Trajectory of body mass index and obesity in children with Crohn's disease compared to healthy children

BACKGROUND

There is increasing recognition that children with Crohn's Disease (CD) can develop obesity.

METHODS

Using the RISK Study, an inception cohort of pediatric CD participants, and Bone Mineral Density in Childhood Study (BMDCS), a longitudinal cohort of healthy children, multivariable linear mixed effects, generalized linear mixed effects, and logistic regression models were used to evaluate factors associated with change in body mass index z-score (BMIZ), obesity, and excessive weight gain, respectively.

RESULTS

1029 CD participants (625 exposed to antitumor necrosis factor (anti-TNF) therapy) and 1880 healthy children were included. Change in BMIZ was higher in CD exposed to anti-TNF as compared to CD unexposed to anti-TNF and the healthy reference group. Sex, age, baseline BMIZ, C-reactive protein, anti-TNF, and steroids were associated with changes in BMIZ in CD. CD exposed (odds ratio [OR] 4.81, confidence interval [CI] 4.00-5.78) and unexposed (OR 3.14, CI 2.62-3.76) had a greater likelihood of becoming obese versus the healthy reference group. While the prevalence of obesity was higher at baseline in the healthy reference group (21.3%) versus CD participants (8.5% exposed vs. 11.1% unexposed), rates of obesity were similar by the end of follow-up (21.4% healthy vs. 20.3% exposed vs. 22.5% unexposed). Anti-TNF therapy was an independent risk factor for the development of obesity and excessive weight gain in CD participants.

CONCLUSIONS

Patients with CD have dynamic changes in BMIZ over time, and while for most, this is restorative, for some, this can lead to obesity and excessive weight gain. It is important to understand the factors that may lead to these changes, including anti-TNF therapy. Counseling of patients and early lifestyle intervention may be necessary.

Bone mineral density loci specific to the skull portray potential pleiotropic effects on craniosynostosis

Skull bone mineral density (SK-BMD) provides a suitable trait for the discovery of key genes in bone biology, particularly to intramembranous ossification, not captured at other skeletal sites. We perform a genome-wide association meta-analysis (n ~ 43,800) of SK-BMD, identifying 59 loci, collectively explaining 12.5% of the trait variance. Association signals cluster within gene-sets involved in skeletal development and osteoporosis. Among the four novel loci (ZIC1, PRKAR1A, AZIN1/ATP6V1C1, GLRX3), there are factors implicated in intramembranous ossification and as we show, inherent to craniosynostosis processes. Functional follow-up in zebrafish confirms the importance of ZIC1 on cranial suture patterning. Likewise, we observe abnormal cranial bone initiation that culminates in ectopic sutures and reduced BMD in mosaic atp6v1c1 knockouts. Mosaic prkar1a knockouts present asymmetric bone growth and, conversely, elevated BMD. In light of this evidence linking SK-BMD loci to craniofacial abnormalities, our study provides new insight into the pathophysiology, diagnosis and treatment of skeletal diseases.

Cardiometabolic risk in young adults with Down syndrome

Studies regarding cardiometabolic risk (CMR) for individuals with Down syndrome (DS) conflict. Our previous research in youth with DS, aged 10-20 years, found increased prevalence of dyslipidemia and prediabetes compared to matched peers without DS. Herein, we compare CMR in young adults with DS, aged 18-35 years, to a similar population-based sample from the 2001-2018 National Health and Nutrition Examination Survey (NHANES). The group with DS had higher NonHDL-C (mean DS 131.9 mg/dL; NHANES 126.1 p < 0.001), lower HDL-C (DS 47.5 mg/dL; NHANES 52.2 p < 0.001), higher LDL-C (DS 109.3 mg/dL; NHANES 105.4 p < 0.001), higher triglycerides (DS 102.9 mg/dL; NHANES 86.9 p < 0.001), but lower fasting glucose (DS 85.8 mg/dL; NHANES 95.2 p < 0.0001), lower HOMA-IR (DS 2.17; NHANES 2.24 p = 0.0006), lower systolic (DS 109.7 mmHg; NHANES 114.6 p < 0.0001) and lower diastolic (DS 60.9 mmHg; NHANES 67.8 p < 0.0001) blood pressures. There was relationship of higher HDL-C, triglycerides, glucose, systolic, and diastolic blood pressure with increasing BMI in the NHANES cohort which was dampened in the group with DS. These results indicate that more information is needed to guide clinicians in screening for CMR in individuals with DS.

Abstract P125: Patterns in Timing of Energy Intake and the Impact on Fat Mass in Adolescents

Introduction: Pediatric obesity is excessively high, tracks into adulthood, and increases the risk of multiple chronic diseases (e.g., heart disease). There are dietary guidelines to help prevent childhood obesity, but they do not account for the timing of energy intake, which may be associated with obesity, independent of diet content. We aimed to determine: 1) energy intake timing patterns in adolescents, 2) if energy intake timing patterns differed by sociodemographic factors, and 3) if energy intake timing patterns associated with obesity-related outcomes.

Methods: The Sleep and Growth Study (S-Grow) assessed diet in adolescents using three 24hr diet recalls in 8 th and 9 th grade. Time-stamped meals were analyzed using Nutrient Data System for Research software. We calculated the average energy (kcal) consumed for two-hour intervals during the 24-hour day (e.g., 00:00-01:59, 02:00-03:59, etc.) and input the 12 energy intake timing variables into a principal component model to identify energy intake timing patterns. Principal components (PC) with an eigen value 1.0 were retained. Linear mixed effect models were used to determine if sociodemographic factors associated with standardized PC loading scores and if the standardized PC loading scores associated with body mass index (BMI) and fat mass index (FMI, measured by dual energy X-ray absorptiometry), adjusting for sociodemographic factors.

Results: Five PCs were identified explaining 58.6% of variance in timing of energy intake. Compared to females, male adolescents were more likely to have a higher PC1 score, corresponding to a “low overnight, moderate morning, high daytime and early evening” intake pattern (beta=0.57, 95% CI=0.20, 0.94). Adolescents living in households with $40-69K (compared to >$99K) annual income were more likely to have a higher PC4 score, corresponding to a “high later evening and overnight, moderate morning, low afternoon and early evening” intake pattern (beta=0.44, 95% CI=0.05, 0.83). Adolescents living in households with <$40K (compared to >$99K) annual income were more likely to have a higher PC5 score, corresponding to a “low overnight, high morning, moderate prolonged daytime and late evening” intake pattern (beta=-0.93, 95% CI=-1.66, -0.19). In addition, the PC5 loading score was associated with lower BMI (beta=-1.38, 95% CI=-2.18,-0.58) and lower FMI (beta=-0.94, 95% CI=-1.45,-0.43).

Conclusion: We detected distinct energy intake timing patterns in adolescents. Demographic factors were associated with some of the energy intake patterns, and the energy intake pattern corresponding to “low overnight, high morning, moderate prolonged daytime and late evening” (PC5) was associated with obesity-related outcomes. These findings need to be replicated but point to future pediatric dietary guidelines considering the timing of energy intake for obesity prevention.

Abstract P126: Sociodemographic Predictors of Diet Quality During Adolescence

Introduction: Optimal nutrition is critical for near-term health, during periods of growth in childhood, and long-term health in adulthood (e.g., heart disease). The Healthy Eating Index (HEI) is an indicator of diet quality that is aligned with the Dietary Guidelines for Americans, which declines in U.S. children aged 2-18 years. Effective nutrition interventions are needed to address this decline in diet quality. Understanding sociodemographic determinants of diet quality in adolescents will help to inform such interventions. We aimed to describe changes in diet quality and to determine if sociodemographic factors associated with diet quality in adolescence.

Methods: Participants of the Sleep and Growth Study (S-Grow) completed three 24-hour diet recalls in 8 th and 9 th grade. The diet data were processed using Nutrient Data System for Research software to calculate HEI-2015 score (range: 0-100, with a higher score indicating greater diet quality) using 13 food group components. Linear mixed effect models were used to assess: 1) changes in HEI-2015 score (and individual components) from 8 th to 9 th grade, 2) sociodemographic associations with HEI-2015 score (sex, race, body mass index [BMI], and household income), and 3) sociodemographic factor-by-grade interactions to determine if any associations differed in 8 th and 9 th grades.

Results: The HEI-2015 score was stable from 8 th (44.6) to 9 th grade (45.3). Similarly, HEI component scores were stable from 8 th to 9 th grade, except for an increase in green vegetables (beta=0.37, P<0.05) and a decline in added sugars (beta=-0.50, P<0.05). Black (compared to White) adolescents and those living in households with <$40K (compared to >$99K) annual income were associated with lower overall diet quality (beta=-3.28, P<0.05; beta=-4.90, P<0.05; respectively). Male (compared to female) sex was associated with higher total dairy intake (beta=1.74, P<0.001); those with obesity (compared to normal weight) were more likely to have lower seafood intake (beta=-1.00, P<0.001) and higher refined grains intake (beta=1.26, P<0.05). The interaction analyses revealed that some household income and BMI associations with changes in HEI outcomes from 8 th and 9 th grades were distinct. For example, total fruit intake declined from 8 th to 9 th grade, but specifically among adolescents living in households with incomes of $40-69K (beta=-0.77, P=0.02) and for adolescents with obesity (beta=-1.03, P=0.003).

Conclusion: Diet quality was consistently suboptimal in 8 th and 9 th grades (i.e., 45/100). Further, we detected sex, race, and household income disparities in diet quality. Overall, these data will help to inform future intervention efforts to improve and prevent reductions in diet quality in adolescents.

Dietary Patterns and Growth From 12 to 24 Months of Age in African American Infants

Objectives

To identify dietary patterns in 12-month-old African American infants and investigate their association with change in infant BMI z-score (BMIz) from 12 to 24 months.

Methods

The prospective longitudinal Infant Growth and Microbiome Study (IGram) enrolled African American women in their 3rd trimester of pregnancy who had a pre-pregnancy BMI &gt;30 or &lt;25 and followed them and their infants from birth to 24 months of age. At 12 months, mothers reported infant intake of 32 food items in the past 7 days using the CDC Infant Feeding Practices Study II questionnaire. With these data we employed principal component analysis to derive dietary patterns for infants aged 12 months. We used multiple regression to test associations of dietary pattern scores with change in infant BMIz between 12 and 24 months.

Results

IGram enrolled 368 infants at birth; 320 and 283 infants completed 12- and 24-month visits, respectively. The prevalence of BMIz &gt; 2SD was 7.8% at 12 months and 6% at 24 months. We derived three dietary patterns which together explained 36% of the variation in the dataset. Based on the highest factor loadings for each pattern, they were named “Transitional/table food,” “Formula/baby cereal,” and “Fruit and vegetable/breast milk.” The former pattern included pancakes, pasta, rice, french fries, meat, eggs, and snack and sweet foods. Regression results suggested that, accounting for maternal pre-pregnancy obesity status, the “Fruit and vegetable/breast milk” pattern explained a small portion of the variance in BMIz increase from 12 to 24 months of age (β = 0.07, 95% CI = 0.01, 0.13, P = 0.03).

Conclusions

Preliminary findings of three distinct dietary patterns in African American infants at 12 months of age are an important first step in characterizing infant feeding patterns across the rich, longitudinal IGram dataset. A positive association of the “Fruit and vegetable/breast milk” pattern with change in infant BMIz from 12 to 24 months was unexpected and requires further investigation.

Funding Sources

An unrestricted donation from the American Beverage Foundation for a Healthy America to support the Children's Hospital of Philadelphia's Healthy Weight Program; the Research Institute of the Children's Hospital of Philadelphia; the National Center for Advancing Translational Sciences; the NIH NIDDK.

670 Changes in Childhood Sleep Patterns in an Intervention Study Prior to and During COVID19 Restrictions

Introduction

We conducted a childhood sleep promotion study between March 2019 and December 2020 in Philadelphia. COVID19 was first detected in Pennsylvania in March 2020 and non-essential services were strictly curtailed (including school closures), with easing of curtailments by the fall 2020 (including hybrid schooling in some districts). We determined if changes in sleep duration were consistent during pre-, earlier, and later COVID19 periods.

Methods

Typically developing children (9-12y) with sleep duration &lt;8.5 hours per weeknight were enrolled. Sleep was measured using Fitbit devices during a baseline week and a 7-week intervention period. A factorial design was used to test five candidate intervention components: 1) sleep goal; 2) electronic device reduction messaging; 3) daily routine messaging; 4) child-directed financial incentive; and 5) parent-directed financial incentive. Sleep data were transmitted to a mobile health platform that automated delivery of the intervention components. We categorized participants when they completed the study: 1) Spring-Fall 2019 semesters (pre-COVID19); 2) Spring 2020 semester (started pre-COVID19, with strict restrictions impacting intervention periods); or 3) Fall 2020 semester (easing of COVID19 restrictions). Mixed effect modelling determined sleep changes.

Results

Mean age of participants was 11.6y (51% female and 29% Black participants). Pre-COVID19 (N=59), average sleep duration increased from baseline by 21 (95% CI: 10, 30) minutes per weeknight during the intervention. In spring 2020 (N=18), the average sleep duration increase was two times larger in magnitude at 41 (95% CI: 25, 59) minutes per weeknight. For fall 2020 (N=20), the average sleep duration increase was 24 (95% CI: 7, 40) minutes per weeknight. Changes in sleep timing from baseline during the intervention were consistent pre-COVID19 and in the fall 2020 (e.g., ≈15 minutes earlier sleep onset throughout the intervention period), whereas sleep timing changes were dynamic in the spring 2020 (e.g., 41 minutes earlier for week 1, and 44 minutes later for week 7).

Conclusion

This sleep intervention demonstrated increases in sleep duration pre-COVID19, with marked duration increases and dynamic timing changes coinciding with COVID19 restrictions during earlier (Spring 2020), but not later (Fall 2020), weeks of the COVID19 pandemic in Pennsylvania.

Support (if any)

K0 1 HL1 2 3 6 1 2 and CHOP

613 Variation in Sleep Beliefs and Behaviors Among Caregiver-Child Dyads Participating in a Sleep Extension Intervention

Introduction

Given the high prevalence and poor outcomes of insufficient child sleep, effective interventions for the pediatric primary care setting are needed. Collecting family perspectives on intervention strategies is critical to understand and enhance outcomes, particularly among children who do not experience improvements. This study examined variation in qualitative family sleep beliefs and behaviors by quantitative child sleep outcomes of a sleep extension intervention.

Methods

A total of 24 caregiver-child dyads (child age 9–12 years, M age 11.3 (SD:1.0) years; 46% male; 50% non-Latinx White; 29% Black) participated in a mobile health sleep extension intervention, between March-December 2019, and completed post-intervention semi-structured telephone interviews to solicit intervention perceptions. The intervention used a 25 factorial design consisting of sleep duration goals and weekly performance feedback, with random assignment to sleep health promotion messaging and financial incentive conditions. Sleep duration was assessed via Fitbit Flex 2 devices during 2-week baseline and 7-week intervention periods. We developed a codebook using a grounded theory approach and conducted coding in NVivo. We compared preliminary qualitative themes among children who showed a &gt;=30-minute improvement in sleep duration (‘responders’) versus those who did not (‘non-responders’).

Results

Of the 24 dyads, 38% (N=9 dyads) were classified as non-responders. Preliminary qualitative themes included: family beliefs about sleep and electronics usage; the study impact on sleep behaviors; and an enhanced awareness of child sleep. Intervention responder and non-responder dyads similarly described family restrictions on evening electronics usage (e.g., electronic parental controls; physical removal of devices) to benefit child sleep. However, more children classified as intervention responders described the benefits of these restrictions and expressed beliefs about the negative impacts of electronics on sleep. Whereas caregivers of both responders and non-responders described efforts to remind their child to go to bed earlier during the intervention, caregivers in the responder group described being more focused on and active in child sleep extension strategies. These included setting bedtime reminders and adjusting family activities to ensure an extended sleep schedule.

Conclusion

Addressing caregiver-child beliefs about sleep behaviors and engagement in sleep extension strategies could augment sleep extension intervention outcomes in future research.

Support (if any)

K01HL123612 (JAM), CHOP (JAM), K23HD094905 (AAW)

Association of Low Muscle Density With Deteriorations in Muscle Strength and Physical Functioning in Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with low muscle density due to the accumulation of intramuscular fat. The present study was undertaken to identify predictors of changes in muscle density and to determine whether low muscle density predicted changes in strength and physical function.

METHODS

Patients with RA, ages 18-70 years, completed whole-body dual-energy x-ray absorptiometry and peripheral quantitative computed tomography to quantify lean and fat mass indices and muscle density. Dynamometry was used to measure strength at the hand, knee, and lower leg. Disability and physical function were measured with the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). Assessments were performed at baseline and at follow-up. Regression analyses assessed associations between patient characteristics, muscle density, and deteriorations in strength and function.

RESULTS

Muscle density was assessed at baseline in 107 patients with RA. Seventy-nine of these patients (74%) returned for a follow-up assessment at a median follow-up time of 2.71 years (interquartile range 2.35-3.57). Factors associated with declines in muscle density included female sex, higher disease activity, smoking, and lower insulin-like growth factor 1 (IGF-1) levels. Greater muscle density Z score at baseline (per 1 SD) was associated with less worsening per year according to HAQ, SPPB, and 4-meter walk time scores and a lower risk of a clinically important worsening in HAQ score (odds ratio [OR] 1.90 [95% confidence interval (95% CI) 1.06, 3.42]; P = 0.03) and walking speed (OR 2.87 [95% CI 1.05, 7.89]; P = 0.04).

CONCLUSION

Worsening of skeletal muscle density occurred in patients with higher disease activity, in smokers, and in those with lower IGF-1. Low muscle density was associated with worsening of physical function. Interventions addressing reductions in muscle quality might prevent functional decline.

Validation of a description of sarcopenic obesity defined as excess adiposity and low lean mass relative to adiposity

BACKGROUND

This study aims to assess the construct validity of a body composition-defined definition of sarcopenic obesity based on low appendicular lean mass relative to fat mass (ALMIFMI ) and high fat mass index (FMI) and to compare with an alternative definition using appendicular lean mass index (ALMI) and percent body fat (%BF).

METHODS

This is a secondary analysis of two cohort studies: the National Health and Examination Survey (NHANES) and the Health, Aging, and Body Composition study (Health ABC). Sarcopenic obesity was defined as low ALMIFMI combined with high FMI and was compared with a widely used definition based on ALMI and %BF cut-points. Body composition Z-scores, self-reported disability, physical functioning, and incident disability were compared across body composition categories using linear and logistic regression and Cox proportional hazards models.

RESULTS

Among 14, 850 participants from NHANES, patients with sarcopenic obesity defined by low ALMIFMI and high FMI (ALMIFMI -FMI) had above-average FMI Z-scores [mean (standard deviation): 1.00 (0.72)]. In contrast, those with sarcopenic obesity based on low ALMI and high %BF (ALMI-%BF) had below-average FMI Z-scores. A similar pattern was observed for 2846 participants from Health ABC. Participants with sarcopenic obesity based on ALMIFMI -FMI had a greater number of disabilities, worse physical function, and a greater risk of incident disability compared with those defined based on ALMI-%BF.

CONCLUSIONS

Body composition-defined measures of sarcopenic obesity defined as excess adiposity and lower-than-expected ALMI relative to FMI are associated with functional deficits and incident disability and overcome the limitations of using %BF in estimating obesity in this context.

Dietary Fiber and Bone Density in Youth with Type 2 Diabetes

Objectives

Assess relationships between dietary fiber and bone density in youth with type 2 diabetes, obesity, and healthy weight.

Methods

Cross-sectional study of youth (56% African American, 67% female) ages 10–23 years with type 2 diabetes (n = 180), obesity (BMI &gt;95th; n = 226), or healthy weight (BMI &lt; 85th; n = 238). Total body bone mineral density (BMD) was assessed via DXA. BMD standard deviation scores (“Z-scores”) were computed using published reference data. Dietary fiber (total, soluble, and insoluble) and total calories were assessed via 3-day food diaries, which were analyzed using the Nutrition Data System for Research. Relationships between dietary fiber and BMD Z-score were assessed using linear regression. Separate analyses were performed for total, soluble, and insoluble fiber, and each regression model included age, sex, ancestry, total calories, group, and fiber (total, soluble, or insoluble), as well as group by fiber interactions.

Results

BMD Z-score was greater in the type 2 diabetes and obese compared to the healthy weight group (P &lt; 0.001). Total, soluble, and insoluble fiber intakes were significantly greater in the healthy weight versus obese group (all P &lt; 0.05), but only marginally greater than the type 2 diabetes group (all P = 0.06–0.10). Regression analyses demonstrated positive relationships between total, soluble, and insoluble fiber intakes and BMD Z-score (all P &lt; 0.05). However, significant group by fiber interactions indicated that the positive relationships between dietary fiber intakes and BMD Z-score was evident only in the healthy weight group (all P &lt; 0.005). Similar relationships were observed when considering BMD Z-score adjusted for height Z-score.

Conclusions

Prior studies have reported a favorable influence of dietary fiber on bone mineral accrual in healthy individuals and metabolic health in adults with insulin resistance. Dietary strategies promoting increased fiber consumption warrant investigation with respect to fracture prevention and glycemic control in youth with type 2 diabetes.

Funding Sources

NIH-NHLBI, American Diabetes Association, and Endocrine Fellows Foundation.

0390 Associations of the Neighborhood Built Environment with Adolescent Sleep Outcomes

Introduction

Over 75% of U.S. high school students obtain insufficient amounts of sleep. Identification of modifiable environmental determinants of adolescent sleep is needed to inform interventions and public health strategies, yet little is known about the influence of the built environment on adolescent sleep. We examined associations of the built environment with objectively-measured adolescent sleep outcomes.

Methods

In this longitudinal, prospective study, we used actigraphy to assess sleep outcomes for 14 days each in 8th grade and 9th grade: duration (hours/night), onset (hours from 00:00), offset (hours from 00:00), and sleeping &gt;8 hours. Home addresses were linked to built environment exposures based on half-mile Euclidian buffers (overall/human-made sound levels, percent tree canopy cover, street density, intersection density) and census block group (population density, housing density). Mixed-effects linear (sleep duration, onset, offset) and logistic (&gt;8 hours) regression estimated associations of each built environment measure with sleep outcomes, adjusting for sex, race, parent education, household income, grade and weeknight status (school or non-school night).

Results

Among 108 adolescents - 53% female and 25% Black - providing 2,388 nights of sleep data across 8th and 9th grades, a 1-standard deviation increase in neighborhood sound (overall and human-made) associated with 11 minutes later sleep onset (β=0.19; 95% CI: 0.01, 0.38) and 20% lower odds of sleeping for &gt;8 hours (OR=0.80, 95% CI: 0.62, 1.02). A 1-standard deviation increase in neighborhood tree canopy cover associated with 11 minutes earlier sleep onset (β= -0.19, 95% CI: -0.35, -0.03) and 7 minutes earlier sleep offset (β= -0.12, 95% CI: -0.23, -0.02). No associations were observed for “density based” exposures.

Conclusion

Higher tree canopy cover associated with more favorable sleep timing while higher neighborhood sound level associated with later timing of sleep onset. These modifiable neighborhood built environment factors should be considered when intervening to support healthier sleep among adolescents.

Support

NIH/NHLBI K01HL123612 (JM) and Sleep Research Society Foundation and K23HD094905 (AAW)

The Adiponectin Paradox in the Elderly: Associations With Body Composition, Physical Functioning, and Mortality

Background

To determine if adiponectin levels are associated with weight loss, low muscle mass, and physical functioning among the elderly and to determine independent associations with incident disability and death.

Methods

Included were 3,044 participants from the Health, Aging and Body Composition Study, who had whole-body dual energy absorptiometry performed to evaluate appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI, kg/m2), computed tomography measures of thigh muscle density, weight histories, estimates of physical functioning, and adiponectin levels at enrollment. Associations between adiponectin levels and body composition, weight loss, and physical functioning were assessed in multivariable linear regression models. Associations between adiponectin and incident disability and mortality were assessed in mediation analyses, adjusting for other factors.

Results

Greater adiponectin at baseline was independently associated with low FMI Z-score, lower waist circumference, low ALMI Z-score, low muscle density, a history of weight loss, and poor physical functioning (all p < .05). Greater adiponectin levels (per SD) were associated with incident disability [HR: 1.14 (1.08, 1.20), p < .001] and greater mortality [HR: 1.17 (1.10, 1.25), p < .001] in models adjusting for demographic factors, adiposity, and comorbid conditions. The association was completely attenuated and no longer significant (all p > 0.05) when adjusting for body composition, muscle density, weight loss, and physical functioning at baseline.

Conclusions

Greater serum adiponectin levels are associated with historical weight loss, low skeletal muscle mass, low muscle density, and poor physical functioning. High adiponectin is associated with a greater risk of incident disability and death, but not independently of these factors.

Estimation of Skeletal Muscle Mass Relative to Adiposity Improves Prediction of Physical Performance and Incident Disability

Purpose

We assessed the discrimination of lean mass estimates that have been adjusted for adiposity for physical functioning deficits and prediction of incident disability.

Methods

Included were 2,846 participants from the Health, Aging and Body Composition Study with available whole-body dual energy absorptiometry measures of appendicular lean mass index (ALMI, kg/m2) and fat mass index (FMI, kg/m2). Age-, sex-, and race-specific Z-Scores and T-Scores were determined by comparison to published reference ranges. ALMI values were adjusted for FMI (ALMIFMI) using a novel published method. Sex-stratified analyses assessed associations between lean mass estimates and the physical performance score, ability to complete a 400-meter walk, grip strength, and incident disability. Dichotomized definitions of low lean for age and sarcopenia were examined and their performance compared to the ALM-to-BMI ratio.

Results

Compared to ALMI T-Scores and Z-Scores, the ALMIFMI scores demonstrated stronger associations with physical functioning, and were similarly associated with grip strength. Greater FMI Z-Scores and T-Scores were associated with poor physical functioning and incident disability. Definitions of low lean for age and sarcopenia using ALMIFMI (compared to ALMI) better discriminated those with poor physical functioning and a greater risk of incident disability. The ALM-to-BMI ratio was modestly associated with grip strength and physical performance, but was not associated with completion of the 400-meter walk or incident disability, independent of adiposity and height.

Conclusion

Estimation of skeletal muscle mass relative to adiposity improves correlations with physical performance and prediction of incident disability suggesting it is an informative outcome for clinical studies.

Prevalence of and Risk Factors for Low Bone Mineral Density in Children With Celiac Disease

BACKGROUND & AIMS

Celiac disease can reduce bone mineral density. We sought to determine the prevalence and risk factors for low areal bone mineral density (aBMD) in children with celiac disease.

METHODS

We performed a retrospective cohort study of 673 children with celiac disease (63% female; median age at diagnosis, 10.6 y; interquartile range, 7.8-13.9) who underwent dual x-ray absorptiometry (DXA) from 2009 through 2016 at the Children's Hospital of Philadelphia. We collected demographic, clinical, and laboratory data from medical records. We performed logistic regression analysis to identify factors associated with low (Z less than -2) lumbar spine aBMD Z (aBMD-Z) scores at initial and subsequent tests.

RESULTS

The time between diagnosis of celiac disease and first DXA was 0 days (interquartile range, -11 to 31 d). The mean aBMD-Z score at the children's initial scan was -0.4 ± 1.2; 46 children had aBMD-Z scores less than -2 (6.8%; 95% CI, 5.2%-9.0%). Those who had a second DXA analysis (n = 108; 16.0%) had a significant increase in aBMD-Z score (mean change, 0.29; P = .0005). Higher body mass index (BMI) was associated with lower odds of a low aBMD-Z score at the initial DXA analysis (odds ratio, 0.46, 95% CI, 0.35-0.50). BMI-Z scores greater than -0.4 identified children with a low aBMD-Z at their initial DXA analysis with a 95% negative predictive value.

CONCLUSIONS

Approximately 7% of subjects with celiac disease had a low aBMD-Z score, determined by DXA, at the time of diagnosis; this value was nearly 3-fold higher than expected from a population of children of this age and sex distribution. BMI-Z scores could be used to identify children with celiac disease at risk for low BMD who should receive DXA screening.

Intramuscular Fat Accumulation and Associations With Body Composition, Strength, and Physical Functioning in Patients With Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with adverse body composition profiles and low muscle density due to the accumulation of intramuscular fat. Linear regression was used to assess differences between RA patients and controls and to determine associations between muscle density, strength, and physical functioning.

METHODS

Patients with RA, ages 18-70 years, and healthy control subjects underwent whole-body dual x-ray absorptiometry and peripheral quantitative computed tomography, in order to quantify the appendicular lean mass index (ALMI) and the fat mass index (FMI), visceral fat area, and muscle density. Dynamometry was used to measure hand grip strength and muscle strength at the knee and lower leg. Disability and physical functioning were measured using the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). Linear regression analyses were performed to assess differences related to RA and associations between muscle density, strength, and function.

RESULTS

The study group included 103 patients with RA (51 men) and 428 healthy control subjects. Among patients with RA, low muscle density was associated with higher disease activity, C-reactive protein and interleukin-6 levels, greater total and visceral fat area, lower ALMI Z scores, physical inactivity, and long-term use of glucocorticoids (>1 year). Patients with low ALMI Z scores had lower muscle density Z scores compared with reference participants with similarly low ALMI scores. Low muscle density was independently associated with lower muscle strength, higher HAQ scores, and lower SPPB scores, after adjustment for ALMI and FMI Z scores.

CONCLUSION

The low muscle density observed in patients with RA was associated with low muscle mass, excess adiposity, poor strength, and greater disability. Interventions to address poor muscle quality could potentially affect important functional outcomes.

The Association of Diet and Exercise With Body Composition in Pediatric Crohn's Disease

BACKGROUND

In pediatric Crohn's disease, fat mass improves over time with treatment, but lean mass deficits persist. This observational study of the associations of physical activity and dietary intake with lean mass and muscle strength in children with Crohn's disease was ancillary to a previously reported randomized clinical trial of an intervention to improve bone health.

METHODS

In this study, 138 participants were followed at baseline and at 6, 12, and 24 months with evaluation of lean and fat mass using DXA, muscle strength (peak torque), Crohn's characteristics, dietary intake, time in moderate to vigorous physical activity (MVPA), and serum insulin-like growth factor-1 (IGF-1) and tumor necrosis factor-alpha (TNF-α). Race- and sex-specific Z-scores for leg lean mass and whole body fat mass were generated. Quasi least square regression evaluated determinants of changes in body composition and muscle strength.

RESULTS

Leg lean mass and muscle strength were positively associated with time in MVPA (P < 0.05) and negatively associated with increasing clinical disease activity (P < 0.05). Both leg lean mass and strength were positively associated with IGF-1 Z-score (P ≤ 0.03) but negatively associated with serum TNF-α (P ≤ 0.04). Neither lean mass nor muscle strength was associated with caloric or protein intake.

CONCLUSIONS

Persistence of lean mass deficits was related to ongoing Crohn's disease activity but improved with greater time spent in moderate to vigorous physical activity. Future trials are needed to evaluate the efficacy of physical activity in improving lean mass in pediatric Crohn's disease.

Changes in arm tissue composition with slowly-progressive weight-lifting among women with breast cancer-related lymphedema

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Background: We evaluated baseline differences in arm tissue composition (fat mass, lean mass, bone mineral content [BMC] and bone mineral density [BMD]) between the affected and unaffected arms in women with breast cancer-related lymphedema (BRCL). We compared changes in arm tissue composition and self-reported lymphedema symptoms after one-year of weight-lifting vs. usual-care. Methods: We utilized data from the PAL trial that included 141 women with BRCL. Arm tissue composition was quantified using dual-energy x-ray absorptiometry. The severity of lymphedema was quantified using self-report survey. Weight-lifting was performed at community fitness facilities. Results: At baseline, the affected arm had more fat (D= 89.7±21.0g; P < 0.001) and lean mass (D= 149.1±25.3g; P < 0.001), but less BMC (D= -3.2±0.9g; P < 0.001) than the unaffected arm. No difference was observed in BMD. After 12-months of weight-lifting, composition of the affected arm was improved: lean mass (71.2±27.9g; P = 0.01) and BMD (0.01±0.01g; P = 0.02) increased, arm fat percentage decreased (0.01±0.01; P = 0.003). No changes observed in fat mass and BMC. Baseline body mass index and BCRL grade modified the relationship between weight-lifting and tissue composition changes. Increases in lean mass were associated with less severe BCRL symptoms. With every one-percent decrease in arm fat percentage, affected limb volume reduced 13.81mL. Conclusions: Among women with BRCL, affected and unaffected arms differ in tissue composition. These differences may be improved with weight-lifting. Changes in arm tissue composition correlate with improved BCRL symptoms. Investigating the combined effects of exercise and weight-loss on arm tissue composition and BCRL symptoms may provide additional insight to the benefits of lifestyle modification on lymphedema biology. Clinical trial information: NCT00194363.

Development of Novel Methods to Define Deficits in Appendicular Lean Mass Relative to Fat Mass

Background

Recent studies suggest that adjustment of measures of lean mass for adiposity improves associations with physical function. Our objective was to develop and test a method to adjust appendicular lean mass for adiposity.

Methods

Whole-body DXA data in 14,850 adults in the National Health and Nutrition Examination Survey were used to generate sex-, and race-specific standard deviation scores (Z-Scores relative to age and T-scores relative to 25 year-olds) for appendicular lean mass index (ALMI, kg/m²) and fat mass index (FMI, kg/m²). Correlations between ALMI and FMI Z- and T-Scores were assessed within demographic categories. Fat-adjusted ALMI (ALMI_FMI) scores were determined using residual methods. Sarcopenia was defined as a T-Score <-2.0 and low lean for age as a Z-Score <-1.0. Correlations with physical function were assessed in an at-risk population.

Results

Positive associations between ALMI and FMI Z- and T-Scores were significant (R >0.50; p<0.001) within all demographic categories. The impact of a unit greater FMI Z-score on ALMI Z-score was less in the elderly, men, white subjects, and among individuals with lower FMI (all tests for interaction p<0.001). There was fair agreement between ALMI and ALMI_FMI estimates of sarcopenia and low lean for age [Kappa: 0.46, 0.52, respectively (p<0.0001)]. Elderly subjects were likely to be re-classified as sarcopenic while young subjects were likely to be re-classified as normal using ALMI_FMI. ALMI_FMI T-scores resulted in approximately twice the number of subjects defined as sarcopenic, compared with ALMI T-Scores. (1299 v. 534). Among rheumatoid arthritis patients, ALMI_FMI Z-scores correlated with physical function (Health Assessment Questionnaire: rho = -0.22, p = 0.04; Short Physical Performance Battery: rho = 0.27, p = 0.01); however, the ALMI Z-Score did not.

Conclusions

Adjustment of ALMI for the confounding association with FMI impacts the definition of lean mass deficits. These methods provide a practical tool for investigators and clinicians based on population-based reference data.

Social jet lag, chronotype and body mass index in 14-17-year-old adolescents

The relationship between sleep duration and obesity in adolescents is inconclusive. This may stem from a more complex relationship between sleep and obesity than previously considered. Shifts toward evening preferences, later sleep-wake times and irregular sleep-wake patterns are typical during adolescence but their relationship to body mass index (BMI) has been relatively unexplored. This cross-sectional study examined associations between sleep duration, midpoint of sleep and social jet lag (estimated from 7 days of continuous actigraphy monitoring), and morningness/eveningness with BMIs (BMI z-scores) and waist-to-height ratios in 14-17-year-old adolescents. Seventy participants were recruited from ninth and tenth grades at a public high school. Participants' characteristics were as follows: 74% female, 75% post-pubertal, 36% Hispanic, 38% White, 22% Black, 4% Asian and 64% free/reduced lunch participants with a mean age of 15.5 (SD, 0.7). Forty-one percent of the participants were obese (BMI ≥ 95th percentile); 54% were abdominally obese (waist-to-height ratio ≥ 0.5). Multivariable general linear models were used to estimate the association between the independent variables (school night sleep duration, free night sleep duration, midpoint of sleep (corrected), social jet lag and morningness/eveningness) and the dependent variables (BMI z-scores and waist-to-height ratios). Social jet lag is positively associated with BMI z-scores (p < 0.01) and waist-to-height ratios (p = 0.01). Midpoint of sleep (corrected) is positively associated with waist-to-height ratios (p = 0.01). After adjusting for social jet lag, school night sleep duration was not associated with waist-to-height ratios or BMI z-scores. Morningness/eveningness did not moderate the association between sleep duration and BMI z-scores. Findings from this study suggest that chronobiological approaches to preventing and treating obesity may be important for accelerating progress in reducing obesity rates in adolescents.

Accurate body composition measures from whole-body silhouettes

PURPOSE

Obesity and its consequences, such as diabetes, are global health issues that burden about 171 × 10(6) adult individuals worldwide. Fat mass index (FMI, kg/m(2)), fat-free mass index (FFMI, kg/m(2)), and percent fat mass may be useful to evaluate under- and overnutrition and muscle development in a clinical or research environment. This proof-of-concept study tested whether frontal whole-body silhouettes could be used to accurately measure body composition parameters using active shape modeling (ASM) techniques.

METHODS

Binary shape images (silhouettes) were generated from the skin outline of dual-energy x-ray absorptiometry (DXA) whole-body scans of 200 healthy children of ages from 6 to 16 yr. The silhouette shape variation from the average was described using an ASM, which computed principal components for unique modes of shape. Predictive models were derived from the modes for FMI, FFMI, and percent fat using stepwise linear regression. The models were compared to simple models using demographics alone [age, sex, height, weight, and body mass index z-scores (BMIZ)].

RESULTS

The authors found that 95% of the shape variation of the sampled population could be explained using 26 modes. In most cases, the body composition variables could be predicted similarly between demographics-only and shape-only models. However, the combination of shape with demographics improved all estimates of boys and girls compared to the demographics-only model. The best prediction models for FMI, FFMI, and percent fat agreed with the actual measures with R(2) adj. (the coefficient of determination adjusted for the number of parameters used in the model equation) values of 0.86, 0.95, and 0.75 for boys and 0.90, 0.89, and 0.69 for girls, respectively.

CONCLUSIONS

Whole-body silhouettes in children may be useful to derive estimates of body composition including FMI, FFMI, and percent fat. These results support the feasibility of measuring body composition variables from simple cameras such as those found in cell phones.

Characteristics Associated with Sleep Duration, Chronotype, and Social Jet Lag in Adolescents

Sleep is a complex behavior with numerous health implications. Identifying sociodemographic and behavioral characteristics of sleep is important for determining those at greatest risk for sleep-related health disparities. In this cross-sectional study, general linear models were used to examine sociodemographic and behavioral characteristics associated with sleep duration, chronotype, and social jet lag in adolescents. One hundred and fifteen participants completed Phase I (self-reported sleep measures), and 69 of these participants completed Phase II (actigraphy-estimated sleep measures). Black adolescents had shorter free night sleep than Hispanics. Youth with later chronotypes ate fewer fruits and vegetables, drank more soda, were less physically active, and took more daytime naps. Based on these findings, recommendations for individual support and school policies are provided.

Adverse Fat Depots and Marrow Adiposity Are Associated With Skeletal Deficits and Insulin Resistance in Long-Term Survivors of Pediatric Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem-cell transplantation (alloHSCT) survivors treated with total body irradiation (TBI) exhibit bone deficits and excess adiposity, potentially related to altered mesenchymal stem cell differentiation into osteoblasts or adipocytes. We examined associations among fat distribution, bone microarchitecture, and insulin resistance in alloHSCT survivors after TBI. This was a cross-sectional observational study of 25 alloHSCT survivors (aged 12 to 25 years) a median of 9.7 (4.3 to 19.3) years after alloHSCT compared to 25 age-, race-, and sex-matched healthy controls. Vertebral MR spectroscopic imaging and tibia micro-MRI were used to quantify marrow adipose tissue (MAT) and trabecular microarchitecture. Additional measures included DXA whole-body fat mass (WB-FM), leg lean mass (Leg-LM), trunk visceral adipose tissue (VAT), and CT calf muscle density. Insulin resistance in alloHSCT survivors was estimated by HOMA-IR. AlloHSCT survivors had lower Leg-LM (p < 0.001) and greater VAT (p < 0.01), MAT (p < 0.001), and fat infiltration of muscle (p = 0.04) independent of WB-FM, versus matched controls; BMI did not differ. Survivors had lower bone volume fraction and abnormal microarchitecture including greater erosion and more rod-like structure versus controls (all p = 0.04); 14 had vertebral deformities and two had compression fractures. Greater WB-FM, VAT, MAT, and muscle fat infiltration were associated with abnormal trabecular microarchitecture (p < 0.04 for all). AlloHSCT HOMA-IR was elevated, associated with younger age at transplantation (p < 0.01), and positively correlated with WB-FM and VAT (both p < 0.01). In conclusion, the markedly increased marrow adiposity, abnormal bone microarchitecture, and abnormal fat distribution highlight the risks of long-term treatment-related morbidity and mortality in alloHSCT recipients after TBI. Trabecular deterioration was associated with marrow and visceral adiposity. Furthermore, long-term survivors demonstrated sarcopenic obesity, insulin resistance, and vertebral deformities. Future studies are needed to identify strategies to prevent and treat metabolic and skeletal complications in this growing population of childhood alloHSCT survivors.

The longitudinal effects of physical activity and dietary calcium on bone mass accrual across stages of pubertal development

Childhood and adolescence are critical periods of bone mineral content (BMC) accrual that may have long-term consequences for osteoporosis in adulthood. Adequate dietary calcium intake and weight-bearing physical activity are important for maximizing BMC accrual. However, the relative effects of physical activity and dietary calcium on BMC accrual throughout the continuum of pubertal development in childhood remains unclear. The purpose of this study was to determine the effects of self-reported dietary calcium intake and weight-bearing physical activity on bone mass accrual across the five stages of pubertal development in a large, diverse cohort of US children and adolescents. The Bone Mineral Density in Childhood study was a mixed longitudinal study with 7393 observations on 1743 subjects. Annually, we measured BMC by dual-energy X-ray absorptiometry (DXA), physical activity and calcium intake by questionnaire, and pubertal development (Tanner stage) by examination for up to 7 years. Mixed-effects regression models were used to assess physical activity and calcium intake effects on BMC accrual at each Tanner stage. We found that self-reported weight-bearing physical activity contributed to significantly greater BMC accrual in both sexes and racial subgroups (black and nonblack). In nonblack males, the magnitude of the activity effect on total body BMC accrual varied among Tanner stages after adjustment for calcium intake; the greatest difference between high- and low-activity boys was in Tanner stage 3. Calcium intake had a significant effect on bone accrual only in nonblack girls. This effect was not significantly different among Tanner stages. Our findings do not support differential effects of physical activity or calcium intake on bone mass accrual according to maturational stage. The study demonstrated significant longitudinal effects of weight-bearing physical activity on bone mass accrual through all stages of pubertal development.

Change in body composition during a weight loss trial in obese adolescents

What is already known about this subject Adolescence is an important period of physiological growth. Loss of central adiposity with preservation of lean mass during weight loss is optimal. There are discrepancies in the literature concerning changes in lean mass during weight loss in adolescents. What this study adds This study provides information of regional and total body composition change in adolescents during weight loss. This study controls for important factors that impact body composition in growing adolescents such as age, sex, height, baseline weight and race. This study provides correlations of changes in waist circumference and body mass index (BMI) with total and trunk fat mass during weight loss in adolescents.

SUMMARY

Background Changes in body composition during weight loss among obese adolescents are poorly understood. This study characterized the composition of weight loss and its association with changes in waist circumference (WC) in obese adolescents. Methods Total (Tot), trunk (Tr) and appendicular (Ap) fat mass (FM) and lean mass (LM) were measured by dual-energy X-ray absorptiometry in 61 obese adolescents (40 girls) who participated in a randomized controlled weight loss trial. Changes in body composition were assessed at 0, 6 and 12 months using mixed-effects regression models. Correlation analysis of change in WC and total and regional compartments of FM and LM were assessed. Results Weight loss for adolescents was 90.3% FM and 15.9% LM at 0-6 months, and 98.2% FM and 7% LM at 0-12 months. At 12 months, girls lost 2.67 kg more TotFM than boys in models adjusted for height, age, race and baseline weight. Boys gained LM in all compartments in all models. At 12 months, girls lost TotLM (2.23 ± 0.74, P < 0.004) and ApLM (0.69 ± 0.31, P = 0.03) and gained TrLM (0.37 ± 0.35, P = 0.29). The percentage LM, increased for boys and girls in all models. TotFM was correlated with body mass index (BMI) change with TotFM (R = 0.70-0.91, P = 0.001) and WC change (R = 0.53-0.55, P < 0.001). Conclusions Weight loss in obese adolescents during a weight loss trial using lifestyle management and sibutramine was primarily from trunk FM. Although absolute LM increased in boys and decreased in girls, the percentage of weight that is LM increased for both boys and girls. Changes in BMI were more reflective of changes in FM than changes in WC.

Bone mineral accretion and its relationship to growth, sexual maturation and body composition during childhood and adolescence

Bone mineral accretion during childhood and adolescence is subject to a number of influences, including body composition changes, sexual maturation and growth. Bone mass and density increase with age and vary by sex, so bone health must be evaluated like other growth outcomes, i.e. in relation to age- and sex-specific reference ranges. Peak bone mass, the amount of bone acquired at the end of skeletal development is an important determinant of lifelong skeletal health. The timing of puberty is inversely related to peak bone mass, such that individuals who experience puberty at older ages have lower bone mass in young adulthood. Height, an indicator of skeletal size, is correlated with bone mineral content and density. Even more importantly, children who are tall for their age have greater bone mass and density than children of average or short stature. Body composition, particularly lean body mass, has a positive effect on bone accretion because of the mechanical strains of muscle mass on bone accretion. The effect of height growth is positively associated with bone accretion, but the magnitude of the effect is not the same at all pubertal stages; in Tanner stage 5, height growth has a more pronounced effect on bone accretion than at the beginning of puberty. Understanding these complex relationships is essential to understanding bone metabolism during this part of the life cycle and the challenges of assessing bone health in children with medical conditions that threaten bone health.

Longitudinal assessment of bone density and structure in childhood survivors of acute lymphoblastic leukemia without cranial radiation

PURPOSE

Children with acute lymphoblastic leukemia (ALL) are at risk for impaired bone accrual. This peripheral quantitative computed tomography study assessed changes in bone mineral density (BMD) and structure after completion of ALL treatment.

METHODS

Fifty ALL participants, ages 5-22 yr, were enrolled within 2 yr (median 0.8 yr) after completing ALL therapy. Tibia peripheral quantitative computed tomography scans were performed at enrollment and 12 months later. Age-, sex-, and race-specific Z-scores for trabecular BMD (TrabBMD), cortical BMD (CortBMD), and cortical area (CortArea) were generated based on more than 650 reference participants. Multivariable linear regression models examined determinants of changes in Z-scores.

RESULTS

At enrollment, mean TrabBMD (-1.03±1.34) and CortBMD (-0.84±1.05) Z-scores were low (both P<0.001) compared with reference participants. TrabBMD and CortBMD Z-scores increased to -0.58±1.41 and -0.51±0.91 over 1 yr, respectively (both P<0.001). Changes in cortical outcomes varied according to the interval since completion of therapy. Among those enrolled less than 6 months after therapy, CortArea Z-scores increased and CortBMD Z-scores decreased (both P<0.01). Among those enrolled 6 months or more after therapy, CortArea Z-scores did not change and CortBMD Z-scores increased (P<0.01). Changes in CortArea and CortBMD Z-scores were inversely associated (r=-0.32, P<0.001). Cumulative glucocorticoid exposure, leukemia risk status, and antimetabolite chemotherapy were not associated with outcomes.

CONCLUSION

TrabBMD was low after completion of ALL therapy and improved significantly. Early increases in cortical dimensions were associated with declines in CortBMD; however, participants further from ALL therapy demonstrated stable cortical dimensions and increases in CortBMD, potentially reflecting the time necessary to mineralize newly formed bone.

Interpretation of body mass index in children with CKD

BACKGROUND AND OBJECTIVES

Clinical practice guidelines recommend that body mass index (BMI) in children with CKD be expressed relative to height-age (BMI-height-age-z) rather than chronologic age (BMI-age-z) to account for delayed growth and sexual maturation. This approach has not been validated. This study sought to (1) compare children who have CKD with healthy children regarding the relationships between BMI-age-z and each of relative lean mass (LM) and adiposity and (2) determine whether BMI-height-age-z reflects relative LM and adiposity in CKD in the same way that BMI-age-z does in healthy children.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a cross-sectional study, dual-energy x-ray absorptiometry was used to assess whole-body fat mass (FM) and LM in 143 participants with CKD and 958 healthy participants (age, 5-21 years); FM and LM were expressed as sex-specific Z-scores relative to height (LM-height-z, FM-height-z), with healthy participants as the reference. BMI-age-z and BMI-height-age-z were determined using the 2000 Centers for Disease Control and Prevention reference data.

RESULTS

Compared with healthy children of the same sex, age, race, and BMI-age-z, LM-height-z was significantly higher in males with all CKD stages (by 0.41-0.43 SDs) and in females with mild to moderate CKD (by 0.38 SD); FM-height-z was significantly higher in both males (by 0.26 SD) and females (by 0.52 SD) with severe CKD. Underestimation of relative LM and adiposity was improved by expressing BMI relative to height-age.

CONCLUSIONS

In children with CKD, BMI-height-age-z reflects relative LM and adiposity in the same way that BMI-age-z does in healthy children.

Bone density and structure in long-term survivors of pediatric allogeneic hematopoietic stem cell transplantation

Children requiring allogeneic hematopoietic stem cell transplantation (alloHSCT) have multiple risk factors for impaired bone accrual. The impact of alloHSCT on volumetric bone mineral density (vBMD) and cortical structure has not been addressed. Tibia peripheral quantitative computed tomography (pQCT) scans were obtained in 55 alloHSCT recipients, ages 5 to 26 years, a median of 7 (range, 3-16) years after alloHSCT. pQCT outcomes were converted to sex- and race- specific Z-scores relative to age based on reference data in >700 concurrent healthy participants. Cortical section modulus (Zp; a summary measure of cortical bone structure and strength), and muscle and fat area Z-scores were further adjusted for tibia length for age Z-scores. AlloHSCT survivors had lower height Z-scores (-1.21 ± 1.25 versus 0.23 ± 0.92; p < 0.001), versus reference participants; BMI Z-scores did not differ. AlloHSCT survivors had lower trabecular vBMD (-1.05; 95% confidence interval [CI], -1.33 to -0.78; p < 0.001), cortical Zp (-0.63; 95% CI, -0.91 to -0.35; p < 0.001), and muscle (-1.01; 95% CI, -1.30 to -0.72; p < 0.001) Z-scores and greater fat (0.82; 95% CI, 0.54-1.11; p < 0.001) Z-scores, versus reference participants. Adjustment for muscle deficits eliminated Zp deficits in alloHSCT. Total body irradiation (TBI) was associated with lower trabecular vBMD (-1.30 ± 1.40 versus -0.49 ± 0.88; p = 0.01) and muscle (-1.34 ± 1.42 versus -0.34 ± 0.87; p < 0.01) Z-scores. Growth hormone deficiency (GHD) was associated with lower Zp Z-scores (-1.64 ± 2.47 versus -0.28 ± 1.24; p = 0.05); however, muscle differences were not significant (-1.69 ± 1.84 versus -0.78 ± 1.01; p = 0.09). History of graft versus host disease was not associated with pQCT outcomes. In summary, alloHSCT was associated with significant deficits in trabecular vBMD, cortical geometry, and muscle area years after transplantation. TBI and GHD were significant risk factors for musculoskeletal deficits. Future studies are needed to determine the metabolic and fracture implications of these deficits, and to identify therapies to improve bone accrual following alloHSCT during childhood.

Vitamin D status in children and young adults with perinatally acquired HIV infection

BACKGROUND & AIMS

To assess vitamin D (Vit-D) [serum 25-hydroxyvitamin D (25-OHD) concentrations] in children and young adults with perinatally acquired HIV compared to geographically similar healthy children.

METHODS

25-OHD in children and young adults with HIV was compared to a healthy group. Vit-D deficiency and insufficiency were defined as 25-OHD <11 ng/mL and 25-OHD <30 ng/mL, respectively.

RESULTS

Children with HIV (n = 81), mean age 13.8 ± 4.1 years, 48% female, 83% Black, were compared to healthy subjects (n = 372), mean age 12.4 ± 3.4 years, 51% female, 37% Black. For the HIV group, 84% were on HAART, 54% had plasma HIV RNA <400 cpm, and 35% had moderate to severe immunosuppression (CD4+ count <500 cells/mm). Vit-D deficiency/insufficiency was present in 36% and 89% of those with HIV, and 15% and 84% of the comparison group, respectively. Vit-D deficiency was more prevalent in those with HIV (unadjusted odds ratio: 3.25; 95% CI: 1.9-5.5). For both groups, prevalence of Vit-D deficiency increased with age, BMI Z-score, Black race, and in winter/spring months. Vit-D deficiency was associated with a greater degree of immunosuppression in the subjects with HIV.

CONCLUSIONS

Vit-D deficiency was increased in subjects with perinatally acquired HIV and may be associated with disease severity.

Age at onset of puberty predicts bone mass in young adulthood

OBJECTIVE

To determine whether the commencement and length of puberty influences dual x-ray absorptiometry (DXA) values of bone mineral content (BMC) and bone mineral density (BMD) in the axial and appendicular skeleton at skeletal maturity.

STUDY DESIGN

From the Bone Mineral Density in Childhood Study, we identified children who began puberty and completed sexual and skeletal development and examined whether the timing and length of puberty influence DXA values of BMC and BMD at skeletal maturity.

RESULTS

A total of 78 girls and 85 boys began puberty and completed skeletal maturity; 4.4 ± 0.8 and 4.5 ± 0.8 years later, respectively. Multiple linear regression analyses indicated that the age of onset of puberty was a strong negative predictor of DXA bone measurements at skeletal maturity, independent of bone values at the beginning of puberty, and the length of puberty. This negative relation was observed for all BMC and BMD measurements at all skeletal sites, in both boys and girls (all P < .0001). In contrast, length of puberty had no relation to any measures of bone.

CONCLUSIONS

In healthy adolescent males and females, bone mass and bone density at skeletal maturity are inversely related to the timing of puberty.

Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial

BACKGROUND

Previous studies comparing low-carbohydrate and low-fat diets have not included a comprehensive behavioral treatment, resulting in suboptimal weight loss.

OBJECTIVE

To evaluate the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program.

DESIGN

Randomized parallel-group trial. (ClinicalTrials.gov registration number: NCT00143936)

SETTING

3 academic medical centers.

PATIENTS

307 participants with a mean age of 45.5 years (SD, 9.7 years) and mean body mass index of 36.1 kg/m(2) (SD, 3.5 kg/m(2)).

INTERVENTION

A low-carbohydrate diet, which consisted of limited carbohydrate intake (20 g/d for 3 months) in the form of low-glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. A low-fat diet consisted of limited energy intake (1200 to 1800 kcal/d; <or=30% calories from fat). Both diets were combined with comprehensive behavioral treatment.

MEASUREMENTS

Weight at 2 years was the primary outcome. Secondary measures included weight at 3, 6, and 12 months and serum lipid concentrations, blood pressure, urinary ketones, symptoms, bone mineral density, and body composition throughout the study.

RESULTS

Weight loss was approximately 11 kg (11%) at 1 year and 7 kg (7%) at 2 years. There were no differences in weight, body composition, or bone mineral density between the groups at any time point. During the first 6 months, the low-carbohydrate diet group had greater reductions in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels, lesser reductions in low-density lipoprotein cholesterol levels, and more adverse symptoms than did the low-fat diet group. The low-carbohydrate diet group had greater increases in high-density lipoprotein cholesterol levels at all time points, approximating a 23% increase at 2 years.

LIMITATION

Intensive behavioral treatment was provided, patients with dyslipidemia and diabetes were excluded, and attrition at 2 years was high.

CONCLUSION

Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial

BACKGROUND

Previous studies comparing low-carbohydrate and low-fat diets have not included a comprehensive behavioral treatment, resulting in suboptimal weight loss.

OBJECTIVE

To evaluate the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program.

DESIGN

Randomized parallel-group trial. (ClinicalTrials.gov registration number: NCT00143936)

SETTING

3 academic medical centers.

PATIENTS

307 participants with a mean age of 45.5 years (SD, 9.7 years) and mean body mass index of 36.1 kg/m(2) (SD, 3.5 kg/m(2)).

INTERVENTION

A low-carbohydrate diet, which consisted of limited carbohydrate intake (20 g/d for 3 months) in the form of low-glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. A low-fat diet consisted of limited energy intake (1200 to 1800 kcal/d; <or=30% calories from fat). Both diets were combined with comprehensive behavioral treatment.

MEASUREMENTS

Weight at 2 years was the primary outcome. Secondary measures included weight at 3, 6, and 12 months and serum lipid concentrations, blood pressure, urinary ketones, symptoms, bone mineral density, and body composition throughout the study.

RESULTS

Weight loss was approximately 11 kg (11%) at 1 year and 7 kg (7%) at 2 years. There were no differences in weight, body composition, or bone mineral density between the groups at any time point. During the first 6 months, the low-carbohydrate diet group had greater reductions in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels, lesser reductions in low-density lipoprotein cholesterol levels, and more adverse symptoms than did the low-fat diet group. The low-carbohydrate diet group had greater increases in high-density lipoprotein cholesterol levels at all time points, approximating a 23% increase at 2 years.

LIMITATION

Intensive behavioral treatment was provided, patients with dyslipidemia and diabetes were excluded, and attrition at 2 years was high.

CONCLUSION

Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years.

PRIMARY FUNDING SOURCE

National Institutes of Health.

The recognition and treatment of growth disorders - a 50-year retrospective

The past 50 years have seen great progress in the understanding and treatment of classic growth disorders. Advances such as the recognition of hormone receptor defects, the development of recombinant growth hormone, and the expanding awareness of epigenetic phenomena affecting growth are among these great achievements. Yet growth failure remains a pervasive problem among children with complex health conditions, such as survivors of childhood cancers, premature infants, organ transplant recipients, and children with cystic fibrosis. The significant increases in life expectancy among these groups underscores the potential consequences of poor growth, whether due to the underlying conditions or medical treatments, as they may have long-lasting effects into adulthood. The ongoing contributions of human biologists to the study of human growth remain essential in the recognition and treatment of growth disorders, by defining normal patterns of growth and body composition, the interplay of growth and maturation, the role of environmental, behavioral and genetic factors, and the long-term consequences of growth patterns. Examples will be given based on two common genetic disorders, cystic fibrosis and sickle-cell anemia, to highlight the relationships between growth failure, survival, and malnutrition. Also, a study of bone mineral accretion in children with cystic fibrosis will illustrate the importance of understanding patterns of growth in healthy children, and their application in the diagnosis and management of children with chronic disease. These examples accentuate the need for continued participation of human biologists in the study of growth and development and the care of children.

Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.

Impact of depression and its treatment on the bones of growing children

Depression in adults has been linked to reduced bone mineral density (BMD), osteoporosis, and increased incidence of fractures. Physiologic factors, such as hypothalamic-pituitary-adrenal axis dysfunction and increased circulation of inflammatory cytokines, may adversely impact bone metabolism. In addition, behavioral factors, such as reduced physical activity and altered dietary intake (especially of bone-related nutrients such as calcium and vitamin D), may be implicated. Antidepressant medications also may have an impact on BMD. Childhood and adolescence may be times of particular vulnerability to the adverse effects of depression due to the rapid bone mineral accrual that occurs during periods of growth. This article will review potential contributing factors and resulting consequences of depression on BMD in these populations and also explore areas of needed research.

Effect of testosterone replacement on trabecular architecture in hypogonadal men

We evaluated the effect of testosterone treatment on trabecular architecture by microMRI in 10 untreated severely hypogonadal men. After 2 years, microMRI parameters of trabecular connectivity improved significantly, suggesting the possibility that testosterone improves trabecular architecture.

INTRODUCTION

Osteoporosis, characterized by low BMD and diminished bone quality, is a significant public health problem in men. Hypogonadal men have decreased BMD and deteriorated trabecular architecture compared with eugonadal men, and testosterone treatment improves their BMD. We tested the hypothesis that testosterone replacement in hypogonadal men would also improve their trabecular architecture.

MATERIALS AND METHODS

We selected 10 untreated severely hypogonadal men and treated them with a testosterone gel for 24 months to maintain their serum testosterone concentrations within the normal range. Each subject was assessed before and after 6, 12, and 24 months of testosterone treatment by magnetic resonance microimaging (microMRI) of the distal tibia and by DXA of the spine and hip. The microMRI parameters reflect the integrity of the trabecular network and include the ratio of all surface voxels (representing plates) to curve voxels (representing rods) and the topological erosion index, a ratio of topological parameters expected to increase on trabecular deterioration to those expected to decrease. The higher the surface-to-curve ratio and the lower the topological erosion index, the more intact the trabecular network.

RESULTS

Serum testosterone concentrations increased to midnormal after 3 months of treatment and remained normal thereafter. After 24 months of testosterone treatment, BMD of the spine increased 7.4% (p<0.001), and of the total hip increased 3.8% (p=0.008). Architectural parameters assessed by microMRI also changed: the surface-to-curve ratio increased 11% (p=0.004) and the topological erosion index decreased 7.5% (p=0.004).

CONCLUSIONS

These results suggest the possibility that testosterone replacement of hypogonadal men improves trabecular architecture.

The role of stress-induced cortisol in the relationship between depression and decreased bone mineral density

BACKGROUND

This study was designed to test the hypothesis that cortisol mediates the relationship between bone density and depression in postmenopausal women.

METHODS

Nineteen women aged 52-79 who had been assessed for bone mineral density by dual-energy x-ray absorptiometer (DEXA) were evaluated for depression and anxiety. Diurnal and stress-induced measures of salivary cortisol were obtained during the following week and at a laboratory session involving a speech task.

RESULTS

Nine volunteers reported depression while 10 were never depressed. Ever depressed women had significantly lower total lumbar and right femur DEXA Z scores than never depressed (t(17) = 2.5, p = .019 and t(17) = 2.06, p = .05, respectively). Ever depressed women demonstrated a significant increase in salivary cortisol (area under the curve (AUC) = 27.83, SD = 37.64) compared to never depressed women (AUC = -13.34, SD = 19.55) (t(17) = -3.041, p = .007) during a psychological challenge. There were significant inverse relationships between salivary cortisol AUC values and bone density Z scores at every measured bone site. Mediation analyses suggest that 51 - 67% of the association between depression and bone density could be attributed to stress-induced changes in cortisol.

CONCLUSIONS

Cortisol hypersecretion in response to stress may, in part, explain the impact of depression on bone density in post-menopausal women.