Bone Turnover Markers: Use in Fracture Prediction

Effect of SGLT2 inhibitors on fractures, BMD, and bone metabolism markers in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

This meta-analysis aims to evaluate the impact of Sodium Glucose Transporter 2 (SGLT2) inhibitors on fractures, bone mineral density (BMD), and bone metabolism markers in type 2 diabetes mellitus (T2DM) patients. Pooled relative risk (RR) with 95% confidence interval (CI) assessed the relationship between SGLT2 inhibitors and fracture risk. Weighted mean difference (WMD) with 95% CI explored the correlation between SGLT2 inhibitors and BMD, as well as bone metabolism markers. A total of 20 randomised controlled trials (RCTs) involving 12,764 patients were analysed. No significant association emerged between SGLT2 inhibitor use and elevated fracture risk (pooled RR = 1.21, 95% CI [0.95, 1.54], I2 = 22%). Furthermore, SGLT2 inhibitors exhibited no substantial effects on BMD changes at the lumbar spine (WMD = -0.02, 95% CI [-0.38, 0.34]), femoral neck (WMD = 0.11, 95% CI [-0.28, 0.50]), total hip (WMD = -0.20, 95% CI [-0.41, 0.01]), and distal forearm (WMD = -0.20, 95% CI [-0.62, 0.22]). Similarly, no notable impact of SGLT2 inhibitors on bone metabolism markers, including CTX (WMD = 0.04, 95% CI [-0.02, 0.09]), P1NP (WMD = 1.06, 95% CI [-0.44, 2.57]), PTH (WMD = 0.34, 95% CI [-0.07, 0.75]), calcium (WMD = 0.01, 95% CI [-0.02, 0.04]), and phosphate (WMD = 2.37, 95% CI [-0.76, 5.49]). The findings suggest that the utilization of SGLT2 inhibitors is not significantly linked to an elevated risk of fractures in individuals with T2DM. However, further clinical investigations and extended follow-up periods are warranted to establish more conclusive determinations.

Aconine attenuates osteoclast-mediated bone resorption and ferroptosis to improve osteoporosis via inhibiting NF-κB signaling

Osteoporosis (OP), a prevalent public health concern primarily caused by osteoclast-induced bone resorption, requires potential therapeutic interventions. Natural compounds show potential as therapeutics for postmenopausal OP. Emerging evidence from in vitro osteoclastogenesis assay suggests that aconine (AC) serves as an osteoclast differentiation regulator without causing cytotoxicity. However, the in vivo functions of AC in various OP models need clarification. To address this, we administered intraperitoneal injections of AC to ovariectomy (OVX)-induced OP mice for 8 weeks and found that AC effectively reversed the OP phenotype of OVX mice, leading to a reduction in vertebral bone loss and restoration of high bone turnover markers. Specifically, AC significantly suppressed osteoclastogenesis in vivo and in vitro by decreasing the expression of osteoclast-specific genes such as NFATc1, c-Fos, Cathepsin K, and Mmp9. Importantly, AC can regulate osteoclast ferroptosis by suppressing Gpx4 and upregulating Acsl4, which is achieved through inhibition of the phosphorylation of I-κB and p65 in the NF-κB signaling pathway. These findings suggest that AC is a potential therapeutic option for managing OP by suppressing NF-κB signaling-mediated osteoclast ferroptosis and formation.

Predisposing factors for a second fragile hip fracture in a population of 1130 patients with hip fractures, treated at Oulu University Hospital in 2013-2016: a retrospective study

OBJECTIVE

The life-time risk of a second fragile hip fracture is 8.4%, but the risk factors that predispose to a second hip fracture remain unresolved. This study aimed to define risk factors that predisposed patients to a second hip fracture.

METHODS

For this retrospective study, we retrieved clinical data on 1130 patients with fragile hip fractures (67.2% female, mean age: 79.3 years) that underwent surgery at the Oulu University Hospital in 2013-2016. These data included the fracture risk assessment score (measured with the FRAX tool), the bone-mass T-score, laboratory values, ambulatory capacity, and the time of death.

RESULTS

In this population, 12.4% of patients sustained a second hip fracture. The predisposing factors for a second hip fracture were: female (p = 0.016), a high FRAX score (p = 0.020), and low physical capacity (p < 0.001). The vitamin D level recommended for treating osteoporosis (i.e., vitamin D > 75 nmol/l) was observed in only 24% of patients, and 42% of patients had ionized calcium levels below the reference range. According to the level of the cross-linked carboxy-terminal telopeptide of type I collagen (ICTP), 37% of patients did not have high bone turnover. We found a positive correlation between age and ICTP (p = 0.001). The risk of death was higher after the second hip fracture (p = 0.005), but we found no difference in age between patients with first and second hip fractures (p = 0.11).

CONCLUSION

After a hip fracture, a second hip fracture is a well-known risk. Nevertheless, we found that only one-third of patients with a second hip fracture had used anti-osteoporosis medication at any time previously. These findings suggested that second hip fractures were most likely to occur in patients with osteopenic T-score values, in women more often than men, and in patients with high FRAX scores and low ambulatory capacity.

Recent advances in the identification of related factors and preventive strategies of hip fracture

Hip fracture is the most devastating type of osteoporosis-related fracture, and is a major worldwide public health problem with a high socioeconomic burden, morbidity rate, and mortality rate. Thus, it is crucial to uncover the risk factors and protective factors to create a hip fracture prevention strategy. In addition to a briefly review of some well accepted risk and protective factors of hip fracture, this review mainly summarized the recent advances in the identification of emerging risk or protective factors for hip fracture, in terms of regional differences in medical services, diseases, drugs, mechanical load, neuromuscular mass, genes, blood types, cultural differences. This review provides a comprehensive review of the associated factors and effective prevention measures for hip fracture, and discusses issues that need further investigation. These issues include the determination of the influencing mechanism of risk factors triggering hip fracture and their interlinked correlation with other factors, as well as the confirmation or correction of emerging factors associated with hip fracture, particularly those that are still controversial. These recent findings will aid in optimizing the strategy for preventing hip fracture.

Clinical application of the fracture risk assessment tool in the general population and its correlation with bone turnover markers

Objective: To compare the risk of osteoporotic fractures between the urban and urban-rural fringe populations in southern China and to explore the effect of bone turnover markers on fracture risk. Methods: Epidemiological investigations were conducted in the urban and urban-rural fringe areas of southern China in June 2018. Residents aged 40 years and over who signed informed consent forms were included. Physical examination and questionnaire collection were completed. Bone turnover markers (BTMs) including osteocalcin (OC) and beta cross-linked C-telopeptide of type 1 collagen (β-CTX) were tested. Bone mineral density (BMD) of the femoral neck and lumbar vertebrae 1-4 were measured using dual energy X-ray absorptiometry. Fracture risk assessment tool (FRAX) values were calculated to show the probability of major osteoporotic fracture (PMOF) and probability of hip fracture (PHF) over the next 10 years. Results: A total of 1,051 participants were included in this study, including 553 in the urban areas and 498 in the urban-rural fringe areas. The average PMOF and PHF were 3.4 (2.3-5.4) % and .6 (.3-1.5) %, respectively. Compared with that in the urban populations, the femoral neck BMD in the urban-rural fringe populations was lower and FRAX values were generally higher, especially for women. FRAX values in various populations were mainly negatively correlated with lumbar and femoral neck BMD and were positively correlated with β-CTX; meanwhile, only PHF was negatively correlated with OC. After adjusting for sex, elevated β-CTX levels significantly increased the risk of high PMOF in various populations and increased the risk of high PHF in the urban-rural fringe populations. In particular, the risks of increased PMOF and PHF could increase by as much as 33 times and 19.5 times, respectively, in the urban-rural fringe areas. Conclusion: The urban-rural fringe populations in Southern China may be at risk of osteoporotic fracture. In addition to being related to BMD, the FRAX value also correlates with some BTMs. Combining FRAX with BMD, and BTMs may better predict the fracture risk.

Sex Specific Global Burden of Osteoporosis in 204 Countries and Territories, from 1990 to 2030: An Age-Period-Cohort Modeling Study

BACKGROUND

Osteoporosis is a highly prevalent disease with distinct sex pattern. We aimed to estimate the sex specific incidence, prevalence, and disability-adjusted life (DALYs) years of osteoporosis between 1990 and 2019, with additional predictions from 2020 to 2034.

METHODS

We collected osteoporosis disease burden data from the Global Burden of Disease study covering the years 1990 through 2019 in 204 countries and territories. The data included information on the number of incident cases of osteoporosis, DALYs, age-standardized incidence rates (ASIR), age-standardized prevalence rates (ASPR) and age-standardized DALYs rates. Additionally, we performed an age-period-cohort analysis to forecast the burden of osteoporosis.

RESULTS

The global number of incidence cases of osteoporosis, in 2019, reached 41.5 million cases. From 1990 to 2019, the low-middle socio-demographic index (SDI) region had the highest estimated annual percentage change in the world. Compared to males, female's ASIR and ASPR were all about 1.5 times higher than males for the same years in the same SDI regions. The projected global total number of incidence cases for osteoporosis between 2030 and 2034 is estimated to reach 263.2 million (154.4 million for females and 108.8 for males). Additionally, the burden in terms of DALYs is predicted to be 128.7 million (with 78.4 million for females and 50.3 million for males).

CONCLUSION

The global burden of osteoporosis is still increasing, mainly observed in high SDI countries. Females bear a burden 1.5 times higher than males in terms of incidence and DALYs. Steps should be taken to reduce the osteoporosis burden, especially in high SDI countries.

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.

Changes in bone turnover markers in patients without bone metastases receiving immune checkpoint inhibitors: An exploratory analysis

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Immune checkpoint inhibitors (ICIs) are correlated with immune-related adverse events (irAEs) that may potentially affect all host tissues.

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The effects of ICIs on the skeleton are poorly investigated, thus we evaluated the changes of specific markers of bone resorption and formation.

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We found an increase of type I collagen C-terminal telopeptide (CTX-I) levels after 3 months of ICIs treatment with a concomitant reduction of N-terminal propeptide of type I procollagen (PINP) levels with a trend toward statistical significance.

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CTX-I increase was also associated with poor prognosis in terms of treatment response and survival.

Immune checkpoint inhibitors (ICIs) has revolutionized the treatment of different advanced solid tumors, but most patients develop severe immune-related adverse events (irAEs). Although a bi-directional crosstalk between bone and immune systems is widely described, the effect of ICIs on the skeleton is poorly investigated. Here, we analyze the changes in plasma levels of type I collagen C-terminal telopeptide (CTX-I) and N-terminal propeptide of type I procollagen (PINP), reference makers of bone turnover, in patients treated with ICIs and their association with clinical outcome.

A series of 44 patients affected by advanced non-small cell lung cancer or renal cell carcinoma, without bone metastases, and treated with ICIs as monotherapy were enrolled. CTX-I and PINP plasma levels were assessed at baseline and after 3 months of ICIs treatment by ELISA kits.

A significant increase of CTX-I with a concomitant decreasing trend towards the reduction of PINP was observed after 3 months of treatment. Intriguingly, CTX-I increase was associated with poor prognosis in terms of treatment response and survival. These data suggest a direct relationship between ICIs treatment, increased osteoclast activity and potential fracture risk.

Overall, this study reveals that ICIs may act as triggers for skeletal events, and if confirmed in larger prospective studies, it would identify a new class of skeletal-related irAEs.

Bone Turnover Marker Profiling and Fracture Risk in Older Women: Fracture Risk from Age 75 to 90

PURPOSE

A major challenge in osteoporosis is to identify individuals at high fracture risk. We investigated six bone turnover markers (BTMs) to determine association with specific fracture types; the time-frame for risk prediction and whether these are influenced by age at assessment.

METHODS

Population-based OPRA cohort (n = 1044) was assessed at ages 75, 80, 85 and fractures documented for up to 15 years. Six BTMs were analyzed at each time-point (N-terminal propeptide of type I collagen, PINP; total osteocalcin, OC; bone-specific alkaline phosphatase, BALP; C-terminal telopeptide of type I collagen, CTX; tartrate-resistant acid phosphatase 5b, TRAcP5b; urinary osteocalcin). Hazard ratios (HR) for any, major osteoporotic, vertebral and hip fractures were calculated as short (1, 2, 3 years) and long-term risk (5, 10, 15 years).

RESULTS

At 75 year, high CTX levels were associated with an increased risk of all fractures, including major osteoporotic fractures, across most time-frames (HRs ranging: 1.28 to 2.28). PINP was not consistently associated. Urinary osteocalcin was consistently associated with elevated short-term risk (HRs ranging: 1.83-2.72). Other BTMs were directionally in accordance, though not all statistically significant. BTMs were not predictive for hip fractures. Association of all BTMs attenuated over time; at 80 year none were associated with an increased fracture risk.

CONCLUSION

CTX, urinary OC and TRAcP5b are predictive for fracture in a 1 to 3 year, perspective, whereas in the long-term or above age 80 years, BTMs appear less valuable. Resorption markers, particularly CTX, were more consistently associated with fracture risk than formation markers in the very elderly.

Insulin-like growth factor binding protein 2 null mice (Igfbp2-/-) are protected against trabecular bone loss after vertical sleeve gastrectomy

BACKGROUND

Bariatric surgery has been shown to result in weight loss, improved hemoglobin A1C, and decreased mortality but can also lead to bone loss and increased fracture rates. Serum IGFBP-2 is elevated in patients after bariatric surgery and although it may lead to improved blood glucose, may also drive bone resorption, and inhibit IGF-I action. This study tested the hypothesis that Igfbp2-/- mice were acutely protected from bone loss after vertical sleeve gastrectomy (VSG).

METHODS

Thirty-four mice, 17 Igfbp2-/- and 17 + / + underwent a hand-sewn VSG or sham surgery, at 16 weeks of age. Mice were harvested at 20 weeks of age. DXA was measured for body composition, areal bone mineral density (aBMD), areal bone mineral content (aBMC), femoral bone mineral density (fBMD), and femoral bone mineral content (fBMC) at 15, 18, and 20 weeks of age. Micro-computed tomography and serum ELISA assays were measured and analyzed at 20 weeks of age.

RESULTS

Both Igfbp2-/- and + / + mice lost significant weight (P = 0.0251, P = 0.0003, respectively) and total fat mass (P = 0.0082, P = 0.0004, respectively) at 4 weeks after VSG. Igfbp2+/+ mice lost significant aBMD, fBMD, fBMC, trabecular BMD, trabecular BV/TV and cortical tissue mineral density (P = 0.0150, P = 0.0313, P = 0.0190, P = 0.0072, and 0.0320 respectively). The Igfbp2-/- mice did not show significant bone loss in these parameters nor in trabecular BV/TV. Both Igfbp2-/- and + / + mice had less cortical bone area (P = 0.0181, P =  < .00001), cortical area over total area (P = 0.0085, P = 0.0007), and cortical thickness (P = 0.0050, P =  < 0.0001), respectively. Igfbp2+/+ mice demonstrated significantly lower polar, minimum, and maximum moments of inertia (P = 0.0031, P = 0.0239, and P = 0.0037, respectively). Igfbp2+/+ had significantly higher levels of IGFBP-2 at 2 weeks postoperatively after VSG (P = 0.035), and elevated levels of CTx and P1NP (P = 0.0127, P = 0.0058, respectively).

CONCLUSIONS

Igfbp2-/- mice were protected against trabecular bone loss and had attenuated cortical bone loss 4 weeks after VSG.

Risk assessment tools for osteoporosis and fractures in 2022

Osteoporosis is one of the frequently encountered non-communicable diseases in the world today. Several hundred million people have osteoporosis, with many more at risk. The clinical feature is a fragility fracture (FF), which results in major reductions in the quality and quantity of life, coupled with a huge financial burden. In recognition of the growing importance, the World Health Organisation established a working group 30 years ago tasked with providing a comprehensive report to understand and assess the risk of osteoporosis in postmenopausal women. Dual-energy X-ray absorptiometry (DXA) is the most widely endorsed technology for assessing the risk of fracture or diagnosing osteoporosis before a fracture occurs, but others are available. In clinical practice, important distinctions are essential to optimise the use of risk assessments. Traditional tools lack specificity and were designed for populations to identify groups at higher risk using a 'one-size-fits-all' approach. Much has changed, though the purpose of risk assessment tools remains the same. In 2022, many tools are available to aid the identification of those most at risk, either likely to have osteoporosis or suffer the clinical consequence. Modern technology, enhanced imaging, proteomics, machine learning, artificial intelligence, and big data science will greatly advance a more personalised risk assessment into the future. Clinicians today need to understand not only which tool is most effective and efficient for use in their practice, but also which tool to use for which patient and for what purpose. A greater understanding of the process of risk assessment, deciding who should be screened, and how to assess fracture risk and prognosis in older men and women more comprehensively will greatly reduce the burden of osteoporosis for patients, society, and healthcare systems worldwide. In this paper, we review the current status of risk assessment, screening and best practice for osteoporosis, summarise areas of uncertainty, and make some suggestions for future developments, including a more personalised approach for individuals.

Association between bone turnover markers and the risk of imminent recurrent osteoporotic fracture

The association between bone turnover markers (BTMs) and the risk of imminent recurrent osteoporotic fracture (ROF) in the elderly remains unclear. The present study thus aimed to explore BTMs in relation to imminent ROF in the elderly with an index OF. For this purpose, data from a prospective cohort study were used for analysis. Elderly patients hospitalized due to an index OF were included and followed-up. The BTMs included bone resorption marker (C-terminal telopeptide of type I collagen) and the bone formation markers, procollagen type I N propeptide, osteocalcin (OC) and total alkaline phosphatase. The outcome was the time to the first ROF following their index fracture. Cox regression analysis was used to assess the association between BTMs and ROF. Model discrimination was calculated to explore whether the BTMs had potential to improve fracture risk prediction. There were 169 eligible patients included in the analysis (median age, 72 years; 87.6% females). During a median follow-up period of 10.5 months, there were seven ROFs (4.1%) observed. Serum OC levels were found to be significantly associated with the risk of ROF [hazard ratio, 0.13; 95% confidence interval (CI) 0.018-0.90; P=0.039] for per-SD increase in OC from multivariable analysis. After incorporating OC into the model, a C-index of 0.83 (95% CI, 0.70-0.96; P<0.001) was observed, which outperformed the model with bone mineral density alone (improvement for C-index, 0.29; 95% CI, 0.028-0.55). On the whole, the present study demonstrates a significant association between serum OC and the decreased risk of imminent ROF in the elderly with index fractures. However, further high-quality evidence is required to further clarify and validate the BTMs in relation to the imminent risk of ROFs among the elderly.

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone-related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross-sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Role of Fracture Risk Assessment Tool and Bone Turnover Markers in Predicting All-Cause and Cardiovascular Mortality in Hemodialysis Patients

Background

Fracture Risk Assessment Tool (FRAX) and bone turnover markers (BTMs) predict fractures in the general population. However, the role of FRAX and BTMs in predicting mortality remains uncertain in hemodialysis (HD) patients.

Methods

One hundred and sixty-four HD patients stratified by low or high risk of 10-year fracture probability using FRAX. High risk of fracture was defined as 10-year probability of hip fracture ≥3% or major osteoporotic fracture ≥20%. The association of high risk of fracture and BTMs with all-cause mortality and cardiovascular (CV) mortality were evaluated using multivariate-adjusted Cox regression analysis.

Results

Eighty-five (51.8%) patients were classified as high risk of fracture based on FRAX among 164 HD patients. During a mean follow-up period of 3.5 ± 1.0 years, there were 39 all-cause deaths and 23 CV deaths. In multivariate-adjusted Cox regression, high risk of fracture based on FRAX was independently associated with all-cause mortality [hazard ratio (HR): 2.493, 95% confidence interval (CI): 1.026–6.056, p = 0.044) but not with CV mortality (HR: 2.129, 95% CI: 0.677–6.700, p = 0.196). There were no associations between BTMs and mortality risk. Furthermore, lower geriatric nutritional risk index (GNRI) was significantly associated with increased CV mortality (HR: 0.888, 95% CI: 0.802–0.983, p = 0.022) after adjusting by confounding variables.

Conclusion

High risk of fracture using FRAX was an independent predictor of all-cause mortality in patients undergoing HD. FRAX, rather than BTMs, has an important role of prognostic significance in HD patients.

Target Values and Daytime Variation of Bone Turnover Markers in Monitoring Osteoporosis Treatment after Fractures

The serum bone turnover markers (BTM) procollagen type 1 N‐terminal propeptide (P1NP) and C‐terminal cross‐linking telopeptide of type 1 collagen (CTX) are recommended for monitoring adherence and response of antiresorptive drugs (ARD). BTM are elevated about 1 year after fracture and therefore BTM target values are most convenient in ARD treatment follow‐up of fracture patients. In this prospective cohort study, we explored the cut‐off values of P1NP and CTX showing the best discriminating ability with respect to adherence and treatment effects, reflected in bone mineral density (BMD) changes. Furthermore, we explored the ability of BTM to predict subsequent fractures and BTM variation during daytime in patients using ARD or not. After a fragility fracture, 228 consenting patients (82.2% women) were evaluated for ARD indication and followed for a mean of 4.6 years (SD 0.5 years). BMD was measured at baseline and after 2 years. Serum BTM were measured after 1 or 2 years. The largest area under the curve (AUC) for discrimination of patients taking ARD or not was shown for P1NP <30 μg/L and CTX <0.25 μg/L. AUC for discrimination of patients with >2% gain in BMD (lumbar spine and total hip) was largest at cut‐off values for P1NP <30 μg/L and CTX <0.25 μg/L. Higher P1NP was associated with increased fracture risk in patients using ARD (hazard ratio [HR]_logP1NP = 15.0; 95% confidence interval [CI] 2.7–83.3), p = 0.002. P1NP and CTX were stable during daytime, except in those patients not taking ARD, where CTX decreased by 21% per hour during daytime. In conclusion, P1NP <30 μg/L and CTX <0.25 μg/L yield the best discrimination between patients taking and not taking ARD and the best prediction of BMD gains after 2 years. Furthermore, higher P1NP is associated with increased fracture risk in patients on ARD. BTM can be measured at any time during the day in patients on ARD. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

The Relationship Between Stress Fractures and Bone Turnover Markers Is Unclear in Athletic and Military Populations: A Critically Appraised Topic

Clinical Scenario: Having an indication of how bone is remodeling in response to training load could help identify athletes and military personnel at increased stress fracture (SFx) risk. Direct assessment of bone remodeling is impractical. Biochemical markers of bone turnover are used as an indirect measure of bone remodeling and have potential to inform prevention and treatment efforts. To date, the relationship between bone turnover markers and SFxs in athletes or military personnel remains unclear. Clinical Question: Are SFxs related to bone turnover markers in athletes and military personnel? Summary of Key Findings: Seven met eligibility criteria. In five studies, an association between SFxs and bone turnover markers existed. Clinical Bottom Line: The evidence supporting a relationship between SFxs and bone turnover markers in athletes and military personnel is mixed. While five of the seven studies reported some type of relationship, no studies prospectively measured bone turnover markers in a group of athletes or military personnel without an SFx or without SFx history and followed them over time to reassess bone turnover markers upon SFx occurrence. Strength of Clinical Recommendation: In accordance with the Strength of Recommendation Taxonomy, Grade C is the most appropriate strength of recommendation rating.

Fracture risk assessment in diabetes mellitus

Growing evidence suggests that diabetes mellitus is associated with an increased risk of fracture. Bone intrinsic factors (such as accumulation of glycation end products, low bone turnover, and bone microstructural changes) and extrinsic factors (such as hypoglycemia caused by treatment, diabetes peripheral neuropathy, muscle weakness, visual impairment, and some hypoglycemic agents affecting bone metabolism) probably contribute to damage of bone strength and the increased risk of fragility fracture. Traditionally, bone mineral density (BMD) measured by dual x-ray absorptiometry (DXA) is considered to be the gold standard for assessing osteoporosis. However, it cannot fully capture the changes in bone strength and often underestimates the risk of fracture in diabetes. The fracture risk assessment tool is easy to operate, giving it a certain edge in assessing fracture risk in diabetes. However, some parameters need to be regulated or replaced to improve the sensitivity of the tool. Trabecular bone score, a noninvasive tool, indirectly evaluates bone microstructure by analyzing the texture sparsity of trabecular bone, which is based on the pixel gray level of DXA. Trabecular bone score combined with BMD can effectively improve the prediction ability of fracture risk. Quantitative computed tomography is another noninvasive examination of bone microstructure. High-resolution peripheral quantitative computed tomography can measure volume bone mineral density. Quantitative computed tomography combined with microstructure finite element analysis can evaluate the mechanical properties of bones. Considering the invasive nature, the use of microindentation and histomorphometry is limited in clinical settings. Some studies found that the changes in bone turnover markers in diabetes might be associated with fracture risk, but further studies are needed to confirm this. This review focused on summarizing the current development of these assessment tools in diabetes so as to provide references for clinical practice. Moreover, these tools can reduce the occurrence of fragility fractures in diabetes through early detection and intervention.

Bone Phenotyping Approaches in Human, Mice and Zebrafish - Expert Overview of the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal traits TranslatiOnal NEtwork")

A synoptic overview of scientific methods applied in bone and associated research fields across species has yet to be published. Experts from the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal Traits translational Network") Working Group 2 present an overview of the routine techniques as well as clinical and research approaches employed to characterize bone phenotypes in humans and selected animal models (mice and zebrafish) of health and disease. The goal is consolidation of knowledge and a map for future research. This expert paper provides a comprehensive overview of state-of-the-art technologies to investigate bone properties in humans and animals - including their strengths and weaknesses. New research methodologies are outlined and future strategies are discussed to combine phenotypic with rapidly developing -omics data in order to advance musculoskeletal research and move towards "personalised medicine".

Perspective of the GEMSTONE Consortium on Current and Future Approaches to Functional Validation for Skeletal Genetic Disease Using Cellular, Molecular and Animal-Modeling Techniques

The availability of large human datasets for genome-wide association studies (GWAS) and the advancement of sequencing technologies have boosted the identification of genetic variants in complex and rare diseases in the skeletal field. Yet, interpreting results from human association studies remains a challenge. To bridge the gap between genetic association and causality, a systematic functional investigation is necessary. Multiple unknowns exist for putative causal genes, including cellular localization of the molecular function. Intermediate traits ("endophenotypes"), e.g. molecular quantitative trait loci (molQTLs), are needed to identify mechanisms of underlying associations. Furthermore, index variants often reside in non-coding regions of the genome, therefore challenging for interpretation. Knowledge of non-coding variance (e.g. ncRNAs), repetitive sequences, and regulatory interactions between enhancers and their target genes is central for understanding causal genes in skeletal conditions. Animal models with deep skeletal phenotyping and cell culture models have already facilitated fine mapping of some association signals, elucidated gene mechanisms, and revealed disease-relevant biology. However, to accelerate research towards bridging the current gap between association and causality in skeletal diseases, alternative in vivo platforms need to be used and developed in parallel with the current -omics and traditional in vivo resources. Therefore, we argue that as a field we need to establish resource-sharing standards to collectively address complex research questions. These standards will promote data integration from various -omics technologies and functional dissection of human complex traits. In this mission statement, we review the current available resources and as a group propose a consensus to facilitate resource sharing using existing and future resources. Such coordination efforts will maximize the acquisition of knowledge from different approaches and thus reduce redundancy and duplication of resources. These measures will help to understand the pathogenesis of osteoporosis and other skeletal diseases towards defining new and more efficient therapeutic targets.

Advances in bone turnover markers

Bone fragility fractures remain an important worldwide health and economic problem due to increased morbidity and mortality. The current methods for predicting fractures are largely based on the measurement of bone mineral density and the utilization of mathematical risk calculators based on clinical risk factors for bone fragility. Despite these approaches, many bone fractures remain undiagnosed. Therefore, current research is focused on the identification of new factors such as bone turnover markers (BTM) for risk calculation. BTM are a group of proteins and peptides released during bone remodeling that can be found in serum or urine. They derive from bone resorptive and formative processes mediated by osteoclasts and osteoblasts, respectively. Potential use of BTM in monitoring these phenomenon and therefore bone fracture risk is limited by physiologic and pathophysiologic factors that influence BTM. These limitations in predicting fractures explain why their inclusion in clinical guidelines remains limited despite the large number of studies examining BTM.

Associations between bone turnover markers and bone mineral density in older adults

OBJECTIVE

To examine the associations between bone turnover markers (BTMs) and bone mineral density (BMD) in older adults aged 60-85 years.

METHODS

A total of 1124 men (mean age, 69.1 years) and 1203 women (mean age, 70.7 years) from the National Health and Nutrition Examination Survey 1999-2002 were included in this cross-sectional analysis. Independent variables were serum bone-specific alkaline phosphatase (sBAP) and urinary N-telopeptide (uNTx), which are biomarkers of bone formation and resorption, respectively. Outcome variable was lumbar BMD. The associations of sBAP and uNTx levels with lumbar BMD was examined using multivariable linear regression models.

RESULTS

sBAP was negatively associated with lumbar BMD in each multivariable linear regression model, and this negative association was stable in both men and women men (men: β = -0.0028, 95% CI: -0.0046 to -0.0010; women: β = -0.0039, 95% CI: -0.0054 to -0.0023). On the other hand, uNTx was negatively associated with lumbar BMD after adjustment of relevant covariables (β = -0.0328, 95% CI: -0.0523 to -0.0133). However, in the subgroup analysis stratified by gender, this negative association remained only in older women (β = -0.0491, 95% CI: -0.0751 to -0.0231).

CONCLUSION

Our study suggested that elevated sBAP and uNTX levels correlated with decreased lumbar BMD, especially in older women. This finding indicated that maintaining BTMs at low levels may be beneficial to bone health for older adults.

Exploring the Relationship of Bone Turnover Markers and Bone Mineral Density in Community-Dwelling Postmenopausal Women

Aims

To explore the relationships of procollagen type 1 N-terminal propeptide (P1NP) and β cross-linked C-telopeptide of type 1 collagen (β-CTX) with bone mineral density (BMD) in postmenopausal women.

Methods

All postmenopausal women were selected from a community-based case-control study. The anteroposterior L1-L4 and left proximal femur BMD were measured. P1NP and β-CTX were also collected and tested. The main correlation analysis was applied to explore the relationships of BMD, P1NP, and β-CTX.

Results

The total 1055 postmenopausal women were enrolled. The BMD at all sites kept a decrease continually with age (P < 0.01). In addition, the level of β-CTX increased significantly from 45 to 50 years old and remained at a high level in the later stage, while the level of P1NP changed little or even decreased with age. Logistic regression model showed that β-CTX has better ability to predict BMD than P1NP, as demonstrated by an area under the curve (AUC) of 0.63.

Conclusion

P1NP and β-CTX are important markers to monitor bone metabolism. This trial is registered with ChiCTR-SOC-17013090. The date of registration is Oct. 23, 2017.

The effect of exercise intensity on bone in postmenopausal women (part 1): A systematic review

BACKGROUND

Previous systematic reviews and meta-analyses of exercise effects on bone have reported null or modest effect sizes. While animal research has determined that a strong positive relationship exists between load magnitude/intensity and bone adaptation, nevertheless many human exercise interventions have been applied at low intensity. Meta-analytic pooling of exercise interventions irrespective of intensity dilutes the ability to detect efficacy of any one training regimen. Parsing out efficacy of low, moderate and high intensity exercise interventions will assist the determination of optimal exercise prescription for bone.

OBJECTIVES

First, to summarise and critically evaluate existing evidence of exercise effect on bone mass, bone structure and bone turnover markers (BTMs) in healthy postmenopausal women. Second, to examine the influence of intensity on bone response to exercise.

METHODS

Electronic databases (Embase, Scopus, CINAHL Plus, SPORTDiscus), database platforms (PubMed, Cochrane CENTRAL, ProQuest Central, Web of Science) and reference lists of included studies were searched for controlled trials and randomised controlled trials that described the effect of any exercise intervention compared to control on bone mass, bone structure or BTMs in healthy postmenopausal women. Fracture incidence was included as an exploratory endpoint. Data was extracted and weighed against the results of a comprehensive risk of bias analysis.

RESULTS

One hundred trials were included, investigating a total of 120 exercise interventions. Of those, 57 interventions were low intensity, 57 were moderate, and six were high intensity. On balance, low intensity exercise was not an effective stimulus to increase bone mass. Higher quality evidence suggests moderate to high intensity interventions, particularly those that combined high intensity resistance and impact training, were most beneficial for bone mass. Only high intensity exercise appears to improve structural parameters of bone strength, however, data are limited. Only low and moderate intensity interventions have measured BTMs and no notable benefits have been observed. The quality of trials varied greatly, and risk of bias determinations were frequently limited by insufficiently reported detail.

CONCLUSION

Heterogeneity in both study quality and outcomes limits the ability to draw strong conclusions from this comprehensive systematic review of RCT and CT reports. Nevertheless, there is a tendency in the higher quality data to indicate exercise intensity is positively related to the adaptive bone response. Part 2 of this review series reports a meta-analysis of the RCT data in order to draw quantitative conclusions from the higher quality trials.

STUDY REGISTRATION

Registered on PROSPERO (CRD42018117254).

Randomised Controlled Trial of Nutritional Supplement on Bone Turnover Markers in Indian Premenopausal Women

Young Indian women may be at risk of poor bone health due to malnutrition. The aim of this study was to examine the effects on bone metabolism of a nutritional supplement in women aged 25 to 44. The nutritional supplement was a protein-rich beverage powder fortified with multi-micronutrients including calcium (600 mg), vitamin D (400 IU), and vitamin K (55 mcg) per daily serving, while a placebo supplement was low-protein non-fortified isocaloric beverage powder. This 6-month randomised, controlled trial showed favorable changes in bone turnover markers (decreased) and calcium homeostasis; such changes in older adults have been associated with slowing of bone loss and reduced fracture risk. For example, serum CTX decreased by about 30% and PINP by about 20% as a result of the increase in calcium intake. There were also changes in the ratio of carboxylated to undercarboxylated osteocalcin and such changes have been linked to a slowing of bone loss in older subjects. For example, the ratio increased by about 60% after 3 months as a result in the improvement in vitamin K status. Finally, there were improvements in the status of B vitamins, and such changes have been associated with reductions in homocysteine, but it is uncertain whether this would affect fracture risk. The product was generally well tolerated. This study shows the nutritional supplement holds promise for improved bone health among young Indian women.

Protocol for a multicentre, prospective cohort study of clinical, proteomic and genomic patterns associated with osteoporosis to develop a multidimensional fracture assessment tool: the PoCOsteo Study

INTRODUCTION

The HORIZON 2020 project PoCOsteo aims (1) to develop a multidimensional fracture risk assessment tool which would take into account all factors known to be related to an individual's fracture risk. The fracture risk model is intended to be developed in two different populations, namely a European and a Middle Eastern one; (2) to develop a medical device, which would measure and/or quantify proteomic as well as genomic factors as present in whole blood samples collected through finger prick; (3) to test the clinical applicability and the validity of prototypes of the to be developed point of care device at both clinical centres.

METHODS AND ANALYSIS

This article presents the protocol of this prospective cohort that will be carried out independently at two different centres (Division of Endocrinology and Diabetology at the Medical University of Graz (MUG) as a clinic-based cohort, and Endocrinology and Metabolism Research Institute (EMRI) at the Tehran University of Medical Sciences (TUMS) as a population-based cohort). The final aim is to develop a fracture risk assessment model, which would include clinical risk factors, biochemical markers of bone turnover, as well as specific genomic factors. The derivation cohorts will consist of individuals aged 50 years and above. The period of observation for each patient will be 12 months; an extension phase, which would last for another 2 years, is also planned.

ETHICS AND DISSEMINATION

These studies are conducted in accordance with the World Medical Association Declaration of Helsinki. The Iranian part was approved by the Research Ethics Committee of EMRI, TUMS. The Austrian part was approved by the Ethics Committee of the Medical University of Graz. Based on the gathered information, a multidimensional fracture assessment tool will be designed which will later be added to the PoCOsteo device.

The Relationship Between Polycystic Ovarian Syndrome, Periodontal Disease, and Osteoporosis

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder to affect women in their reproductive years. There has been growing concern that women with PCOS may suffer from long-term metabolic consequences due to the high degree of insulin resistance that is often present in PCOS. However, few longitudinal studies exist in this area and there is a paucity of data on whether women with PCOS are at risk of other chronic diseases as they age. Specifically, current evidence suggests that reproductive-age women with PCOS may be at increased risk for both osteoporosis and periodontal disease (PD)-both these chronic diseases can have serious implications for health and quality of life. However, few studies have addressed how risk factors for osteoporosis and PD may be altered by aging in PCOS. The PCOS phenotype of women beyond reproductive years is poorly understood, and it is not known whether the metabolic profile of older women with PCOS results in an increased risk of osteoporosis and PD. The objective of this review is to discuss the relationships between PCOS, osteoporosis, and PD, and how these relationships could be impacted during aging. The long-term goal of this review is to provide direction for future research that is needed to more clearly elucidate these relationships and eventually provide a basis for evidence-based health recommendations.

The challenge of long-term adherence: The role of bone turnover markers in monitoring bisphosphonate treatment of osteoporosis

Oral Bisphosphonates (BPs) are the mainstay of osteoporotic treatment, however long-term adherence remains a challenge, primarily owing to the chronic character of the disease and the regimen complexity. Poor compliance has been shown to have a clear link to fracture risk. The role of bone turnover markers (BTMs) as a tool to ascertain adherence and response to therapy is supported by their rapid response to treatment; a decrease in values is witnessed within days or weeks of commencing treatment. A greater reduction of serum CTX and NTX is evidenced with alendronate and ibandronate compared to risedronate. A change in bone formation BTMs appears to be related to vertebral fracture risk reduction, whereas no significant relationship is evident for hip and non-vertebral fractures. The utility of BTMs as an adjunct for monitoring withdrawal of treatment with oral BP has also been suggested. Finally, studies evaluating BTMs as an intervention, failed to demonstrate any effect on adherence. This review explores the challenge of long-term adherence with bisphosphonates and provides an analytic framework with respect to the role of BTMs in monitoring bisphosphonate treatment, adherence and the offset of treatment effect.

Assessment of baseline bone turnover marker levels and response to risedronate treatment: Data from a Japanese phase III trial

Background

Risedronate increases bone mineral density (BMD) and reduces fracture risk, but treatment response may depend on the baseline state of bone turnover. Data regarding the selection of therapeutic drugs or the prediction of therapeutic effects with baseline levels of bone turnover markers (BTMs) as a reference are insufficient. We hypothesized that when the baseline levels of BTMs are higher, baseline BMD might be lower, changes in BMD at 12 months after risedronate treatment might be higher, and the reduction of fracture incidence might be greater. This study aimed to analyze the data of a phase III clinical trial of risedronate from Japan to investigate the relationships between baseline BTM levels and (1) baseline BMD, (2) changes in BMD at 12 months after the start of treatment, and (3) the incidence of new vertebral fractures.

Methods

This post-hoc analysis included 788 postmenopausal women with osteoporosis whose baseline BTM levels as well as baseline and endpoint BMDs were measured. Relationships between baseline BTM levels and BMD at baseline and 12 months after risedronate treatment and new vertebral fractures were examined. One-way analysis of variance, two-tailed Student's t-test, and Fisher's exact test were used to analyze the data.

Results

Baseline BMD showed a significant upward trend when baseline BTM levels were lower in the analysis by tertiles. New vertebral fractures tended to occur in patients with prevalent vertebral fractures, but the relationship between new fractures and BTM levels was not statistically significant. Regardless of BTM types, BMD percentage increments (%) and increments (g/cm²) with the 12-month treatment were high when pretreatment BTM levels were high (P < 0.0001), and a >5.0% increase in BMD was observed even if baseline BTM levels were within the normal range. A new vertebral fracture occurred in only six patients (0.77%), and there was not enough statistical power to clarify the relationship between baseline BTM levels and fracture risk reduction.

Conclusions

When pretreatment BTM levels increased, baseline BMD tended to be lower and the increase in BMD with 12-month risedronate treatment was higher. However, BMD could still be increased even if the baseline BTM levels are within the normal range. Combined with available evidence, baseline BTMs may not have an important role in deciding the optimal therapy. To elucidate the relationship between baseline BTM levels and long-term fracture risk, it will be necessary to conduct more large-scale studies with a longer follow-up period in severe osteoporotic patients with a high fracture risk.

Mini abstract

We evaluated the significance of baseline bone turnover markers in the response to risedronate treatment. The increase in the bone mineral density (BMD) with the 12-month treatment may be higher when the state of bone turnover at baseline is higher, and BMD could still be increased even if the baseline bone turnover is within the normal range.

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Baseline bone turnover markers in response to risedronate treatment are unknown.

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Higher BMD may be achieved when the state of bone turnover at baseline is higher.

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Further increase in BMD is possible even if the baseline bone turnover is normal.

Correlation between Bone Turnover Markers and Bone Mineral Density in Patients Undergoing Long-Term Anti-Osteoporosis Treatment: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to evaluate the correlations between the bone turnover markers (BTMs) and the bone mineral density (BMD) in patients treated for primary osteoporosis and to identify promising BTMs for the prediction of future BMD changes. The PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched for relevant studies that investigated the relationship between the BTMs and the BMD changes in patients treated for osteoporosis. All significant correlation coefficients of the baseline BTMs or changes in BTMs from baseline with the BMD changes from baseline under different interventions from eligible studies were used for systematic review and the subgroup analyses. The correlations were analyzed in terms of bone sites, intervention, time duration of BTMs measurements, and time duration of BMD measurements. Twenty-two records reporting correlation coefficients and the corresponding p-values were included, 13 of which were enrolled in the further subgroup analyses. The combined results from the systematic review and meta-analyses indicated that the changes in osteocalcin (OC), procollagen type I N propeptide (PINP), and urine N-terminal crosslinking telopeptide of type I collagen (U-NTX), or the PINP at baseline tended to be useful in evaluating the long-term BMD changes after drug intervention.

Osteocalcin improves outcome after acute ischemic stroke

Background: Osteocalcin is related to energy metabolism, memory and the acute stress response, suggesting a relationship between bone and the brain. The need to explore the effect of osteocalcin on acute ischemic stroke is therefore urgent.

Results: Patients with better outcomes had higher serum osteocalcin levels than those whose NIHSS scores did not improve. Multivariable logistic regression analysis showed acceptable performance (area under the curve = 0.766). The effect of osteocalcin on the promotion of neuron survival was confirmed by Cell Counting Kit-8 experiments. In addition, osteocalcin could decrease proline hydroxylase 1 and inhibit the degradation of gasdermin D.

Conclusions: We propose that osteocalcin can improve outcome after acute ischemic stroke in the acute period. By downregulating proline hydroxylase 1, osteocalcin leads glucose metabolism to the pentose phosphate pathway and therefore promotes neuronal survival through inhibiting pyroptosis.

Methods: Demographic data and laboratory results were obtained from patients with ischemic stroke in the acute period for analysis. A receiver operating characteristic curve was used to assess the discrimination of the prediction model. The potential effect of osteocalcin on cerebral ischemia and osteocalcin mechanism were explored in cultured primary rat cerebral cortical neurons treated with oxygen-glucose deprivation and reoxygenation.

Does the Prediction Accuracy of Osteoporotic Fractures by BMD and Clinical Risk Factors Vary With Fracture Site?

Several clinical risk factors (CRFs) have been shown to predict the risk of fragility fractures independently of BMD, but their accuracy in the prediction of a particular fracture site has not been extensively studied. In this study based on longitudinal data from the FRISBEE cohort (Fracture Risk Brussels Epidemiological Enquiry), we evaluated if CRFs are specific for sites of incident osteoporotic fractures during follow‐up. We recruited 3560 postmenopausal women, aged 60 to 85 years, from 2007 to 2013, and surveyed yearly for the occurrence of fragility fractures during 6.2 years (median). We analyzed the association between CRFs included in the FRAX (fracture risk assessment tool) model or additional CRFs (falls, sedentary lifestyle, early untreated menopause, diabetes, use of selective serotonin reuptake inhibitors or proton pump inhibitors) and the first incident validated major osteoporotic fracture (MOF; n = 362; vertebra, hip, shoulder, and wrist) or other major fractures (n = 74; ankle, pelvis/sacrum, elbow, knee, long bones). Uni‐ and multivariate analyses using the Cox proportional hazards model were used. For MOFs considered together, the risk of fracture was highly associated in uni‐ and multivariate analyses (p<0.01) with osteoporosis (T‐score < −2.5), prior fracture, age, BMD (assessed by DXA), and fall history (HR 2.34, 1.82,1.71, 1.38, and 1.32, respectively). For each site analyzed separately, prior OF, age, smoking, and total hip BMD remained independent predictors for hip fractures (HR 5.72, 3.98, 3.10, 2.32, and 1.92, respectively); osteoporosis, age, prior OF, glucocorticoids, and spine BMD for vertebral fracture (HR 2.08, 1.87, 1.78, 1.76, and 1.45, respectively); osteoporosis, prior OF, and femoral neck BMD (HR 1.83, 1.60, and 1.56, respectively) for wrist fracture; osteoporosis, prior OF, and spine BMD (HR 2.48, 1.78, and 1.31, respectively) for shoulder fracture; prior OF and diabetes (HR 2.62 and 2.03) for other major fractures. Thus, a prior fracture and BMD were the best predictors of fracture risk at any site. Other CRFs have a weaker predictive value, which is a function of the site of a future fracture. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Biochemical markers of bone turnover and risk of incident hip fracture in older women: the Cardiovascular Health Study

The relationships of osteocalcin (OC) and C-telopeptide of type I collagen (CTX) with long-term incidence of hip fracture were examined in 1680 post-menopausal women from a population-based study. CTX, but not OC, levels were associated with incident hip fracture in these participants, a relationship characterized by an inverted U-shape.

INTRODUCTION

We sought to investigate the relationships of OC, a marker of bone formation, and CTX, a marker of bone resorption, with long-term incidence of hip fracture in older women.

METHODS

We included 1680 women from the population-based Cardiovascular Health Study (mean [SD] age 74.5 [5.0] years). The longitudinal association of both markers with incidence of hip fracture was examined using multivariable Cox models.

RESULTS

During a median follow-up of 12.3 years, 288 incident hip fractures occurred. Linear spline analysis did not demonstrate an association between OC levels and incident hip fracture. By contrast, increasing levels of CTX up to the middle-upper range were associated with a significantly greater risk of hip fracture (HR = 1.52 per SD increment, 95% CI = 1.10-2.09), while further increases were associated with a marginally non-significant lower risk (HR = 0.80 per SD increment, 95% CI = 0.63-1.01), after full adjustment for potential confounders. In analyses of quartiles, CTX exhibited a similar inverted U-shaped relationship with incident fracture after adjustment, with a significant association observed only for the comparison of quartile 3 to quartile 1 (HR = 1.63, 95% CI = 1.10-2.43). In a subset with available measures, both OC and CTX were inversely associated with bone mineral density of the hip.

CONCLUSION

CTX, but not OC, levels were associated with incident hip fracture in post-menopausal women, a relationship characterized by an inverted U-shape. These findings highlight the complex relationship of bone turnover markers with hip fracture risk.

Executive summary of the Japan Osteoporosis Society Guide for the Use of Bone Turnover Markers in the Diagnosis and Treatment of Osteoporosis (2018 Edition)

With the aging of society, the number of osteoporosis-related fractures is increasing. Prevention of osteoporosis and maintenance of the quality of life of osteoporosis patients require early diagnosis, effective treatment, and highly precise treatment monitoring. Although bone biopsy is clinically one of the essential techniques for diagnosis of osteoporosis, it is invasive and difficult to perform in general clinical practice. Bone mineral density measurement is another essential technique available in clinical practice that provides good precision. However, it is not effective for determining the appropriate treatment options or evaluating short-term treatment efficacy. On the other hand, bone turnover markers (BTMs) have gained attention because they provide information that is valuable for both the selection of treatment and short-term monitoring. BTMs are now positioned to become a tool for clinically assessing bone turnover outcomes. Since the Japan Osteoporosis Society issued its Guidelines for the Use of Bone Turnover Markers in the Diagnosis and Treatment of Osteoporosis in 2012, new drugs, drug formulations, and combination drug therapies have been approved; therefore, we updated the 2012 guidelines in the Guide for the Use of Bone Turnover Markers in the Diagnosis and Treatment of Osteoporosis (2018 Edition).

Reference markers of bone turnover for prediction of fracture: a meta-analysis

OBJECTIVE

To explore whether bone turnover biomarkers (BTMs), i.e., C-terminal telopeptide of type I collagen (CTX) and procollagen type I aminoterminal propeptide (PINP), are associated with fracture.

METHODS

We searched electronic database including PubMed, Embase and Cochrane Library, and the reference lists of relevant articles published from inception to August 22, 2018. An updated meta-analysis was performed to assess the prediction value of CTX and PINP in fracture.

RESULTS

Nine articles met our inclusion criteria and were included in the meta-analysis. The crude and adjusted effect size between PINP and fracture were extracted from two and five studies, respectively. PINP was not associated with fracture incidence without adjusting covariates (crude GR, 1.03; 95% CI, 0.91-1.17). After adjusting for potential confounders, PINP demonstrated a significant positive association with fracture (adjusted GR, 1.28; 95% CI, 1.15-1.42). In the subgroup analysis of studies after adjusting covariates, there were significant associations in women. Both the crude (1.16, 95%CI, 1.04-1.20) and adjusted GR (1.20, 95%CI, 1.05-1.37) shown positive relationships between CTX and fracture, which were extracted from four and six studies, separately. The sensitivity analysis confirmed the stability of the results. In the subgroup analysis of studies after adjusting covariates, there were significant associations in the subgroups of elderly, female, and hip fracture patients.

CONCLUSIONS

Our results indicate a statistically significant but modest association between BTMs (s-PINP or s-CTX) and future fracture risk after adjusting for BMD and clinical risk factors. The causal relationship between the two clinical conditions requires future validation with more standardized studies.

REGISTRATION NUMBER

CRD42018107879.

Osteoporosis and the Ageing Skeleton

Osteoporosis is a "skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture" which, in light of demographic change, is becoming an increasing burden on health care worldwide. Increasing age and female gender are associated with the condition, although a wider range of clinical risk factors are being used increasingly to identify those at risk of osteoporosis and its most important sequelae, fracture.While osteoporosis and fracture have long been associated with women in the post-menopausal age, fracture incidence increases because of the ageing of our population. Interventions to abate the progression of osteoporosis and to prevent fractures must focus on the old and the very old. Evidence associating nutritional factors, particularly calcium and vitamin D are reviewed as are the association of falls risk with fracture and the potential for interventions to prevent falls. Finally, the assessment of frailty in the oldest old, associated sarcopenia and multi-morbidity are considered in the evaluation of fall and fracture risk and the management of osteoporosis in the ninth decade of life and beyond.

Bone turnover: Biology and assessment tools

Bone turnover includes two processes: resorption (removal of old bone) and formation (laying down of new bone). N-terminal propeptide of type I procollagen (PINP) and C-telopeptide of type I collagen (CTX-I) are markers of bone formation and resorption, respectively, that the International Osteoporosis Foundation and the International Federation of Clinical Chemistry recommend for clinical use. Bone turnover markers (BTM) are subject to sources of variability, including feeding (lower resorption) and recent fracture (increased levels of all markers). Controllable patient-related factors should be adapted as much as possible (eg blood collection after an overnight fast) to minimize pre-analytical variability. Uncontrollable factors should be considered in the interpretation of the BTM measurements. BTM do not improve prediction of bone loss or fracture within an individual. In osteoporotic patients, BTM may help to assess the response to anabolic and antiresorptive therapies, to assess compliance to the treatment, or to indicate possible secondary causes of osteoporosis. BTM reflect changes in bone metabolism induced by anti-osteoporotic treatment. Anti-resorptive drugs induce a rapid dose-dependent decrease in bone resorption, whereas bone formation stimulating medications increase the levels of bone formations markers. BTM may be used for monitoring anti-osteoporosis therapy. The expected effect during the anti-resorptive therapy is to decrease the PINP by at least 10 ng/mL and to attain the target level of less than 35 ng/mL. The expected effect during the bone formation-stimulating therapy is to increase the PINP by at least 10 ng/mL and to attain the target level of more than 69 ng/mL.

Association of Adrenergic Receptor α2A (α2A-AR) Gene rs1800544 Polymorphism with Bone Mineral Density and Bone Turnover Markers in an Elderly Chinese Population

BACKGROUND Adrenergic receptor α2A (α2A-AR) is up-regulated in osteoporotic bone osteoblasts. Previous research demonstrated an association between polymorphism of a2A-AR gene and bone mineral density (BMD) as well as bone turnover markers (BTMs) in the Slovenian population. The present study aimed to investigate the association of rs1800544 polymorphism of α2A-AR gene with BMD and BTMs in the Chinese elderly population with osteoporosis (OP) or with osteoporotic fractures. MATERIAL AND METHODS A total of 346 unrelated elderly individuals were recruited in the study. Rs1800544 polymorphism was determined by Snapshot technology. BTMs were determined by electrochemiluminescence. BMDs at lumbar spine (LS) and proximal femur were measured with dual-energy X-ray absorptiometry (DEXA). Hardy-Weinberg equilibrium and distribution of genotype frequencies were verified using the chi-squared test. Analysis of co-variance (ANCOVA) adjusted for confounding factors was performed to explore the relationship of rs1800544 polymorphism with BMD and BTMs in all participants and in subgroups. RESULTS The genotype distributions in all subjects and in subgroups conformed to Hardy-Weinberg equilibrium (P>0.1). Distribution of genotype frequencies of subgroups showed no significant differences (P>0.05). Patients with GG genotype in the fracture group had significantly higher serum BTMs level compared with those carrying other genotypes (P<0.05). No significant association between rs1800544 and BTMs was detected in the elderly population with OP. Comparison of BMD at each site in all participants did not show any significant difference in subgroups with CC, CG, and GG genotypes (P>0.05). CONCLUSIONS Rs1800544 polymorphism is associated with BTMs level in Chinese elderly individuals with osteoporotic fractures, indicating the involvement of genetic variation of a2A-AR gene in bone metabolism.

DIAGNOSIS OF ENDOCRINE DISEASE: Bone turnover markers: are they clinically useful?

Bone turnover markers (BTMs) are useful in clinical practice as they are inexpensive, and they have proven useful for treatment monitoring and identification of poor adherence. BTMs cannot be used in individual patients for identifying accelerated bone loss or an increase in fracture risk or in deciding on the optimal therapy. They are useful for monitoring both anti-resorptive and anabolic treatment. Response can be defined as a result that exceeds an absolute target, or by a change greater than the least significant change; if such a response is not present, then poor compliance or secondary osteoporosis are likely causes. A baseline BTM measurement is not always made; in that case, a value of BTM on anti-resorptive treatment that is low or low normal or above the reference interval for anabolic therapy may be taken to indicate a satisfactory response. We provide an approach to using these bone turnover markers in clinical practice by describing algorithms for anti-resorptive and anabolic therapy and describing the changes we observe in the clinical practice setting.