Ogo Egbuna

Effects of denosumab on fracture and bone mineral density by level of kidney function.

The incidences of osteoporosis and chronic kidney disease (CKD) both increase with increasing age, yet there is a paucity of data on treatments for osteoporosis in the setting of impaired kidney function. We examined the efficacy and safety of denosumab (DMAb) among subjects participating in the Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) Study. We estimated creatinine clearance (eGFR) using Cockcroft‐Gault and classified levels of kidney function using the modified National Kidney Foundation classification of CKD. We examined incident fracture rates; changes in bone mineral density (BMD), serum calcium, and creatinine; and the incidence of adverse events after 36 months of follow‐up in subjects receiving DMAb or placebo, stratified by level of kidney function. We used a subgroup interaction term to determine if there were differences in treatment effect by eGFR. Most (93%) women were white, and the mean age was 72.3 ± 5.2 years; 73 women had an eGFR of 15 to 29 mL/min; 2817, between 30 to 59 mL/min; 4069, between 60 to 89 mL/min, and 842 had an eGFR of 90 mL/min or greater. None had stage 5 CKD. Fracture risk reduction and changes in BMD at all sites were in favor of DMAb. The test for treatment by subgroup interaction was not statistically significant, indicating that treatment efficacy did not differ by kidney function. Changes in creatinine and calcium and the incidence of adverse events were similar between groups and did not differ by level of kidney function. It is concluded that DMAb is effective at reducing fracture risk and is not associated with an increase in adverse events among patients with impaired kidney function.

Elevated calcium phosphate product after renal transplantation is a risk factor for graft failure

Abstract:  Background:  Abnormal mineral metabolism is not uncommon after renal transplant (TXP). In dialysis patients, elevated serum phosphorous (P), calcium (Ca), CaP product, and parathyroid hormone (PTH) are associated with increased morbidity and mortality. The effect of these abnormalities on recipient and graft survival after renal transplantation is unknown.

A Cluster of Parvovirus B19 Infections in Renal Transplant Recipients: A Prospective Case Series and Review of the Literature

Up to 9% of renal transplant recipients have severe multifactorial erythropoietin‐resistant anemia. Human parvovirus B19 (PVB19) infection can cause severe anemia and is likely underreported. Sparse information on epidemiology and management in this population exists. To address these issues, after our first index case, we modified our clinical practice to prospectively screen patients with persistent hemoglobin (Hb) <10 mg/dL for PVB19 infection after excluding common causes of anemia including erythropoietin resistance. Potentially infected patients were further evaluated by serology, qualitative polymerase chain reaction (quPCR) and bone marrow biopsy (BMB) for cytomegalovirus, Epstein‐Barr virus, PVB19 and other etiologies. Over 3 months, 212 kidney recipients visited outpatient clinics. Of 52 recipients with anemia, 8 had an Hb <10 mg/dL with erythropoietin resistance and were screened for PVB19 infection. Three cases had PVB19 infection by quPCR and often‐inconclusive serology/BMB results. Cases had immunosuppression reduced and received IVIG (0.5 gm/kg × 4 doses) with recovery from anemia, viral clearance in two cases and one recurrence. PVB19‐mediated anemia occurred in up to three out of eight (38%) screened kidney recipients with Hb <10 mg/dL resistant to erythrypoietin. We recommend prospective risk stratification for this population, high indices of suspicion using at least qualitative techniques for diagnosis and treatment goal for viral eradication.

RANKL Inhibition With Denosumab Does Not Influence 3-Year Progression of Aortic Calcification or Incidence of Adverse Cardiovascular Events in Postmenopausal Women With Osteoporosis and High Cardiovascular Risk

Atherosclerosis and osteoporosis are chronic diseases that progress with age, and studies suggest aortic calcification, an indicator of atherosclerosis, is inversely associated with bone mineral density (BMD). The osteoprotegerin (OPG)/receptor activator of NF‐κB (RANK)/RANK ligand (RANKL) system has been proposed as a shared regulatory system for bone and vasculature. Denosumab (DMAb), a monoclonal antibody against RANKL, improved BMD and reduced fracture risk in the Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) trial. We evaluated whether or not treatment with DMAb influenced progression of aortic calcification (AC) and incidence of cardiovascular (CV) adverse events. We included 2363 postmenopausal women with osteoporosis (1142 placebo, 1221 DMAb), selected from 7808 participants in the FREEDOM trial (3906 placebo, 3902 DMAb), at high risk of CV events according to modified Raloxifene Use for the Heart (RUTH) criteria. CV adverse events were reported by participants. AC scores were assessed using a semiquantitative method from lateral spine X‐rays. Change in AC score from baseline to 12 (n = 1377), 24 (n = 1231), and 36 months (n = 1045) was calculated as AC score at follow‐up minus AC score at baseline. AC progression was defined as change in AC score >0. Baseline characteristics, CV risk factors, and AC scores were similar between treatment groups. Mean age of participants was 74 years (range, 60–90), 88% were white, and 77% had AC score >0 at baseline. Frequency of AC progression over 3 years did not differ between women in placebo (22%) and DMAb (22%) groups (p = 0.98). AC progression did not differ between treatment groups when analyzed by baseline estimated glomerular filtration rate or by baseline AC scores. Frequency of CV adverse events did not differ between placebo (40%) and DMAb (38%) groups (p = 0.26). In conclusion, DMAb treatment had no effect on progression of AC or incidence of CV adverse events compared to placebo.

The "House Calls" Trial: A Randomized Controlled Trial to Reduce Racial Disparities in Live Donor Kidney Transplantation: Rationale and Design☆ , ☆☆

Despite a substantially lower rate of live donor kidney transplantation among Black Americans compared to White Americans, there are few systematic efforts to reduce this racial disparity. This paper describes the rationale and design of a randomized controlled trial evaluating the comparative effectiveness of three different educational interventions for increasing live donor kidney transplantation in Black Americans. This trial is a single-site, urn-randomized controlled trial with a planned enrollment of 180 Black Americans awaiting kidney transplantation. Patients are randomized to receive transplant education in one of three education conditions: through group education at their homes (e.g., House Calls), or through group (Group-Based) or individual education (Individual Counseling) in the transplant center. The primary outcome of the trial is the occurrence of a live donor kidney transplant, with secondary outcomes including living donor inquiries and evaluations as well as changes in patient live donor kidney transplantation readiness, willingness, knowledge, and concerns. Sex, age, dialysis status, and quality of life are evaluated as moderating factors. Findings from this clinical trial have the potential to inform strategies for reducing racial disparities in live donor kidney transplantation. Similar trials have been developed recently to broaden the evaluation of House Calls as an innovative disparity-reducing intervention in kidney transplantation.

Making House Calls Increases Living Donor Inquiries and Evaluations for Blacks on the Kidney Transplant Waiting List

Background Blacks receive live donor kidney transplant (LDKT) less often than patients of all other races. We evaluated the effectiveness of educational interventions in removing barriers to LDKT for blacks. Methods Patients were randomized to three interventions in which health educator(s) delivered an intervention to (a) the patient and his/her guests in the patient’s home (house calls [HC], n=54), (b) clusters of patients and their guests in the transplant center (group based [GB], n=49), and (c) the individual patient alone in the transplant center (individual counseling [IC], n=49). Results At the 2-year endpoint, 15% (n=8), 8% (n=4), and 6% (n=3) of HC, GB, and IC patients, respectively, received LDKT (P=0.30). Patients in the HC group were more likely than patients in the GB and IC groups to have at least one donor inquiry (82% vs. 61% vs. 47%, P=0.001) and evaluation (65% vs. 39% vs. 27%, P<0.001). Patients in the HC group also were more likely to have higher knowledge, fewer concerns, and higher willingness to talk to others about donation 6 weeks after intervention. Conclusions These findings underscore the importance of including the patient’s social network in LDKT education and the potential of the HC intervention to reduce racial disparity in LDKT rates.

The full-length calcium-sensing receptor dampens the calcemic response to 1α,25(OH)2 vitamin D3 in vivo independently of parathyroid hormone

1Alpha,25(OH)(2) vitamin D(3) [1,25(OH)(2)D(3)] increases serum Ca(2+) concentration in vivo, an action counteracted by activation of the Ca(2+)-sensing receptor (CaSR), which decreases parathyroid hormone (PTH) secretion and increases renal Ca(2+) excretion. Relatively little is known of the role the CaSR plays in this response through its potentially direct actions in kidney, gut, and bone independently of PTH. We report PTH-independent roles of the CaSR in modulating the response to exogenous 1,25(OH)(2)D(3) in mice with targeted disruption of both the CaSR and PTH genes (C(-)P(-)) compared with that in mice with disruption of the PTH gene alone (C(+)P(-)) or wild-type mice (C(+)P(+)). After intraperitoneal injection of 0.5 ng/g body wt 1,25(OH)(2)D(3), peak calcemic responses were observed at 24 h in all three genotypes in association with 1) a greater increase in serum Ca(2+) in C(-)P(-) mice than in the other genotypes on a Ca(2+)-replete diet that was attenuated by a Ca(2+)-deficient diet and pamidronate, 2) increased urinary Ca(2+)-to-creatinine ratios (UCa/Cr) in the C(+)P(-) and C(+)P(+) mice but a lowered ratio in the C(-)P(-) mice on a Ca(2+)-replete diet, and 3) no increase in calcitonin (CT) secretion in the C(+)P(+) and C(+)P(-) mice and a small increase in the C(-)P(-) mice. PTH deficiency had the anticipated effects on the expression of key genes involved in Ca(2+) transport at baseline in the duodenum and kidney, and injection of 1,25(OH)(2)D(3) increased gene expression 8 h later. However, the changes in the genes evaluated did not fully explain the differences in serum Ca(2+) seen among the genotypes. In conclusion, mice lacking the full-length CaSR have increased sensitivity to the calcemic action of 1,25(OH)(2)D(3) in the setting of PTH deficiency. This is principally from enhanced 1,25(OH)(2)D(3)-mediated gut Ca(2+) absorption and decreased renal Ca(2+) excretion, without any differences in bone-related release of Ca(2+) or CT secretion among the three genotypes that could explain the differences in their calcemic responses.

Timing of sirolimus conversion influences recovery of renal function in liver transplant recipients

Abstract:  The long‐term use of calcineurin inhibitors (CNI) leads to renal dysfunction in many liver transplant (LT) recipients. The purpose of this analysis is to evaluate renal function in patients converted from CNI to sirolimus (SRL). From May 2002–November 2006, 137 LT were performed in 125 patients, 72 of which were converted to SRL. Evaluation of SRL conversion was stratified by early conversion (<90 d from LT) (EC) vs. late conversion (LC). Renal function was evaluated using the six‐point modification of diet in renal disease formula (estimated glomerular filtration rate [eGFR]). Forty‐two patients on SRL and 40 on CNI had at least three months of follow‐up and are included in the eGFR evaluation. At all time points after conversion, the EC group demonstrated a significantly higher mean eGFR than those in the LC group. A significant improvement in eGFR was seen within the EC group when comparing eGFR at time of conversion to eGFR at three, six, nine, and 12 months after conversion and last follow‐up. The only improvement in the LC group was from conversion to the three‐month time point. We conclude that EC to SRL results in a profound improvement in eGFR that begins at three months and is sustained beyond one yr.

CaSR-mediated interactions between calcium and magnesium homeostasis in mice

Calcium (Ca) and magnesium (Mg) homeostasis are interrelated and share common regulatory hormones, including parathyroid hormone (PTH) and vitamin D. However, the role of the calcium-sensing receptor (CaSR) in Mg homeostasis in vivo is not well understood. We sought to investigate the interactions between Mg and Ca homeostasis using genetic mouse models with targeted inactivation of PTH (PTH KO) or both PTH and the calcium-sensing receptor (CaSR) (double knockout, DKO). Serum Mg is lower in PTH KO and DKO mice than in WT mice on standard chow, whereas supplemental dietary Ca leads to equivalent Mg levels for all three genotypes. Mg loading increases serum Mg in all genotypes; however, the increase in serum Mg is most pronounced in the DKO mice. Serum Ca is increased with Mg loading in the PTH KO and DKO mice but not in the WT mice. Here, too, the hypercalcemia is much greater in the DKO mice. Serum and especially urinary phosphate are reduced during Mg loading, which is likely due to intestinal chelation of phosphate by Mg. Mg loading decreases serum PTH in WT mice and increases serum calcitonin in both WT and PTH KO mice but not DKO mice. Furthermore, Mg loading elevates serum 1,25-dihydroxyvitamin D in all genotypes, with greater effects in PTH KO and DKO mice, possibly due to reduced levels of serum phosphorus and FGF23. These hormonal responses to Mg loading and the CaSRs role in regulating renal function may help to explain changes in serum Mg and Ca found during Mg loading.

Outcomes with conversion from calcineurin inhibitors to sirolimus after renal transplantation in the context of steroid withdrawal or steroid continuation.

Background. A number of studies have suggested that conversion from calcineurin inhibitors (CNI) to sirolimus (SRL) can improve graft function in renal transplant patients. None of these studies has converted patients to SRL in the absence of steroids. Methods. We describe our experience with 278 renal transplants of which 153 were converted from CNI to SRL. The majority of patients had steroids withdrawn after 6 days. Almost all patients received antithymocyte globulin induction and were maintained on mycophenolate mofetil. Results. Six months after conversion, patients remaining on SRL therapy had a mean increase in estimated glomerular filtration rate of 6.93 mL/min/1.73 m2 (P<0.0001) compared with preconversion values. SRL-converted patients analyzed by intention-to-treat increased estimated glomerular filtration rate by 5.00 mL/min/1.73 m2 (P=0.0005). Eighty-one percent of patients remaining on SRL had a successful conversion, defined as stable or improved renal function at 6 months. The only factor predictive of unsuccessful conversion was urine protein-to-creatinine ratio more than 1. The benefits of SRL conversion were seen in patients at high immunological risk as well as those at lower risk. Proteinuria increased by a mean of 0.1 (P=0.43) at 6 months. Thirty-six percent of SRL-converted patients experienced adverse effects requiring conversion back to CNI. Rates of rejection, graft loss, and patient death with SRL conversion were low. Conclusions. The results from our clinical practice suggest that even in the absence of steroids, SRL conversion significantly improves renal function, with acceptable rates of adverse events.