Alendronate treatment in women with normal to severely impaired renal function: an analysis of the fracture intervention trial

Phosphate in Cardiovascular Disease: From New Insights Into Molecular Mechanisms to Clinical Implications

Hyperphosphatemia is a common feature in patients with impaired kidney function and is associated with increased risk of cardiovascular disease. This phenomenon extends to the general population, whereby elevations of serum phosphate within the normal range increase risk; however, the mechanism by which this occurs is multifaceted, and many aspects are poorly understood. Less than 1% of total body phosphate is found in the circulation and extracellular space, and its regulation involves multiple organ cross talk and hormones to coordinate absorption from the small intestine and excretion by the kidneys. For phosphate to be regulated, it must be sensed. While mostly enigmatic, various phosphate sensors have been elucidated in recent years. Phosphate in the circulation can be buffered, either through regulated exchange between extracellular and cellular spaces or through chelation by circulating proteins (ie, fetuin-A) to form calciprotein particles, which in themselves serve a function for bulk mineral transport and signaling. Either through direct signaling or through mediators like hormones, calciprotein particles, or calcifying extracellular vesicles, phosphate can induce various cardiovascular disease pathologies: most notably, ectopic cardiovascular calcification but also left ventricular hypertrophy, as well as bone and kidney diseases, which then propagate phosphate dysregulation further. Therapies targeting phosphate have mostly focused on intestinal binding, of which appreciation and understanding of paracellular transport has greatly advanced the field. However, pharmacotherapies that target cardiovascular consequences of phosphate directly, such as vascular calcification, are still an area of great unmet medical need.

Osteoporosis management in patients with chronic kidney disease (ERCOS Study): A challenge in nephrological care

Fracture risk assessment in patients with chronic kidney disease (CKD) has been included in the CKD-MBD ("Chronic Kidney Disease-Mineral and Bone Disorders") complex in international and national nephrology guidelines, suggesting for the first time the assessment of bone mineral density (BMD) if the results can influence therapeutic decision-making. However, there is very little information on actual clinical practice in this population. The main objective of the ERCOS (ERC-Osteoporosis) study is to describe the profile of patients with CKD G3-5D with osteoporosis (OP) and/or fragility fractures treated in specialized nephrology, rheumatology and internal medicine clinics in Spain. Fifteen centers participated and 162 patients (mostly women [71.2%] postmenopausal [98.3%]) with a median age of 77 years were included. Mean estimated glomerular filtration rate (eGFR) was 36 mL/min/1.73 m2 and 38% of the included patients were on dialysis. We highlight the high frequency of prevalent fragility fractures [37.7%), mainly vertebral (52.5%) and hip (24.6%)], the disproportionate history of patients with glomerular disease compared to purely nephrological series (corticosteroids) and undertreatment for fracture prevention, especially in nephrology consultations. This study is an immediate call to action with the dissemination of the new, more proactive, clinical guidelines, and underlines the need to standardize a coordinated and multidisciplinary care/therapeutic approach to these patients in an efficient way to avoid current discrepancies and therapeutic nihilism.

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.

Osteoporosis in Renal Disease

Introduction

Osteoporosis is a disorder characterized by decreased bone mass and skeletal fragility with increased fracture risk. Chronic kidney disease presents with wide range of bone metabolic disorders, including osteoporosis. Osteoporosis prevalence is high in early stages of CKD; whereas in late stages, it coexists with renal osteodystrophy.

Risk factors

Risk factors for osteoporosis include advancing age, low bone mineral density (BMD), glucocorticoid therapy, smoking, alcohol intake, etc.

Diagnosis

The diagnosis of osteoporosis in renal disease is made after assessment of BMD, in addition to exclusion of chronic kidney disease-mineral bone disorder (CKD-MBD), eliciting history of prior fragility fractures and relevant laboratory investigations.

Management

The treatment of osteoporosis varies with the different stages of CKD, with management in stages 1-3 being similar to the general population. Special emphasis must be laid on prevention of fractures as well.

Clinical Features Associated With Rate of Fractures in Patients With Systemic Sclerosis: A US Cohort Study

OBJECTIVE

Systemic sclerosis (SSc) is associated with several specific risk factors for fracture due to the complications of the disease and related medications. The present study was undertaken to examine the relationship between SSc-associated clinical features and fracture rate in a large US cohort.

METHODS

Participants with SSc in FORWARD, The National Databank for Rheumatic Diseases, were included (1998-2019). Age- and sex-matched individuals with osteoarthritis (OA) from the same database were included as comparators. The primary end point was self-reported major osteoporotic fracture. Cox proportional hazards models were used to study the associations between risk factors and fractures.

RESULTS

The study included 922 individuals (SSc patients, n = 154; OA patients, n = 768). Eighty-seven percent were female, with a mean age of 57.8 years. Fifty-one patients developed at least 1 fracture during a median of 4.2 years (0.5-22.0 years) of follow-up. Patients with SSc had more frequent fractures compared to OA comparators (hazard ratio [HR] 2.38 [95% confidence interval (95% CI) 1.47-3.83]). Among patients with SSc, a higher Rheumatic Disease Comorbidity Index score (HR 1.45 [95% CI 1.20-1.75]) and a higher Health Assessment Questionnaire disability index score (HR 3.83 [95% CI 2.12-6.93]) were associated with more fractures. Diabetes mellitus (HR 5.89 [95% CI 2.51-13.82]) and renal disease (HR 2.43 [95% CI 1.10-5.37]) were independently associated with fracture among SSc patients relative to SSc patients without these comorbidities.

CONCLUSION

Our findings highlight factors associated with fracture among patients with SSc. Disability as measured by the HAQ DI is a particularly strong indicator of fracture rate in SSc. Improving SSc patients' functional status, where possible, may lead to better long-term outcomes.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Effectiveness and Safety of Treatments to Prevent Fractures in People With Low Bone Mass or Primary Osteoporosis: A Living Systematic Review and Network Meta-analysis for the American College of Physicians

BACKGROUND

The prevalence of osteoporosis is increasing in the United States.

PURPOSE

To evaluate low bone mass and osteoporosis treatments to prevent fractures.

DATA SOURCES

Ovid MEDLINE ALL, Ovid Evidence Based Medicine Reviews: Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and ClinicalTrials.gov from 2014 through February 2022.

STUDY SELECTION

Adults receiving eligible interventions for low bone mass or osteoporosis. Randomized controlled trials (RCTs) for fracture outcomes, and RCTs and large observational studies (n ≥1000) for harms.

DATA EXTRACTION

Abstracted by 1 reviewer and verified by a second. Independent, dual assessments of risk of bias and certainty of evidence (CoE).

DATA SYNTHESIS

We included 34 RCTs (in 100 publications) and 36 observational studies. Bisphosphonates and denosumab reduced hip, clinical and radiographic vertebral, and other clinical fractures in postmenopausal females with osteoporosis (moderate to high CoE). Bisphosphonates for 36 months or more may increase the risk for atypical femoral fractures (AFFs) and osteonecrosis of the jaw (ONJ), but the absolute risks were low. Abaloparatide and teriparatide reduced clinical and radiographic vertebral fractures but increased the risk for withdrawals due to adverse events (WAEs; moderate to high CoE). Raloxifene and bazedoxifene for 36 months or more reduced radiographic vertebral but not clinical fractures (low to moderate CoE). Abaloparatide, teriparatide, and sequential romosozumab, then alendronate, may be more effective than bisphosphonates in reducing clinical fractures for 17 to 24 months in older postmenopausal females at very high fracture risk (low to moderate CoE). Bisphosphonates may reduce clinical fractures in older females with low bone mass (low CoE) and radiographic vertebral fractures in males with osteoporosis (low to moderate CoE).

LIMITATION

Few studies examined participants with low bone mass, males, or Black-identifying persons, sequential therapy, or treatment beyond 3 years.

CONCLUSION

Bisphosphonates, denosumab, abaloparatide, teriparatide, and romosozumab, followed by alendronate, reduce clinical fractures in postmenopausal females with osteoporosis. Abaloparatide and teriparatide increased WAEs; longer duration bisphosphonate use may increase AFF and ONJ risk though these events were rare.

PRIMARY FUNDING SOURCE

American College of Physicians. (PROSPERO: CRD42021236220).

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Is Adynamic Bone Always a Disease? Lessons from Patients with Chronic Kidney Disease

Renal osteodystrophy (ROD) is a common complication of end-stage kidney disease that often starts early with loss of kidney function, and it is considered an integral part in management of patients with chronic kidney disease (CKD). Adynamic bone (ADB) is characterized by suppressed bone formation, low cellularity, and thin osteoid seams. There is accumulating evidence supporting increasing prevalence of ADB, particularly in early CKD. Contemporarily, it is not very clear whether it represents a true disease, an adaptive mechanism to prevent bone resorption, or just a transitional stage. Several co-players are incriminated in its pathogenesis, such as age, diabetes mellitus, malnutrition, uremic milieu, and iatrogenic factors. In the present review, we will discuss the up-to-date knowledge of the ADB and focus on its impact on bone health, fracture risk, vascular calcification, and long-term survival. Moreover, we will emphasize the proper preventive and management strategies of ADB that are pivotal issues in managing patients with CKD. It is still unclear whether ADB is always a pathologic condition or whether it can represent an adaptive process to suppress bone resorption and further bone loss. In this article, we tried to discuss this hard topic based on the available limited information in patients with CKD. More studies are needed to be able to clearly address this frequent ROD finding.

Pediatric CKD-MBD: existing and emerging treatment approaches

The effects of bone and mineral metabolism on skeletal formation, as well as vascular and soft tissue calcifications, define chronic kidney disease-metabolic bone disease (CKD-MBD). Treatment recommendations center on establishing adequate vitamin D status, phosphate control through diet restriction and phosphate binders, and the use of vitamin D analogs for specific indications. Several emerging bone-promoting therapies have now been studied in adults with CKD, including bisphosphonates and denosumab. These approaches are associated with improved bone mass and, in some cases, decreased fracture rates in adults with CKD-MBD and are of potential interest for some children with CKD-MBD. In children with CKD and immobilization and/or muscle weakness, bisphosphonates appear to be an effective treatment to increase bone mass; baseline assessment and careful monitoring of bone density and/or bone biopsy findings are important in consideration of any new bone therapies for children with CKD-MBD.

Management of osteoporosis in patients with chronic kidney disease

Patients with CKD have a 4-fivefold higher rate of fractures. The incidence of fractures increases with deterioration of kidney function. The process of skeletal changes in CKD patients is characterized by compromised bone strength because of deterioration of bone quantity and/or quality. The fractures lead to a deleterious effect on the quality of life and higher mortality in patients with CKD. The pathogenesis of bone loss and fracture is complex and multi-factorial. Renal osteodystrophy, uremic milieu, drugs, and systemic diseases that lead to renal failure all contribute to bone damage in CKD patients. There is no consensus on the optimal diagnostic method of compromised bone assessment in patients with CKD. Bone quantity and mass can be assessed by dual-energy x-ray absorptiometry (DXA) or quantitative computed tomography (QCT). Bone quality on the other side can be assessed by non-invasive methods such as trabecular bone score (TBS), high-resolution bone imaging methods, and invasive bone biopsy. Bone turnover markers can reflect bone remodeling, but some of them are retained by kidneys. Understanding the mechanism of bone loss is pivotal in preventing fracture in patients with CKD. Several non-pharmacological and therapeutic interventions have been reported to improve bone health. Controlling laboratory abnormalities of CKD-MBD is crucial. Anti-resorptive therapies are effective in improving BMD and reducing fracture risk, but there are uncertainties about safety and efficacy especially in advanced CKD patients. Accepting the prevalent of low bone turnover in patients with advanced CKD, the osteo-anabolics are possibly promising. Parathyroidectomy should be considered a last resort for intractable cases of renal hyperparathyroidism. There is a wide unacceptable gap in osteoporosis management in patients with CKD. This article is focusing on the updated management of CKD-MBD and osteoporosis in CKD patients. Chronic kidney disease deteriorates bone quality and quantity. The mechanism of bone loss mainly determines pharmacological treatment. DXA and QCT provide information about bone quantity, but assessing bone quality, by TBS, high-resolution bone imaging, invasive bone biopsy, and bone turnover markers, can guide us about the mechanism of bone loss.

Efficacy and Safety of Romosozumab Among Postmenopausal Women With Osteoporosis and Mild-to-Moderate Chronic Kidney Disease

Patients with osteoporosis and chronic kidney disease (CKD) are at increased risk of fracture and associated negative outcomes, including increased mortality. The present post hoc analysis of two randomized, multicenter, phase 3 clinical trials-Fracture Study in Postmenopausal Women with Osteoporosis (FRAME) and Active-Controlled Fracture Study in Postmenopausal Women with Osteoporosis at High Risk (ARCH)-investigated the efficacy and safety of romosozumab in postmenopausal women with osteoporosis and mild-to-moderate CKD. The analysis included data from 7147 patients from FRAME and 4077 from ARCH. Eighty-one percent of patients from FRAME and 85% from ARCH had mild or moderate reduction in estimated glomerular filtration rate (eGFR) at baseline, and part of this reduction is likely age related. During the 1-year double-blind phases of the trials, patients received romosozumab 210 mg sc or placebo monthly in FRAME and romosozumab 210 mg sc monthly or alendronate 70 mg po weekly in ARCH. Bone mineral density (BMD) at the lumbar spine, total hip, and femoral neck and vertebral and nonvertebral fractures were assessed at baseline and month 12. In both trials, the least-square mean percent change from baseline BMD was significantly greater in the romosozumab groups versus controls across all kidney function categories at month 12. Romosozumab reduced the relative risk of new vertebral fractures at month 12 among patients with eGFR of 30-59, 60-89, and ≥90 mL/min by 72% (95% confidence interval [CI] 14-91; p = 0.017), 70% (40-85; p < 0.001), and 84% (30-96; p = 0.005), respectively, in FRAME versus placebo, and by 51% (5-75; p = 0.04), 19% (-28 to 49; p = 0.39), and 57% (1-81, p = 0.04), respectively, in ARCH versus alendronate. Incidences of adverse events, asymptomatic decreases in serum calcium, and evolution of kidney function during the studies were similar across all baseline kidney function groups. Romosozumab is an effective treatment option for postmenopausal women with osteoporosis and mild-to-moderate reduction in kidney function, with a similar safety profile across different levels of kidney function. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Bisphosphonates and bone mineral density in patients with end-stage kidney disease and renal transplants: A 15-year single-centre experience

Chronic Kidney Disease Stage 5 (CKD-5) imparts a 4-fold increase in minimal trauma fracture with a substantial increase in mortality following hip fracture. Bone disease in CKD is complex, characterised by abnormal levels of PTH, calcium, phosphate, ALP, and vitamin D, manifesting as a condition known as CKD-Mineral and Bone Disorder (CKD-MBD). While bisphosphonates (BPs) are widely used in the management of osteoporosis, their therapeutic role when end-stage renal function and bone disease co-exist remains unclear. This 15-year retrospective cohort study examines the long-term use of BPs in CKD-4 and -5 patients receiving no renal replacement therapy, haemodialysis and renal transplant in a tertiary centre in Sydney, Australia. In multivariate regression adjusting for age, baseline bone mineral density (BMD) and history of fracture, BP use was associated with net gain in lumbar spine bone density in renal transplant recipients over a mean treatment period of 3.5 years (net annual BMD gain of 0.039 g/cm², p = 0.005). No such benefit was seen in hip BMD in CKD subjects. Regardless of transplant status, CKD patients treated with BPs had no improvement in hip BMD with a general decline in hip BMD across both groups during the study period (hip BMD: transplant recipients decline 0.024 ± 0.81 g/cm², non-transplant CKD patients decline 0.055 ± 0.84 g/cm²). BP therapy did not result in significant changes in biochemical parameters (ALP, PTH, and phosphate) and no serious adverse effects were detected in association with BP use. In particular, kidney function was not affected by BPs post-transplant (eGFR = 43 ± 29 ml/min/1.73 m², p = 0.80). BPs preserved lumbar spine bone density in kidney transplant recipients but did not prevent declines in hip bone mineral density in either transplant patients or those with CKD-4 and -5.

Summary

There remains a lack of clarity of the risks vs. benefits of bone-sparing pharmacotherapy in chronic kidney disease Stages 4 and 5. This single-centre 15-year retrospective data analysis showed that bisphosphonates are not associated with any detectable serious adverse effects in CKD-4 and -5 and effective at mitigating lumbar spine bone loss in kidney transplant patients.

•

In patients with CKD stages 4 and 5, effects of Bisphosphonates on bone mineral density over time were assessed.

•

Hip bone mineral density declined in CKD and transplant recipients, regardless of bisphosphonate use.

•

Bone density at the lumbar spine improved, but only in transplant recipients treated with bisphosphonates.

•

Kidney function in CKD stages 4 and 5 was not impacted by the use of bisphosphonates.

•

Biochemical parameters of CKD-MBD (Chronic Kidney Disease-Mineral Bone Disorder) were not influenced by bisphosphonates.

•

Our study demonstrated that bisphosphonates were generally not effective in improving bone density, particularly at the hip.

•

Specific strategies to promote cortical bone in CKD patients require further evaluation.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Efficacy of Osteoporosis Medications for Patients With Chronic Kidney Disease: An Updated Systematic Review and Network Meta-Analysis

Background: Chronic kidney disease (CKD) is associated with bone and mineral metabolism. In this study we evaluated the comparative efficacies and safety of osteoporosis medications in patients with CKD or a history of kidney transplantation, and make recommendations for the best choice of osteoporosis treatment among patients with CKD or a history of kidney transplantation. Methods: We systemically searched for randomized controlled trials published in PubMed, Embase, and Cochrane databases up to June 2020. Network-meta analysis was used to compare the relative effectiveness of different treatments. A random-effects model was used when heterogeneity was expected. The safety of different treatments was also evaluated in terms of reported major adverse events. Results: A total of 17 studies with data from 10,214 patients who had stage 2-5 CKD, were receiving dialysis, or had a history of kidney transplantation were included in the network meta-analysis. Treatment with teriparatide, denosumab, alendronate, and raloxifene were all associated with a significantly reduced risk of fractures compared to treatment with placebos [teriparatide: odds ratio (OR) = 0.19, 95% confidence interval (CI): 0.10-0.35; denosumab: OR = 0.40, 95% CI: 0.27-0.58; alendronate: OR = 0.61, 95% CI: 0.40-0.92; raloxifene: OR = 0.52, 95% CI: 0.41-0.67]. The rank probability and the surface under the cumulative ranking (SUCRA) values suggested that teriparatide ranked the highest for improvement in vertebral bone mineral density (BMD) (SUCRA = 97.8%), whereas denosumab ranked the highest for improvement in femoral neck BMD (SUCRA = 88.3%). Conclusion: Teriparatide and denosumab seem to be the most effective treatments for preventing bone loss and reducing the risk of fracture in our network comparison. However, because of the limitations and potential biases in the reviewed studies, there is still some uncertainty about the best treatment options for osteoporosis in patients with CKD or a history of kidney transplantation. Systematic Review Registration: [PROSPERO], identifier [CRD42020209830].

Effects of osteoporosis medications on bone fracture in patients with chronic kidney disease

PURPOSE OF THE STUDY

The risk of bone fracture is high in patients with chronic kidney disease (CKD), and aggressive treatment to reduce fragility fracture risk is the major strategy. However, the outcomes of osteoporosis medications in patients with CKD remain unclear.

STUDY DESIGN

Patients with stage 3-5 CKD during 2011-2019 were enrolled. Patients were divided into two groups based on receiving osteoporosis medications (bisphosphonates, raloxifene, teriparatide or denosumab) or not. Two groups were matched at a 1:1 ratio by using propensity scores. The outcomes of interest were bone fractures, cardiovascular (CV) events and all-cause mortality. Cox proportional hazard regression models were applied to identify the risk factors. Additional stratified analyses by cumulative dose, treatment length and menopause condition were performed.

RESULTS AND CONCLUSIONS

67 650 patients were included. After propensity score matching, 1654 patients were included in the study and control group, respectively. The mean age was 70.2±12.4 years, and 32.0% of patients were men. After a mean follow-up of 3.9 years, the incidence rates of bone fracture, CV events and all-cause mortality were 2.0, 1.7 and 6.5 per 1000 person-months, respectively. Multivariate analysis results showed that osteoporosis medications reduced the risk of CV events (HR, 0.35; 95% CI, 0.18 to 0.71; p=0.004), but did not alleviate the risks of bone fracture (HR, 1.48; 95% CI, 0.73 to 2.98; p=0.28) and all-cause mortality (HR, 0.93; 95% CI, 0.67 to 1.28; p=0.65). Stratified analysis showed that bisphosphonates users have most benefits in the reduction of CV events (HR, 0.26; 95% CI, 0.11 to 0.64; p=0.003). In conclusion, osteoporosis medications did not reduce the risk of bone fractures, or mortality, but improved CV outcomes in patients with CKD.

The Impact of High Dose Glucocorticoids on Bone Health and Fracture Risk in Systemic Vasculitides

Systemic vasculitides are a range of conditions characterized by inflammation of blood vessels which may manifest as single organ or life-threatening multisystem disease. The treatment of systemic vasculitis varies depending on the specific disease but historically has involved initial treatment with high dose glucocorticoids alone or in conjunction with other immunosuppressive agents. Prolonged glucocorticoid treatment is frequently required as maintenance treatment. Patients with small and large vessel vasculitis are at increased risk of fracture. Osteoporosis may occur due to intrinsic factors such as chronic inflammation, impaired renal function and to a large extent due to pharmacological therapy with high dose glucocorticoid or combination treatments. This review will outline the known mechanism of bone loss in vasculitis and will summarize factors attributing to fracture risk in different types of vasculitis. Osteoporosis treatment with specific consideration for patients with vasculitis will be discussed. The use of glucocorticoid sparing immunosuppressive agents in the treatment of systemic vasculitis is a significant area of ongoing research. Adjunctive treatments are used to reduce cumulative doses of glucocorticoids and therefore may significantly decrease the associated fracture risk in patients with vasculitis. Lastly, we will highlight the many unknowns in the relation between systemic vasculitis, its treatment and bone health and will outline key research priorities for this field.

Alendronate use in older patients with reduced renal function: challenges and opportunities in clinical practice

In this retrospective cohort study, alendronate use among older osteoporosis patients (age>65 years) with reduced renal function (creatinine clearance<35ml/min) was not associated with significant deterioration in renal function from baseline nor increased incidence of osteoporotic fractures or acute kidney injury, compared with patients conservatively managed with only calcium/vitamin D supplementation.

INTRODUCTION

Oral bisphosphonates are not recommended in patients with creatinine clearance (CrCl) <35ml/min, although this is not supported by post hoc analyses of pivotal oral bisphosphonate studies. As both osteoporosis and renal insufficiency are more prevalent with advancing age, it is important to determine the safety and efficacy of oral bisphosphonates among these patients.

METHODS

Patients with CrCl <35ml/min on alendronate (group A, n=98), with CrCl <35ml/min conservatively managed (group B, n=96), and with CrCl ≥35ml/min on alendronate (group C, n=96) were followed up to 22 months. Primary outcomes were mean change in CrCl from baseline in group A compared with groups B and C, respectively. Secondary outcomes were the incidence of osteoporotic fractures and adverse events between groups.

RESULTS

There was no significant change in CrCl from baseline when comparing group A (-1.53±6.83ml/min) with group B (0.59±5.17ml/min) (p=0.075), and group A with group C (-3.71±7.54ml/min) (p=0.163). There was no significant increase in incidences of osteoporotic fractures in group A compared with group B (adjusted relative risk (aRR) 2.02, 95% confidence interval (CI) 0.64-6.37) and group A compared with group C (aRR 1.15, 95% CI 0.46-2.89). There was no significant difference in incidences of acute kidney injury (AKI) in group A compared with group B (aRR 0.48, 95% CI 0.20-1.12). Although statistically non-significant, there was an increase in AKI incidence in group A compared with group C (RR 7.84, 95% CI 0.98-62.66).

CONCLUSION

Among patients with CrCl <35ml/min, alendronate therapy was not associated with significant deterioration in renal function from baseline. Although not powered for secondary outcomes, there were no statistically significant differences in osteoporotic fracture or AKI incidence between the groups.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

Diagnosis and Management of Osteoporosis in Advanced Kidney Disease: A Review

Osteoporosis and fractures are common in persons with advanced chronic kidney disease (CKD) and on maintenance dialysis. Although the diagnosis of osteoporosis in this population can be difficult, imaging, especially with dual-energy x-ray absorptiometry (DXA), is helpful in identifying persons with CKD at the highest risk of fracture. Although blood biomarkers including parathyroid hormone and bone-specific alkaline phosphatase concentrations can aid in assessing bone turnover state, bone biopsy remains the gold standard in determining bone turnover in persons with advanced kidney disease and osteoporosis. With the increasing armamentarium of osteoporosis drugs, it now may be possible to prevent many fractures in advanced CKD. Unfortunately, data on these drugs are limited in persons with advanced CKD. Clinicians, aided by advances in imaging, biomarkers, and bone biopsy can now use these novel agents to target bone turnover abnormalities such as adynamic bone disease and high bone turnover disease. This review will discuss the most recent literature surrounding the diagnosis, management, and monitoring of osteoporosis and fractures in persons with advanced CKD or on maintenance dialysis.

Pharmacological interventions versus placebo, no treatment or usual care for osteoporosis in people with chronic kidney disease stages 3-5D

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for osteoporosis and is more prevalent among people with CKD than among people who do not have CKD. Although several drugs have been used to effectively treat osteoporosis in the general population, it is unclear whether they are also effective and safe for people with CKD, who have altered systemic mineral and bone metabolism.

OBJECTIVES

To assess the efficacy and safety of pharmacological interventions for osteoporosis in patients with CKD stages 3-5, and those undergoing dialysis (5D).

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 25 January 2021 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

Randomised controlled trials comparing any anti-osteoporotic drugs with a placebo, no treatment or usual care in patients with osteoporosis and CKD stages 3 to 5D were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed their quality using the risk of bias tool, and extracted data. The main outcomes were the incidence of fracture at any sites; mean change in the bone mineral density (BMD; measured using dual-energy radiographic absorptiometry (DXA)) of the femoral neck, total hip, lumbar spine, and distal radius; death from all causes; incidence of adverse events; and quality of life (QoL). Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Seven studies involving 9164 randomised participants with osteoporosis and CKD stages 3 to 5D met the inclusion criteria; all participants were postmenopausal women. Five studies included patients with CKD stages 3-4, and two studies included patients with CKD stages 5 or 5D. Five pharmacological interventions were identified (abaloparatide, alendronate, denosumab, raloxifene, and teriparatide). All studies were judged to be at an overall high risk of bias. Among patients with CKD stages 3-4, anti-osteoporotic drugs may reduce the risk of vertebral fracture (RR 0.52, 95% CI 0.39 to 0.69; low certainty evidence). Anti-osteoporotic drugs probably makes little or no difference to the risk of clinical fracture (RR 0.91, 95% CI 0.79 to 1.05; moderate certainty evidence) and adverse events (RR 0.99, 95% CI 0.98 to 1.00; moderate certainty evidence). We were unable to incorporate studies into the meta-analyses for BMD at the femoral neck, lumbar spine and total hip as they only reported the percentage change in the BMD in the intervention group. Among patients with severe CKD stages 5 or 5D, it is uncertain whether anti-osteoporotic drug reduces the risk of clinical fracture (RR 0.33, 95% CI 0.01 to 7.87; very low certainty evidence). It is uncertain whether anti-osteoporotic drug improves the BMD at the femoral neck because the certainty of this evidence is very low (MD 0.01, 95% CI 0.00 to 0.02). Anti-osteoporotic drug may slightly improve the BMD at the lumbar spine (MD 0.03, 95% CI 0.03 to 0.04, low certainty evidence). No adverse events were reported in the included studies. It is uncertain whether anti-osteoporotic drug reduces the risk of death (RR 1.00, 95% CI 0.22 to 4.56; very low certainty evidence).

AUTHORS' CONCLUSIONS

Among patients with CKD stages 3-4, anti-osteoporotic drugs may reduce the risk of vertebral fracture in low certainty evidence. Anti-osteoporotic drugs make little or no difference to the risk of clinical fracture and adverse events in moderate certainty evidence. Among patients with CKD stages 5 and 5D, it is uncertain whether anti-osteoporotic drug reduces the risk of clinical fracture and death because the certainty of this evidence is very low. Anti-osteoporotic drug may slightly improve the BMD at the lumbar spine in low certainty evidence. It is uncertain whether anti-osteoporotic drug improves the BMD at the femoral neck because the certainty of this evidence is very low. Larger studies including men, paediatric patients or individuals with unstable CKD-mineral and bone disorder are required to assess the effect of each anti-osteoporotic drug at each stage of CKD.

The renal patient seen by non-renal physicians: the kidney embedded in the 'milieu intérieur'

Chronic kidney disease is defined as a decrease in renal function or evidence of kidney injury for >3 months. This represents an oversimplification that may confuse physicians. Thus kidney function is equated to glomerular filtration rate, which represents one of multiple kidney functions. Some potentially more important renal functions are lost earlier, such as the production for the anti-ageing factor Klotho. Overall, these changes modify the emergent properties of the body, altering the relationships between different organs and systems, in a manner that is difficult to predict the response to interventions based on normal physiology concepts, as there is a novel steady state of interorgan relations. In this regard we now discuss the impact of CKD on heart failure; osteomuscular and joint pain and bone fragility and fractures; and osteosarcopaenia as seen by a cardiologist, a rheumatologist and a geriatrician.

The Non-invasive Diagnosis of Bone Disorders in CKD

Abnormal bone metabolism is an integral part of the chronic kidney disease-mineral bone disorder (CKD-MBD). For several reasons, the difficult bone compartment was neglected for some time, but there has been renewed interest as a result of the conception of bone as a new endocrine organ, the increasing recognition of the cross-talk between bone and vessels, and, especially, the very high risk of osteoporotic fractures (and associated mortality) demonstrated in patients with CKD. Therefore, it has been acknowledged in different guidelines that action is needed in respect of fracture risk assessment and the diagnosis and treatment of osteoporosis in the context of CKD and CKD-MBD, even beyond renal osteodystrophy. These updated guidelines clearly underline the need to improve a non-invasive approach to these bone disorders in order to guide treatment decisions aimed at not only controlling CKD-MBD but also decreasing the risk of fracture. In this report, we review the current role of the most often clinically used or promising biochemical circulating biomarkers such as parathyroid hormone, alkaline phosphatases, and other biochemical markers of bone activity as alternatives to some aspects of bone histomorphometry. We also mention the potential role of classic and new imaging techniques for CKD patients. Information on many aspects is still scarce and heterogeneous, but many of us consider that it is indeed time for action, recognizing our definitely limited ability to base certain treatment decisions only on our current non-comprehensive knowledge.

European Consensus Statement on the diagnosis and management of osteoporosis in chronic kidney disease stages G4-G5D

Controlling the excessive fracture burden in patients with chronic kidney disease (CKD) Stages G4-G5D remains an impressive challenge. The reasons are 2-fold. First, the pathophysiology of bone fragility in patients with CKD G4-G5D is complex and multifaceted, comprising a mixture of age-related (primary male/postmenopausal), drug-induced and CKD-related bone abnormalities. Second, our current armamentarium of osteoporosis medications has not been developed for, or adequately studied in patients with CKD G4-G5D, partly related to difficulties in diagnosing osteoporosis in this specific setting and fear of complications. Doubts about the optimal diagnostic and therapeutic approach fuel inertia in daily clinical practice. The scope of the present consensus paper is to review and update the assessment and diagnosis of osteoporosis in patients with CKD G4-G5D and to discuss the therapeutic interventions available and the manner in which these can be used to develop management strategies for the prevention of fragility fracture. As such, it aims to stimulate a cohesive approach to the management of osteoporosis in patients with CKD G4-G5D to replace current variations in care and treatment nihilism.

Bisphosphonates to reduce bone fractures in stage 3B+ chronic kidney disease: a propensity score-matched cohort study

BACKGROUND

Bisphosphonates are contraindicated in patients with stage 4+ chronic kidney disease. However, they are widely used to prevent fragility fractures in stage 3 chronic kidney disease, despite a lack of good-quality data on their effects.

OBJECTIVES

The aims of each work package were as follows. Work package 1: to study the relationship between bisphosphonate use and chronic kidney disease progression. Work package 2: to study the association between using bisphosphonates and fracture risk. Work package 3: to determine the risks of hypocalcaemia, hypophosphataemia, acute kidney injury and upper gastrointestinal events associated with using bisphosphonates. Work package 4: to investigate the association between using bisphosphonates and changes in bone mineral density over time.

DESIGN

This was a new-user cohort study design with propensity score matching.

SETTING AND DATA SOURCES

Data were obtained from UK NHS primary care (Clinical Practice Research Datalink GOLD database) and linked hospital inpatient records (Hospital Episode Statistics) for work packages 1-3 and from the Danish Odense University Hospital Databases for work package 4.

PARTICIPANTS

Patients registered in the data sources who had at least one measurement of estimated glomerular filtration rate of < 45 ml/minute/1.73 m2 were eligible. A second estimated glomerular filtration rate value of < 45 ml/minute/1.73 m2 within 1 year after the first was requested for work packages 1 and 3. Patients with no Hospital Episode Statistics linkage were excluded from work packages 1-3. Patients with < 1 year of run-in data before index estimated glomerular filtration rate and previous users of anti-osteoporosis medications were excluded from work packages 1-4.

INTERVENTIONS/EXPOSURE

Bisphosphonate use, identified from primary care prescriptions (for work packages 1-3) or pharmacy dispensations (for work package 4), was the main exposure.

MAIN OUTCOME MEASURES

Work package 1: chronic kidney disease progression, defined as stage worsening or starting renal replacement. Work package 2: hip fracture. Work package 3: acute kidney injury, hypocalcaemia and hypophosphataemia identified from Hospital Episode Statistics, and gastrointestinal events identified from Clinical Practice Research Datalink or Hospital Episode Statistics. Work package 4: annualised femoral neck bone mineral density percentage change.

RESULTS

Bisphosphonate use was associated with an excess risk of chronic kidney disease progression (subdistribution hazard ratio 1.12, 95% confidence interval 1.02 to 1.24) in work package 1, but did not increase the probability of other safety outcomes in work package 3. The results from work package 2 suggested that bisphosphonate use increased fracture risk (hazard ratio 1.25, 95% confidence interval 1.13 to 1.39) for hip fractures, but sensitivity analyses suggested that this was related to unresolved confounding. Conversely, work package 4 suggested that bisphosphonates improved bone mineral density, with an average 2.65% (95% confidence interval 1.32% to 3.99%) greater gain in femoral neck bone mineral density per year in bisphosphonate users than in matched non-users.

LIMITATIONS

Confounding by indication was a concern for the clinical effectiveness (i.e. work package 2) data. Bias analyses suggested that these findings were due to inappropriate adjustment for pre-treatment risk. work packages 3 and 4 were based on small numbers of events and participants, respectively.

CONCLUSIONS

Bisphosphonates were associated with a 12% excess risk of chronic kidney disease progression in participants with stage 3B+ chronic kidney disease. No other safety concerns were identified. Bisphosphonate therapy increased bone mineral density, but the research team failed to demonstrate antifracture effectiveness.

FUTURE WORK

Randomised controlled trial data are needed to demonstrate antifracture efficacy in patients with stage 3B+ chronic kidney disease. More safety analyses are needed to characterise the renal toxicity of bisphosphonates in stage 3A chronic kidney disease, possibly using observational data.

STUDY REGISTRATION

This study is registered as EUPAS10029.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 17. See the NIHR Journals Library website for further project information. The project was also supported by the National Institute for Health Research Biomedical Research Centre, Oxford.

Promoting bone health in children and adolescents following solid organ transplantation

Solid organ transplantation in children and adolescents provides many benefits through improving critical organ function, including better growth, development, cardiovascular status, and quality of life. Unfortunately, bone status may be adversely affected even when overall status is improving, due to issues with pre-existing bone disease as well as medications and nutritional challenges inherent post-transplantation. For all children and adolescents, bone status entering adulthood is a critical determinant of bone health through adulthood. The overall health and bone status of transplant recipients benefits from attention to regular physical activity, good nutrition, adequate calcium, phosphorous, magnesium and vitamin D intake and avoidance/minimization of soda, extra sodium, and obesity. Many immunosuppressive agents, especially glucocorticoids, can adversely affect bone function and development. Minimizing exposure to "bone-toxic" medications is an important part of promoting bone health in children post-transplantation. Existing guidelines detail how regular monitoring of bone status and biochemical markers can help detect bone abnormalities early and facilitate valuable bone-directed interventions. Attention to calcium and vitamin D supplementation, as well as tapering and withdrawing glucocorticoids as early as possible after transplant, can provide best bone outcomes for these children. Dual-energy X-ray absorptiometry can be useful to detect abnormal bone mass and fracture risk in this population and newer bone assessment methods are being evaluated in children at risk for poor bone outcomes. Newer bone therapies being explored in adults with transplants, particularly bisphosphonates and the RANKL inhibitor denosumab, may offer promise for children with low bone mass post-transplantation.

Denosumab Safety and Efficacy Among Participants in the FREEDOM Extension Study With Mild to Moderate Chronic Kidney Disease

CONTEXT

The effects of long-term exposure to denosumab in individuals with renal insufficiency are unknown.

OBJECTIVE

This post hoc analysis evaluates the long-term safety and efficacy of denosumab in individuals with mild-to-moderate chronic kidney disease (CKD) (stages 2 and 3) using data from the pivotal phase 3, double-blind, 3-year FREEDOM (NCT00089791) and open-label, 7-year extension (NCT00523341) studies.

PARTICIPANTS AND METHODS

Women age 60 to 90 years with a bone mineral density (BMD) T-score of less than -2.5 to greater than -4.0 at the total hip or lumbar spine were randomly assigned 1:1 to receive denosumab 60 mg subcutaneously every 6 months (long-term arm) or placebo (cross-over arm) in FREEDOM; eligible participants could enroll in the extension to receive denosumab 60 mg subcutaneously every 6 months. Change in estimated glomerular filtration rate (eGFR) from study baseline and annualized rates of fracture and adverse events (AEs) were the main outcome measures.

RESULTS

Most participants (1259/1969 [64%] long-term arm; 1173/1781 [66%] crossover arm) with baseline CKD stage 2 or 3 remained within the same CKD subgroup at study completion; less than 3% progressed to CKD stage 4. Participants in all eGFR subgroups showed similar, persistent BMD gains over time and a low incidence of fractures. The percentage of participants reporting serious AEs was similar among renal subgroups (normal, CKD stage 2, CKD stage 3a, CKD stage 3b) both for the long-term (54% vs 52% vs 57% vs 58%) and crossover (43% vs 42% vs 43% vs 68%) arms, except CKD stage 3b subgroup, crossover arm.

CONCLUSION

The safety and efficacy of denosumab did not differ among participants with mild to moderate CKD.

Is there a role for bisphosphonates in vascular calcification in chronic kidney disease?

Theoretically bisphosphonates could accelerate or retard vascular calcification. In subjects with low GFR, the position is further confounded by a combination of uncertain pharmacokinetics (GI absorption is poor and inconsistent at all levels of renal function and the effect of low GFR generally is to increase bioavailability) and a highly variable skeletal substrate with extremes of turnover that increase unpredictably further. Although bisphosphonates reduce bone formation by 70-90% in subjects with normal GFR and reduce the ability of bone to buffer exogenous calcium fluxes, in bisphosphonate treated postmenopausal women accelerated vascular calcification has not been documented. The kidneys assist with this buffering, but the capacity to modulate calcium excretion declines as GFR falls, increasing the risk of hypercalcaemia in the event of high calcium influx. In the ESRD patient, decreased buffering capacity substantially increases the risk of transient hypercalcaemia, especially in the setting of dialysis, and as such may promote vascular calcification which is highly prevalent in the CKD population. Low bone turnover may thus be less of a vascular problem in patients with preserved renal function and a bigger problem when the GFR is low. In patients with stage 4 and 5 CKD, adynamic bone disease associates with the severity and progression of arterial calcification, including coronary artery calcification, and further suppression of bone turnover by a bisphosphonate might exacerbate an already high predisposition to vascular calcification. No convincing signal of harm has emerged from clinical studies thus far. For example 51 individuals with CKD stage 3-4 treated with either alendronate 70 mg per week or placebo for 18 months showed no difference in the rate of vascular calcifications. Conversely an observational study of women with stage 3-4 CKD with pre-existing cardiovascular disease found an increased risk of mortality with a hazard ratio of 1.22 (1.04-1.42) in those given bisphosphonates. Direct suppression of vascular calcification by bisphosphonates is probably confined to etidronate - treatment of soft tissue calcification was a recognized indication for this drug and etidronate markedly reduced progression of vascular calcification in CKD patients. Bisphosphonates are analogues of pyrophosphate, a potent calcification inhibitor in bone and soft tissue. Thus the efficacy of etidronate as treatment for soft tissue calcification brought with it a problematic tendency to cause osteomalacia. In contrast, conventional doses of nitrogen-containing bisphosphonates fail to yield circulating concentrations sufficient to exert direct anti-calcifying effects, at least in patients with good renal function and studies using alendronate and ibandronate have yielded inconsistent vascular outcomes.

Comparison of the Efficacy and Renal Safety of Bisphosphonate Between Low-Dose/High-Frequency and High-Dose/Low-Frequency Regimens in a Late-Stage Chronic Kidney Disease Rat Model

The efficacy and renal safety of low-dose/high-frequency (LDHF) dosing and high-dose/low-frequency (HDLF) dosing of bisphosphonates (BPs) are comparable in patients with normal kidney function but might be different in patients with late-stage chronic kidney disease (CKD). This study aimed to compare the efficacy and renal safety of two different dosage regimens of a BP, alendronate (ALN), in stage 4 CKD using a rat model. Male, 10-week-old Sprague-Dawley rats were subjected to either 5/6 nephrectomy or sham surgery. The animals received subcutaneous administration of vehicle (daily) or ALN in LDHF dosage regimen (LDHF-ALN: 0.05 mg/kg/day) or HDLF dosage regimen (HDLF-ALN: 0.70 mg/kg/2 weeks). Medications commenced at 20 weeks of age and continued for 10 weeks. Micro-computed tomography, histological analysis, infrared spectroscopic imaging, and serum and urine assays were performed to examine the efficacy and renal safety of the ALN regimens. Both LDHF-ALN and HDLF-ALN increased bone mass, improved micro-structure, and enhanced mechanical properties, without causing further renal impairment in CKD rats. Histologically, however, HDLF-ALN more efficiently suppressed bone turnover, leading to more mineralized trabecular bone, than LDHF-ALN in CKD rats, whereas such differences between LDHF-ALN and HDLF-ALN were not observed in sham rats. Both LDHF-ALN and HDLF-ALN showed therapeutic effects on high bone turnover osteoporosis in CKD stage 4 rats without causing further renal impairment. However, as HDLF-ALN more efficiently suppressed bone turnover than LDHF-ALN in late-stage CKD, HDLF-ALN might be more appropriate than LDHF-ALN for fracture prevention in high bone turnover osteoporosis patients with late-stage CKD.

Osteoporosis in Patients with Chronic Kidney Diseases: A Systemic Review

Chronic kidney disease (CKD) is associated with the development of mineral bone disorder (MBD), osteoporosis, and fragility fractures. Among CKD patients, adynamic bone disease or low bone turnover is the most common type of renal osteodystrophy. The consequences of CKD-MBD include increased fracture risk, greater morbidity, and mortality. Thus, the goal is to prevent the occurrences of fractures by means of alleviating CKD-induced MBD and treating subsequent osteoporosis. Changes in mineral and humoral metabolism as well as bone structure develop early in the course of CKD. CKD-MBD includes abnormalities of calcium, phosphorus, PTH, and/or vitamin D; abnormalities in bone turnover, mineralization, volume, linear growth, or strength; and/or vascular or other soft tissue calcification. In patients with CKD-MBD, using either DXA or FRAX to screen fracture risk should be considered. Biomarkers such as bALP and iPTH may assist to assess bone turnover. Before initiating an antiresorptive or anabolic agent to treat osteoporosis in CKD patients, lifestyle modifications, such as exercise, calcium, and vitamin D supplementation, smoking cessation, and avoidance of excessive alcohol intake are important. Managing hyperphosphatemia and SHPT are also crucial. Understanding the complex pathogenesis of CKD-MBD is crucial in improving one's short- and long-term outcomes. Treatment strategies for CKD-associated osteoporosis should be patient-centered to determine the type of renal osteodystrophy. This review focuses on the mechanism, evaluation and management of patients with CKD-MBD. However, further studies are needed to explore more details regarding the underlying pathophysiology and to assess the safety and efficacy of agents for treating CKD-MBD.

Bisphosphonate and denosumab initiation in older adults in Ontario, Canada: a population-based cohort study

We provide an update on how commonly prescribed osteoporosis therapies are being initiated in older adults in Ontario. Patients newly prescribed denosumab are older, more often female, and have more comorbidities than those prescribed bisphosphonates. Their characteristics, monitoring, and persistence with prescribed therapy differ from clinical trial participants. Real-world studies on oral bisphosphonates and denosumab might be valuable.

PURPOSE

To provide a contemporary view on oral bisphosphonate and denosumab prescribing to older adults in routine care.

METHODS

Using linked healthcare databases, we conducted a population-based cohort study of adults ≥ 66 years newly prescribed oral bisphosphonates or denosumab between February 2013 and March 2017 in Ontario, Canada. We captured their clinical characteristics, monitoring, and continuous use of prescribed therapies. We illustrate how "real-world" new users of bisphosphonates and denosumab differ from randomized controlled trial (RCT) participants.

RESULTS

There were 107,847 individuals newly prescribed oral bisphosphonates (n = 59,996) or denosumab (n = 47,851) over the study period. Compared with new users of oral bisphosphonates, denosumab users were older (mean age 79.1 vs. 75.7 years), more often female (97.2 vs. 71.8%), from non-rural areas (93.9 vs. 89.9%), and resided in long-term care (10.9 vs. 3.3%). They had more comorbidities including dementia, falls, and fractures. Following their new prescription, denosumab users had more frequent testing of serum calcium. Duration of continuous use of denosumab was longer than bisphosphonates, and more bisphosphonate users had evidence of treatment discontinuation (56.7 bisphosphonate vs. 33.8% denosumab users discontinued therapy at 365 days). Compared with RCT participants, a higher proportion of "real-world" bisphosphonate and denosumab users had comorbidities including advanced kidney disease.

CONCLUSION

The clinical characteristics and monitoring of new users of bisphosphonates and denosumab generally align with practice guidelines, product monographs, and drug reimbursement criteria. Given differences between real-world users and RCT participants, there may be a role for safety and effectiveness studies of bisphosphonates and denosumab in routine care.

Canadian Society of Nephrology Commentary on the Kidney Disease Improving Global Outcomes 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder

Purpose of review:

(1) To provide commentary on the 2017 update to the Kidney Disease Improving Global Outcomes (KDIGO) 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD); (2) to apply the evidence-based guideline update for implementation within the Canadian health care system; (3) to provide comment on the care of children with chronic kidney disease (CKD); and (4) to identify research priorities for Canadian patients.

Sources of information:

The KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD.

Methods:

The commentary committee co-chairs selected potential members based on their knowledge of the Canadian kidney community, aiming for wide representation from relevant disciplines, academic and community centers, and different geographical regions.

Key findings:

We agreed with many of the recommendations in the clinical practice guideline on the diagnosis, evaluation, prevention, and treatment of CKD-MBD. However, based on the uncommon occurrence of abnormalities in calcium and phosphate and the low likelihood of severe abnormalities in parathyroid hormone (PTH), we recommend against screening and monitoring levels of calcium, phosphate, PTH, and alkaline phosphatase in adults with CKD G3. We suggest and recommend monitoring these parameters in adults with CKD G4 and G5, respectively. In children, we agree that monitoring for CKD-MBD should begin in CKD G2, but we suggest measuring ionized calcium, rather than total calcium or calcium adjusted for albumin. With regard to vitamin D, we suggest against routine screening for vitamin D deficiency in adults with CKD G3-G5 and G1T-G5T and suggest following population health recommendations for adequate vitamin D intake. We recommend that the measurement and management of bone mineral density (BMD) be according to general population guidelines in CKD G3 and G3T, but we suggest against routine BMD testing in CKD G4-G5, CKD G4T-5T, and in children with CKD. Based on insufficient data, we also recommend against routine bone biopsy in clinical practice for adults with CKD or CKD-T, or in children with CKD, although we consider it an important research tool.

Limitations:

The committee relied on the evidence summaries produced by KDIGO. The CSN committee did not replicate or update the systematic reviews.

The association between renal function and BMD response to bisphosphonate treatment: Real-world cohort study using linked national registers

BACKGROUND

Management of osteoporosis given reduced renal function is one of the largest challenges in the bone clinic.

OBJECTIVES

Identify the cut-off for renal function below which there would be no overall BMD benefit associated with bisphosphonate use. Track safety outcomes resulting in hospital encounters.

METHODS

Population-based, observational register-linked study of BMD trajectories in adults from the island of Funen (pop 465,000) as a function of estimated creatinine clearance (CKD-epi), treatment and adherence to oBP. One laboratory performed all the biochemical analyses for the area while all DXA scans were in a central facility. For inclusion, patients were required to have both a DXA scan and an eGFR measurement (CKD-EPI) within 1 year prior to their study index date. Medication Possession Ratio (MPR) was calculated from national data.

RESULTS

Out of 6176 incident BP users, 1789 had eGFR and DXA measurements at appropriate timepoints for the planned analysis, while this was the case for 3908 of 29,336 non-users. Users of oBPs exhibited progressively smaller gains in BMD with decreasing renal function. However, for CKD stage 3A and better, the annual change in BMD was significantly more positive than in the non-user group at similar levels of renal function. In non-users, the average annual change in BMD was negative but largely unaffected by renal function down to stage 3B. There were no new cases of acute renal injury, glomerulonephritis or dialysis. The rate of new kidney transplantation was zero in non-users and 0.26 per 1000 PY in the BP user population. Hypocalcaemia encounters did not differ significantly from that seen in non-users.

CONCLUSIONS

The BMD changes observed in real-world users of oBP in this population based single-clinic are consistent with those observed in the original RCTs of alendronate. We noted a gradual decrease in the absolute gains in BMD in oBP users with decreasing renal function though there was no significant interaction - largely explained by low numbers of treated patients with poor renal function - between CKD stage and adherence driven BMD change. There were no cases of acute renal injury resulting in hospital encounters. More data is needed on the efficacy and safety of bisphosphonates in CKD stage 3B to 5 and prescribers should reconsider the low use of DXA in patients with renal function impairment now that a wider range of treatment options are available.

Bisphosphonate utilization across the spectrum of eGFR

Bisphosphonates are the most common treatment for osteoporosis but there are concerns regarding its use in CKD. We evaluated the frequency of BSP by eGFR categories among patients with osteoporosis from two healthcare systems. Our results show that 56% of patients were treated, with reduced odds in those with lower eGFR.

INTRODUCTION

Osteoporosis is common in patients with chronic kidney disease (CKD). Bisphosphonates (BSP) are the most common treatment but there are concerns regarding its efficacy and toxicity in CKD. We evaluated the frequency of BSP use by level of estimated glomerular filtration rate (eGFR) in patients with osteoporosis.

METHODS

We assessed BSP use in patients with incident osteoporosis from the SCREAM-Cohort, Stockholm-Sweden, and Geisinger Healthcare, PA, USA. Osteoporosis was defined as the first encountered ICD diagnosis, and BSP use was defined as the dispensation or prescription of any BSP from 6 months prior to 3 years after the diagnosis. Multinomial logistic regression was used to account for the competing risk of death.

RESULTS

A total of 15,719 women and 3011 men in SCREAM and 17,325 women and 3568 men in Geisinger with incident osteoporosis were included. Overall, 56% of individuals used BSP in both studies, with a higher proportion in women. After adjustments, the odds of BSP was lower across lower eGFR in SCREAM, ranging from 0.90 (0.81-0.99) for eGFR 75-89 mL/min/1.73m² to 0.56 (0.46-0.68) for eGFR 30-44 mL/min/1.73m² in women and from 0.72 (0.54-0.97) for eGFR of 60-74 to 0.42 (0.25-0.70) for eGFR 30-44 mL/min/1.73m² in men. In Geisinger, odds were lower for eGFR < 30 mL/min/1.73m² in both sexes and the frequency of BSP use dropped over time.

CONCLUSION

In the two healthcare systems, approximately half of the people diagnosed with osteoporosis received BSP. Practices of prescription in relation to eGFR varied, but those with lower eGFR were less likely to receive BSP.

Comparison of the clinical effectiveness and safety between the use of denosumab vs bisphosphonates in renal transplant patients

A retrospective chart review was conducted on 85 renal transplant patients aged 19-88 years, treated with denosumab or bisphosphonate therapy. Bone densitometry measures were compared between treatment groups at baseline; at years 1, 2, and 3; and at final follow-up (average of 3.4 years). Both bisphosphonate and denosumab treatments increased lumbar spine bone density; however, the effect of denosumab was greater compared with that of bisphosphonate treatment. Denosumab treatment increased femoral neck BMD, whereas bisphosphonate treatment had a mean decrease in femoral neck BMD at final follow-up. Thus, our study provides evidence for the efficacy of denosumab treatment in renal transplant patients. Caution around hypocalcemia is warranted. We recommend more prospective studies to analyze the effects of long-term antiresorptive therapy in patients with a renal transplant.

INTRODUCTION

To compare the clinical effectiveness and safety between the use of denosumab and bisphosphonates on bone density and incidence of adverse events in renal transplant patients.

METHODS

A retrospective chart review was conducted on 85 renal transplant patients aged 19-88 years, treated with denosumab or bisphosphonate therapy. Bone densitometry measures were compared between treatment groups at baseline; years 1, 2, and 3; and at final follow-up (average of 3.4 years).

RESULTS

Absolute change in lumbar spine and femoral neck BMD over the treatment period was 0.029 ± 0.075 g/cm² and - 0.003 ± 0.064 g/cm², respectively, in the bisphosphonate group. Absolute change in lumbar spine and femoral neck BMD at final follow-up was 0.072 ± 0.094 g/cm² and 0.025 ± 0.063 g/cm², respectively, in the denosumab group. Denosumab resulted in significantly greater increases in lumbar spine BMD (0.045 g/cm² greater in the denosumab group). Similarly, the absolute change in BMD at the femoral neck was 0.022 g/cm² greater in the denosumab group as compared with the bisphosphonate group. The denosumab group had one event of severe hypocalcemia following first injection and one report of hospitalized pneumonia. No serious adverse events were reported in the bisphosphonate group.

CONCLUSIONS

Both treatments increased lumbar spine BMD; however, the effect of denosumab was greater compared with that of bisphosphonate treatment. Our study provides evidence for the efficacy of denosumab treatment in renal transplant patients. Caution around hypocalcemia is warranted. We recommend more prospective studies to analyze the effects of long-term antiresorptive therapy in patients with a renal transplant.

Oral Bisphosphonate Use and All-Cause Mortality in Patients With Moderate-Severe (Grade 3B-5D) Chronic Kidney Disease: A Population-Based Cohort Study

Oral bisphosphonates (oBPs) have been associated with reduced fractures and mortality. However, their risks and benefits are unclear in patients with moderate-severe CKD. This study examined the association between oBPs and all-cause mortality in G3B-5D CKD. This is a population-based cohort study including all subjects with an estimated glomerular filtration rate (eGFR) <45/mL/min/1.73 m² (G3B: eGFR <45/mL/min/1.73 m² G4: eGFR 15-29/mL/min/1.73 m² G5: eGFR <15/mL/min/1.73 m² G5D: hemodialysis) aged 40+ years from the UK Clinical Practice Research Datalink (CPRD) and the Catalan Information System for Research in Primary Care (SIDIAP). Previous and current users of other anti-osteoporosis drugs were excluded. oBP use was modeled as a time-varying exposure to avoid immortal time bias. Treatment episodes in oBP users were created by concatenating prescriptions until patients switched or stopped therapy or were censored or died. A washout period of 180 days was added to (date of last prescription +180 days). Propensity scores (PSs) were calculated using prespecified predictors of mortality including age, gender, baseline eGFR, socioeconomic status, comorbidities, previous fracture, co-medications, and number of hospital admissions in the previous year. Cox models were used for PS adjustment before and after PS trimming (the first and last quintiles). In the CPRD, of 19,351 oBP users and 210,954 non-oBP users, 5234 (27%) and 85,105 (40%) deaths were recorded over 45,690 and 915,867 person-years of follow-up, respectively. oBP users had 8% lower mortality risk compared to non-oBP users (hazard ratio [HR] 0.92; 95% CI, 0.89 to 0.95). Following PS trimming, this became nonsignificant (HR 0.98; 95% CI, 0.94 to 1.04). In the SIDIAP, of 4146 oBP users and 86,127 non-oBP users, 1330 (32%) and 36,513 (42%) died, respectively. oBPs were not associated with mortality in PS adjustment and trimming (HR 1.04; 95% CI, 0.99 to 1.1 and HR 0.95; 95% CI, 0.89 to 1.01). In this observational, patient-based cohort study, oBPs were not associated with increased mortality among patients with moderate-severe CKD. However, further studies are needed on other effects of oBPs in CKD patients. © 2020 American Society for Bone and Mineral Research.

Bisphosphonate therapy in CKD: the current state of affairs

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with the development of mineral and bone disorders (MBD), including renal osteodystrophy (ROD). ROD is a global disorder of bone strength that is associated with an increased fracture risk. The use of bisphosphonates for fracture risk reduction in CKD remains controversial. This review provides a synopsis of the state-of-the literature regarding the safety and potential antifracture benefits of bisphosphonates in CKD patients.

RECENT FINDINGS

In preclinical studies of animals with CKD 3-4 and evidence of CKD-MBD, bisphosphonates resulted in changes in bone quality that improve bone strength. Bone turnover was generally reduced to a similar extent in animals with and without CKD. Post hoc analyses of randomized trials in patients with CKD 3-4 reported increases in bone mineral density (BMD) and fracture reduction that were similar in patients with and without CKD. There are no primary clinical trial data in patients with CKD-MBD.

SUMMARY

In patients with CKD without evidence of CKD-MBD, the use of bisphosphonates should follow general population guidelines. The lack of data for patients with CKD 4-5D and evidence of CKD-MBD makes treatment decisions challenging. Clinical studies are urgently needed to provide data on the safety and antifracture benefits of bisphosphonates in these cohorts.

Efficacy and safety of once-monthly risedronate in osteoporosis subjects with mild-to-moderate chronic kidney disease: a post hoc subgroup analysis of a phase III trial in Japan

Limited data are available on the safety and efficacy of anti-resorptive agents, particularly once-monthly bisphosphonates, for use in osteoporotic patients with chronic kidney disease (CKD). We conducted a post hoc analysis of data from a 12-month, randomized, double-blind, phase III study to evaluate the safety and efficacy of once-monthly risedronate (RIS-OM) 75 mg tablets in Japanese osteoporosis patients with mild-to-moderate CKD. Patients who received RIS-OM 75 mg were stratified by baseline estimated glomerular filtration rate (eGFR; ≥ 90, ≥ 60 to < 90, or ≥ 30 to < 60 mL/min/1.73 m²). Safety endpoints were incidence of adverse events (AEs) and percent change from baseline in eGFR, serum creatinine, calcium, and phosphorus. Efficacy endpoints were percent change from baseline in lumbar spine bone mineral density (BMD) and bone turnover markers (BTMs). In 420 patients included (age 67.7 ± 6.7 years, women 98.8%), the incidence of all AEs, gastrointestinal disorders, acute phase reaction, non-vertebral fractures, and renal and urinary disorders was not significantly different among subgroups. Interaction between subgroups and time was significant for eGFR (p = 0.010) and serum creatinine (p = 0.001) but considered to be regression to the mean and clinically insignificant. BMD significantly increased while BTMs significantly decreased from baseline with a similar degree of change among the subgroups. In conclusion, RIS-OM 75 mg showed consistent safety and efficacy in suppressing bone turnover and increasing BMD in Japanese primary osteoporosis patients with mild-to-moderate CKD. These results should, however, be interpreted with caution because the number of patients with moderate CKD was limited.

Bone health in chronic kidney disease-mineral and bone disorder: a clinical case seminar and update

The metabolic abnormalities affecting bone in the setting of chronic kidney disease (CKD) are complex with overlapping and interacting aetiologies and have challenging diagnostic and management strategies. Disturbances in calcium, phosphate, fibroblast growth factor 23, parathyroid hormone concentrations and vitamin D deficiency are commonly encountered and contribute to the clinical syndromes of bone disorders in CKD, including hyperparathyroidism, osteomalacia, osteoporosis and adynamic bone disease. Mineral and bone abnormalities may also persist or arise de novo post-renal transplantation. The Kidney Disease Improving Global Outcomes organisation describes these mineral metabolism derangements and skeletal abnormalities as 'CKD Mineral and Bone Disorder'. Patients with this disorder have an increased risk of fracture, cardiovascular events and overall increased mortality. In light of the recently updated 2017 guidelines from the Kidney Disease Improving Global Outcomes, we present a clinical case-based discussion to highlight the complexities of investigating and managing the bone health of patients with CKD with a focus on these updates.

Pharmacology of bisphosphonates

The biological effects of the bisphosphonates (BPs) as inhibitors of calcification and bone resorption were first described in the late 1960s. In the 50 years that have elapsed since then, the BPs have become the leading drugs for the treatment of skeletal disorders characterized by increased bone resorption, including Paget's disease of bone, bone metastases, multiple myeloma, osteoporosis and several childhood inherited disorders. The discovery and development of the BPs as a major class of drugs for the treatment of bone diseases is a paradigm for the successful journey from "bench to bedside and back again". Several of the leading BPs achieved "blockbuster" status as branded drugs. However, these BPs have now come to the end of their patent life, making them highly affordable. The opportunity for new clinical applications for BPs also exists in other areas of medicine such as ageing, cardiovascular disease and radiation protection. Their use as inexpensive generic medicines is therefore likely to continue for many years to come. Fifty years of research into the pharmacology of bisphosphonates have led to a fairly good understanding about how these drugs work and how they can be used safely in patients with metabolic bone diseases. However, while we seemingly know much about these drugs, a number of key aspects related to BP distribution and action remain incompletely understood. This review summarizes the existing knowledge of the (pre)clinical and translational pharmacology of BPs, and highlights areas in which understanding is lacking.