Interventions for preventing bone disease in kidney transplant recipients

Impact of bisphosphonate treatment on bone mineral density after kidney transplant

BACKGROUND

Mineral bone disease is associated with chronic kidney disease and persists after kidney transplantation. Immunosuppressive treatment contributes to the pathogenesis of this disease. Bisphosphonate treatments have shown positive but indefinite results.

AIM

To evaluate the effectiveness and safety of bisphosphonate treatment on post kidney transplantation bone mineral density (BMD).

METHODS

We included kidney transplant recipients (KTRs) whose BMD was measured after the operation but before the initiation of treatment and their BMD was measured at least one year later. We also evaluated the BMD of KTRs using two valid measurements after transplantation who received no treatment (control group).

RESULTS

Out of 254 KTRs, 62 (39 men) were included in the study. Bisphosphonates were initiated in 35 KTRs in total (20 men), 1.1 ± 2.4 years after operation and for a period of 3.9 ± 2.3 years while 27 (19 men) received no treatment. BMD improved significantly in KTRs who received bisphosphonate treatments (from -2.29 ± 1.07 to -1.66 ± 1.09, P < 0.0001). The control group showed a non-significant decrease in BMD after 4.2 ± 1.4 years of follow-up after surgery. Kidney function was not affected by bisphosphonate treatment. In KTRs with established osteoporosis, active treatment had a similar and significant effect on those with osteopenia or normal bone mass.

CONCLUSION

In this retrospective study of KTRs receiving bisphosphonate treatment, we showed that active treatment is effective in preventing bone loss irrespective of baseline BMD.

Interventions for preventing bone disease in kidney transplant recipients

BACKGROUND

People who have chronic kidney disease (CKD) have important changes to bone structure, strength, and metabolism. Children experience bone deformity, pain, and delayed or impaired growth. Adults experience limb and vertebral fractures, avascular necrosis, and pain. The fracture risk after kidney transplantation is four times that of the general population and is related to Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) occurring with end-stage kidney failure, steroid-induced bone loss, and persistent hyperparathyroidism after transplantation. Fractures may reduce quality of life and lead to being unable to work or contribute to community roles and responsibilities. Earlier versions of this review have found low certainty evidence for effects of treatment. This is an update of a review first published in 2005 and updated in 2007.

OBJECTIVES

This review update evaluates the benefits and harms of interventions for preventing bone disease following kidney transplantation.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 16 May 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

RCTs and quasi-RCTs evaluating treatments for bone disease among kidney transplant recipients of any age were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial risks of bias and extracted data. Statistical analyses were performed using random effects meta-analysis. The risk estimates were expressed as a risk ratio (RR) for dichotomous variables and mean difference (MD) for continuous outcomes together with the corresponding 95% confidence interval (CI). The primary efficacy outcome was bone fracture. The primary safety outcome was acute graft rejection. Secondary outcomes included death (all cause and cardiovascular), myocardial infarction, stroke, musculoskeletal disorders (e.g. skeletal deformity, bone pain), graft loss, nausea, hyper- or hypocalcaemia, kidney function, serum parathyroid hormone (PTH), and bone mineral density (BMD).

MAIN RESULTS

In this 2019 update, 65 studies (involving 3598 participants) were eligible; 45 studies contributed data to our meta-analyses (2698 participants). Treatments included bisphosphonates, vitamin D compounds, teriparatide, denosumab, cinacalcet, parathyroidectomy, and calcitonin. Median duration of follow-up was 12 months. Forty-three studies evaluated bone density or bone-related biomarkers, with more recent studies evaluating proteinuria and hyperparathyroidism. Bisphosphonate therapy was usually commenced in the perioperative transplantation period (within 3 weeks) and regardless of BMD. Risks of bias were generally high or unclear leading to lower certainty in the results. A single study reported outcomes among 60 children and adolescents. Studies were not designed to measure treatment effects on fracture, death or cardiovascular outcomes, or graft loss.Compared to placebo, bisphosphonate therapy administered over 12 months in transplant recipients may prevent fracture (RR 0.62, 95% CI 0.38 to 1.01; low certainty evidence) although the 95% CI included the possibility that bisphosphonate therapy might make little or no difference. Fracture events were principally vertebral fractures identified during routine radiographic surveillance. It was uncertain whether any other drug class decreased fracture (low or very low certainty evidence). It was uncertain whether interventions for bone disease in kidney transplantation reduce all-cause or cardiovascular death, myocardial infarction or stroke, or graft loss in very low certainty evidence. Bisphosphonate therapy may decrease acute graft rejection (RR 0.70, 95% CI 0.55 to 0.89; low certainty evidence), while it is uncertain whether any other treatment impacts graft rejection (very low certainty evidence). Bisphosphonate therapy may reduce bone pain (RR 0.20, 95% CI 0.04 to 0.93; very low certainty evidence), while it was very uncertain whether bisphosphonates prevent spinal deformity or avascular bone necrosis (very low certainty evidence). Bisphosphonates may increase to risk of hypocalcaemia (RR 5.59, 95% CI 1.00 to 31.06; low certainty evidence). It was uncertain whether vitamin D compounds had any effect on skeletal, cardiovascular, death, or transplant function outcomes (very low certainty or absence of evidence). Evidence for the benefits and harms of all other treatments was of very low certainty. Evidence for children and young adolescents was sparse.

AUTHORS' CONCLUSIONS

Bisphosphonate therapy may reduce fracture and bone pain after kidney transplantation, however low certainty in the evidence indicates it is possible that treatment may make little or no difference. It is uncertain whether bisphosphonate therapy or other bone treatments prevent other skeletal complications after kidney transplantation, including spinal deformity or avascular bone necrosis. The effects of bone treatment for children and adolescents after kidney transplantation are very uncertain.

Need for quality improvement in renal systematic reviews

BACKGROUND AND OBJECTIVES

Systematic reviews of clinical studies aim to compile best available evidence for various diagnosis and treatment options. This study assessed the methodologic quality of all systematic reviews relevant to the practice of nephrology published in 2005.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched electronic databases (Medline, Embase, American College of Physicians Journal Club, Cochrane) and hand searched Cochrane renal group records. Clinical practice guidelines, case reports, narrative reviews, and pooled individual patient data meta-analyses were excluded. Methodologic quality was measured using a validated questionnaire (Overview Quality Assessment Questionnaire). For reviews of randomized trials, we also evaluated adherence to recommended reporting guidelines (Quality of Reporting of Meta-Analyses).

RESULTS

Ninety renal systematic reviews were published in year 2005, 60 of which focused on therapy. Many systematic reviews (54%) had major methodologic flaws. The most common review flaws were failure to assess the methodologic quality of included primary studies and failure to minimize bias in study inclusion. Only 2% of reviews of randomized trials fully adhered to reporting guidelines. A minority of journals (four of 48) endorsed adherence to consensus guidelines for review reporting, and these journals published systematic reviews of higher methodologic quality (P < 0.001).

CONCLUSIONS

The majority of systematic reviews had major methodologic flaws. The majority of journals do not endorse consensus guidelines for review reporting in their instructions to authors; however, journals that recommended such adherence published systemic reviews of higher methodologic quality.

Calcium and bone metabolism pre- and post-kidney transplantation

Chronic kidney disease (CKD) is associated with significant disturbances in bone and mineral metabolism, the manifestations of which are heterogeneous in their expression and clinical impact. Over the last 2 decades, advances in the management of CKD and improved outcomes of kidney transplantation have led to the emergence of post-transplantation bone disease as a serious cause of morbidity in long-term survivors. The management of post-kidney transplantation bone disease represents a difficult challenge because of its complex pathophysiology and the paucity of clinical data on effective therapies. The optimal management of disturbances of bone and mineral metabolism before kidney transplantation forms the cornerstone of their successful management after transplantation. Therapeutic strategies to effectively and safely decrease skeletal morbidity after kidney transplantation are not yet clearly established.

Interventions for preventing bone disease in kidney transplant recipients

BACKGROUND

Patients with chronic kidney disease have significant abnormalities of bone remodeling and mineral homeostasis and are at increased risk of fracture. The fracture risk for a kidney transplant recipient is four times that of the general population and higher than for a patient on dialysis. Randomised controlled trials (RCTs) report the use of bisphosphonates, vitamin D sterols, calcitonin, and hormone replacement therapy to treat bone disease following transplantation.

OBJECTIVES

To evaluate the use of interventions for treating bone disease following kidney transplantation.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library), Cochrane Renal Group's specialised register, MEDLINE, EMBASE, reference lists, and conference proceedings abstracts without language restriction. Date of last search: May 2006

SELECTION CRITERIA

RCTs and quasi-RCTs comparing different treatments for kidney transplant recipients of any age were selected. We excluded all other transplant recipients, including kidney-pancreas transplant recipients.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) with 95% confidence intervals (CI) for dichotomous variables and mean difference (MD) for continuous outcomes.

MAIN RESULTS

Twenty-four trials (1,299 patients) were included. No individual intervention (bisphosphonates, vitamin D sterol or calcitonin) was associated with a reduction in fracture risk compared with placebo. Combining results for all active interventions against placebo demonstrated any treatment of bone disease was associated with a reduction in the RR of fracture (RR 0.51, 95% CI 0.27 to 0.99). Bisphosphonates (any route), vitamin D sterol, and calcitonin all had a beneficial effect on the bone mineral density at the lumbar spine. Bisphosphonates and vitamin D sterol also had a beneficial effect on the bone mineral density at the femoral neck. Bisphosphonates had greater efficacy for preventing bone mineral density loss when compared head-to-head with vitamin D sterols. Few or no data were available for combined hormone replacement, testosterone, selective oestrogen receptor modulators, fluoride or anabolic steroids. Other outcomes including all-cause mortality and drug-related toxicity were reported infrequently.

AUTHORS' CONCLUSIONS

Treatment with a bisphosphonate, vitamin D sterol or calcitonin after kidney transplantation may protect against immunosuppression-induced reductions in bone mineral density and prevent fracture. Adequately powered trials are required to determine whether bisphosphonates are better than vitamin D sterols for fracture prevention in this population. The optimal route, timing, and duration of administration of these interventions remains unknown.

Failure of successful renal transplant to produce appropriate levels of 1,25-dihydroxyvitamin D

INTRODUCTION

Bone metabolism disturbances following renal transplantation (RT) are complex and multifactorial in origin. Abnormalities in 1,25-dihydroxyvitamin D levels in RT patients under treatment at our Bone Center prompted this retrospective study.

METHODS

Parameters of vitamin D metabolism were compared in RT patients and a cohort of patients with primary hyperparathyroidism (PHTP) who mimicked the hyperparathyroid state of the RT patients. Thirty-one RT recipients (from 300 reviewed) matched our inclusion criteria with a stable graft function for more than 1 year and a glomerular filtration rate (GFR) >50 mL/min per 1.73 m(2) (Group A); these were compared with 42 consecutive patients with PHTP who had been referred to the same Bone Center for treatment for over 1 month (Group B). Statistical analysis included the chi-square or Fisher's exact tests for categorical data and the Wilcoxon rank sum test for quantitative measures.

RESULTS

The mean (+/-SD) 1,25-dihydroxyvitamin D level was significantly lower (p < 0.001) in Group A patients (29.8 +/- 16.2) than in Group B patients (70.2 +/- 25.9) despite non-significant differences in the levels of parathyroid hormone (PTH) (mean: 184.0 vs.101.1;p < 0.29), phosphorus (mean: 3.2 vs. 3.1; p < 0.3) and 1,25-vitamin D (mean: 19.5 vs. 25.2; p < 0.06). Group A patients had lower levels (p < 0.05) of mean serum calcium and calculated GFR (9.3 mg/dL, 65.7 mL/min) than Group B patients (10.6 mg/dL, 97.6 mL/min). 1,25-Dihydroxyvitamin D significantly correlated with calcium (p < 0.001), 25-vitamin D (p < 0.005) and GFR (p < 0.001) in both groups, but there was a notable lack of association between 1,25-dihydroxyvitamin D and PTH (p < 0.64) or phosphorus (p < 0.26) in Group A patients. In this group, 1,25-dihydroxyvitamin D was not influenced by the type of immunosuppresion regimen (p < 0.06), use of biphosphonates (p < 0.73), presence of diabetes (p < 0.59), menopause in women (p < 0.08), season (p < 0.43) or race (p < 0.31). Our data indicate that 1,25-dihydroxyvitamin D metabolism remains disturbed for a considerable time after successful RT, with the result that the level of 1,25-dihydroxyvitamin D in RT patients is lower despite physiological signals that should stimulate its production. Our analysis of many clinical variables was unable to elucidate the underlying mechanism(s) for this disturbance.

CONCLUSION

Successful RT may not produce appropriate levels of 1,25-dihydroxyvitamin D commensurate to the elevated levels of PTH. This abnormality along with sustained hyperparathyroidism may contribute to bone loss following transplantation.

Medical Care of Kidney Transplant Recipients after the First Posttransplant Year

Kidney transplantation is the treatment of choice for patients with ESRD. Despite improvements in short-term patient and graft outcomes, there has been no major improvement in long-term outcomes. The use of kidney allografts from expanded-criteria donors, polyoma virus nephropathy, underimmunosuppression, and incomplete functional recovery after rejection episodes may play a role in the lack of improvement in long-term outcomes. Other factors, including cardiovascular disease, infections, and malignancies, also shorten patient survival and therefore reduce the functional life of an allograft. There is a need for interventions that improve long-term outcomes in kidney transplant recipients. These patients are a unique subset of patients with chronic kidney disease. Therefore, interventions need to address disease progression, comorbid conditions, and patient mortality through a multifaceted approach. The Kidney Disease Outcomes Quality Initiative from the National Kidney Foundation, the European Best Practice Guidelines, and the forthcoming Kidney Disease: Improving Global Outcomes clinical practice guidelines can serve as a cornerstone of this approach. The unique aspects of chronic kidney disease in the transplant recipient require the integration of specific transplant-oriented problems into this care schema and a concrete partnership among transplant centers, community nephrologists, and primary care physicians. This article reviews the contemporary aspects of care for these patients.