Low hip bone mineral density predicts mortality in maintenance hemodialysis patients: a five-year follow-up study

Bone mineral density and related clinical and laboratory factors in peritoneal dialysis patients: Implications for bone health management

BACKGROUND

End-stage renal disease (ESRD) patients often experience accelerated bone turnover, leading to osteoporosis and osteopenia. This study aimed to determine the prevalence of osteoporosis in Peritoneal Dialysis (PD) patients using bone mineral density (BMD) measurements obtained through dual-energy X-ray absorptiometry (DEXA) scan and to explore any possible associations with clinical and biochemical factors.

METHODS

In this cross-sectional study, we enrolled 76 peritoneal dialysis patients from the dialysis center at An-Najah National University Hospital in Nablus, Palestine. We used the DEXA scan to measure BMD at the lumbar spine and hip, with values expressed as T-scores. We conducted a multivariate analysis to explore the relationship between BMD and clinical and biochemical parameters.

RESULTS

Over half (52.6%) of the PD patients had osteoporosis, with a higher prevalence observed among patients with lower BMI (p<0.001). Higher alkaline phosphatase levels were found among osteoporotic patients compared to non-osteoporotic patients (p = 0.045). Vitamin D deficiency was also prevalent in this population, affecting 86.6% of patients. No significant correlation was found between 25 vitamin D levels and BMD. No significant correlation was found between Parathyroid hormone (PTH) levels and BMD.

CONCLUSION

A notable proportion of PD patients experience reduced BMD. Our study found no correlation between vitamin D levels and BMD, but it highlighted the significant vitamin D deficiency in this population. Furthermore, our analysis indicated a positive correlation between BMI and BMD, especially in the femoral neck area. This underscores the significance of addressing bone health in PD patients to mitigate the risk of fractures and improve their overall well-being.

Evaluation of the Association between Low-Density Lipoprotein (LDL) and All-Cause Mortality in Geriatric Patients with Hip Fractures: A Prospective Cohort Study of 339 Patients

BACKGROUND

Many factors affect the prognosis of hip fractures in the elderly. Some studies have suggested a direct or indirect association among serum lipid levels, osteoporosis, and hip fracture risk. LDL levels were found to have a statistically significant nonlinear U-shaped relationship with hip fracture risk. However, the relationship between serum LDL levels and the prognosis of patients with hip fractures remains unclear. Therefore, in this study, we assessed the influence of serum LDL levels on patient mortality over a long-term follow-up period.

METHODS

Elderly patients with hip fractures were screened between January 2015 and September 2019, and their demographic and clinical characteristics were collected. Linear and nonlinear multivariate Cox regression models were used to identify the association between LDL levels and mortality. Analyses were performed using Empower Stats and R software.

RESULTS

Overall, 339 patients with a mean follow-up period of 34.17 months were included in this study. Ninety-nine patients (29.20%) died due to all-cause mortality. Linear multivariate Cox regression models showed that LDL levels were associated with mortality (HR = 0.69, 95%CI: 0.53, 0.91, p = 0.0085) after adjusting for confounding factors. However, the linear association was unstable, and nonlinearity was identified. An LDL concentration of 2.31 mmol/L was defined as the inflection point for prediction. A LDL level < 2.31 mmol/L was associated with mortality (HR = 0.42, 95%CI: 0.25, 0.69, p = 0.0006), whereas LDL > 2.31 mmol/L was not a risk factor for mortality (HR = 1.06, 95%CI: 0.70, 1.63, p = 0.7722).

CONCLUSIONS

The preoperative LDL level was nonlinearly associated with mortality in elderly patients with hip fractures, and the LDL level was a risk indicator of mortality. Furthermore, 2.31 mmol/L could be considered a predictor cut-off for risk.

Bone Mineral Density Is Inversely Associated With Mortality in Chronic Kidney Disease Patients: A Meta-Analysis

Low bone mineral density (BMD) is suggested to be associated with increased mortality in the general health population, but the relationship in chronic kidney disease (CKD) patients is still unclear. We performed a meta-analysis to investigate the association of BMD in different sites with risk of all-cause mortality in CKD patients. We searched PubMed, EMBASE, and Web of Science to identify eligible cohort studies that evaluated the association between BMD at different sites and risk of all-cause mortality in CKD patients. Twelve cohort studies were identified, which included 2828 CKD patients and 1052 deaths. Compared with normal/high level of total body BMD, lower total body BMD was associated with 25% higher risk of all-cause mortality. The pooled relative risk (RR) was 1.25 (95% confidence interval [CI] 1.09, 1.42) with little heterogeneity across studies. Regarding BMD measured at different sites, the risk of all-cause mortality was highest for lower BMD at hip/femoral neck (pooled RR = 1.69; 95% CI 1.20, 2.40). The pooled RRs were 1.26 (95% CI 1.04, 1.53) and 1.17 (95% CI 1.00, 1.37) for lower BMD at arm and spine, respectively. Similarly, the risk of death for per SD decrease in BMD was also higher at hip/femoral neck (pooled RR = 1.43, 95% CI 1.15, 1.77) compared with arm (pooled RR = 1.03, 95% CI 1.00, 1.06) and spine (pooled RR = 1.17, 95% CI 0.98, 1.39). In conclusion, lower BMD values at hip, arm, spine, as well as the whole body are associated with increased risk of all-cause mortality in CKD patients. The excess risk is highest for patients with lower BMD at hip/femoral neck, suggesting BMD measured at hip region may be the best indicator of mortality risk in CKD patients. © 2022 American Society for Bone and Mineral Research (ASBMR).

Is Radiographic Osteoporotic Hip Morphology A Predictor For High Mortality Following Intertrochanteric Femur Fractures?: Osteoporotic Hip Morphology & Mortality

INTRODUCTION

Factors related to mortality after intertrochanteric femur fractures (ITFF) have been investigated intensively in the literature except for radiographic osteoporotic hip morphology. The aim of this study is to investigate the relationship between mortality and radiographic osteoporotic hip morphology of patients with ITFF.

PATIENTS AND METHODS

Patients who underwent surgery between the dates of January 2012 and June 2018 due to ITFF were retrospectively reviewed. Osteoporotic status of the proximal femur was determined based on Singh Index grading and Dorr classification systems on preoperative anteroposterior pelvis radiographs of contralateral hips. The mortality rates of the patients were measured at 1st, 3rd, 6th, and 12th months. For controlling the confounders, multiple regression analysis was performed.

RESULTS

A total of 321 consecutive ITFFs were included in the study. The mean age of the patients was 81.5 ± 6.6 years. All patients were treated with osteosynthesis utilizing a cephalomedullary nail. The overall mortality rates at 1st, 3rd, 6th, and 12th months were 7.2%, 13.4%, 16.2%, 22.7%, respectively. There was 2.196 (1.140 - 4.229) folds increase in the mortality rate of patients with the Dorr type C femurs at 6th month (p=0.019). However, Singh index grade was not significantly associated with mortality.

CONCLUSION

Patients with Dorr type C femur seem to have 2.1 times increased mortality at 6th months following ITFFs. A simple anteroposterior pelvis radiograph obtained during the initial evaluation of the patients may be used to estimate the mortality rate after ITFF.

Sparing effect of peritoneal dialysis vs hemodialysis on BMD changes and its impact on mortality

INTRODUCTION

Bone loss in end stage renal disease (ESRD) patients associates with fractures, vascular calcification, cardiovascular disease (CVD) and increased mortality. We investigated factors associated with changes of bone mineral density (ΔBMD) during the initial year on dialysis therapy and associations of ΔBMD with subsequent mortality in ESRD patients initiating dialysis.

MATERIALS AND METHODS

In 242 ESRD patients (median age 55 years, 61% men) starting dialysis with peritoneal dialysis (PD; n = 138) or hemodialysis (HD; n = 104), whole-body dual-energy X-ray absorptiometry (DXA), body composition, nutritional status and circulating biomarkers were assessed at baseline and 1 year after dialysis start. We used multivariate linear regression analysis to determine factors associated with ΔBMD, and fine and gray competing risk analysis to determine associations of ΔBMD with subsequent mortality risk.

RESULTS

BMD decreased significantly in HD patients (significant reductions of BMD_total and BMD_{leg, trunk, rib, pelvis and spine}) but not in PD patients. HD compared to PD therapy associated with negative changes in BMD_{total (β=- 0.15)}, BMD_{head (β=- 0.14)}, BMD_{leg (β=- 0.18)} and BMD_{trunk (β=- 0.16)}. Better preservation of BMD associated with significantly lower all-cause mortality for ΔBMD_total (sub-hazard ratio, sHR, 0.91), ΔBMD_head (sHR 0.91) and ΔBMD_leg (sHR 0.92), while only ΔBMD_head (sHR 0.92) had a beneficial effect on CVD-mortality.

CONCLUSIONS

PD had beneficial effect compared with HD on BMD changes during first year of dialysis therapy. Better preservation of BMD, especially in bone sites rich in cortical bone, associated with lower subsequent mortality. BMD in cortical bone may have stronger association with clinical outcome than BMD in trabecular bone.

Association and predictive value of geriatric nutritional risk index, body composition, or bone mineral density in haemodialysis patients

AIM

Assess the association and predictive value of geriatric nutritional risk index (GNRI), body composition, and bone mineral density (BMD) in haemodialysis (HD) patients.

METHODS

Laboratory data, body composition parameters measured via body composition monitor, and radius, lumbar spine, femoral neck BMD measured using dual energy X-ray absorptiometry were assessed in all subjects on HD or online haemodiafiltration (HDF) at baseline. Regression analysis for GNRI, Cox proportional hazard analyses and comparison of multiple receiver operating characteristic (ROC) curves were performed.

RESULTS

Among all 264 patients, age was 65 ± 12 years and dialysis vintage was 79 (39-144) months. GNRI tertile (T)1, T2, and T3 were 88 (85-91), 94 (93-95), and 98 (97-101), respectively. Patients in GNRI T1 had lower fat tissue index (FTI), lean tissue index, and femoral neck, lumbar spine, and distal mid-third radius BMD, but higher overhydration/extracellular fluid than patients in GNRI T2 or T3 (P < .05). GNRI was significantly associated with FTI, lean tissue index, and femoral neck, lumbar spine, and distal mid-third radius BMD (P < .01). GNRI was a significant predictor of 2-year all-cause mortality (HR 0.92, P < .05). Area under the ROC curve for all-cause mortality using traditional risk factors (age, sex, diabetes mellitus, cardiovascular disease, use of vasopressors for dialysis-related hypotension, and C-reactive protein) was 0.67 and changed by adding GNRI (0.78, P < .05), FTI (0.75), or femoral neck BMD (0.66), respectively.

CONCLUSION

Associations between GNRI, body composition, and BMD were confirmed in HD patients. Combining GNRI with traditional risk factors improved mortality prediction in HD patients.

Can bone mineral density loss in the non-weight bearing distal forearm predict mortality?

PURPOSE

Low bone mineral density (BMD) is associated with increased risk of fractures and mortality. We investigated if rate of BMD loss in the distal forearm over seven years predicted mortality.

METHODS

1725 postmenopausal women and 1879 men aged 50-74 who participated in the longitudinal Tromsø Study waves 4 (1994-95) and 5 (2001-2002) were included. Cox regression models adjusted for lifestyle- and health related variables were used to assess associations between BMD change over seven years and subsequent mortality during up to 17 years of follow-up in participants with normal and low BMD at baseline.

RESULTS

Baseline BMD decreased and seven-year bone loss increased with increasing age. Overall, mortality rates were higher among those with low versus normal BMD (38 vs 19 per 1000 py in women, 56 vs 34 in men) and at higher bone loss rates (rate ratio high:low = 1.2 in women, 1.7 in men). BMD change was associated with increased mortality only in men with normal baseline BMD. In this group, men with a BMD loss of >4% had significantly higher mortality (HR 1.50, 95% CI 1.21, 1.87) than men with increased or unchanged BMD. BMD change was not significantly associated with increased mortality in women or in men with low BMD at baseline.

CONCLUSIONS

BMD loss in the distal forearm was associated with increased mortality in men with normal BMD at baseline, but not in women. We found no clear association between BMD loss and mortality in those with low BMD at baseline.

Bone mineral density and mortality in end-stage renal disease patients

Osteoporosis characterized by low bone mineral density (BMD) as assessed by dual-energy X-ray absorptiometry (DXA) is common among end-stage renal disease (ESRD) patients and associates with high fracture incidence and high all-cause mortality. This is because chronic kidney disease-mineral bone disorders (CKD-MBDs) promote not only bone disease (osteoporosis and renal dystrophy) but also vascular calcification and cardiovascular disease. The disturbed bone metabolism in ESRD leads to 'loss of cortical bone' with increased cortical porosity and thinning of cortical bone rather than to loss of trabecular bone. Low BMD, especially at cortical-rich bone sites, is closely linked to CKD-MBD, vascular calcification and poor cardiovascular outcomes. These effects appear to be largely mediated by shared mechanistic pathways via the 'bone-vascular axis' through which impaired bone status associates with changes in the vascular wall. Thus, bone is more than just the scaffolding that holds the body together and protects organs from external forces but is-in addition to its physical supportive function-also an active endocrine organ that interacts with the vasculature by paracrine and endocrine factors through pathways including Wnt signalling, osteoprotegerin (OPG)/receptor activator of nuclear factor-κB (RANK)/RANK ligand system and the Galectin-3/receptor of advanced glycation end products axis. The insight that osteogenesis and vascular calcification share many similarities-and the knowledge that vascular calcification is a cell-mediated active rather than a passive mineralization process-suggest that low BMD and vascular calcification ('vascular ossification') to a large extent represent two sides of the same coin. Here, we briefly review changes of BMD in ESRD as observed using different DXA methods (central and whole-body DXA) at different bone sites for BMD measurements, and summarize recent knowledge regarding the relationships between 'low BMD' and 'fracture incidence, vascular calcification and increased mortality' in ESRD patients, as well as potential 'molecular mechanisms' underlying these associations.

Bone mineral density at different sites and 5 years mortality in end-stage renal disease patients: A cohort study

BACKGROUND

Bone disease with osteoporosis and renal osteodystrophy is common in end stage renal disease (ESRD) patients and associates with cardiovascular disease (CVD) and increased morbimortality. We investigated associations of low bone mineral density (BMD) at various bone sites with five year all-cause and CVD mortality in ESRD patients.

METHODS

In a post hoc analysis of 426 ESRD patients (median age 56 years, 62% men) starting dialysis, BMD (whole-body dual-energy X-ray absorptiometry, DXA), body composition, nutritional status (subjective global assessment, SGA), handgrip strength (%HGS), Framingham CVD risk score (FRS) and biochemical biomarkers of nutrition and inflammation were assessed. We used the Fine and Gray competing risk regression analysis to assess survival analysis.

RESULTS

In multivariate logistic regression analysis, %HGS and intact parathyroid hormone associated with low tertile of: BMD_total, BMD_head and BMD_pelvis, after adjusting for FRS, SGA, %HGS, s-albumin, hsCRP, lean body mass index and year of recruitment. Patients with high FRS had low BMD_head (p<0.001). Low tertile of BMD_total (sHR, 1.53), BMD_head (sHR 1.54) and BMD_pelvis (sHR 1.60) associated with increased all-cause mortality whereas no such associations were found for the trabecular bone rich sites BMD arm, leg, trunk, rib or spine. Low tertile of BMD_total (sHR 1.94), BMD_head (sHR 1.68), BMD_leg (sHR 2.25) and BMD_pelvis (sHR 2.45) associated with increased CVD mortality whereas BMD at other sites did not associate with CVD mortality.

CONCLUSION

Low head and pelvis BMD, and low total BMD, as assessed by whole-body DXA, were independent predictors of increased risk of all-cause and CVD mortality. Cortical BMD appeared to have stronger association to survival in ESRD than trabecular BMD.

Differences in association of lower bone mineral density with higher coronary calcification in female and male end-stage renal disease patients

Background

Risk of cardiac events and cardiovascular disease (CVD) in end-stage renal disease (ESRD) patients are predicted by coronary artery calcification (CAC) independently. It is not clear to what extent low bone mineral density (BMD) is associated with higher risk of CAC and if sex interacts. We investigated the sex-specific associations of CAC score with total body BMD (tBMD) as well as with BMD of different skeletal sub-regions.

Methods

In 174 ESRD patients, median age 57 (10th–90th percentiles 29–75) years, 63% males, BMD (measured by dual-energy X-ray absorptiometry; DXA), CAC score (measured by cardiac CT) and circulating inflammatory biomarkers were analysed.

Results

A total of 104 (60%) patients with CAC > 100 AUs were older, had higher prevalence of both clinical CVD and diabetes, higher level of high sensitivity C-reactive protein, tumour necrosis factor, interleukin-6 and lower T-score of tBMD. Female patients had significantly lower tBMD and BMD of all skeletal sub-regions, except head, than male patients. Female patients with high CAC (> 100 AUs) had significantly decreased T-score of tBMD, and lower BMD of arms, legs than those low CAC (≤ 100 AUs); elevated CAC score were associated with tBMD, T-score, Z-score of tBMD and BMD of arms and legs, while no such differences was observed in males. Multivariate generalized linear model (GLM) analysis adjusted for age, diabetes and hsCRP showed that in females per SD higher CAC score (1057 AUs) was predicted by either per SD (0.13 g/cm²) lower tBMD or per SD (0.17 g/cm²) lower BMD at legs. No such associations were found in male ESRD patients.

Conclusions

In female, but not male, lower BMD, in particular sub-regions of legs, was associated with higher CAC score independently. Low BMD has the potential to identify increased risk for high CAC score in ESRD patients.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1235-z) contains supplementary material, which is available to authorized users.

Bone Mineral Density of the Radius Predicts All-Cause Mortality in Patients With Type 2 Diabetes: Diabetes Heart Study

This study aimed to determine the association between areal and volumetric bone mineral density (BMD) with all-cause mortality in patients with type 2 diabetes (T2D). Associations between BMD and all-cause mortality were examined in 576 women and 517 men with T2D in the Diabetes Heart Study. Volumetric BMD in the thoracic and lumbar spine was measured with quantitative computed tomography. Areal BMD (aBMD) in the lumbar spine, total hip, femoral neck, ultradistal radius, mid radius, and whole body was measured using dual X-ray absorptiometry. Association of BMD with all-cause mortality was determined using sequential models, stratified by sex: (1) unadjusted; (2) adjusted for age, race, smoking, alcohol, estrogen use; (3) model 2 plus history of cardiovascular disease, hypertension, and coronary artery calcification; (4) model 3 plus lean mass; and (5) model 3 plus fat mass. At baseline, mean age was 61.2 years for women and 62.7 years for men. At mean 11.0 ± 3.7 years' follow-up, 221 (36.4%) women and 238 (43.6%) men were deceased. In women, BMD at all skeletal sites (except spine aBMD and whole body aBMD) was inversely associated with all-cause mortality in the unadjusted model. These associations remained significant in the mid radius (hazard ratio per standard deviation  = 0.79; p = 0.0057) and distal radius (hazard ratio per standard deviation  = 0.76; p = 0.0056) after adjusting for all covariates, including lean mass. In men, volumetric BMD measurements but not aBMD were inversely associated with mortality and only in the unadjusted model. In this longitudinal study, lower baseline aBMD in the radius was associated with increased all-cause mortality in women with T2D, but not men, independent of other risk factors for death.

Changes in bone mineral density after total parathyroidectomy without autotransplantation in the end-stage renal disease patients with secondary hyperparathyroidism

Background

The patients with secondary hyperparathyroidism (SHPT) usually had reduced bone mineral density, which might lead to a substantial increase in osteoporosis, fracture and mortality. Although surgical intervention is effective in reducing parathyroid hormone (PTH) levels in suitable candidates refractory to medical therapy, the effect of surgery on bone mass changes still requires further evaluation. Thus, the aim of this study was to evaluate the characteristics of BMD changes after total parathyroidectomy (PTX) without autotransplantation and its associated factors.

Methods

The records of 34 patients who underwent successful total PTX without autotransplantation with a preoperative and postoperative dual energy X-ray absorptiometry (DEXA) scan in our institution within 4 years of operative intervention were reviewed. Correlation and regression analysis were used to identify factors that independently predict BMD changes.

Results

At baseline, we found that the prevalence of osteoporosis seemed to be much higher in the load-bearing lumbar spine than in the hip, varying greatly even between different lumbar vertebrae. The bone loss in SHPT had its predilection site in the load-bearing cancellous bone. After curative total PTX without autotransplantation, BMD improved significantly in both lumbar spine and hip overall. The largest increase in BMD occurred at L4 vertebrae with the lowest pre-operative BMD. At the most affected site L4, BMD improved in up to 94.1% of patients: 86.2% had significant improvement, 5.9% moderate improvement, and 5.9% declining bone mineral density. Correlation and regression analysis suggested that percentage changes in BMD were predicted negatively by the preoperative BMD and positively by the preoperative parathyroid mass but not intact PTH levels.

Conclusion

Total parathyroidectomy without autotransplantation could improve BMD of secondary hyperparathyroidism at L1-L4 and the hip. Furthermore, the large parathyroid glandular mass and the preoperative BMD predicted the BMD changes after surgery.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-0934-1) contains supplementary material, which is available to authorized users.

Bone mineral density of extremities is associated with coronary calcification and biopsy-verified vascular calcification in living-donor renal transplant recipients

Chronic kidney disease (CKD) mineral and bone disorders (CKD-MBD) may lead to low bone mineral density (BMD) and vascular calcification (VC), but links to the latter are unclear. Here we investigated associations between BMD, coronary artery calcium (CAC) scores, and histological signs of VC in end-stage renal disease (ESRD) patients undergoing living-donor kidney transplantation (LD-Rtx). In 66 ESRD patients (median age 45 years, 68% males), BMD (by dual-energy X-ray absorptiometry, DXA), CAC score (by computed tomography, CT; n = 54), and degree of VC score (graded by histological examination of epigastric artery specimens collected at LD-Rtx; n = 55) were assessed at the time of LD-Rtx. Of the patients, 26% had osteopenia and 7% had osteoporosis. Of those undergoing artery biopsy, 16% had extensive VC, and of those undergoing CT 28% had high CAC score (>100 Agatston units). CAC scores correlated with BMD of legs and pelvis. BMDs of leg and pelvic sub-regions were significantly lower in patients with extensive VC. In multivariate regression analysis adjusted for age and gender, lower BMD of leg sub-region was associated with CAC score >100 AUs and extensive VC, and patients with extensive VC had significantly higher CAC score. Both high CAC and extensive VC were independently predicted by low BMD of legs. Low BMD has the potential to identify ESRD patients at risk of vascular calcification.

Forearm bone mass predicts mortality in chronic hemodialysis patients

We aim to determine the relationship between bone mineral density (BMD), measured by T- and Z-score, and mortality risk in hemodialysis (HD) patients. We also investigate which are the most suitable skeletal sites for predicting mortality rate. We analyzed the survival of 102 patients who had been treated with chronic HD according to BMD. Patients with a T-score ≤2.5 at the middle, ultradistal and proximal part of the forearm had a higher mortality risk than those with a T-score of -2.5 or higher. Furthermore, no statistically significant association was found between loss of bone mass at other measuring points-lumbar spine (anteroposterior orientation from L1-L4) and hip (neck, trochanter, intertrochanter, total and Ward's triangle)-and mortality risk. We were also interested in exploring the relationship between Z-score at different skeletal regions and mortality risk. We found that patients with a Z-score of -1 or lower at all three parts of the forearm had a greater mortality risk. It is also worth noting that the Z-score at all three parts of the forearm was a more apparent predictor of mortality, compared to the T-score at the same skeletal regions. This empirical analysis showed that BMD assessments should be obtained at the forearm, due to the good predictability of this skeletal site regarding mortality of HD patients. Moreover, data concerning bone density should be reported as Z-scores.

Role of different imaging modalities of vascular calcification in predicting outcomes in chronic kidney disease

Vascular calcification (VC) is common among patients with chronic kidney disease (CKD). The severity of VC is associated with increased risk of cardiovascular events and mortality. Risk factors for VC include traditional cardiovascular risk factors as well as CKD-related risk factors such as increased calcium and phosphate load. VC is observed in arteries of all sizes from small arterioles to aorta, both in the intima and the media of arterial wall. Several imaging techniques have been utilized in the evaluation of the extent and the severity of VC. Plain radiographs are simple and readily available but with the limitation of decreased sensitivity and subjective and semi-quantitative quantification methods. Mammography, especially useful among women, offers a unique way to study breast arterial calcification, which is largely a medial-type calcification. Ultrasonography is suitable for calcification in superficial arteries. Analyses of wall thickness and lumen size are also possible. Computed tomography (CT) scan, the gold standard, is the most sensitive technique for evaluation of VC. CT scan of coronary artery calcification is not only useful for cardiovascular risk stratification but also offers an accurate and an objective analysis of the severity and progression.

Vertebral bone density associates with coronary artery calcification and is an independent predictor of poor outcome in end-stage renal disease patients

OBJECTIVE

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a major complication of end-stage renal disease (ESRD). Reduced bone mineral density (BMD) is associated with vascular calcification. Here we investigated associations between vertebral bone density (VBD) and coronary artery calcification (CAC), quantified by cardiac computed tomography (CT), and BMD quantified by dual-energy X-ray absorptiometry (DXA), and their relations with mortality.

METHODS

In 231 ESRD patients (median age 56years, 63% males) comprising incident dialysis patients, prevalent peritoneal dialysis patients and recipients of living donor kidney transplant, VBD (Hounsfield units, HUs) and CAC scores (Agatston units, AUs) were quantified by cardiac CT, and, in 143 of the patients, BMD was measured by DXA of total body. Metabolic and inflammation biomarkers potentially linked to CKD-MBD were also analysed.

RESULTS

Patients with low tertile of VBD were older and had more often cardiovascular disease (CVD), and higher HbA1c (non-diabetics), interleukin-6 and CAC score. Low VBD was independently associated with higher CAC score (>100 AUs) after adjustment for age, gender, diabetes, CVD, inflammation and cohorts. In Cox proportional hazards analysis, low VBD was independently associated with all-cause mortality after adjustment for age, gender, diabetes, CVD, inflammation and subjective global assessment (SGA). The root mean-squared error of prediction (RMSE) showed a good degree of association between VBD and BMD evaluated from DXA. In receiver-operator characteristics curve (ROC) analysis, lower VBD was more strongly associated with higher CAC score and all-cause mortality than BMD evaluated from DXA.

CONCLUSIONS

While assessments of BMD by DXA and CT showed good degree of agreement, associations of high CAC, and mortality, with low VBD were stronger than those based on low BMD by DXA. The strong independent associations of low VBD with high CAC score and increased mortality risk suggest that VBD may serve as an important prognosticator in ESRD patients.

Mineral and bone disorder after kidney transplantation

After successful kidney transplantation, accumulated waste products and electrolytes are excreted and regulatory hormones return to normal levels. Despite the improvement in mineral metabolites and mineral regulating hormones after kidney transplantation, abnormal bone and mineral metabolism continues to present in most patients. During the first 3 mo, fibroblast growth factor-23 (FGF-23) and parathyroid hormone levels decrease rapidly in association with an increase in 1,25-dihydroxyvitamin D production. Renal phosphate excretion resumes and serum calcium, if elevated before, returns toward normal levels. FGF-23 excess during the first 3-12 mo results in exaggerated renal phosphate loss and hypophosphatemia occurs in some patients. After 1 year, FGF-23 and serum phosphate return to normal levels but persistent hyperparathyroidism remains in some patients. The progression of vascular calcification also attenuates. High dose corticosteroid and persistent hyperparathyroidism are the most important factors influencing abnormal bone and mineral metabolism in long-term kidney transplant (KT) recipients. Bone loss occurs at a highest rate during the first 6-12 mo after transplantation. Measurement of bone mineral density is recommended in patients with estimated glomerular filtration rate > 30 mL/min. The use of active vitamin D with or without bisphosphonate is effective in preventing early post-transplant bone loss. Steroid withdrawal regimen is also beneficial in preservation of bone mass in long-term. Calcimimetic is an alternative therapy to parathyroidectomy in KT recipients with persistent hyperparathyroidism. If parathyroidectomy is required, subtotal to near total parathyroidectomy is recommended. Performing parathyroidectomy during the waiting period prior to transplantation is also preferred in patients with severe hyperparathyroidism associated with hypercalcemia.