Responding to the workforce crisis: consensus recommendations from the Second Workforce Summit of the American Society of Pediatric Nephrology.

IMPORTANCE: Pediatric patients with complex medical problems benefit from pediatric sub-specialty care; however, a significant proportion of children live greater than 80 mi. away from pediatric sub-specialty care. OBJECTIVE: To identify current knowledge gaps and outline concrete next steps to make progress on issues that have persistently challenged the pediatric nephrology workforce. EVIDENCE REVIEW: Workforce Summit 2.0 employed the round table format and methodology for consensus building using adapted Delphi principles. Content domains were identified via input from the ASPN Workforce Committee, the ASPN's 2023 Strategic Plan survey, the ASPN's Pediatric Nephrology Division Directors survey, and ongoing feedback from ASPN members. Working groups met prior to the Summit to conduct an organized literature review and establish key questions to be addressed. The Summit was held in-person in November 2023. During the Summit, work groups presented their preliminary findings, and the at-large group developed the key action statements and future directions. FINDINGS: A holistic appraisal of the effort required to cover inpatient and outpatient sub-specialty care will help define faculty effort and time distribution. Most pediatric nephrologists practice in academic settings, so work beyond clinical care including education, research, advocacy, and administrative/service tasks may form a substantial amount of a faculty member's time and effort. An academic relative value unit (RVU) may assist in creating a more inclusive assessment of their contributions to their academic practice. Pediatric sub-specialties, such as nephrology, contribute to the clinical mission and care of their institutions beyond their direct billable RVUs. Advocacy throughout the field of pediatrics is necessary in order for reimbursement of pediatric sub-specialist care to accurately reflect the time and effort required to address complex care needs. Flexible, individualized training pathways may improve recruitment into sub-specialty fields such as nephrology. CONCLUSIONS AND RELEVANCE: The workforce crisis facing the pediatric nephrology field is echoed throughout many pediatric sub-specialties. Efforts to improve recruitment, retention, and reimbursement are necessary to improve the care delivered to pediatric patients.

Child Health Needs and the Pediatric Endocrinology Workforce: 2020-2040.

The pediatric endocrinology (PE) workforce in the United States is struggling to sustain an adequate, let alone optimal, workforce capacity. This article, one of a series of articles in a supplement to Pediatrics, focuses on the pediatric subspecialty workforce and furthers previous evaluations of the US PE workforce to model the current and future clinical PE workforce and its geographic distribution. The article first discusses the children presenting to PE care teams, reviews the current state of the PE subspecialty workforce, and presents projected headcount and clinical workforce equivalents at the national, census region, and census division level on the basis of a subspecialty workforce supply model through 2040. It concludes by discussing the educational and training, clinical practice, policy, and future workforce research implications of the data presented. Data presented in this article are available from the American Board of Pediatrics, the National Resident Matching Program, and the subspecialty workforce supply model. Aging, part-time appointments, and unbalanced geographic distribution of providers diminish the PE workforce capacity. In addition, limited exposure, financial concerns, and lifestyle perceptions may impact trainees. Additional workforce challenges are the subspecialty's increasingly complex cases and breadth of conditions treated, reliance on international medical graduates to fill fellowship slots, and high relative proportion of research careers. The recent limitations on pediatric endocrinologists providing gender-affirming care may also impact the geographic distribution of the subspecialty's workforce. Deliberate actions need to be taken now to continue serving the needs of children.

Child Health and the US Pediatric Subspecialty Workforce: Planning for the Future.

This article opens a multi-article Pediatrics supplement that provides a rigorous analysis of the projected pediatric subspecialty workforce in the United States. Congenital variations, epigenetics, exposures, lifestyle, preventive care, and medical interventions from conception through young adulthood set the stage for health and wellbeing in adulthood. Although care provided by pediatric subspecialists is associated with better outcomes and lower costs compared with adult providers, the authors of recent articles in the lay and medical literature have questioned the capacity of pediatric subspecialists to meet children's health care needs. This article highlights that, despite numerous advances in prevention, diagnosis, and treatment, the last decade has witnessed increasing numbers of children with acute or chronic physical and mental health disorders, including medical complexity, obesity, type 2 diabetes, anxiety, depression, and suicidality, all of which are exacerbated by poverty, racism, and other social drivers of health. In this article, we then describe the variability in the demographics, practice characteristics, and geographic distribution of the 15 core pediatric subspecialties certified by the American Board of Pediatrics. We then discuss the rationale and approach to the development of a pediatric subspecialty workforce model that forecasts subspecialist supply from 2020 to 2040 for 14 subspecialties at the national and subnational levels (not including the newest subspecialty, pediatric hospital medicine), accounting for US Census Bureau child population projections. The model does not account for the unique physical and mental needs of individual children, nor does it address the increasingly precarious commitment to, and financing of, pediatric subspecialty care in the US health care system impacting market demand.

Child Health Needs and the Pediatric Nephrology Subspecialty Workforce: 2020-2040.

Pediatric nephrology is dedicated to caring for children with kidney disease, a unique blend of acute care and chronic longitudinal patient relationships. Though historically a small field, trainee interest has declined over the past 2 decades. This has led to growing alarm about the health of the pediatric nephrology workforce, although concerns have been hampered by a lack of available data to enable feasible projections. This article is part of a supplement that anticipates the future pediatric subspecialty workforce supply. It draws on existing literature, data from the American Board of Pediatrics, and findings from a model that estimates the future supply of pediatric subspecialists developed by the Carolina Health Workforce Research Center at the University of North Carolina Chapel Hill's Cecil G. Sheps Center for Health Services Research and Strategic Modeling Analytics & Planning Ltd. The workforce projections from 2020 to 2040 incorporate population growth, clinical effort, and geographic trends and model alternate scenarios adjusting for changes in trainee interest, clinical efforts, and workforce attrition. The baseline model predicts growth of clinical work equivalents by 26% by 2040, but further widening geographic disparities worsen the existing mismatch between supply, clinical need, and market demand. The worst-case scenario projects 13% growth by 2040 which, at best, maintains the status quo of an already strained workforce. The models do not account for many factors expected to heighten demand over the coming decades. Urgent reforms are necessary now. Proposed solutions require multipronged changes in education and training pathways, remuneration, clinical practice models, and government policy.

Child Health Needs and the Pediatric Rheumatology Workforce: 2020-2040.

The Pediatric Rheumatology (PRH) workforce supply in the United States does not meet the needs of children. Lack of timely access to PRH care is associated with poor outcomes for children with rheumatic diseases. This article is part of a Pediatrics supplement focused on anticipating the future pediatric subspecialty workforce supply. It draws on information in the literature, American Board of Pediatrics data, and findings from a model that estimates the future supply of pediatric subspecialists developed by the Sheps Center for Health Services Research at the University of North Carolina at Chapel Hill, Strategic Modeling and Analysis Ltd., and the American Board of Pediatrics Foundation. PRH has a smaller workforce per capita of children than most other pediatric subspecialties. The model demonstrates that the clinical workforce equivalent of pediatric rheumatologists in 2020 was only 0.27 per 100 000 children, with a predicted increase to 0.47 by 2040. Although the model predicts a 72% increase in providers, this number remains inadequate to provide sufficient care given the number of children with rheumatic diseases, especially in the South and West regions. The likely reasons for the workforce shortage are multifactorial, including lack of awareness of the field, low salaries compared with most other medical specialties, concerns about working solo or in small group practices, and increasing provider retirement. Novel interventions are needed to increase the workforce size. The American College of Rheumatology has recognized the dire consequences of this shortage and has developed a workforce solutions initiative to tackle these problems.

Projecting the Future Pediatric Subspecialty Workforce: Summary and Recommendations.

This article summarizes the findings of a Pediatrics supplement addressing the United States workforce for 15 pediatric subspecialties. It includes results from a microsimulation model projecting supply through 2040; growth is forecasted to be uneven across the subspecialties with worsening geographic maldistribution. Although each subspecialty has unique characteristics, commonalities include (1) the changing demographics and healthcare needs of children, including mental health; (2) poor outcomes for children experiencing adverse social drivers of health, including racism; and (3) dependence on other subspecialties. Common healthcare delivery challenges include (1) physician shortages for some subspecialties; (2) misalignment between locations of training programs and subspecialists and areas of projected child population growth; (3) tension between increasing subsubspecialization to address rare diseases and general subspecialty care; (4) the need to expand clinical reach through collaboration with other physicians and advanced practice providers; (5) the lack of parity between Medicare, which funds much of adult care, and Medicaid, which funds over half of pediatric subspecialty care; and (6) low compensation of pediatric subspecialists compared with adult subspecialists. Overall, subspecialists identified the lack of a central authority to monitor and inform child healthcare provided by pediatric subspecialists as a challenge. Future research on the pediatric subspecialty workforce and the children it serves will be necessary to ensure these children's needs are met. Together, these articles provide overarching and subspecialty-specific recommendations to improve training, recruitment, and retention of a diverse workforce, implement innovative models of care, drive policy changes, and advise future research.

Association of Fibroblast Growth Factor 23 with Blood Pressure in Primary Proteinuric Glomerulopathies.

INTRODUCTION: Fibroblast growth factor 23 (FGF23) has direct effects on the vasculature and myocardium, and high levels of FGF23 are a risk factor for cardiovascular disease (CVD); however, the impact of FGF23 on CVD in primary proteinuric glomerulopathies has not been addressed. METHODS: The associations of baseline plasma intact FGF23 levels with resting blood pressure (BP) and lipids over time among adults and children with proteinuric glomerulopathies enrolled in the Nephrotic Syndrome Study Network (NEPTUNE) were analyzed using generalized estimating equation regression analyses. Models were adjusted for age, sex, glomerular diagnosis, follow-up time, estimated glomerular filtration rate, urine protein/creatinine ratio, obesity, and serum phosphorous levels. RESULTS: Two hundred and four adults with median FGF23 77.5 (IQR 51.3-119.3) pg/mL and 93 children with median FGF23 62.3 (IQR 44.6-83.6) pg/mL were followed for a median of 42 (IQR 20.5-54) months. In adjusted models, each 1 µg/mL increase in FGF23 was associated with a 0.3 increase in systolic BP index at follow-up (p < 0.001). Greater baseline FGF23 was associated with greater odds of hypertensive BP (OR = 1.0003; 95% CI 1.001-1.006, p = 0.03) over time. Compared to tertile 1, tertile 2 (OR = 2.1; 95% CI 1.12-3.99, p = 0.02), and tertile 3 (OR = 3; 95% CI 1.08-8.08, p = 0.04), FGF23 levels were associated with greater odds of hypertensive BP over time. Tertile 2 was associated with greater triglycerides compared to tertile 1 (OR = 48.1; 95% CI 4.4-91.9, p = 0.03). CONCLUSION: Overall, higher baseline FGF23 was significantly associated with hypertensive BP over time in individuals with proteinuric glomerulopathies. Further study of FGF23 as a therapeutic target for reducing CVD in proteinuric glomerular disease is warranted.

Derivation of paediatric blood pressure percentiles from electronic health records.

BACKGROUND: Identification of abnormal blood pressure (BP) in children requires normative data. We sought to examine the feasibility of using "real-world" office BP data obtained from electronic health records (EHR) to generate age-, sex- and height-specific BP percentiles for children. METHODS: Using data collected 01/01/2009-8/31/2021 from eight large children's healthcare organisations in PEDSnet, we applied a mixed-effects polynomial regression model with random slopes to generate Z-scores and BP percentiles and compared them with currently used normative BP distributions published in the 2017 American Academy of Paediatrics (AAP) Clinical Practise Guidelines (CPG). FINDINGS: We identified a study sample of 292,412 children (1,085,083 BP measurements), ages 3-17 years (53% female), with no chronic medical conditions, who were not overweight/obese and who were primarily seen for general paediatric care in outpatient settings. Approximately 45,000-75,000 children contributed data to each age category. The PEDSnet systolic BP percentile values were 1-4 mmHg higher than AAP CPG BP values across age-sex-height groups, with larger differences observed in younger children. Diastolic BP values were also higher in younger children; starting with age 7 years, diastolic BP percentile values were 1-3 mmHg lower than AAP CPG values. Cohen's Kappa was 0.90 for systolic BP, 0.66 for diastolic BP, and 0.80 overall indicating excellent agreement between PEDSnet and 2017 AAP CPG data for systolic BP and substantial agreement for diastolic BP. INTERPRETATION: Our analysis indicates that real-word EHR data can be used to generate BP percentiles consistent with current clinical practise on BP management in children. FUNDING: Funding for this work was provided by the Preserving Kidney Function in Children with Chronic Kidney Disease (PRESERVE) study; Patient-Centred Outcomes Research Institute (PCORI) RD-2020C2020338 (Principal Investigator: Dr. Forrest; Co-Principal Investigator: Dr. Denburg).

Vitamin D Metabolites and Risk of Cardiovascular Disease in Chronic Kidney Disease: The CRIC Study.

Background The ratio of 24,25-dihydroxyvitamin D3/25-hydroxyvitamin D3 (vitamin D metabolite ratio [VDMR]) may reflect functional vitamin D activity. We examined associations of the VDMR, 25-hydroxyvitamin D (25[OH]D), and 1,25-dihydroxyvitamin D (1,25[OH]2D) with cardiovascular disease (CVD) in patients with chronic kidney disease. Methods and Results This study included longitudinal and cross-sectional analyses of 1786 participants from the CRIC (Chronic Renal Insufficiency Cohort) Study. Serum 24,25-dihydroxyvitamin D3, 25(OH)D, and 1,25(OH)2D were measured by liquid chromatography-tandem mass spectrometry 1 year after enrollment. The primary outcome was composite CVD (heart failure, myocardial infarction, stroke, and peripheral arterial disease). We used Cox regression with regression-calibrated weights to test associations of the VDMR, 25(OH)D, and 1,25(OH)2D with incident CVD. We examined cross-sectional associations of these metabolites with left ventricular mass index using linear regression. Analytic models adjusted for demographics, comorbidity, medications, estimated glomerular filtration rate, and proteinuria. The cohort was 42% non-Hispanic White race and ethnicity, 42% non-Hispanic Black race and ethnicity, and 12% Hispanic ethnicity. Mean age was 59 years, and 43% were women. Among 1066 participants without prevalent CVD, there were 298 composite first CVD events over a mean follow-up of 8.6 years. Lower VDMR and 1,25(OH)2D were associated with incident CVD before, but not after, adjustment for estimated glomerular filtration rate and proteinuria (hazard ratio, 1.11 per 1 SD lower VDMR [95% CI, 0.95-1.31]). Only 25(OH)D was associated with left ventricular mass index after full covariate adjustment (0.6 g/m2.7 per 10 ng/mL lower [95% CI, 0.0-1.3]). Conclusions Despite modest associations of 25(OH)D with left ventricular mass index, 25(OH)D, the VDMR, and 1,25(OH)2D were not associated with incident CVD in chronic kidney disease.

Strength training is more effective than aerobic exercise for improving glycaemic control and body composition in people with normal-weight type 2 diabetes: a randomised controlled trial.

AIMS/HYPOTHESIS: Type 2 diabetes in people in the healthy weight BMI category (<25 kg/m2), herein defined as 'normal-weight type 2 diabetes', is associated with sarcopenia (low muscle mass). Given this unique body composition, the optimal exercise regimen for this population is unknown. METHODS: We conducted a parallel-group RCT in individuals with type 2 diabetes (age 18-80 years, HbA1c 47.5-118.56 mmol/mol [6.5-13.0%]) and BMI <25 kg/m2). Participants were recruited in outpatient clinics or through advertisements and randomly assigned to a 9 month exercise programme of strength training alone (ST), aerobic training alone (AER) or both interventions combined (COMB). We used stratified block randomisation with a randomly selected block size. Researchers and caregivers were blinded to participants' treatment group; however, participants themselves were not. Exercise interventions were conducted at community-based fitness centres. The primary outcome was absolute change in HbA1c level within and across the three groups at 3, 6 and 9 months. Secondary outcomes included changes in body composition at 9 months. Per adherence to recommended exercise protocol (PP) analysis included participants who completed at least 50% of the sessions. RESULTS: Among 186 individuals (ST, n=63; AER, n=58; COMB, n=65) analysed, the median (IQR) age was 59 (53-66) years, 60% were men and 83% were Asian. The mean (SD) HbA1c level at baseline was 59.6 (13.1) mmol/mol (7.6% [1.2%]). In intention-to-treat analysis, the ST group showed a significant decrease in HbA1c levels (mean [95% CI] -0.44 percentage points [-0.78, -0.12], p=0.002), while no significant change was observed in either the COMB group (-0.35 percentage points, p=0.13) or the AER group (-0.24 percentage points, p=0.10). The ST group had a greater improvement in HbA1c levels than the AER group (p=0.01). Appendicular lean mass relative to fat mass increased only in the ST group (p=0.0008), which was an independent predictor of HbA1c change (beta coefficient -7.16, p=0.01). Similar results were observed in PP analysis. Only one adverse event, in the COMB group, was considered to be possibly associated with the exercise intervention. CONCLUSIONS/INTERPRETATION: In normal-weight type 2 diabetes, strength training was superior to aerobic training alone, while no significant difference was observed between strength training and combination training for HbA1c reduction. Increased lean mass relative to decreased fat mass was an independent predictor of reduction in HbA1c level. TRIAL REGISTRATION: ClinicalTrials.gov NCT02448498. FUNDING: This study was funded by the National Institutes of Health (NIH; R01DK081371).

Bone Mineral Density and Vascular Calcification in Children and Young Adults With CKD 4 to 5 or on Dialysis.

Introduction: Older adults with chronic kidney disease (CKD) can have low bone mineral density (BMD) with concurrent vascular calcification. Mineral accrual by the growing skeleton may protect young people with CKD from extraosseous calcification. Our hypothesis was that children and young adults with increasing BMD do not develop vascular calcification. Methods: This was a multicenter longitudinal study in children and young people (5-30 years) with CKD stages 4 to 5 or on dialysis. BMD was assessed by tibial peripheral quantitative computed tomography (pQCT) and lumbar spine dual-energy X-ray absorptiometry (DXA). The following cardiovascular imaging tests were undertaken: cardiac computed tomography for coronary artery calcification (CAC), ultrasound for carotid intima media thickness z-score (cIMTz), pulse wave velocity z-score (PWVz), and carotid distensibility for arterial stiffness. All measures are presented as age-adjusted and sex-adjusted z-scores. Results: One hundred participants (median age 13.82 years) were assessed at baseline and 57 followed up after a median of 1.45 years. Trabecular BMD z-score (TrabBMDz) decreased (P = 0.01), and there was a nonsignificant decrease in cortical BMD z-score (CortBMDz) (P = 0.09). Median cIMTz and PWVz showed nonsignificant increase (P = 0.23 and P = 0.19, respectively). The annualized increase in TrabBMDz (ΔTrabBMDz) was an independent predictor of cIMTz increase (R 2 = 0.48, ß = 0.40, P = 0.03). Young people who demonstrated statural growth (n = 33) had lower ΔTrabBMDz and also attenuated vascular changes compared with those with static growth (n = 24). Conclusion: This hypothesis-generating study suggests that children and young adults with CKD or on dialysis may develop vascular calcification even as their BMD increases. A presumed buffering capacity of the growing skeleton may offer some protection against extraosseous calcification.

Cystatin C and Creatinine Concentrations Are Uninformative Biomarkers of Sarcopenia: A Cross-Sectional NHANES Study.

OBJECTIVES: Differences in creatinine and cystatin C-based estimates of glomerular filtration rate (eGFRDiff = eGFRCr - eGFRCysC) may reflect differences in muscle mass. We sought to determine if eGFRDiff (1) reflects lean mass, (2) identifies sarcopenic individuals beyond estimates based on age, body mass index (BMI), and sex; and (3) demonstrates associations differently in those with and without chronic kidney disease (CKD). DESIGN AND METHODS: This cross-sectional study included 3,754 participants, ages 20-85 years, with creatinine and cystatin C concentration levels, and dual-energy X-ray absorptiometry scans from National Health and Nutrition Examination Survey data (1999-2006). Dual-energy X-ray absorptiometry-derived appendicular lean mass index (ALMI) estimated muscle mass. Non-race-based CKD Epidemiology Collaboration equations estimated glomerular filtration rate using eGFRCr, eGFRCysC, and both biomarkers (eGFRCysC&Cr). CKD was defined as eGFRCysC&Cr <60 mL/minute/1.73 m2. ALMI sex-specific T-scores (compared with young adult) < -2.0 defined sarcopenia. In estimating ALMI, we compared the coefficient of determination (R2) values from: 1) eGFRDiff, 2) clinical characteristics (age, BMI, and sex), and 3) clinical characteristics plus eGFRDiff. Using logistic regression, we evaluated each model's C-statistic to diagnose sarcopenia. RESULTS: eGFRDiff was negatively and weakly associated with ALMI (No CKD: R2 = 0.006, p-value 0.002; CKD: R2 = 0.001, P value .9). Clinical characteristics explained most of the variation in ALMI (No CKD: R2 = 0.851, CKD: R2 = 0.828), and provided strong discrimination of sarcopenia (No CKD C-statistic: 0.950; CKD C-statistic: 0.943). Adding eGFRDiff improved the R2 by 0.025, and the C-statistic by 0.003. Tests for interaction between eGFRDiff and CKD were not significant (all P values > .05). CONCLUSIONS: Although eGFRDiff has statistically significant associations with ALMI and sarcopenia in univariate analyses, multivariate analyses demonstrate that eGFRDiff does not capture more information beyond routine clinical characteristics (age, BMI, and sex).

Design and rationale of re-energize fontan: Randomized exercise intervention designed to maximize fitness in fontan patients.

In this manuscript, we describe the design and rationale of a randomized controlled trial in pediatric Fontan patients to test the hypothesis that a live-video-supervised exercise (aerobic+resistance) intervention will improve cardiac and physical capacity; muscle mass, strength, and function; and endothelial function. Survival of children with single ventricles beyond the neonatal period has increased dramatically with the staged Fontan palliation. Yet, long-term morbidity remains high. By age 40, 50% of Fontan patients will have died or undergone heart transplantation. Factors that contribute to onset and progression of heart failure in Fontan patients remain incompletely understood. However, it is established that Fontan patients have poor exercise capacity which is associated with a greater risk of morbidity and mortality. Furthermore, decreased muscle mass, abnormal muscle function, and endothelial dysfunction in this patient population is known to contribute to disease progression. In adult patients with 2 ventricles and heart failure, reduced exercise capacity, muscle mass, and muscle strength are powerful predictors of poor outcomes, and exercise interventions can not only improve exercise capacity and muscle mass, but also reverse endothelial dysfunction. Despite these known benefits of exercise, pediatric Fontan patients do not exercise routinely due to their chronic condition, perceived restrictions to exercise, and parental overprotection. Limited exercise interventions in children with congenital heart disease have demonstrated that exercise is safe and effective; however, these studies have been conducted in small, heterogeneous groups, and most had few Fontan patients. Critically, adherence is a major limitation in pediatric exercise interventions delivered on-site, with adherence rates as low as 10%, due to distance from site, transportation difficulties, and missed school or workdays. To overcome these challenges, we utilize live-video conferencing to deliver the supervised exercise sessions. Our multidisciplinary team of experts will assess the effectiveness of a live-video-supervised exercise intervention, rigorously designed to maximize adherence, and improve key and novel measures of health in pediatric Fontan patients associated with poor long-term outcomes. Our ultimate goal is the translation of this model to clinical application as an "exercise prescription" to intervene early in pediatric Fontan patients and decrease long-term morbidity and mortality.

Trabecular Bone Score (TBS) Varies with Correction for Tissue Thickness Versus Body Mass Index: Implications When Using Pediatric Reference Norms.

Trabecular bone score (TBS) derived from secondary analysis of lumbar spine dual-energy X-ray absorptiometry (DXA) scans improves fracture prediction independent of bone mineral density (BMD) in adults. The utility of TBS to assess fracture risk in younger patients has not been established because pediatric norms have been lacking. Robust TBS reference data from the Bone Mineral Density in Childhood Study (BMDCS) have been published. TBS values for the BMDCS study were derived using an algorithm that accounts for tissue thickness (TBSTH ) rather than the commercially available algorithm that adjusts for body mass index (BMI; TBSBMI ). We examined the magnitude of differences in TBSTH and TBSBMI in a cohort of 189 healthy youth. TBS values using both algorithms increased with age and pubertal development in a similar pattern. However, TBSBMI values were systematically and significantly higher than TBSTH (mean = 0.06, p < 0.0001). The difference between calculated TBSBMI and TBSTH was not uniform. Differences were greater at lower TBS values, in males, in older individuals, in those at later Tanner stages, and in those with a greater BMI Z-score. These systematic differences preclude the development of a simple formula to allow conversion of TBSBMI to TBSTH "equivalents." Because of these systematic differences in these two algorithms, using an individual's TBSBMI to calculate a Z-score using the BMDCS TBSTH reference values results in a falsely higher TBS Z-score (differences mean = 0.73, interquartile range [IQR] = 0.3 to 1.6). Until TBSTH software for Hologic DXA equipment becomes commercially available, BMDCS TBS reference norms should not be used. © 2023 American Society for Bone and Mineral Research (ASBMR).

Challenging obesity and sex based differences in resting energy expenditure using allometric modeling, a sub-study of the DIETFITS clinical trial.

BACKGROUND & AIMS: Resting energy expenditure (REE) is a major component of energy balance. While REE is usually indexed to total body weight (BW), this may introduce biases when assessing REE in obesity or during weight loss intervention. The main objective of the study was to quantify the bias introduced by ratiometric scaling of REE using BW both at baseline and following weight loss intervention. DESIGN: Participants in the DIETFITS Study (Diet Intervention Examining The Factors Interacting with Treatment Success) who completed indirect calorimetry and dual-energy X-ray absorptiometry (DXA) were included in the study. Data were available in 438 participants at baseline, 340 at 6 months and 323 at 12 months. We used multiplicative allometric modeling based on lean body mass (LBM) and fat mass (FM) to derive body size independent scaling of REE. Longitudinal changes in indexed REE were then assessed following weight loss intervention. RESULTS: A multiplicative model including LBM, FM, age, Black race and the double product (DP) of systolic blood pressure and heart rate explained 79% of variance in REE. REE indexed to [LBM0.66 × FM0.066] was body size and sex independent (p = 0.91 and p = 0.73, respectively) in contrast to BW based indexing which showed a significant inverse relationship to BW (r = -0.47 for female and r = -0.44 for male, both p < 0.001). When indexed to BW, significant baseline differences in REE were observed between male and female (p < 0.001) and between individuals who are overweight and obese (p < 0.001) while no significant differences were observed when indexed to REE/[LBM0.66 × FM0.066], p > 0.05). Percentage predicted REE adjusted for LBM, FM and DP remained stable following weight loss intervention (p = 0.614). CONCLUSION: Allometric scaling of REE based on LBM and FM removes body composition-associated biases and should be considered in obesity and weight-based intervention studies.

Vitamin D supplementation in children and young adults with persistent proteinuria secondary to glomerular disease.

BACKGROUND: Vitamin D deficiency is common in glomerular disease. Supplementation may be ineffective due to ongoing urinary losses of vitamin D binding protein. We sought to determine if daily cholecalciferol supplementation would increase vitamin D concentrations in children with glomerular disease and persistent proteinuria, without adverse effects. METHODS: Eighteen participants at least 5 years of age with primary glomerular disease and urine protein:creatinine ratio ≥ 0.5 were enrolled from four pediatric nephrology practices to receive cholecalciferol supplementation: 4,000 IU or 2,000 IU per day for serum 25 hydroxyvitamin vitamin D (25OHD) concentrations < 20 ng/mL and 20 ng/mL to < 30 ng/mL, respectively. Measures of vitamin D and mineral metabolism were obtained at baseline and weeks 6 and 12. Multivariable generalized estimating equation (GEE) regression estimated mean percent changes in serum 25OHD concentration. RESULTS: Median baseline 25OHD was 12.8 ng/mL (IQR 9.3, 18.9) and increased to 27.8 ng/mL (20.5, 36.0) at week 6 (p < 0.001) without further significant increase at week 12. A total of 31% of participants had a level ≥ 30 ng/mL at week 12. Supplementation was stopped in two participants at week 6 for mildly elevated calcium and phosphorus, respectively, with subsequent declines in 25OHD of > 20 ng/mL. In the adjusted GEE model, 25OHD was 102% (95% CI: 64, 141) and 96% (95% CI: 51, 140) higher versus baseline at weeks 6 and 12, respectively (p < 0.001). CONCLUSION: Cholecalciferol supplementation in vitamin D deficient children with glomerular disease and persistent proteinuria safely increases 25OHD concentration. Ideal dosing to fully replete 25OHD concentrations in this population remains unknown. CLINICAL TRIAL: NCT01835639. A higher resolution version of the Graphical abstract is available as Supplementary information.