Association between body mass index and body fat measured by dual-energy X-ray absorptiometry (DXA) in China: a systematic review and meta-analysis

Objective:We examined the association between body mass index(BMI)and body fat percentage(BF%)measured by dual-energy X-ray absorptiometry(DXA)among adults and children in China.Methods:We searched four databases-PubMed,China National Knowledge Infrastructure,Wanfang,and Vip for studies published in the past 22 years.Meta-analysis was conducted using random-or fixed-effect models.Results:In total of 21 studies met inclusion criteria and were included in review,and 17 ot them in meta-analysis.They were conducted across China.Their sample size ranged from 62 to 5726,and participants'age ranged from 6-80 years.Meta-analysis revealed strong associations between BMI and BF% measured by DXA in adults(pooled r=0.71,95% CI:0.66 to 0.74)and children(pooled r=0.60,95% CI:0.52 to 0.68).The association was stronger in Northern China than in East China in children(β=-0.40,95%CI:-0.65 to-0.14)and in Central China in adults(β=-0.25;95% CI:-0.51 to-0.01).Urban children's BMI was strongly associated with BF%than rural(β=0.19;95%CI:0.04 to 0.35),whereas it was stronger in adults living in rural than in urban(β=-0.35;95% CI:-0.66 to-0.05).Conclusions:BMI was strongly associated with BF%measured by DXA,and the association in children and adults in China varied by residence and region.

Prevalence and risk factors of osteoporosis detected by dual-energy X-ray absorptiometry among Chinese patients with primary biliary cholangitis

BACKGROUND Osteoporosis is an extrahepatic complication of primary biliary cholangitis(PBC)that increases the risk of fractures and mortality.However,Epidemiological studies of osteoporosis in patients with PBC in China and the Asia-Pacific region is lack.AIM To assess the prevalence and clinical characteristics of osteoporosis in Chinese patients with PBC.METHODS This retrospective analysis included consecutive patients with PBC from a tertiary care center in China who underwent bone mineral density(BMD)assessment using dual-energy X-ray absorptiometry between January 2013 and December 2021.We defined subjects with T-scores≤-2.5 in any sites(L1 to L4,femoral neck,or total hip)as having osteoporosis.Demographic,serological,clinical,and histological data were collected.Independent risk factors for osteoporosis were identified by multivariate logistic regression analysis.RESULTS A total of 268 patients with PBC[236 women(88.1%);mean age,56.7±10.6 years;163 liver biopsies(60.8%)]were included.The overall prevalence of osteoporosis in patients with PBC was 45.5%(122/268),with the prevalence of osteoporosis in women and men being 47.0%and 34.4%,respectively.The prevalence of osteoporosis in postmenopausal women was significantly higher than that in premenopausal women(56.3%vs 21.0%,P<0.001).Osteoporosis in patients with PBC is associated with age,fatigue,menopausal status,previous steroid therapy,body mass index(BMI),splenomegaly,gastroesophageal varices,ascites,Mayo risk score,histological stage,alanine aminotransferase,albumin,bilirubin,platelet and prothrombin activity.Multivariate regression analysis identified that older age,lower BMI,previous steroid therapy,higher Mayo risk score,and advanced histological stage as the main independent risk factors for osteoporosis in PBC.CONCLUSION Osteoporosis is very common in Chinese patients with PBC,allowing for prior screening of BMD in those PBC patients with older age,lower BMI,previous steroid therapy and advanced liver disease.

Comparative Analysis of the Multi-Frequency Bio-impedance and Dual-energy X-ray Absorptiometry on Body Composition in Obese Subjects

To examine accuracy of body composition predicted by the Multi-Frequency Bioelectric Impedance Analysis （MF-BIA） compared with the Dual-energy X-ray Absorptiometry （DXA） in adults with obese. We measured body composition of 749 adults with obese both by the MF-BIA and DXA. The Lin＇s concordance correlation and the Bland-Altman plots were used to examine the consistency. The concordance correlation coefficient of %BF between the MF-BIA and DXA in men and women was 0.560, and 0.669, respectively. Compared with the DXA, the MF-BIA significantly underestimated %BF by 4.33% in men （P 〈 0.001）, however overestimated %BF by 0.50% in women （P 〈 0.001）. After corrected by the correction equations established in this study, the differences were significantly decreased. Therefore, the MF-BIA （TANITA MC-180） may need to be corrected in estimating body composition for adults with obese.

Reduced upper limb lean mass on dual energy X-ray absorptiometry predicts adverse outcomes in male liver transplant recipients

BACKGROUND Pre-transplant muscle wasting measured by computed tomography has been associated with adverse clinical outcomes after liver transplantation including increased rates of sepsis and hospitalisation days.Upper limb lean mass(LM)measured by dual-energy X-ray absorptiometry(DEXA)was recently identified as a novel predictor of sarcopenia-associated mortality in men waitlisted for transplantation.AIM To investigate the use of DEXA LM in predicting gender-stratified early posttransplant outcomes.METHODS Liver transplant recipients who underwent pre-transplant DEXA body composition imaging between 2002 and 2017 were included.Endpoints included posttransplant mortality and graft failure,bacterial infections,acute cellular rejection(ACR)and intensive care and total hospital length of stay.RESULTS Four hundred and sixty-nine patients met inclusion criteria of which 338 were male(72%).Median age was 55.0 years(interquartile range 47.4,59.7)and model for end-stage liver disease(MELD)score 16.Median time from assessment to transplantation was 7 mo(3.5,12).Upper limb LM was inversely associated with bacterial infections at 180 d post-transplant(hazard ratio=0.42;95%confidence interval:0.20-0.89;P=0.024)in males only.There was a negative correlation between upper limb LM and intensive care(τb=-0.090,P=0.015)and total hospital length of stay(τb=-0.10,P=0.0078)in men.In women,neither MELD nor body composition parameters were associated with post-transplant adverse outcomes or increased length of stay.Body composition parameters,MELD and age were not associated with 90-d mortality or graft failure in either gender.There were no significant predictors of early ACR.CONCLUSION Sarcopenia is an independent and potentially modifiable predictor of increased post-transplant bacterial infections and hospital length of stay in men with cirrhosis.DEXA upper limb LM provides a novel measure of muscle wasting that has prognostic value in this cohort.The lack of association in women requires further investigation.

Deep Learning in DXA Image Segmentation

Many existing techniques to acquire dual-energy X-ray absorptiometry(DXA)images are unable to accurately distinguish between bone and soft tissue.For the most part,this failure stems from bone shape variability,noise and low contrast in DXA images,inconsistent X-ray beam penetration producing shadowing effects,and person-to-person variations.This work explores the feasibility of using state-of-the-art deep learning semantic segmentation models,fully convolutional networks(FCNs),SegNet,and U-Net to distinguish femur bone from soft tissue.We investigated the performance of deep learning algorithms with reference to some of our previously applied conventional image segmentation techniques(i.e.,a decision-tree-based method using a pixel label decision tree[PLDT]and another method using Otsu’s thresholding)for femur DXA images,and we measured accuracy based on the average Jaccard index,sensitivity,and specificity.Deep learning models using SegNet,U-Net,and an FCN achieved average segmentation accuracies of 95.8%,95.1%,and 97.6%,respectively,compared to PLDT(91.4%)and Otsu’s thresholding(72.6%).Thus we conclude that an FCN outperforms other deep learning and conventional techniques when segmenting femur bone from soft tissue in DXA images.Accurate femur segmentation improves bone mineral density computation,which in turn enhances the diagnosing of osteoporosis.

Nutritional assessment in cirrhotic patients with hepatic encephalopathy

Hepatic encephalopathy(HE) is one of the worst complications of liver disease and can be greatly influenced by nutritional status. Ammonia metabolism, inflammation and muscle wasting are relevant processes in HE pathophysiology. Malnutrition worsens the prognosis in HE, requiring early assessment of nutritional status of these patients. Body composition changes induced by liver disease and limitations superimposed by HE hamper the proper accomplishment of exams in this population, but evidence is growing that assessment of muscle mass and muscle function is mandatory due to the role of skeletal muscles in ammonia metabolism. In this review, we present the pathophysiological aspects involved in HE to support further discussion about advantages and drawbacks of some methods for evaluating the nutritional status of cirrhotic patients with HE, focusing on body composition.

Bone mineral density in lifelong trained male football players compared with young and elderly untrained men

Purpose: The purpose of the present controlled cross-sectional study was to investigate proximal femur and whole-body bone mineral density(BMD), as well as bone turnover profile, in lifelong trained elderly male football players and young elite football players compared with untrained age-matched men.Methods: One hundred and forty healthy, non-smoking men participated in the study, including lifelong trained football players(FTE, n = 35)aged 65—80 years, elite football players(FTY, n = 35) aged 18—30 years, as well as untrained age-matched elderly(UE, n = 35) and young(UY,n = 35) men. All participants underwent a regional dual-energy X-ray Absorptiometry(DXA) scan of the proximal femur and a whole-body DXA scan to determine BMD. From a resting blood sample, the bone turnover markers(BTMs) osteocalcin, carboxy-terminal type-1 collagen crosslinks(CTX-1), procollagen type-1 amino-terminal propeptide(P1NP), and sclerostin were measured.Results: FTE had 7.3%—12.9% higher(p < 0.05) BMD of the femoral neck, wards, shaft, and total proximal femur in both legs compared to UE,and 9.3%—9.7% higher(p < 0.05) BMD in femoral trochanter in both legs compared to UY. FTY had 24.3%—37.4% higher(p < 0.001) BMD in all femoral regions and total proximal femur in both legs compared to UY. The whole-body DXA scan confirmed these results, with FTE showing similar whole-body BMD and 7.9% higher(p < 0.05) leg BMD compared to UY, and with FTY having 9.6% higher(p < 0.001) wholebody BMD and 18.2% higher(p < 0.001) leg BMD compared to UY. The plasma concentration of osteocalcin, CTX-1, and P1NP were 29%,53%, and 52% higher(p < 0.01), respectively, in FTY compared to UY.Conclusion: BMD of the proximal femur and whole-body BMD are markedly higher in lifelong trained male football players aged 65—80 years and young elite football players aged 18—30 years compared to age-matched untrained men. Elderly football players even show higher BMD in femoral trochanter and leg BMD than untrained young despite an age difference of 47 years.

Adiposity and spinal cord injury

The drastic changes in body composition following spinal cord injury(SCI) have been shown to play a significant role in cardiovascular and metabolic health. The pattern of storage and distribution of different types of adipose tissue may impact metabolic health variables similar to carbohydrate, lipid and bone metabolism. The use of magnetic resonance imaging provides insights on the interplay among different regional adipose tissue compartments and their role in developing chronic diseases. Regional adipose tissue can be either distributed centrally or peripherally into subcutaneous and ectopic sites. The primary ectopic adipose tissue sites are visceral, intramuscular and bone marrow. Dysfunction in the central nervous system following SCI impacts the pattern of distribution of adiposity especially between tetraplegia and paraplegia. The current editorial is focused primarily on introducing different types of adipose tissue and establishing scientific basis to develop appropriate dietary, rehabilitation or pharmaceutical interventions to manage the negative consequences of increasing adiposity after SCI. We have also summarized the clinical implications and future recommendations relevant to study adiposity after SCI.

Monitoring osteoporosis therapy:Can FRAX help assessing success or failure in achieving treatment goals?

AIM: To assess:(1) Whether the World Health Organization fracture risk assessment tool(FRAX) can be used for monitoring osteoporosis patients receiving treatment as well as its clinical implications; and(2) The relation between fracture incidence and post-treatment FRAX.METHODS: Five hundred and seventy-nine osteoporotic women known to be adherent to the prescribed osteoporosis medication, had dual-energy X-ray absorptiometry scan and fracture probability calculated at baseline, 2 and 5-year of osteoporosis treatment. Those patients who responded to treatment and did not sustain a new low trauma fracture during the first 2 years, continued their treatment and were re-assessed 3-year later. The patient subgroup who did not achieve an improvement in their bone mineral density(BMD)or sustain any fracture within the first 2-year, had their osteoporosis treatment changed. Outcome measures included BMD and FRAX assessment calculated 3-year after commencing new osteoporosis treatment. RESULTS: There was a significant negative correlation between 10-year probability of major osteoporotic and hip fractures and BMD at the total proximal femur at 2-year of treatment(R =-0.449 and-0.479 respectively), and at 5-year(R =-0.489 and-0.594 respectively). At both 2 years and 5 years of treatment, the 10-year fracture probability showed significant correlation with the incidence of fracture(P < 0.01). On comparing fracture probability, there was a significant difference(P < 0.05) between the responders and non-responders to osteoporosis treatment.CONCLUSION: In women currently or previously treated for osteoporosis, the FRAX tool can be used to predict fracture probability. Osteoporosis treatment does not annul prediction of fractures. FRAX tool may be of value in guiding clinicians towards the need for continuation or withdrawal of treatment.

Prevalence of osteoporosis and vertebral fractures and related factors in patients with ankylosing spondylitis

Background Osteoporosis and vertebral factures are well recognized features in patients with ankylosing spondylitis （AS）.The aim of this study was to investigate the prevalence and risk factors of osteoporosis and vertebral fractures in patients with AS.Methods Fifty-nine AS patients and 40 healthy controls were enrolled.Bone mineral density （BMD） was measured using dual-energy X-ray absorptiometry （DEXA） at posterior-anterior （PA） lumbar,lateral lumbar and hip regions.Thoracic and lumbar X-rays were obtained for morphometric measurements.Clinical,biological and radiological statuses were evaluated with Bath Ankylosing Spondylitis Disease Activity Index （BASDAI）,Bath Ankylosing Spondylitis Metrology Index （BASMI）,Bath Ankylosing Spondylitis Functional Index （BASFI）,Bath Ankylosing Spondylitis Radiology Index-total （BASRI-t）,erythrocyte sedimentation rate （ESR） and the C-reactive protein levels.Results Osteoporosis was present in 32% of patients and 5% of controls according to lateral vertebral BMD measurements.Fracture was present in 31% of patients.The effect of some clinical and laboratory parameters on BMD status and vertebral fractures was analyzed in the patient group.Osteoporosis in lateral lumbar DEXA was associated with higher BASMI,BASFI,BASRI-t scores and ESR level.Low hip BMD was associated with low BMI and high BASFI and BASRI-t scores.Vertebral fractures were associated with advanced age,longer disease duration,longer duration since diagnosis,higher BASMI and BASRI-t scores,higher ESR level,reduced femoral and lateral lumbar BMD.Logistic regression analysis revealed that only BASRI-t score was significantly associated with low lateral spinal BMD and BMI and BASFI score were independently associated with low hip BMD.The presence of compression fractures was independently associated with BASRI-t score and low lateral lumbar BMD.Conclusions Osteoporosis and vertebral fractures in AS seem to be related to the extent of radiological involvement.A low lateral lumbar BMD is an important risk factor for vertebral fractures.

Efficacy of weight adjusted bone mineral content in osteoporosis diagnosis in Chinese female population

Background:Areal bone mineral density(aBMD)applied for osteoporosis diagnosis unavoidably results in the missingdiagnosis in patients with large bones and misdiagnosis in those with small bones.Therefore,we try to find a new adjusted index of bone mineral content(BMC)to make up shortcomings of aBMD in osteoporosis diagnosis.Methods:In this multi-center epidemiological study,BMC and aBMD of lumbar spines(n=5510)and proximal femurs(n=4710)were measured with dual energy X-ray absorptiometry(DXA).We analyzed the correlation between the bone mass and body weight in all subjects including four age groups(<19 years,20-39 years,40-49 years,>50 years).And then the body weight was used for standardizing BMC(named wBMC)and applied for the epidemiological analysis of osteoporosis?Results:The correlation of body weight and BMC is 0.839 to 0.931 of lumbar vertebra 1-4(Li_4),and 0.71 to 0.95 of femoral neck in different age groups.When aBMD was applied for diagnosing osteoporosis,the prevalence was 7.55%,16.39%,and 25.83%in patients with a high,intermediate,and low body weight respectively.However,the prevalence was 21.8%,18.03%,and 11.64%by wBMC applied for diagnosing osteoporosis.Moreover,the prevalence of osteoporosis increased by 3.76%by wBMC with the body weight increased by 5 kg.The prevalence decreased by 1.94%when the body weight decreased by 5 kg.Conclusions:wBMC can reduce the missed diagnosis in patients with large body weight and reduce misdiagnosis in those with small body weight.Including children,wBMC may be feasible for osteoporosis diagnosis individuals at any age.

128层螺旋 CT 在Ⅰ型骨质疏松症诊断中的临床应用

目的：探讨128层螺旋 CT 多项技术在Ⅰ型骨质疏松症诊断中的临床应用价值。方法收集100例Ⅰ型骨质疏松症患者的128排螺旋 CT 腰椎薄层高分辨扫描、多平面重建图像观察结果，并与双能 X 线吸收测定（DEXA）检查结果对照。结果100例Ⅰ型骨质疏松症患者128层螺旋 CT 在诊断骨小梁等细微结构、形态学观察、稳定性及是否合并骨折与 DEXA 骨密度（BMD）检测骨质疏松有较强互补性，椎体骨松质 CT 值测量与 DEXA 骨密度 T 值间有高度相关性。结论128层螺旋 CT 对Ⅰ型骨质疏松症诊断有较高临床应用价值，是 DEXA 骨密度检测必要的补充检查。