Bone Morbidity and Recovery in Children With Acute Lymphoblastic Leukemia: Results of a Six-Year Prospective Cohort Study

Glucocorticoid Therapy in Acute Lymphoblastic Leukemia: Navigating Short-Term and Long-Term Effects and Optimal Regimen Selection

PURPOSE OF REVIEW

Glucocorticoids are a mainstay in acute lymphoblastic leukemia treatment and lack of early response is predictive for overall disease prognosis. Given the vital position of glucocorticoids and well known long and short-term side effects associated with differing glucocorticoids, we aim to highlight the wide breadth of historical and more contemporary data to describe the current landscape of glucocorticoid use in this arena.

RECENT FINDINGS

Emerging studies aim to overcome issues such as steroid resistance and to optimize the antileukemic effects of glucocorticoids while aiming to mitigate the risks and side effects associated with their exposure. Glucocorticoids have and likely always will be a fundamental component of acute lymphoblastic leukemia treatment and understanding how to navigate short- and long-term effects and how to optimize regimens is at the heart of continued treatment success.

Predictors of low and very low bone mineral density in long-term childhood acute lymphoblastic leukemia survivors: Toward personalized risk prediction

BACKGROUND

Cohorts of childhood acute lymphoblastic leukemia (cALL) survivors reaching adulthood are increasing. Approximately 30% of survivors meet criteria for low bone mineral density (BMD) 10 years after diagnosis. We investigated risk factors for low BMD in long-term cALL survivors.

METHODS

We recruited 245 cALL survivors from the PETALE (Prévenir les effets tardifs des traitements de la leucémie aiguë lymphoblastique chez l'enfant) cohort, who were treated with the Dana Farber Cancer Institute protocols, did not experience disease relapse or hematopoietic stem cell transplants, and presented with more than 5 years of event-free survival. Median time since diagnosis was 15.1 years.

RESULTS

Prevalence of low DXA-derived BMD (Z-score ≤-1) ranged between 21.9% and 25.3%, depending on site (lumbar spine (LS-BMD), femoral neck (FN-BMD), and total body (TB-BMD), and between 3.7% and 5.8% for very low BMD (Z-score ≤-2). Males had a higher prevalence of low BMD than females for all three outcomes (26%-32% vs. 18%-21%), and male sex acted as a significant risk factor for low BMD in all models. Treatment-related factors such as cumulative glucocorticoid (GC) doses and cranial radiation therapy (CRT) were associated with lower BMDs in the full cohort and in females at the FN-BMD site.

CONCLUSION

Low and very low BMD is more prevalent in male cALL survivors. Male sex, high cumulative GC doses, CRT, risk group, and low body mass index (BMI) were identified as risk factors for low BMD. A longer follow-up of BMD through time in these survivors is needed to establish if low BMD will translate into a higher risk for fragility fractures through adulthood.

Demographic and disease-related factors impact bone turnover and vitamin D in children with hemato-oncological diseases

Children with hemato-oncological diseases may have significant skeletal morbidity, not only during and after treatment but also at the time of diagnosis before cancer treatment. This study was designed to evaluate the vitamin D status and circulating bone metabolic markers and their determinants in children at the time of diagnostic evaluation for hemato-oncological disease. This cross-sectional study included 165 children (91 males, median age 6.9 yr range 0.2-17.7 yr). Of them, 76 patients were diagnosed with extracranial or intracranial solid tumors, 83 with leukemia, and 6 with bone marrow failure. Bone metabolism was assessed by measuring serum 25OHD, PTH, bone alkaline phosphatase, intact N-terminal propeptide of type I procollagen, and C-terminal cross-linked telopeptide of type I collagen. Vitamin D deficiency was found in 30.9% of children. Lower 25OHD levels were associated with older age, lack of vitamin D supplementation, season outside summer, and a country of parental origin located between latitudes -45° and 45°. Children diagnosed with leukemia had lower levels of markers of bone formation and bone resorption than those who had solid tumors or bone marrow failure. In conclusion, vitamin D deficiency was observed in one-third of children with newly diagnosed cancer. Bone turnover markers were decreased in children with leukemia, possibly because of the suppression of osteoblasts and osteoclasts by leukemic cells. The identification of patients with suboptimal vitamin D status and compromised bone remodeling at cancer diagnosis may aid in the development of supportive treatment to reduce the adverse effects of cancer and its treatment.

Association of Insulin-like Growth Factor-1 with Bone Mineral Density in Survivors of Childhood Acute Leukemia

In this study, we investigated bone mineral deficits in children who survived childhood acute leukemia and explored the association between the insulin-like growth factor-1 (IGF-1) level and bone mineral density (BMD). This retrospective analysis enrolled 214 patients treated for acute leukemia, measuring various factors including height, weight, body mass index (BMI), and lumbar spine BMD after the end of treatment. The study found an overall prevalence of low BMD in 15% of participants. Notably, IGF-1 levels were significantly different between patients with low BMD and those with normal BMD, and correlation analyses revealed associations of the IGF-1 level and BMI with lumbar spine BMD. Regression analyses further supported this relationship, suggesting that higher IGF-1 levels were associated with a decreased risk of low BMD. The study findings suggest that IGF-1 may serve as a valuable tool for evaluating and predicting osteoporosis in survivors of childhood acute leukemia.

Genetic susceptibility and late bone outcomes in childhood acute lymphoblastic leukemia survivors

Childhood acute lymphoblastic leukemia (cALL) survivors are at increased risk for bone comorbidities, but accurate screening tools for such comorbidities are limited. Polygenic scores (PGS) could stratify cALL survivors for risk of long-term adverse bone outcomes. We evaluated 214 (51% female) cALL survivors from the Prévenir les Effets TArdifs de la LEucémie study (median age 21 yr). Bone mineral density (BMD) measurements were obtained using dual X-ray absorptiometry at the lumbar spine (LS-BMD), femoral neck (FN-BMD), and total body (TB-BMD), and vertebral fractures (VF) were documented using the vertebral deformity criterion. We computed a PGS for adult heel quantitative ultrasound speed of sound (gSOS), known to be associated with the risk of osteoporotic fracture, using imputed genotype data of the participants, and tested it for association with BMD Z-scores and VF risk, adjusting for clinical risk factors, and in sex and prognostic risk-stratified analyses. We found that a gSOS below the mean was associated with lower BMD in all three sites in univariate and multivariate models. In univariate analyses, 1 SD increase in gSOS conferred a 0.16 SD increase in LS-BMD (95% CI 0.005-0.31), whereas a gSOS above the mean was associated with a 0.31 SD higher LS-BMD (95% CI 0.008-0.61), a 0.36 SD higher TB-BMD (95% CI 0.06-0.67), and a 0.43 SD higher FN-BMD (95% CI 0.13-0.72). Models combining gSOS with clinical risk factors explained up to 16% of the variance of BMD phenotypes and obtained an area under the receiver operating characteristic curve for VF of 0.77 in subgroup analyses. Cranial radiation, high cumulative glucocorticoid doses, high risk group, and male sex were significant risk factors for lower BMD Z-scores. In conclusion, a PGS, in combination with clinical risk factors, could be used as a tool to risk stratify cALL survivors for treatment-related bone morbidity.

Vertebral Body Reshaping after Fractures: An Important Index of Recovery in Glucocorticoid-Treated Children

PURPOSE

In this 6-year study we identified factors associated with spontaneous vertebral body reshaping in glucocorticoid (GC)-treated children with leukemia, rheumatic disorders, and nephrotic syndrome.

METHODS

Subjects were 79 children (mean age 7.4 years) who had vertebral fracture (VF) evaluation on lateral spine radiographs at least 1 year after VF detection. VF were graded using the modified Genant semiquantitative method and fracture burden for individuals was quantified using the spinal deformity index (SDI; sum of grades from T4 to L4).

RESULTS

Sixty-five children (82.3%) underwent complete vertebral body reshaping (median time from VF detection to complete reshaping 1.3 years by Cox proportional hazard modeling). Of 237 VF, the majority (83.1%) ultimately reshaped, with 87.2% reshaping in the thoracic region vs 70.7% in the lumbar region (P = .004). Cox models showed that (1) every g/m2 increase in GC exposure in the first year after VF detection was associated with a 19% decline in the probability of reshaping; (2) each unit increase in the SDI at the time of VF detection was associated with a 19% decline in the probability of reshaping [hazard ratio (HR) = 0.81; 95% confidence interval (CI) = 0.71, 0.92; P = .001]; (3) each additional VF present at the time of VF detection reduced reshaping by 25% (HR = 0.75; 95% CI = 0.62, 0.90; P = .002); and (4) each higher grade of VF severity decreased reshaping by 65% (HR = 0.35; 95% CI = 0.21, 0.57; P < .001).

CONCLUSION

After experiencing a VF, children with higher GC exposure, higher SDI, more severe fractures, or lumbar VF were at increased risk for persistent vertebral deformity.

Bisphosphonate treatment for skeletal complications in paediatric cancer-Experience from a single tertiary centre

AIMS

The aim was to analyse the use and safety of bisphosphonate treatment for metabolic bone complications in paediatric cancer patients.

METHODS

We retrospectively describe our experience with bisphosphonate treatment in 25 childhood cancer patients (aged <18 years) in a single tertiary hospital between 1999 and 2020.

RESULTS

The most common primary diagnosis was acute lymphoblastic leukaemia (n = 16) and Hodgkin lymphoma (n = 3). Eleven patients (44%) had received allogeneic stem cell transplantation and two patients autologous stem cell transplantation. Sixteen patients (64%) had been treated with radiotherapy, either total-body (n = 11) or local (n = 5). The main indication for bisphosphonates was osteoporosis with vertebral compression fractures in 13/25, osteonecrosis in 6/25 and hypercalcaemia in 2/25. The bisphosphonate treatment was started on average 13 (range 0-76) months after the diagnosis of the bone complication. Bisphosphonate treatment lasted between weeks (hypercalcaemia) to 5 years (severe osteoporosis). Mild, non-symptomatic hypophosphatemia (n = 8), hypocalcaemia (n = 6) and moderate, transient pain (n = 6) were the most common adverse effects. No severe side effects were observed even when bisphosphonates were administered concomitantly with chemotherapy. Bone mineral density significantly improved with the bisphosphonate treatment (mean lumbar spine Z-score -1.17 vs. -0.07, p < 0.001).

CONCLUSION

Bisphosphonate treatment was well tolerated in this paediatric patient cohort.

A practical guide to the diagnosis and management of osteoporosis in childhood and adolescence

Osteoporosis in childhood distinguishes itself from adulthood in four important ways: 1) challenges in distinguishing otherwise healthy children who have experienced fractures due to non-accidental injury or misfortunate during sports and play from those with an underlying bone fragility condition; 2) a preponderance of monogenic "early onset" osteoporotic conditions that unveil themselves during the pediatric years; 3) the unique potential, in those with residual growth and transient bone health threats, to reclaim bone density, structure, and strength without bone-targeted therapy; and 4) the need to benchmark bone health metrics to constantly evolving "normal targets", given the changes in bone size, shape, and metabolism that take place from birth through late adolescence. On this background, the pediatric osteoporosis field has evolved considerably over the last few decades, giving rise to a deeper understanding of the discrete genes implicated in childhood-onset osteoporosis, the natural history of bone fragility in the chronic illness setting and associated risk factors, effective diagnostic and monitoring pathways in different disease contexts, the importance of timely identification of candidates for osteoporosis treatment, and the benefits of early (during growth) rather than late (post-epiphyseal fusion) treatment. While there has been considerable progress, a number of unmet needs remain, the most urgent of which is to move beyond the monotherapeutic anti-resorptive landscape to the study and application of anabolic agents that are anticipated to not only improve bone mineral density but also increase long bone cross-sectional diameter (periosteal circumference). The purpose of this review is to provide a practical guide to the diagnosis and management of osteoporosis in children presenting to the clinic with fragility fractures, one that serves as a step-by-step "how to" reference for clinicians in their routine clinical journey. The article also provides a sightline to the future, emphasizing the clinical scenarios with the most urgent need for an expanded toolbox of effective osteoporosis agents in childhood.

Bisphosphonates in Glucocorticoid-Treated Patients With Duchenne Muscular Dystrophy: A Systematic Review and Grading of the Evidence

BACKGROUND AND OBJECTIVES

Bisphosphonates are routinely used to treat osteoporosis in patients with Duchenne muscular dystrophy (DMD), a rare, severely debilitating neuromuscular disease. We sought to synthesize and grade benefits and harms evidence of bisphosphonates in glucocorticoid-treated patients with DMD.

METHODS

In this systematic review (PROSPERO identifier: CRD42020157606), we searched MEDLINE, CINAHL, Embase, PsycINFO, Web of Science, and CENTRAL for articles published from inception up to and including March 31, 2023, reporting results in any language from any study type. Quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations framework.

RESULTS

We identified 19 publications involving 1,010 children and adults from 12 countries across all inhabited continents except South America. We found high-quality evidence that bisphosphonates significantly increase the areal lumbar spine bone mineral density (BMD) Z score in glucocorticoid-treated patients with DMD. The greatest improvements were recorded in controlled settings among patients treated with intravenous zoledronate. Evidence of benefits to fracture risks was inconclusive and/or of low quality, primarily due to lack of controlled data and small samples. Bisphosphonates were generally well-tolerated, although adverse events related to the first infusion (i.e., "acute phase reaction") were frequently reported.

DISCUSSION

There is high-quality evidence supporting the use of bisphosphonates to increase the areal lumbar spine BMD Z score in patients with DMD and glucocorticoid-induced osteoporosis. Our synthesis and grading affirm current recommendations put forward in the 2018 DMD Clinical Care Considerations and should be helpful in raising awareness about anticipated benefits of bisphosphonates, prevailing unmet needs, and potential safety issues in their use.

Risk Factors Associated with Incident Vertebral Fractures in Steroid-treated Males with Duchenne Muscular Dystrophy

PURPOSE

Prevention of fractures is an unmet need in glucocorticoid (GC)-treated Duchenne muscular dystrophy. This study explored factors associated with incident vertebral fractures (VFs) to inform future fracture prevention efforts.

METHODS

VFs were evaluated prospectively at study baseline and 12 months on lateral spine radiographs in participants aged 4 to 25 years with Duchenne muscular dystrophy. Clinical factors were analyzed for their association with the change in Spinal Deformity Index (sum of the Genant-defined VF grades from T4 to L4) between baseline and 12 months.

RESULTS

Thirty-eight males were evaluated (mean ± SD age at baseline 11.0 ± 3.6 years; mean ± SD GC duration at baseline 4.1 ± 3.1 years; 74% ambulatory). Nine of 38 participants (24%) had 17 incident VFs, of which 3/17 VFs (18%) were moderate/severe. Participants with 12-month incident VF had lower mean ± SD baseline lumbar spine areal bone mineral density Z-scores (-2.9 ± 1.0 vs -1.9 ± 1.1; P = .049) and lower total body less head areal bone mineral density Z-scores (-3.1 ± 1.2 vs -1.6 ± 1.7; P = .036). Multivariable linear regression showed that at least 1 VF at baseline (P < .001), a higher number of antecedent non-VF (P < .001), and greater bone age delay at baseline (P = .027) were significant predictors of an increase in the Spinal Deformity Index from baseline to 12 months.

CONCLUSION

The observation that ≥ 1 prevalent VF and/or non-VF were the strongest predictors of incident VFs at 12 months supports the need for prevention of first fractures in this high-risk setting. Bone age delay, a marker of GC exposure, may assist in the prioritization of patients in efforts to prevent first fractures.

Humanin Treatment Protects Against Venetoclax-Induced Bone Growth Retardation in Ex Vivo Cultured Rat Bones

Context

Recent preclinical studies reported that the BCL-2 inhibitor venetoclax can impair bone growth. A strategy to prevent such a side effect of this promising anticancer drug is highly desired. Earlier in vitro and in vivo studies suggested that the mitochondrial peptide humanin has the potential to prevent drug-induced growth impairment.

Objective

We hypothesized that co-treatment with the humanin analog HNG may prevent venetoclax-induced bone growth impairment.

Methods

Ex vivo studies were performed in fetal rat metatarsal bones and human growth plate samples cultured for 12 and 2 days, respectively, while in vivo studies were performed in young neuroblastoma mice being treated daily for 14 days. The treatment groups included venetoclax, HNG, venetoclax plus HNG, or vehicle. Bone growth was continuously monitored and at the end point, histomorphometric and immunohistochemical analyses were performed in fixed tissues.

Results

Venetoclax suppressed metatarsal bone growth and when combined with HNG, bone growth was rescued and all histological parameters affected by venetoclax monotherapy were normalized. Mechanistic studies showed that HNG downregulated the pro-apoptotic proteins Bax and p53 in cultured metatarsals and human growth plate tissues, respectively. The study in a neuroblastoma mouse model confirmed a growth-suppressive effect of venetoclax treatment. In this short-term in vivo study, no significant bone growth-rescuing effect could be verified when testing HNG at a single dose. We conclude that humanin dose-dependently protects ex vivo cultured metatarsal bones from venetoclax-induced bone growth impairment by restoring the growth plate microstructure.

Reporting of paediatric osteoporotic vertebral fractures in Duchenne muscular dystrophy and potential impact on clinical management: the need for standardised and structured reporting

BACKGROUND

In boys with Duchenne muscular dystrophy (DMD), initiation of bisphosphonate is recommended upon identification of moderate or severe vertebral fractures, even if asymptomatic. Clear radiological reporting is important for consistency of clinical interpretation and management.

OBJECTIVES

To audit radiology reports of spine imaging for vertebral fracture assessment in DMD, and assess potential impact on diagnosis and management.

MATERIALS AND METHODS

Lateral thoracolumbar spine imaging (71 lateral spine radiographs and 13 lateral dual energy absorptiometry spine image) in 84 boys with DMD performed across two centres. Anonymised radiology reports by paediatric radiologists were circulated to two neuromuscular clinicians and two endocrinologists. Clinicians determined if there was vertebral fracture, no vertebral fracture, or unclear interpretation. Endocrinologists also determined if bisphosphonate was indicated. A single observer (a clinician with expertise in vertebral fracture assessment) performed vertebral fracture assessment in 37 images and re-reported using a structured format. Structured reports were re-circulated to the four clinicians to re-evaluate the degree of concordance in clinical diagnosis of vertebral fracture and treatment decisions with bisphosphonate.

RESULTS

The term "fracture" was used in 25/84 (30%) radiology reports and only in 8/43 (19%) with description of vertebral body abnormalities. Fracture grading was included in 7/43 (16%) radiology reports. Diagnostic concordance by the clinicians was noted in 36/84 (43%). Unclear interpretation was noted in 22% to 51% based on radiology reports. No unclear interpretation was noted with structured reports. Complete diagnostic (37/37, 100%) and treatment (37/37, 100%) concordance was noted with the structured reports, whereas complete diagnostic and treatment concordance was noted in only 16/37 (43%) and 17/37 (46%) of the radiology reports, respectively.

CONCLUSION

Only a third of radiology reports of spine imaging in DMD explicitly used the terminology "fracture". Grading was only noted in a small percentage. Variability in diagnostic interpretation by clinicians may lead to differing management plans. As identification of vertebral fracture is a trigger for treatment, developing reporting guidelines for paediatric vertebral fracture assessment will improve care. A structured template should be introduced for radiological reporting of paediatric vertebral fracture assessment.

Reductions in Bone Mineral Density Are Apparent Early in Children With Prevalent Osteonecrosis Lesions Following Leukemia Therapy

Osteonecrosis (ON) is a serious complication of childhood acute lymphoblastic leukemia. We determined the prevalence of osteonecrotic lesions in our patient population by a one-time multisite magnetic resonance imaging (MRI) more than 1 year following leukemia therapy. MRI findings were evaluated in relationship to clinical factors (including longitudinal changes in bone mineral density [BMD]). Eighty-six children enrolled in the Steroid Associated Osteoporosis in the Pediatric Population (STOPP) study were evaluated for ON at 3.1 ± 1.3 years following therapy. Thirty children had a total of 150 confirmed ON lesions (35%). Lumbar spine (LS) BMD Z-scores (mean ± SD) were low at diagnosis and similar between patients with and without ON (-1.09 ± 1.53 versus -1.27 ± 1.25, p = 0.549). LS BMD Z-scores declined from baseline to 12 months in children with ON (-0.31 ± 1.02) but not in those without (0.13 ± 0.82, p = 0.035); the hip BMD Z-scores from baseline to 24 months declined in both groups, but to a greater extent in those with ON (-1.77 ± 1.22) compared to those without (-1.03 ± 1.07, p = 0.045). At the time of the MRI, mean total hip and total body (TB) BMD Z-scores were lower in children with ON (hip -0.98 ± 0.95 versus -0.28 ± 1.06, p = 0.010; TB -1.36 ± 1.10 versus -0.48 ± 1.50, p = 0.018). Pain occurred in 11/30 (37%) with ON versus 20/56 (36%) without, p = 0.841. In multivariable models, older age at diagnosis (odds ratio [OR] 1.57; 95% confidence interval [CI], 1.15-2.13; p = 0.004), and hip BMD Z-score at MRI (OR 2.23; 95% CI, 1.02-4.87; p = 0.046) were independently associated with ON. Overall, one-third of children demonstrated ON after leukemia therapy. Those with ON had greater reductions in spine and hip BMD Z-scores in the first 1 and 2 years of therapy, respectively. Older age and lower hip BMD Z-scores at MRI were significantly associated with prevalent, off-therapy ON. These data assist in identifying children at risk of ON. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

OPG/RANK/RANKL Axis in Egyptian Children With Acute Lymphoblastic Leukemia After Maintenance Therapy: Relationship to Bone Mineral and Vitamin D Status

Policies to maximize peak bone mass in survivor's children of acute lymphoblastic leukemia (ALL) have been recognized as a priority area for research. The present study aimed to evaluate the relationship between osteoprotegerin (OPG)/receptor activator of nuclear factor kappa-B (RANK)/RANK ligand (RANKL) axis, vitamin D status, and serum magnesium in ALL survivors. Sixty ALL survivors treated with chemotherapy and 60 age and sex-matched controls were included. Vitamin D and parathyroid hormone, RANK, RANKL, and OPG levels were immunoassayed, in addition to serum calcium, phosphorus, magnesium levels, and alkaline phosphatase activity assessment. Furthermore, standard anthropometric measurement, history of fractures since treatment and clinical assessment were recorded. History of bone fractures after the start of therapy was detected in 17 ALL subjects (28.33%). Significantly lower vitamin D, magnesium, calcium, and OPG levels, meanwhile, significantly higher serum parathyroid hormone, RANK, and RANKL levels were detected in survivors compared with the control group. Vitamin D level was significantly positively correlated with magnesium, calcium, and OPG levels. Meanwhile, negatively correlated with RANK and RANKL levels. ALL survivors had a high prevalence of impaired vitamin D status, decreased Mg, and altered OPG/RANK/RANKL axis with impaired bone remodeling. The results herein may open the door for new interventional actions in ALL survivors to protect against bone resorption.

Osteoporosis in children and adolescents: how to treat and monitor?

Osteoporosis is a condition of increased bone fragility associated with fractures. Apart from primary genetic osteoporotic conditions, secondary osteoporosis in children is being increasingly recognized. As a result, there is growing interest in its prevention and treatment. Important goals of care are to prevent fractures, increase bone mass and trabecular and cortical thickness, reshape vertebral fractures, prevent (or correct) skeletal deformities, and improve mobility, independence, and quality of life. Secondary pediatric osteoporosis is often of multifactorial origin since affected children frequently have more than one acquired factor that is detrimental to bone health. Typical conditions causing osteoporosis are leukemias, progressive muscle or neurological disorders, as well as chronic inflammatory conditions and their treatment. Management of children with osteoporosis involves a multidisciplinary team involving pediatric experts from different subspecialties. With regard to prevention and early intervention, it is important to provide optimal management of any underlying systemic conditions including avoidance, or dose-reduction, of osteotoxic medications. Basic supporting life-style measures, such as appropriate nutrition, including adequate calcium intake and vitamin D, and physical activity are recommended, where possible. When pediatric treatment criteria for osteoporosis are met, antiresorptive drugs constitute the first pharmacological line treatment.

CONCLUSION

This clinical review focuses on the prevention, treatment, and follow-up of children with, or at risk of developing, osteoporosis and the transition from pediatric to adult care.

WHAT IS KNOWN

• Osteoporosis and associated fractures can cause significant morbidity and reduce the quality of life. • The developing skeleton has huge potential for recovery and reshaping, thus early detection of fractures, assessment of recovery potential, and treatment of children with osteoporosis can prevent future fractures, deformities, and scoliosis, improve function and mobility, and reduce pain.

WHAT IS NEW

• Osteoporosis in children and adolescents requires a multidisciplinary approach with a thorough assessment of recovery potential, and indication for therapy should be personalized. • Although bisphosphonates still represent the drug most commonly used to increase bone mass, improve mobility, and reduce pain and recurrence of fractures, new agents are being developed and could be beneficial in children with specific conditions.

Bone health in childhood and adolescence: an overview on dual-energy X-ray absorptiometry scanning, fracture surveillance and bisphosphonate therapy for low-middle-income countries

Bone accrual in childhood determines bone health in later life. Loss of bone strength in early life can lead to increased morbidity and reduced quality of life in childhood and adolescence. Increased availability of assessment tools and bisphosphonate therapy, together with increased awareness on the significance of fracture history and risk factors, have led to greater opportunities, to improve detection and optimize management of children and adolescents with bone fragility globally, including those in lower resource settings. Bone mineral density z-scores and bone mineral content are surrogate measures of bone strength, which can be measured by dual-energy X-ray absorptiometry (DXA), in growing individuals. DXA can aid in the diagnosis and management of primary and secondary bone fragility disorders in childhood. DXA helps evaluate children with clinically significant fractures, and monitor those with bone fragility disorders, or at high risk for compromised bone strength. Obtaining DXA images can however be challenging, especially in younger children, due to difficulty in positioning and movement artefacts, while paediatric DXA interpretation can be confounded by effects of growth and puberty. Furthermore, access to DXA facilities as well as appropriate paediatric reference norms and expertise for interpretation, may not be easily available especially in lower resource settings. Pediatric bone experts are now placing increasing emphasis on the fracture phenotype and clinical context to diagnose osteoporosis over bone mineral density (BMD) by DXA. Low trauma vertebral fractures are now recognized as a hallmark of bone fragility, and spinal fracture surveillance by either conventional lateral thoracolumbar radiographs or vertebral fracture assessment by DXA is gaining increasing importance in diagnosing childhood osteoporosis, and initiating bone protective therapy. Furthermore, it is now understood that even a single, low-trauma long bone fracture can signal osteoporosis in those with risk factors for bone fragility. Intravenous bisphosphonate therapy is the mainstay of treatment for childhood bone fragility disorders. Other supportive measures to improve bone strength include optimizing nutrition, encouraging weight bearing physical activity within the limits of the underlying condition, and treating any associated endocrinopathies. With this paradigm shift in childhood osteoporosis evaluation and management, lack of DXA facilities to assess BMD at baseline and/or provide serial monitoring is not a major barrier for initiating IV bisphosphonate therapy in children in whom it is clinically indicated and would benefit from its use. DXA is useful, however, to monitor treatment response and optimal timing for treatment discontinuation in children with transient risk factors for osteoporosis. Overall, there is lack of awareness and paucity of guidelines on utilizing and adopting available resources to manage paediatric bone disorders optimally in lower-resource settings. We provide an evidence-based approach to the assessment and management of bone fragility disorders in children and adolescents, with appropriate considerations for lower resource settings including LMIC countries.

Risk and determinants of low and very low bone mineral density and fractures in a national cohort of Dutch adult childhood cancer survivors (DCCSS-LATER): a cross-sectional study

BACKGROUND

Childhood cancer survivors are at risk of developing skeletal comorbidities later in life. We aimed to assess risk factors for low and very low bone mineral density (BMD), and the risk of and risk factors for any fractures and vertebral fractures in a national cohort of Dutch adult childhood cancer survivors.

METHODS

In this cross-sectional study, we used data from the DCCSS LATER cohort, which comprised individuals who were alive for at least 5 years after diagnosis of childhood cancer (ie, histologically confirmed malignancies or Langerhans cell histiocytosis), were diagnosed before the age of 19 years, and who had been treated at one of seven Dutch paediatric oncology centres between 1963 and 2002 (hereafter referred to as survivors). For this study, we invited survivors aged 18-45 years, who were alive as of Oct 10, 2016, living in the Netherlands, and who were deemed eligible by their treating physician to participate. We assessed BMD using dual-energy x-ray absorptiometry (DXA). Self-reported fractures that occurred at least 5 years after cancer diagnosis were assessed using available medical history and compared with population-level data from the Swedish national registry. We assessed vertebral fractures in a subset of participants using a vertebral fracture assessment. We assessed associations between the occurrence of low (Z-score of ≤-1) or very low (Z-score of ≤-2) BMD, fractures, and vertebral fractures and demographic, treatment-related, endocrine, and lifestyle-related factors using logistic regression analysis.

FINDINGS

Between April 29, 2016, and Jan 22, 2020, 3996 (64·8%) of 6165 individuals from the DCCSS LATER cohort were invited to participate, of whom 2003 (50·1%) were enrolled (mean age at participation was 33·1 years [SD 7·2], 966 [48·2%] were female, and 1037 [51·8%] were male [data on ethnicity and race were not available due to national policies]). 1548 (77·3%) had evaluable DXA scans for assessment of BMD, 1892 (94·5%) provided medical history of fractures, and 249 (12·4%) were assessed for vertebral fractures. 559 (36·1%) of 1548 had low BMD at any site, and 149 (9·6%) had very low BMD at any site. The standardised incidence ratio of any first fracture was 3·53 (95% CI 3·06-4·06) for male participants and 5·35 (4·46-6·52) for female participants. 33 (13·3%) of 249 participants had vertebral fractures. Male sex, underweight, high carboplatin dose, any dose of cranial radiotherapy, hypogonadism, hyperthyroidism, low physical activity, and severe vitamin D deficiency were associated with low BMD at any site and male sex, underweight, cranial radiotherapy, growth hormone deficiency, and severe vitamin D deficiency were associated with very low BMD at any site. Additionally, male sex, former and current smoking, and very low lumbar spine BMD were associated with any fractures, whereas older age at follow-up, previous treatment with platinum compounds, growth hormone deficiency, and low physical activity were specifically associated with vertebral fractures.

INTERPRETATION

Survivors of childhood cancer are at increased risk of any first fracture. Very low lumbar spine BMD was associated with fractures, highlighting the importance of active BMD surveillance in high-risk survivors (ie, those treated with cranial, craniospinal, or total body irradiation). Moreover, our results indicate that intensive surveillance and timely interventions for endocrine disorders and vitamin deficiencies might improve bone health in childhood cancer survivors, but this needs to be assessed in future studies.

FUNDING

Children Cancer-free Foundation (KiKa), KiKaRoW, and ODAS foundation.

Transition of young adults with metabolic bone diseases to adult care

As more accurate diagnostic tools and targeted therapies become increasingly available for pediatric metabolic bone diseases, affected children have a better prognosis and significantly longer lifespan. With this potential for fulfilling lives as adults comes the need for dedicated transition and intentional care of these patients as adults. Much work has gone into improving the transitions of medically fragile children into adulthood, encompassing endocrinologic conditions like type 1 diabetes mellitus and congenital adrenal hyperplasia. However, there are gaps in the literature regarding similar guidance concerning metabolic bone conditions. This article intends to provide a brief review of research and guidelines for transitions of care more generally, followed by a more detailed treatment of bone disorders specifically. Considerations for such transitions include final adult height, fertility, fetal risk, heritability, and access to appropriately identified specialists. A nutrient-dense diet, optimal mobility, and adequate vitamin D stores are protective factors for these conditions. Primary bone disorders include hypophosphatasia, X-linked hypophosphatemic rickets, and osteogenesis imperfecta. Metabolic bone disease can also develop secondarily as a sequela of such diverse exposures as hypogonadism, a history of eating disorder, and cancer treatment. This article synthesizes research by experts of these specific disorders to describe what is known in this field of transition medicine for metabolic bone diseases as well as unanswered questions. The long-term objective is to develop and implement strategies for successful transitions for all patients affected by these various conditions.

Safety and Efficacy of Alendronate to Treat Osteopenia in Children During Therapy for Acute Lymphoblastic Leukemia: A Retrospective Cohort Study of Sequential Outcomes

BACKGROUND

Low bone mineral density is encountered in children with acute lymphoblastic leukemia (ALL) before, during, and after treatment. Prior experience with alendronate, an oral bisphosphonate, demonstrated high tolerability and evident clinical efficacy. However, concerns have been expressed about the long-term safety and utility of such agents in children.

PROCEDURE

Sixty-nine children with ALL received alendronate for a mean of 87 weeks after dual-energy x-ray absorptiometry. Dual-energy x-ray absorptiometry was repeated following the completion of alendronate, and 5 to 9 years later in a subgroup of 32 children. Lumbar spine areal bone mineral density (LS aBMD) Z scores were obtained.

RESULTS

The mean LS aBMD Z score rose from -1.78 to-0.47 (P <0.0001). There was a modest median loss of LS aBMD subsequently in the 32 subjects on long-term follow-up. Almost 80% (N=172) of the children remain in continuous complete remission at a mean of 14.5 years from diagnosis. Of those who received alendronate, which was almost uniformly well tolerated, 7/69 (10.3%) relapsed compared with 19/89 (21.3%) who did not receive the drug.

DISCUSSION

Alendronate appears to be well tolerated and moderately effective in osteopenic children with ALL. Whether it offers protection against relapse of leukemia needs further study.

Osteoporosis in children and young adults

Osteoporosis is a major public health problem with serious long-term complications. In children, the definition of osteoporosis is not only based on densitometric criteria but also takes into account vertebral and long bone fragility fractures. Several factors, such as long-term high-dose steroids, chronic inflammation, malnutrition, immobility, lack of sex steroids, and medication can reduce bone density and increase the risk for fragility fractures when left untreated. Also, genetic conditions can predispose to primary bone fragility disorders, with osteogenesis imperfecta being the most common. Furthermore, since the growing skeleton is at an increased rate of bone remodeling, the ability to heal long bone fractures and reshape vertebral fractures differentiates children from adults. The scope of this chapter is to review the risk factors of osteoporosis and fragility fractures and describe the commonest causes of primary and secondary osteoporosis and their management in children and young adults.

Evaluating and optimizing bone health in children with chronic health conditions

Paediatric health care providers (HCPs) play an important role in optimizing bone health. Early intervention is essential to maximize the accrual of peak bone mass in adolescence and young adulthood and to reduce osteoporosis and fracture risk later in life. Children and adolescents with chronic health conditions may have several risk factors for poor bone health, including underlying inflammatory conditions, reduced weight-bearing activity, delayed puberty, and inadequate intake of calcium and vitamin D. Some medications-particularly glucocorticoids-can compromise bone mass and place a child at risk for fragility fractures. This practice point describes a targeted approach to identifying bone health risk factors in children and youth with chronic health conditions, highlights office initiatives aimed at optimizing bone mass accrual, and links HCPs to useful web-based tools and medical references. Indications for referral to a bone health specialist and bone-specific pharmacotherapeutic interventions are also reviewed.

L'évaluation et l'optimisation de la santé osseuse chez les enfants ayant des affections chroniques

Les professionnels de la santé des enfants jouent un rôle important dans l'optimisation de la santé osseuse. Il est essentiel d'intervenir rapidement pour maximiser le pic de masse osseuse à l'adolescence et au début de l'âge adulte et d'ainsi réduire le risque d'ostéoporose et de fractures plus tard dans la vie. Les enfants et les adolescents ayant une affection chronique peuvent présenter plusieurs facteurs de risque de mauvaise santé osseuse, notamment des maladies inflammatoires sous-jacentes, des activités avec mise en charge limitées, un retard pubertaire et un apport insuffisant de calcium et de vitamine D. Certains médicaments, et particulièrement les glucocorticoïdes, peuvent compromettre la masse osseuse et exposer l'enfant à un risque de fractures de fragilisation. Le présent point de pratique décrit une approche ciblée pour déterminer les facteurs de risque liés à la santé osseuse chez les enfants et les adolescents ayant une affection chronique, expose les mesures à prendre en cabinet pour optimiser l'acquisition de la masse osseuse et propose des outils en ligne utiles et des références médicales à l'intention des professionnels de la santé des enfants. Les indications pour diriger les patients vers un spécialiste de la santé osseuse et pour procéder à des interventions pharmacologiques visant les os sont également abordées.

Orthopaedic adverse events among adolescents and adults treated with asparaginase for acute lymphoblastic leukaemia

Osteonecrosis (ON) is a complication of acute lymphoblastic leukaemia (ALL) treatment with patient- (age, female sex, genetic polymorphisms, presence of metabolic syndrome) and treatment-specific (glucocorticoid type and schedule) risk factors described. The potential role of asparaginase in increasing risk of ON via effects on coagulation, lipid metabolism, and steroid clearance is now also recognised. Paediatric studies consistently identify age as a key risk factor for ON, with adolescents at higher risk than young children. Fewer studies comprehensively report on risk of ON in adults, but available evidence suggests that adolescents and young adults (AYAs) treated with corticosteroid and asparaginase-containing paediatric-inspired regimens are more at risk than older adults treated with paediatric-inspired or traditional adult regimens. There are few proven strategies to prevent or mitigate the severity of ON and other orthopaedic complications of ALL therapy. Future clinical trials should carefully ascertain orthopaedic adverse events in adults. Evidence-based guidelines should be developed for management of orthopaedic adverse events in adults being treated for ALL, especially high-risk AYAs being treated with paediatric-inspired regimens.

Osteoporosis in children and adolescents: when to suspect and how to diagnose it

Early recognition of osteoporosis in children and adolescents is important in order to establish an appropriate diagnosis of the underlying condition and to initiate treatment if necessary. In this review, we present the diagnostic work-up, and its pitfalls, of pediatric patients suspected of osteoporosis including a careful collection of the medical and personal history, a complete physical examination, biochemical data, molecular genetics, and imaging techniques. The most recent and relevant literature has been reviewed to offer a broad overview on the topic. Genetic and acquired pediatric bone disorders are relatively common and cause substantial morbidity. In recent years, there has been significant progress in the understanding of the genetic and molecular mechanistic basis of bone fragility and in the identification of acquired causes of osteoporosis in children. Specifically, drugs that can negatively impact bone health (e.g. steroids) and immobilization related to acute and chronic diseases (e.g. Duchenne muscular dystrophy) represent major risk factors for the development of secondary osteoporosis and therefore an indication to screen for bone mineral density and vertebral fractures. Long-term studies in children chronically treated with steroids have resulted in the development of systematic approaches to diagnose and manage pediatric osteoporosis.

CONCLUSIONS

Osteoporosis in children requires consultation with and/or referral to a pediatric bone specialist. This is particularly relevant since children possess the unique ability for spontaneous and medication-assisted recovery, including reshaping of vertebral fractures. As such, pediatricians have an opportunity to improve bone mass accrual and musculoskeletal health in osteoporotic children.

WHAT IS KNOWN

• Both genetic and acquired pediatric disorders can compromise bone health and predispose to fractures early in life. • The identification of children at risk of osteoporosis is essential to make a timely diagnosis and start the treatment, if necessary.

WHAT IS NEW

• Pediatricians have an opportunity to improve bone mass accrual and musculoskeletal health in osteoporotic children and children at risk of osteoporosis. • We offer an extensive but concise overview about the risk factors for osteoporosis and the diagnostic work-up (and its pitfalls) of pediatric patients suspected of osteoporosis.

Prevalence of osteopathologies in a single center cohort of survivors of childhood primary brain tumor

BACKGROUND

Childhood primary brain tumors (CPBT) are the second largest group of childhood malignancies and associated with a high risk for endocrine late effects.

OBJECTIVE

To assess endocrine late effects and their relevance for the development of osteopathologies in survivors.

METHODS

This single center cross sectional study investigated data from 102 CPBT survivors with a mean age of 13.0 years and a mean age at diagnosis of 8.7 years. Clinical, biochemical, radiographic, and anamnestic data regarding endocrine and bone health were obtained at study visits. In addition, data regarding tumor stage and therapy was obtained by chart review. An expert opinion was applied to define presence of osteopathologies.

RESULTS

Impaired bone health, defined by at least one pathological screening parameter, was present in 65% of patients. 27.5% were found to have overt osteopathologies per expert opinion. 37.8% displayed a severe vitamin D deficiency (25-OH vitamin D < 10 ng/ml) and 11% a secondary hyperparathyroidism. Patients with osteopathologies had lower 25-OH vitamin D levels compared to patients without osteopathologies. Multiple endocrine late effects were present: diabetes insipidus in 10.8%, aberrant pubertal development in 13.7%, central hypocortisolism in 14.9%, thyroid dysfunction in 23.8% and growth hormone deficiency in 21.8%. A total of 31.3% of survivors displayed any endocrinopathy. Tumors located near hypothalamic structures and patients who received irradiation had a higher likelihood of endocrine morbidity.

CONCLUSION

This study indicates that endocrine deficiencies are common in pediatric survivors of CPBTs. Osteopathologies are present in this cohort. A prominent effect of hormonal deficiencies on bone health was not detected, possibly because patients were sufficiently treate for their endocrine conditions or indicating resilience of the childhood bone remodeling process. Vitamin D deficiency is frequent and should be treated as recommended.

A Validated Risk Prediction Model for Bone Fragility in Children With Acute Lymphoblastic Leukemia

Although bone fragility may already be present at diagnosis of pediatric acute lymphoblastic leukemia (ALL), routine performance of dual-energy X-ray absorptiometry (DXA) in every child is not universally feasible. The aim of this study was to develop and validate a risk prediction model for low lumbar spine bone mineral density (LS BMD Z-score ≤ -2.0) at diagnosis, as an important indicator for fracture risk and further treatment-related BMD aggravation. Children with ALL (4-18 years), treated according to the Dutch Childhood Oncology Group protocol (DCOG-ALL9; model development; n = 249) and children from the Canadian Steroid-Associated Osteoporosis in the Pediatric Population cohort (STOPP; validation; n = 99) were included in this study. Multivariable logistic regression analyses were used to develop the prediction model and to confirm the association of low LS BMD at diagnosis with symptomatic fractures during and shortly after cessation of ALL treatment. The area under the receiver operating characteristic curve (AUC) was used to assess model performance. The prediction model for low LS BMD at diagnosis using weight (β = -0.70) and age (β = -0.10) at diagnosis revealed an AUC of 0.71 (95% CI, 0.63-0.78) in DCOG-ALL9 and 0.74 (95% CI, 0.63-0.84) in STOPP, and resulted in correct identification of 71% of the patients with low LS BMD. We confirmed that low LS BMD at diagnosis is associated with LS BMD at treatment cessation (OR 5.9; 95% CI, 3.2-10.9) and with symptomatic fractures (OR 1.7; 95% CI, 1.3-2.4) that occurred between diagnosis and 12 months following treatment cessation. In meta-analysis, LS BMD at diagnosis (OR 1.6; 95% CI, 1.1-2.4) and the 6-month cumulative glucocorticoid dose (OR 1.9; 95% CI, 1.1-3.2) were associated with fractures that occurred in the first year of treatment. In summary, a prediction model for identifying pediatric ALL patients with low LS BMD at diagnosis, as an important indicator for bone fragility, was successfully developed and validated. This can facilitate identification of future bone fragility in individual pediatric ALL patients. © 2021 American Society for Bone and Mineral Research (ASBMR).

Zoledronic Acid vs Placebo in Pediatric Glucocorticoid-induced Osteoporosis: A Randomized, Double-blind, Phase 3 Trial

CONTEXT

Glucocorticoids (GCs) prescribed for chronic pediatric illnesses are associated with osteoporotic fractures.

OBJECTIVE

This study aims to determine the efficacy and safety of intravenous (IV) zoledronic acid (ZA) compared with placebo to treat pediatric GC-induced osteoporosis (GIO).

METHODS

Children aged 5 to 17 years with GIO were enrolled in this multinational, randomized, double-blind, placebo-controlled phase 3 trial (ClinicalTrials.gov NCT00799266). Eligible children were randomly assigned 1:1 to 6 monthly IV ZA 0.05 mg/kg or IV placebo. The primary end point was the change in lumbar spine bone mineral density z score (LSBMDZ) from baseline to month 12. Incident fractures and safety were assessed.

RESULTS

Thirty-four children were enrolled (mean age 12.6 ± 3.4 years [18 on ZA, 16 on placebo]), all with low-trauma vertebral fractures (VFs). LSBMDZ increased from -2.13 ± 0.79 to -1.49 ± 1.05 on ZA, compared with -2.38 ± 0.90 to -2.27 ± 1.03 on placebo (least squares means difference 0.41 [95% CI, 0.02-0.81; P = .04]); when corrected for height z score, the least squares means difference in LBMDZ was 0.75 [95% CI, 0.27-1.22; P = .004]. Two children on placebo had new low-trauma VF vs none on ZA. Adverse events (AEs) were reported in 15 of 18 children (83%) on ZA, and in 12 of 16 (75%) on placebo, most frequently within 10 days after the first infusion. There were no deaths or treatment discontinuations due to treatment-emergent AEs.

CONCLUSION

LSBMDZ increased significantly on ZA compared with placebo over 1 year in children with GIO. Most AEs occurred after the first infusion.

Osteoporotic Fractures and Vertebral Body Reshaping in Children With Glucocorticoid-treated Rheumatic Disorders

CONTEXT

Osteoporotic fractures are an important cause of morbidity in children with glucocorticoid-treated rheumatic disorders.

OBJECTIVE

This work aims to evaluate the incidence and predictors of osteoporotic fractures and potential for recovery over six years following glucocorticoid (GC) initiation in children with rheumatic disorders.

METHODS

Children with GC-treated rheumatic disorders were evaluated through a prospective inception cohort study led by the Canadian STeroid-induced Osteoporosis in the Pediatric Population (STOPP) Consortium. Clinical outcomes included lumbar spine bone mineral density (LS BMD), vertebral fractures (VF), non-VF, and vertebral body reshaping.

RESULTS

A total of 136 children with GC-treated rheumatic disorders were enrolled (mean age 9.9 years, SD 4.4). The 6-year cumulative fracture incidence was 16.3% for VF, and 10.1% for non-VF. GC exposure was highest in the first 6 months, and 24 of 38 VF (63%) occurred in the first 2 years. Following VF, 16 of 19 children (84%) had complete vertebral body reshaping. Increases in disease activity and body mass index z scores in the first year and declines in LS BMD z scores in the first 6 months predicted incident VF over the 6 years, while higher average daily GC doses predicted both incident VF and non-VF. LS BMD z scores were lowest at 6 months (mean -0.9, SD 1.2) and remained low by 6 years even when adjusted for height z scores (-0.6, SD 0.9).

CONCLUSION

VF occurred early and were more common than non-VF in children with GC-treated rheumatic disorders. Eighty-four percent of children with VF underwent complete vertebral body reshaping, whereas vertebral deformity persisted in the remainder of children. On average, LS BMD z scores remained low at 6 years, consistent with incomplete recovery.

Can screening for low vitamin D levels prevent bone health complications in paediatric oncology patients?

Background

No international standards include vitamin D levels at diagnosis or during treatment. It is included in the Children's Oncology Group long‐term follow‐up guidelines. However, bone health complications (like osteopenia and atraumatic fractures) can occur at diagnosis or during treatment as well.

Cases

In this small case series, we illustrate the complexity of bone health complications among our broad paediatric oncology population. If the vitamin D level is low we supplement the patient with one standard oral dose (150 000 units for 1–2 year olds, 300 000 units for 2–5 year olds and 600 000 units for >5 year olds). We do not adjust depending on diagnosis.

Conclusion

Because of the potentially negative outcomes on short, medium and long term, we recommend checking vitamin D levels on diagnosis for all newly diagnosed patients. It is a simple, low cost test and one dose of oral supplementation can easily treat the deficiency.

Bone health in glucocorticoid-treated childhood acute lymphoblastic leukemia

Glucocorticoids (GCs) are widely used in the treatment of childhood acute lymphoblastic leukemia (ALL), but their long-term use is also associated with bone-related morbidities. Among others, growth deficit, decreased bone mineral density (BMD) and increased fracture rate are well-documented and severely impact quality of life. Unfortunately, no efficient treatment for the management of bone health impairment in patients and survivors is currently available. The overall goal of this review is to discuss the existing data on how GCs impair bone health in pediatric ALL and attempts made to minimize these side effects.

The effect of oral bisphosphonate therapy on vertebral morphometry and fractures in patients with Duchenne muscular dystrophy and glucocorticoid-induced osteoporosis

INTRODUCTION/AIMS

Glucocorticoid-induced osteoporosis with vertebral fractures is frequent in patients with Duchenne muscular dystrophy (DMD). In this study, we evaluated the effects of oral bisphosphonate (BP) therapy on the prevalence and severity of vertebral fractures by vertebral morphometry assessment.

METHODS

We reviewed the records and radiographs of patients with DMD who had been treated with oral BP (weekly alendronate) and had undergone routine spine radiographic monitoring for glucocorticoid-induced osteoporosis at Cincinnati Children's Hospital Medical Center between 2010 and 2017. Study outcomes were thoracic and lumbar vertebral fracture prevalence and severity, assessed by Genant semiquantitative grading of vertebral morphometry, for up to 5 years of treatment.

RESULTS

Fifty-two patients (median age, 11.8 years; 88% prepubertal; 31% nonambulatory) had been treated with long-term glucocorticoids (median duration, 4.7 years at BP start). Most patients (75%) had mild vertebral height loss or fractures (Genant grade = 0 or 1) at baseline. The prevalence of vertebral fractures at each year of treatment was not statistically different from that at baseline (P = .08-1.00). Serial radiographs showed no longitudinal change in severity by Genant grade in most vertebrae (64%-80%). Improvement in vertebral fracture grade was observed in some patients.

DISCUSSION

We observed stable prevalence of vertebral fractures and no change in severity by Genant grade in most vertebrae for up to 5 years of treatment. Oral BP may mitigate development or progression of vertebral fractures and be beneficial for secondary prevention of glucocorticoid-induced osteoporosis in this population.

Bone mineral density surveillance for childhood, adolescent, and young adult cancer survivors: evidence-based recommendations from the International Late Effects of Childhood Cancer Guideline Harmonization Group

Childhood, adolescent, and young adult cancer survivors are at increased risk of reduced bone mineral density. Clinical practice surveillance guidelines are important for timely diagnosis and treatment of these survivors, which could improve bone mineral density parameters and prevent fragility fractures. Discordances across current late effects guidelines necessitated international harmonisation of recommendations for bone mineral density surveillance. The International Late Effects of Childhood Cancer Guideline Harmonization Group therefore established a panel of 36 experts from ten countries, representing a range of relevant medical specialties. The evidence of risk factors for very low and low bone mineral density and fractures, surveillance modality, timing of bone mineral density surveillance, and treatment of very low and low bone mineral density were evaluated and critically appraised, and harmonised recommendations for childhood, adolescent, and young adult cancer survivors were formulated. We graded the recommendations based on the quality of evidence and balance between potential benefits and harms. Bone mineral density surveillance is recommended for survivors treated with cranial or craniospinal radiotherapy and is reasonable for survivors treated with total body irradiation. Due to insufficient evidence, no recommendation can be formulated for or against bone mineral density surveillance for survivors treated with corticosteroids. This surveillance decision should be made by the survivor and health-care provider together, after careful consideration of the potential harms and benefits and additional risk factors. We recommend to carry out bone mineral density surveillance using dual-energy x-ray absorptiometry at entry into long-term follow-up, and if normal (Z-score > -1), repeat when the survivor is aged 25 years. Between these measurements and thereafter, surveillance should be done as clinically indicated. These recommendations facilitate evidence-based care for childhood, adolescent, and young adult cancer survivors internationally.

Musculoskeletal impairments in children receiving intensive therapy for acute leukemia or undergoing hematopoietic stem cell transplant: A report from the Children's Oncology Group

BACKGROUND

Children receiving intensive chemotherapy for leukemia or undergoing hematopoietic stem cell transplant (HSCT) for solid tumors or leukemia are at risk for musculoskeletal (MSK) impairment from their underlying disease and from treatment. Data are limited on the incidence and nature of these disorders during intensive therapy. This study's objective was to provide a cross-sectional description of MSK impairments in this population.

PROCEDURE

Children with acute myeloid leukemia (AML), relapsed acute lymphoblastic leukemia (rALL), or undergoing HSCT were systematically assessed for MSK impairments as part of Children's Oncology Group study ACCL0934. Assessments occurred at study entry, at 2 months, and at 12 months and included evaluation for signs or symptoms of MSK impairment and the type, site, and diagnosis.

RESULTS

Six hundred three patients were included. MSK signs or symptoms were present in 48 (8.0%) children at study entry, 64 (13.5%) children at 2 months, and 40 (11.6%) children at 12 months. Arthralgia and/or gait abnormalities were the most common impairments; the knee was the most common site. Arthritis and tendonitis were both rare. Vincristine neuropathy, MSK impacts from central nervous system pathology, and bone or joint pain from underlying cancer were the most common diagnoses. Multivariate analysis demonstrated that having rALL (odds ratio [OR] 2.00, 95% CI 1.07-3.76, p = .03) or obesity (OR 2.10, 95% CI 1.12-3.95, p = .02) were risk factors for MSK impairment at study entry.

CONCLUSIONS

MSK impairments are common in this intensively treated patient population, especially in those with rALL and those who are obese.

The Accuracy of Incident Vertebral Fracture Detection in Children Using Targeted Case-Finding Approaches

Vertebral fractures are clinically important sequelae of a wide array of pediatric diseases. In this study, we examined the accuracy of case-finding strategies for detecting incident vertebral fractures (IVF) over 2 years in glucocorticoid-treated children (n = 343) with leukemia, rheumatic disorders, or nephrotic syndrome. Two clinical situations were addressed: the prevalent vertebral fracture (PVF) scenario (when baseline PVF status was known), which assessed the utility of PVF and low lumbar spine bone mineral density (LS BMD; Z-score <-1.4), and the non-PVF scenario (when PVF status was unknown), which evaluated low LS BMD and back pain. LS BMD was measured by dual-energy X-ray absorptiometry, vertebral fractures were quantified on spine radiographs using the modified Genant semiquantitative method, and back pain was assessed by patient report. Forty-four patients (12.8%) had IVF. In the PVF scenario, both low LS BMD and PVF were significant predictors of IVF. Using PVF to determine which patients should have radiographs, 11% would undergo radiography (95% confidence interval [CI] 8-15) with 46% of IVF (95% CI 30-61) detected. Sensitivity would be higher with a strategy of PVF or low LS BMD at baseline (73%; 95% CI 57-85) but would require radiographs in 37% of children (95% CI 32-42). In the non-PVF scenario, the strategy of low LS BMD and back pain produced the highest specificity of any non-PVF model at 87% (95% CI 83-91), the greatest overall accuracy at 82% (95% CI 78-86), and the lowest radiography rate at 17% (95% CI 14-22). Low LS BMD or back pain in the non-PVF scenario produced the highest sensitivity at 82% (95% CI 67-92), but required radiographs in 65% (95% CI 60-70). These results provide guidance for targeting spine radiography in children at risk for IVF. © 2021 American Society for Bone and Mineral Research (ASBMR).

Recent perspectives on the association between osteonecrosis and bone mineral density decline in childhood acute lymphoblastic leukemia

The attention to treatment-related toxicity has increased since the survival of children with acute lymphoblastic leukemia (ALL) has improved significantly over the past few decades. Intensive ALL treatment schedules including corticosteroids and asparaginase have been shown to give rise to skeletal abnormalities such as osteonecrosis and low bone mineral density (BMD), which may lead to debilitating sequelae in survivors. Although osteonecrosis and low BMD are different entities with suggested separate pathophysiological mechanisms, recent studies indicate that osteonecrosis is associated with accelerated BMD decline. Common underlying mechanisms for osteonecrosis and BMD decline are considered, such as an enhanced sensitivity to corticosteroids in children who suffer from both osteonecrosis and low BMD. In addition, restriction of weight-bearing activities, which is generally advised in patients with osteonecrosis, could aggravate BMD decline. This induces a clinical dilemma, since bone stimulation is important to maintain BMD but alternative interventions for osteonecrosis are limited. Furthermore, this recent finding of accelerated BMD decline in children with osteonecrosis emphasizes the need to develop effective preventive measures for osteonecrosis, which may include targeting BMD decline.

Vitamin D supplementation for children with cancer: A systematic review and consensus recommendations

Background

Prevalent vitamin D deficiency (VDD) and low bone mineral density (BMD) have led to vitamin D supplementation for children with cancer, regardless vitamin D status. However, it remains unsettled whether this enhances bone strength. We sought to address this issue by carrying out a systematic review of the literature.

Methods

We conducted a literature search using PubMed, Embase, and Cochrane databases. Studies including children up to 5 years after cancer therapy were assessed for the association between 25‐hydroxyvitamin D (25OHD) levels and BMD Z‐scores or fractures, and the effect of vitamin D supplementation on BMD or fractures. Evidence quality was assessed using the GRADE methodology.

Results

Nineteen studies (16 observational and 3 interventional, mainly involving children with hematologic malignancies) were included. One study which analyzed 25OHD as a threshold variable (≤10 ng/ml) found a significant association between 25OHD levels and BMD Z‐scores, while 25OHD as a continuous variable was not significantly associated with BMD Z‐scores in 14 observational studies. We found neither a significant association between lower 25OHD levels and fractures (2 studies), nor between vitamin D (and calcium) supplementation and BMD or fracture frequency (3 studies) (very low quality evidence).

Conclusion

There is a lack of evidence for an effect of vitamin D (and calcium) supplementation on BMD or fractures in children with cancer. Further research is needed; until then, we recommend dietary vitamin D/calcium intake in keeping with standard national guidelines, and periodic 25OHD monitoring to detect levels <20 ng/ml. Vitamin D/calcium supplementation is recommended in children with low levels, to maintain levels ≥20 ng/ml year‐long.

Part I: Which Child with a Chronic Disease Needs Bone Health Monitoring?

PURPOSE OF THE REVIEW

Underlying conditions which adversely affect skeletal strength are one of the most common reasons for consultations in pediatric bone health clinics. The diseases most frequently linked to fragility fractures include leukemia and other cancers, inflammatory disorders, neuromuscular disease, and those treated with osteotoxic drugs (particularly glucocorticoids). The decision to treat a child with secondary osteoporosis is challenged by the fact that fractures are frequent in childhood, even in the absence of risk factors. Furthermore, some children have the potential for medication-unassisted recovery from osteoporosis, obviating the need for bisphosphonate therapy.

RECENT FINDINGS

Over the last decade, there have been important advances in our understanding of the skeletal phenotypes, fracture frequencies, and risk factors for bone fragility in children with underlying disorders. With improved knowledge about the importance of fracture characteristics in at-risk children, there has been a shift away from a bone mineral density (BMD)-centric definition of osteoporosis in childhood, to a fracture-focused approach. As a result, attention is now drawn to the early identification of fragility fractures, which includes asymptomatic vertebral collapse. Furthermore, even a single, long bone fracture can represent a major osteoporotic event in an at-risk child. Fundamental biological principles of bone strength development, and the ways in which these go awry in chronic illnesses, form the basis for monitoring and diagnosis of osteoporosis in children with underlying conditions. Overall, the goal of monitoring is to identify early, rather than late, signs of osteoporosis in children with limited potential to undergo medication-unassisted recovery. These are the children who should undergo bisphosphonate therapy, as discussed in part 1 (monitoring and diagnosis) and part 2 (recovery and the decision to treat) of this review.

Part 2: When Should Bisphosphonates Be Used in Children with Chronic Illness Osteoporosis?

PURPOSE OF REVIEW

Part 1 of this review on secondary osteoporosis of childhood was devoted to understanding which children should undergo bone health monitoring, when to label a child with osteoporosis in this setting, and how best to monitor in order to identify early, rather than late, signs of bone fragility. In Part 2 of this review, we discuss the next critical step in deciding which children require bisphosphonate therapy. This involves distinguishing which children have the potential to undergo "medication-unassisted" recovery from secondary osteoporosis, obviating the need for bisphosphonate administration, from those who require anti-resorptive therapy in order to recover from osteoporosis.

RECENT FINDINGS

Unlike children with primary osteoporosis such as osteogenesis imperfecta, where the potential for recovery from osteoporosis without medical therapy is limited, many children with secondary osteoporosis can undergo complete recovery in the absence of bisphosphonate intervention. Over the last decade, natural history studies have unveiled the spectrum of this recovery, which spans overt deterioration (i.e., incident vertebral and non-vertebral fractures and declines in bone mineral density (BMD)), to spectacular reclamation of BMD, and complete restoration of normal vertebral dimensions after spine fractures. The fact that reshaping of vertebral bodies following fractures is growth-dependent underscores the need to identify and treat those at risk for permanent vertebral deformity in a timely fashion. The decision to treat a child with a bisphosphonate hinges on distinguishing bone fragility from typical childhood fractures, and determining the potential for medication-unassisted recovery following an osteoporotic fragility fracture. While improvements in BMD are a well-known sign of recovery, restitution of bone structure is also a key indicator of recuperation, one that is unique to childhood, and that plays a pivotal role in the decision to intervene or not.

Predictors of Vertebral Deformity in Long-Term Survivors of Childhood Acute Lymphoblastic Leukemia: The PETALE Study

BACKGROUND

The prevalence of vertebral deformities in long-term survivors of childhood acute lymphoblastic leukemia (ALL) is unknown. Our objectives were to identify the prevalence of vertebral deformities and their risk factors among long-term childhood ALL survivors.

METHODS/RESULTS

We recruited 245 (49% male) long-term childhood ALL survivors from the Preventing Late Adverse Effects of Leukemia Cohort (French-Canadian ALL survivors treated between the years 1987 and 2010 with the Dana Farber Cancer Institute clinical trials protocols, who did not experience disease relapse and/or receive hematopoietic stem cell transplant). Median age at recruitment was 21.7 years (range, 8.5-41) and median time since diagnosis was 15.1 years (range, 5.4-28.2). All participants underwent spine radiograph and dual-energy X-ray absorptiometry scans. The prevalence of vertebral deformity was 23% with 88% classified as grade 1 according to the Genant method. The majority of vertebral deformities were clinically silent. Regression analysis confirmed male sex (risk ratio [RR] = 1.94; 95% confidence interval [CI], 1.16-3.24; P = 0.011), higher glucocorticoid cumulative dose (RR = 1.05; 95% CI, 1.00-1.10; P = 0.032), and back pain (RR = 2.44; 95% CI, 1.56-3.84; P < 0.001) as predictors of prevalent vertebral deformity. Sex differences in vertebral deformity predictors emerged.

CONCLUSIONS

We report a significant prevalence of vertebral deformities in this young cohort. Male sex, cumulative glucocorticoid dose, and back pain were identified as predictors of prevalent vertebral deformity. Back pain emerging as a strong predictor of vertebral deformity underscores the importance of ongoing bone health surveillance in survivors with persistent vertebral deformities treated with these earlier protocols.

Bone Mineral Density Evolution and Its Determinants in Long-term Survivors of Childhood Acute Leukemia: A Leucémies Enfants Adolescents Study

This prospective study aimed to analyze determinants that can influence bone mineral density evolution in childhood acute leukemia survivors. Patients included were selected from the long-term follow-up LEA cohort and had dual energy radiograph absorptiometry scan between 10 and 18 years and after the age of 18. All scans were centrally reviewed. Bone mineral density was measured at the lumbar spine, femoral neck, total hip, and whole body, and expressed as z-score. Eighty-nine patients (female 39, lymphoblastic leukemia 68, relapse 25, hematopoietic stem cell transplantation 44, and mean age 15.4 and 20.1 years at the first and second scans, respectively) were studied. The first and second scan z-scores were significantly correlated (P < 10⁻³). Mean femoral neck and total hip z-scores improved significantly between the first and second scans, whereas no significant evolution occurred at the lumbar spine and whole-body level. On the second evaluation, 14.6% of patients had z-score <−2 at the lumbar spine and 4.3% at the femoral neck level. Gender, type of leukemia, transplantation, relapse, cumulative corticosteroid doses, or growth hormone deficiency did not have any significant impact on z-score variation. Younger age at diagnosis (≤8.5 years) proved an unfavorable risk factor for z-score evolution at the lumbar spine (P = 0.041); the trend did not reach statistical significance for metabolic syndrome (P = 0.054). At the femoral neck, both were associated with unfavorable z-score evolution (P = 0.003 and 0.025, respectively). Patients treated at a younger age and those with metabolic syndrome seem to be at higher risk of bone mineral density decline and should benefit from specific interventions.

Effect of Vertebral Fracture on Auxological Profiles of Children Undergoing Acute Lymphoblastic Leukemia Treatment

Background: Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy, and children with ALL often experience skeletal morbidity such as vertebral fractures (VF) during and after ALL treatment. Among various treatment-associated factors that affect growth pattern, the presence of VF might trigger growth impairment. Objective: This study aimed to investigate the overall VF incidence following childhood ALL treatment and examined the association of VF with growth. Methods: Children diagnosed with ALL whose treatment was completed between 2 and 15 years of age and who were screened with lateral thoracolumbar spine radiographs were enrolled. Clinical data, including anthropometric parameters were obtained at leukemia diagnosis (LD), treatment completion (TC), and 12 months following TC while VF assessment were obtained at TC and 12 months following TC. Results: In total, 155 children were included, and height status was decreased, whereas weight and BMI status were increased throughout three observational points. VF incidence at TC was 18.7%. Height status were lower in children with VF at LD, TC, and 12 months following TC, while a greater height decline was observed during the treatment period. Age and height status at LD and average glucocorticoid (GC) dose were associated VF incidence at TC. The presence of VF was a significant risk factor of height decline during the treatment period. Conclusion: A substantial number of children experienced VF following ALL treatment completion, and the presence of VF might adversely affect auxological status in children. VF detection by routine surveillance throughout childhood ALL treatment is recommended to try to prevent compromised growth.

Relationships of Bone Mineral Density to Whole Body Mass, Fat Mass and Fat-free Mass in Long-term Survivors of Acute Lymphoblastic Leukemia in Childhood

Body size influences bone mineral density (BMD) in health. Relationships of BMD with body mass index, fat mass (FM), fat-free mass, and appendicular lean mass were explored in acute lymphoblastic leukemia (ALL) survivors (n=75; 41 males; 45 standard risk ALL) >10 years from diagnosis. Dual energy radiograph absorptiometry performed body composition analysis. Relationships were assessed by regression analyses and Pearson correlation coefficients (r). Twenty subjects (26.3%) were osteopenic; lumbar spine (LS) BMD Z score <-1.00. Age at diagnosis, sex, ALL risk-category, type of post-induction steroid or cranial radiation did not correlate with LS or whole body (WB) BMD. Body mass index correlated significantly with LS BMD (r=0.333, P=0.004) and WB BMD (r=0.271, P=0.033). FM index (FM/height²) Z score showed no significant correlation with LS or WB BMD. Fat-free mass index Z score correlated strongly with LS BMD (r=0.386, P=0.013) and WB BMD (r=0.605, P<0.001) in males but not in females. The appendicular lean mass index, a surrogate for skeletal muscle mass, correlated significantly with LS BMD (r=0.367, P=0.018) and WB BMD (r=0.604, P<0.001) in males but not in females. Future studies to evaluate interventions to enhance BMD focused on improving body composition particularly skeletal muscle mass are warranted.

Bone Health in Childhood Chronic Disease

Many children with chronic disease are now surviving into adulthood. As a result, there is a growing interest in optimizing bone health early in the disease course with the dual goals of improving quality of life during childhood and reducing life-long fracture risk. Risk factors for impaired bone health in these children include immobility, nutritional deficiency, exposure to bone toxic therapies, hormonal deficiencies affecting growth and pubertal development, and chronic inflammation. This review focuses on the chronic diseases of childhood most commonly associated with impaired bone health. Recent research findings and clinical practice recommendations, when available, for specific disorders are summarized.

Advances in the Bone Health Assessment of Children

The last 2 decades have seen tremendous growth in understanding the clinical characteristics of various childhood bone disorders, their mechanisms and natural histories, and their responses to treatment. In this review, the authors describe advances in bone assessment techniques for children. In addition, they provide their skeletal site-specific applications, underscore the principles that are relevant to the biology of the growing child, show how these methods assist in the diagnosis and management of pediatric bone diseases, and highlight how these techniques have shed light on bone development and underlying disease mechanisms.

Management of primary and secondary osteoporosis in children

Osteoporosis in children differs from adults in terms of definition, diagnosis, monitoring and treatment options. Primary osteoporosis comprises primarily of osteogenesis imperfecta (OI), but there are significant other causes of bone fragility in children that require treatment. Secondary osteoporosis can be a result of muscle disuse, iatrogenic causes, such as steroids, chronic inflammation, delayed or arrested puberty and thalassaemia major. Investigations involve bone biochemistry, dual-energy X-ray absorptiometry scan for bone densitometry and vertebral fracture assessment, radiographic assessment of the spine and, in some cases, quantitative computed tomography (QCT) or peripheral QCT. It is important that bone mineral density (BMD) results are adjusted based on age, gender and height, in order to reflect size corrections in children. Genetics are being used increasingly for the diagnosis and classification of various cases of primary osteoporosis. Bone turnover markers are used less frequently in children, but can be helpful in monitoring treatment and transiliac bone biopsy can assist in the diagnosis of atypical cases of osteoporosis. The management of children with osteoporosis requires a multidisciplinary team of health professionals with expertise in paediatric bone disease. The prevention and treatment of fragility fractures and improvement of the quality of life of patients are important aims of a specialised service. The drugs used most commonly in children are bisphosphonates, that, with timely treatment, can give good results in improving BMD and reshaping vertebral fractures. The data regarding their effect on reducing long bone fractures are equivocal. Denosumab is being used increasingly for various conditions with mixed results. There are more drugs trialled in adults, but these are not yet licenced for children. Increasing awareness of risk factors for paediatric osteoporosis, screening and referral to a specialist team for appropriate management can lead to early detection and treatment of asymptomatic fractures and prevention of further bone damage.

Osteoporose im Kindes- und Jugendalter

Osteoporose ist eine Erkrankung des Skelettapparats, die durch eine Beeinträchtigung der Knochenmikroarchitektur zu einer erhöhten Knochenbruchrate führt. Während Osteoporose im höheren Erwachsenenalter eine häufige Diagnose darstellt, wird der Osteoporose des Kindes- und Jugendalters erst seit relativ kurzer Zeit zunehmend Bedeutung zugesprochen. Generell werden zwei unterschiedliche Formen der Erkrankung unterschieden: Die primäre Osteoporose wird verursacht durch genetische Veränderungen in skelettrelevanten Genen, die häufigste Erkrankungsgruppe stellt die Osteogenesis imperfecta mit ursächlichen Mutationen im Kollagen-1-Gen dar. Internistische Maßnahmen umfassen neben funktionell-therapeutischen Maßnahmen auch pharmakologische Therapien mit Bisphosphonaten. Die sekundäre Osteoporose als Symptom chronischer Grunderkrankungen oder pharmakologischer Interventionen weist eine deutlich höhere Prävalenz als die primären Formen der Osteoporose auf. Abhängig von Pathomechanismus und Verlauf der Grunderkrankung kommt es zu osteoporotischen Symptomen unterschiedlichster Ausprägung. Die Therapiekonzepte müssen der individuellen Symptomatik angepasst werden, die Datenlage zum Einsatz von Bisphosphonaten ist deutlich geringer als bei der Osteogenesis imperfecta. Ziel dieses Artikels ist es, einen Überblick über Diagnostik und Therapie der sehr unterschiedlichen Formen der pädiatrischen Osteoporose sowie einen Einblick in die rezenten Entwicklungen für den primär und Sekundärversorgungsbereich zu geben.

A survey of the feasibility of developing osteoporosis clinical trials in Duchenne muscular dystrophy: Survey of the opinion of young people with Duchenne muscular dystrophy, families and clinicians

BACKGROUND/AIMS

Given the extent of osteoporosis in people with Duchenne muscular dystrophy treated with glucocorticoids and the limited evidence of bone-protective therapies, clinical trials are needed. We conducted surveys to obtain the opinion of young people with Duchenne muscular dystrophy, parents/guardians and neuromuscular clinicians on the feasibility of osteoporosis clinical trials in this population.

METHODS

Online surveys were sent to three groups: (a) people with a confirmed diagnosis of Duchenne muscular dystrophy (≥14 years), (b) parents and guardians and (c) neuromuscular clinicians in the UK NorthStar Clinical Network. Surveys (a) and (b) were distributed via the UK Duchenne muscular dystrophy Registry.

RESULTS

Survey respondents included 52 people with Duchenne muscular dystrophy with a median age of 17 years (range: 14, 40) and 183 parents/guardians. Fourteen out of 23 (61%) NorthStar centres responded. Of the 52 people with Duchenne muscular dystrophy, 13 (25%) were very concerned about their bone health and 21 (40%) were slightly concerned. Of the 183 parents/guardians, 75 (41%) were very concerned about their son's bone health and 90 (49%) were slightly concerned. Fractures and quality of life were the top two main outcome measures identified by people with Duchenne muscular dystrophy. Fractures and bone density were the top two main outcome measures identified by parents/guardians and neuromuscular clinicians. Thirty percent of people with Duchenne muscular dystrophy and 40% of parents/guardians would not take part if an osteoporosis trial involved a placebo that was administered parenterally. Only 2 of the 14 NorthStar centres (14%) would enrol people with Duchenne muscular dystrophy if a parenteral placebo was used in an osteoporosis trial in Duchenne muscular dystrophy.

CONCLUSION

There is great awareness of bone health and the need for bone-protective trials among people with Duchenne muscular dystrophy and their carers. However, a proportion of people with Duchenne muscular dystrophy and parents are reluctant to participate in a placebo-controlled osteoporosis trial that included a parenteral therapy. A larger proportion of health care experts are unwilling to enrol their patients in such a trial. Our finding is relevant for the design of bone-protective studies in Duchenne muscular dystrophy.