 to 89mL/min/1.73m², respectively. Corresponding HRs were 3.76 (95% CI, 1.48-9.58), 1.62 (95% CI, 1.20-2.19), and 0.99 (95% CI, 0.80-1.21) for infection-related death. Compared to ACRs<10mg/g, HRs of incident hospitalization with infection were 2.30 (95% CI, 1.81-2.91), 1.56 (95% CI, 1.36-1.78), and 1.34 (95% CI, 1.20-1.50) for ACRs≥300, 30 to 299, and 10 to 29mg/g, respectively. Corresponding HRs were 3.44 (95% CI, 2.28-5.19), 1.57 (95% CI, 1.18-2.09), and 1.39 (95% CI, 1.09-1.78) for infection-related death. Results were consistent when separately assessing risk for pneumonia, kidney and urinary tract infections, bloodstream infections, and cellulitis and when taking into account recurrent episodes of infection.

LIMITATIONS

Outcome ascertainment relied on diagnostic codes at time of discharge.

CONCLUSIONS

Increasing provider awareness of chronic kidney disease as a risk factor for infection is needed to reduce infection-related morbidity and mortality.