Are blood lipids risk factors for fracture? Integrative evidence from instrumental variable causal inference and mediation analysis using genetic data

Remnant cholesterol is associated with hip BMD and low bone mass in young and middle-aged men: a cross-sectional study

PURPOSE

Remnant cholesterol (RC) is a contributor to cardiovascular diseases, obesity, diabetes, and metabolic syndrome. However, the specific relationship between RC and bone metabolism remains unexplored. Therefore, we aimed to investigate the relationships of RC with hip bone mineral density (BMD) and the risk of low bone mass.

METHODS

Physical examination data was collected from men aged < 60 years as part of the Kailuan Study between 2014 and 2018. The characteristics of the participants were compared between RC quartile groups. A generalized linear regression model was used to evaluate the relationship between RC and hip BMD and a logistic regression model was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for low bone mass. Additional analyses were performed after stratification by body mass index (BMI) (≥ or < 24 kg/m2). Sensitivity analyses were performed by excluding individuals who were taking lipid-lowering therapy or had cancer, cardiovascular diseases, or diabetes.

RESULTS

Data from a total of 7,053 participants were included in the analysis. After adjustment for confounding factors, RC negatively correlated with hip BMD (β =  - 0.0079, 95% CI: - 0.0133, - 0.0025). The risk of low bone mass increased from the lowest to the highest RC quartile, with ORs of 1 (reference), 1.09 (95% CI: (0.82, 1.44), 1.35 (95%CI: 1.02, 1.77), and 1.43 (95% CI: 1.09, 1.89) for Q1, Q2, Q3, and Q4, respectively (P for trend = 0.004) in the fully adjusted model. Compared to RC < 0.80 mmol/l group, the risk of low bone mass increased 39% in RC ≥ 0.80 mmol/l group (P < 0.001). The correlation between RC and hip BMD was stronger in participants with BMI ≥ 24 kg/m2 group (β =  - 0.0159, 95% CI: - 0.0289, - 0.0029). The results of sensitivity analyses were consistent with the main results.

CONCLUSION

We have identified a negative correlation between serum RC and hip BMD, and a higher RC concentration was found to be associated with a greater risk of low bone mass in young and middle-aged men.

Confounding association between plasma HDL-C levels and increased fracture risk: A correspondence

Background

This article explores the association between fractures, particularly in the elderly, and elevated plasma high-density lipoprotein cholesterol (HDL-C) levels. The study challenges the conventional idea of HDL-C as "good cholesterol" by revealing its potential role as a risk factor for fractures. Factors contributing to fractures in the elderly, such as diminishing bone strength due to aging-related tissue breakdown, are discussed. Sedentary lifestyles, low bone mineral density (BMD), and habits like smoking and alcohol consumption compound fracture susceptibility.

Materials and Methods

The study delves into mechanisms linking elevated HDL-C to fractures, using data from the ASPREE-Fracturesub-study of the ASPREE trial involving Australian and American participants aged 65 and above.

Results

The study showed that over a 4-year period, elevated HDL-C levels in healthy older people were linked to a 14% higher fracture risk. This revelation expands the understanding of fracture risk factors beyond the established norms.

Conclusion

The article emphasizes the need to reconsider HDL-C's traditional role as an indicator of cardiovascular health, particularly in light of medications like Statins and Anacetrapib that raise HDL-C levels. It calls for further exploration into the relationship between HDL-C, fractures at varying sites, and different age groups. Practical implications involve incorporating fracture risk associated with high HDL-C into clinical considerations, alongside advocating lifestyle changes for optimal HDL-C levels. In summary, this study prompts a reevaluation of HDL-C's implications in clinical practice, demanding further investigation into the intricacies of this relationship.

The association of lipid metabolism with bone metabolism and the role of human traits: a Mendelian randomization study

Background

The impact of lipid metabolism on bone metabolism remains controversial, and the extent to which human traits mediate the effects of lipid metabolism on bone metabolism remains unclear.

Objective

This study utilized mendelian randomization to investigate the effects of blood lipids on bone mineral density (BMD) at various skeletal sites and examined the mediating role of human traits in this process.

Methods

We leveraged genetic data from large-scale genome-wide association studies on blood lipids (n=1,320,016), forearm bone mineral density (FA-BMD) (n=10,805), lumbar spine bone mineral density (LS-BMD) (n=44,731), and femoral neck bone mineral density (FN-BMD) (n=49,988) to infer causal relationships between lipid and bone metabolism. The coefficient product method was employed to calculate the indirect effects of human traits and the proportion of mediating effects.

Results

The results showed that a 1 standard deviation(SD) increase in HDL-C, LDL-C and TC was associated with a decrease in LS-BMD of 0.039 g/cm2, 0.045 g/cm2 and 0.054 g/cm2, respectively. The proportion of mediating effects of systolic blood pressure (SBP) on HDL-C to LS-BMD was 3.17%, but suppression effects occurred in the causal relationship of LDL-C and TC to LS-BMD. Additionally, the proportion of mediating effects of hand grip strength (HGS) on the TC to LS-BMD pathway were 6.90% and 4.60% for the left and right hands, respectively.

Conclusion

In conclusion, a negative causal relationship was established between lipid metabolism and bone metabolism. Our results indicated that SBP and HGS served as mediators for the effects of lipid metabolism on bone metabolism.

The interplay between circulating high-density lipoprotein, age and fracture risk: a new cohort study and systematic meta-analysis

Previous findings on the association between high-density lipoprotein cholesterol (HDL-C) and fracture have yielded inconsistent results and it is unclear if the association varies with age and sex. We sought to evaluate the prospective association between HDL-C levels and fracture risk and assess if the association is modified by age and sex. Circulating HDL-C levels were measured at baseline in a population-based sample of 2,448 men aged 42-61 years. Cox regression was used to estimate hazard ratios (HRs) and 95% CIs. Incident fractures (n = 134) occurred during a median follow-up of 25.7 years. In analysis adjusted for several risk factors, the HR (95% CI) for fractures was 1.00 (0.85-1.20) per 1 standard deviation (SD) increase in HDL-C levels. Comparing the extreme tertiles of HDL-C levels, the corresponding adjusted HR (95% CI) was 0.94 (0.62-1.45). In a meta-analysis of eight cohort studies (including the current study) comprising 74,378 participants and 4,621 fracture cases, the fully-adjusted risk estimate (95% CI) for fracture was 1.03 (0.96-1.10) per 1SD increase in HDL-C levels and 1.05 (0.92-1.20) comparing extreme tertiles of HDL-C. The pooled risk estimate (95% CIs) for fracture per 1SD increase were 1.09 (1.01-1.17) and 0.98 (0.93-1.04) for age groups ≥ 60 and < 60 years, respectively, and the corresponding risks comparing the extreme tertiles of HDL-C levels were 1.21 (1.09-1.33) and 0.95 (0.85-1.07) (p-value for interaction < 0.05). Age may modify the association between HDL-C levels and fracture risk - an increased fracture risk associated with increased HDL-C levels is only evident in older age (≥ 60 years).

Association of apolipoprotein A1 with osteoporosis: a cross-sectional study

Higher levels of apolipoprotein A1 (ApoA1) were associated with higher risk of osteoporosis, which supports the argument that lipid metabolism is involved in bone metabolism.

BACKGROUND

Although the current evidence shows that lipid metabolism and osteoporosis are closely related to cardiovascular disease, the association between ApoA1 and osteoporosis is still unknown. Therefore, the purpose of this study was to explore the relationship between ApoA1 and osteoporosis.

METHODS

In this cross-sectional study, we included 7743 participants in the Third National Health and Nutrition Examination Survey. ApoA1 was regarded as an exposure variable and osteoporosis was considered as an outcome variable. Multivariate logistic regression analysis, sensitivity analysis, and receiver operator characteristic (ROC) were used to assess the association of ApoA1 with osteoporosis.

RESULTS

Participants with higher ApoA1 had higher rates of osteoporosis compared to participants with lower ApoA1 (P <  0.05). Individuals with osteoporosis had higher levels of ApoA1 than individuals without osteoporosis (P <  0.05). In multivariate logistic regression analysis adjusted for age, sex, race, hypertension, diabetes, gout, hypotensive drugs, hypoglycemic drugs, systolic blood pressure, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoprotein B, blood urea nitrogen, albumin, uric acid, hemoglobin A1c, alkaline phosphatase and total calcium, higher ApoA1 was strongly associated with higher risk of osteoporosis, whether as a continuous variable or a categorical variable [Model 3, OR (95% CI), P value: 2.289 (1.350, 3.881), 0.002 and 1.712 (1.183, 2.478), 0.004]. And after excluding individuals with gout, the correlation between them remained and was significant (P <  0.01). And ROC analysis also showed that ApoA1 could predict the development of osteoporosis (AUC = 0.650, P <  0.001).

CONCLUSION

ApoA1 was closely associated with osteoporosis.

Association of Plasma High-Density Lipoprotein Cholesterol Level With Risk of Fractures in Healthy Older Adults

Importance

Increased levels of high-density lipoprotein cholesterol (HDL-C) have been associated with osteoporosis. Preclinical studies have reported that HDL-C reduces bone mineral density by reducing osteoblast number and function. However, the clinical significance of these findings is unclear.

Objective

To determine whether higher HDL-C levels are predictive of an increased fracture risk in healthy older adults.

Design, Setting, and Participants

This cohort study is a post hoc analysis of data from the Aspirin in Reducing Events in the Elderly (ASPREE) clinical trial and the ASPREE-Fracture substudy. ASPREE was a double-blind, randomized, placebo-controlled primary prevention trial of aspirin that recruited participants between 2010 and 2014. These comprised community-based older adults (16 703 Australians aged ≥70 years, 2411 US participants ≥65 years) without evident cardiovascular disease, dementia, physical disability, and life-limiting chronic illness. The ASPREE-Fracture substudy collected data on fractures reported postrandomization from Australian participants. Cox regression was used to calculate hazard ratio (HR) and 95% CI. Data analysis for this study was performed from April to August 2022.

Exposure

Plasma HDL-C.

Main Outcomes and Measures

Fractures included were confirmed by medical imaging and included both traumatic and minimal trauma fractures. Fractures were adjudicated by an expert review panel.

Results

Of the 16 262 participants who had a plasma HDL-C measurement at baseline (8945 female participants [55%] and 7319 male [45%]), 1659 experienced at least 1 fracture over a median (IQR) of 4.0 years (0.02-7.0 years). In a fully adjusted model, each 1-SD increment in HDL-C level was associated with a 14% higher risk of fractures (HR, 1.14; 95% CI, 1.08-1.20). The results remained similar when these analyses were stratified by sex. Sensitivity and stratified analyses demonstrated that these associations persisted when the analyses were repeated to include only (1) minimal trauma fractures, (2) participants not taking osteoporosis medications, (3) participants who were never smokers and reported that they did not drink alcohol, and (4) participants who walked outside for less than 30 minutes per day and reported no participation in moderate/vigorous physical activity and to examine only (5) statin use. No association was observed between non-HDL-C levels and fractures.

Conclusions and Relevance

This study suggests that higher levels of HDL-C are associated with an increased fracture risk. This association was independent of common risk factors for fractures.

Metabolomic patterns, redox-related genes and metals, and bone fragility endpoints in the Hortega Study

BACKGROUND

The potential joint influence of metabolites on bone fragility has been rarely evaluated. We assessed the association of plasma metabolic patterns with bone fragility endpoints (primarily, incident osteoporosis-related bone fractures, and, secondarily, bone mineral density BMD) in the Hortega Study participants. Redox balance plays a key role in bone metabolism. We also assessed differential associations in participant subgroups by redox-related metal exposure levels and candidate genetic variants.

MATERIAL AND METHODS

In 467 participants older than 50 years from the Hortega Study, a representative sample from a region in Spain, we estimated metabolic principal components (mPC) for 54 plasma metabolites from NMR-spectrometry. Metals biomarkers were measured in plasma by AAS and in urine by HPLC-ICPMS. Redox-related SNPs (N = 341) were measured by oligo-ligation assay.

RESULTS

The prospective association with incident bone fractures was inverse for mPC1 (non-essential and essential amino acids, including branched-chain, and bacterial co-metabolites, including isobutyrate, trimethylamines and phenylpropionate, versus fatty acids and VLDL) and mPC4 (HDL), but positive for mPC2 (essential amino acids, including aromatic, and bacterial co-metabolites, including isopropanol and methanol). Findings from BMD models were consistent. Participants with decreased selenium and increased antimony, arsenic and, suggestively, cadmium exposures showed higher mPC2-associated bone fractures risk. Genetic variants annotated to 19 genes, with the strongest evidence for NCF4, NOX4 and XDH, showed differential metabolic-related bone fractures risk.

CONCLUSIONS

Metabolic patterns reflecting amino acids, microbiota co-metabolism and lipid metabolism were associated with bone fragility endpoints. Carriers of redox-related variants may benefit from metabolic interventions to prevent the consequences of bone fragility depending on their antimony, arsenic, selenium, and, possibly, cadmium, exposure levels.

Association of major blood lipids with post-stroke dementia: a community-based cohort study

Background and purpose

The roles of blood low‐density lipoprotein cholesterol (LDL‐C), high‐density lipoprotein cholesterol (HDL‐C) and triglycerides in the development of post‐stroke dementia remain uncertain. This study was to investigate their potential associations.

Methods

A retrospective cohort study was conducted using the Clinical Practice Research Datalink. Patients with first‐ever stroke but no prior dementia were followed up for 10 years. Cox regression was used to examine the association of baseline LDL‐C, HDL‐C and triglycerides with post‐stroke dementia.

Results

Amongst 63,959 stroke patients, 15,879 had complete baseline data and were included in our main analysis. 10.8% developed dementia during a median of 4.6 years of follow‐up. The adjusted hazard ratio of dementia for LDL‐C (per log mmol/l increase) was 1.29 (95% confidence interval [CI] 1.14–1.47), with a linear increasing trend (p trend <0.001). The counterpart for triglycerides was 0.79 (95% CI 0.69–0.89), with a linear decreasing trend (p trend <0.001). For HDL‐C, there was no association with dementia (adjusted hazard ratio 0.89, 95% CI 0.74–1.08) or a linear trend (p trend = 0.22).

Conclusions

Blood lipids may affect the risk of post‐stroke dementia in different ways, with higher risk associated with LDL‐C, lower risk associated with triglycerides, and no association with HDL‐C.

Type 2 Diabetes Is Causally Associated With Reduced Serum Osteocalcin: A Genomewide Association and Mendelian Randomization Study

Recent advances indicate that bone and energy metabolism are closely related. However, little direct evidence on causality has been provided in humans. We aimed to assess the association of three bone-related biomarkers-25 hydroxyvitamin D (25OHD), parathyroid hormone (PTH), and osteocalcin (OCN)-with several metabolic phenotypes and investigate any causal relevance to the associations using a Mendelian randomization (MR) study. Serum 25OHD, PTH, and total OCN were measured at baseline in 5169 eligible Chinese participants in Changfeng study. Partial correlation and bivariate GREML analysis were used to estimate phenotypic and genetic correlations, respectively. Multiple linear regression and logistic regression were used to assess linear associations. Genomewide association analysis (GWAS) was performed. Bidirectional two-sample MR analyses were conducted to examine causal relationships between OCN and body mass index (BMI), diastolic blood pressure (DBP), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), glycated hemoglobin A1c (HbA1c), and type 2 diabetes (T2DM), using our GWAS result of OCN and GWAS statistics from Biobank Japan project (BBJ) and the largest meta-analysis of T2DM GWAS in East Asian population. Circulating OCN was significantly associated with higher DBP and HDL-C and decreased TG, blood glucose level, insulin resistance, liver fat content, bone mineral density, BMI, and a favorable body fat distribution pattern. GWAS identified one novel serum PTH locus and two novel serum OCN loci, explaining 0.81% and 1.98% of variances of PTH and OCN levels, respectively. MR analysis suggested a causal effect of T2DM on lower circulating OCN concentration (causal effect: -0.03; -0.05 to -0.01; p = 0.006 for T2DM_BBJ and -0.03; -0.05 to -0.01; p = 0.001 for T2DM_EAS). These findings indicate that T2DM might impact bone remodeling and provide a resource for understanding complex relationships between osteocalcin and metabolic (and related) traits in humans. © 2021 American Society for Bone and Mineral Research (ASBMR).

Brachial-ankle pulse wave velocity is associated with the risk of osteoporosis: a cross-sectional evidence from a Chinese community-based cohort

Background

Association of arterial stiffness and osteoporosis has been well documented in elderly population. However, it is not clear whether they co-progress from the early stages through common mechanisms. The object of this study was to evaluate possible associations between arterial stiffness and osteoporosis by measuring brachial-ankle pulse wave velocity (baPWV) and the Osteoporosis Self-Assessment Tool for Asia (OSTA) index among a healthy population of Chinese aged 40 years and older. Whether baPWV can be used as a predictor of osteoporosis on OSTA was further assessed.

Methods

This study was cross-sectional in design. Of 3984 adults aged 40 years and older in the Yunyan district of Guiyang (Guizhou, China) who underwent both OSTA and baPWV measurements within 1 month, 1407 were deemed eligible for inclusion (women, 1088; men, 319).

Results

The mean baPWV was 1475 ± 302 cm/s (range,766–3459 cm/s). baPWV in 110 individuals with high risk of osteoporosis (OSTA index < − 4) was higher than that of individuals with non-high risk (1733 ± 461 cm/s vs. 1447 ± 304 cm/s, P < 0.001). OSTA index was negatively correlated with baPWV(ρ = − 0.296, P < 0.001) after adjusting for age, sex, body mass index, waist circumference, diastolic blood pressure, and creatinine clearance rate. baPWV was an independent predictor for the presence of high risk of osteoporosis (β = − 0.001, P < 0.001) and was consistent across age and sex subgroups, and the optimal baPWV cutoff value for predicting the presence of high risk of osteoporosis and fracture was 1693 cm/s. The AUC was 0.722 (95% confidence interval [CI], 0.667–0.777; P < 0.001, sensitivity of 52.8% and specificity of 83.6%).

Conclusions

We conclude that arterial stiffness measured by baPWV is well correlated with the severity of osteoporosis evaluated by OSTA. baPWV index may be a valuable tool for identifying individuals with risk of developing osteoporosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-020-02125-3.

Genetic Pleiotropy of Bone-Related Phenotypes: Insights from Osteoporosis

PURPOSE OF REVIEW

We summarize recent evidence on the shared genetics within and outside the musculoskeletal system (mostly related to bone density and osteoporosis).

RECENT FINDINGS

Osteoporosis is determined by an interplay between multiple genetic and environmental factors. Significant progress has been made regarding its genetic background revealing a number of robustly validated loci and respective pathways. However, pleiotropic factors affecting bone and other tissues are not well understood. The analytical methods proposed to test for potential associations between genetic variants and multiple phenotypes can be applied to bone-related data. A number of recent genetic studies have shown evidence of pleiotropy between bone density and other different phenotypes (traits, conditions, or diseases), within and outside the musculoskeletal system. Power benefits of combining correlated phenotypes, as well as unbiased discovery, make these studies promising. Studies in humans are supported by evidence from animal models. Drug development and repurposing should benefit from the pleiotropic approach. We believe that future studies should take into account shared genetics between the bone and related traits.