Gut Microbiome Wellness Index 2 enhances health status prediction from gut microbiome taxonomic profiles.

Recent advancements in translational gut microbiome research have revealed its crucial role in shaping predictive healthcare applications. Herein, we introduce the Gut Microbiome Wellness Index 2 (GMWI2), an enhanced version of our original GMWI prototype, designed as a standardized disease-agnostic health status indicator based on gut microbiome taxonomic profiles. Our analysis involves pooling existing 8069 stool shotgun metagenomes from 54 published studies across a global demographic landscape (spanning 26 countries and six continents) to identify gut taxonomic signals linked to disease presence or absence. GMWI2 achieves a cross-validation balanced accuracy of 80% in distinguishing healthy (no disease) from non-healthy (diseased) individuals and surpasses 90% accuracy for samples with higher confidence (i.e., outside the "reject option"). This performance exceeds that of the original GMWI model and traditional species-level α-diversity indices, indicating a more robust gut microbiome signature for differentiating between healthy and non-healthy phenotypes across multiple diseases. When assessed through inter-study validation and external validation cohorts, GMWI2 maintains an average accuracy of nearly 75%. Furthermore, by reevaluating previously published datasets, GMWI2 offers new insights into the effects of diet, antibiotic exposure, and fecal microbiota transplantation on gut health. Available as an open-source command-line tool, GMWI2 represents a timely, pivotal resource for evaluating health using an individual's unique gut microbial composition.

Limited Sampling Strategies Fail to Accurately Predict Mycophenolic Acid Area Under the Curve in Kidney Transplant Recipients and the Impact of Enterohepatic Recirculation.

BACKGROUND: Therapeutic drug monitoring for mycophenolic acid (MPA) is challenging due to difficulties in measuring the area under the curve (AUC). Limited sampling strategies (LSSs) have been developed for MPA therapeutic drug monitoring but come with risk of unacceptable performance. The authors hypothesized that the poor predictive performance of LSSs were due to the variability in MPA enterohepatic recirculation (EHR). This study is the first to evaluate LSSs models performance in the context of EHR. METHODS: Adult kidney transplant recipients (n = 84) receiving oral mycophenolate mofetil underwent intensive MPA pharmacokinetic sampling. MPA AUC0-12hr and EHR were determined. Published MPA LSSs in kidney transplant recipients receiving tacrolimus were evaluated for their predictive performance in estimating AUC0-12hr in our full cohort and separately in individuals with high and low EHR. RESULTS: None of the evaluated LSS models (n = 12) showed good precision or accuracy in predicting MPA AUC0-12hr in the full cohort. In the high EHR group, models with late timepoints had better accuracy but low precision, except for 1 model with late timepoints at 6 and 10 hours postdose, which had marginally acceptable precision. For all models, the good guess of predicted AUC0-12hr (±15% of observed AUC0-12hr) was highly variable (range, full cohort = 19%-61.9%; high EHR = 4.5%-65.9%; low EHR = 27.5%-62.5%). CONCLUSIONS: The predictive performance of the LSS models varied according to EHR status. Timepoints ≥5 hours postdose in LSS models are essential to capture EHR. Models and strategies that incorporate EHR during development are required to accurately ascertain MPA exposure.

A Short-Term Enteral Nutrition Protocol for Management of Adult Crohn's Disease-A Pilot Trial.

Crohn's disease (CD) is often treated with either exclusive or supplemental enteral nutrition (EN) in pediatrics, but adult practice guidelines primarily focus on medications. Here, we demonstrate the feasibility of a 4-week semi-elemental-formula-based oral nutrition delivery program for managing adult CD (n = 4). Patients consumed ~66% of calories from the formula, a finding that might provide an improved calorie target for future trials. We identified Flavinofractor as the only differentially abundant genus, distinguishing post-intervention samples from pre-intervention samples. Findings from this pilot trial demonstrate the feasibility of a partial enteral nutrition protocol in adult CD management and contribute to the growing body of literature on the potential role of EN therapy in adults with CD.

Pharmacomicrobiomics: Immunosuppressive Drugs and Microbiome Interactions in Transplantation.

The human microbiome is associated with human health and disease. Exogenous compounds, including pharmaceutical products, are also known to be affected by the microbiome, and this discovery has led to the field of pharmacomicobiomics. The microbiome can also alter drug pharmacokinetics and pharmacodynamics, possibly resulting in side effects, toxicities, and unanticipated disease response. Microbiome-mediated effects are referred to as drug-microbiome interactions (DMI). Rapid advances in the field of pharmacomicrobiomics have been driven by the availability of efficient bacterial genome sequencing methods and new computational and bioinformatics tools. The success of fecal microbiota transplantation for recurrent Clostridioides difficile has fueled enthusiasm and research in the field. This review focuses on the pharmacomicrobiome in transplantation. Alterations in the microbiome in transplant recipients are well documented, largely because of prophylactic antibiotic use, and the potential for DMI is high. There is evidence that the gut microbiome may alter the pharmacokinetic disposition of tacrolimus and result in microbiome-specific tacrolimus metabolites. The gut microbiome also impacts the enterohepatic recirculation of mycophenolate, resulting in substantial changes in pharmacokinetic disposition and systemic exposure. The mechanisms of these DMI and the specific bacteria or communities of bacteria are under investigation. There are little or no human DMI data for cyclosporine A, corticosteroids, and sirolimus. The available evidence in transplantation is limited and driven by small studies of heterogeneous designs. Larger clinical studies are needed, but the potential for future clinical application of the pharmacomicrobiome in avoiding poor outcomes is high.

Validation of the Minnesota Pectoralis Risk Score to predict mortality in the HeartMate 3 population.

BACKGROUND: The Minnesota Pectoralis Risk Score (MPRS) utilizes computed tomography-quantified thoracic muscle and clinical variables to predict survival after left ventricular assist device (LVAD) implantation. The model has not been prospectively tested in HeartMate 3 recipients. METHODS: A single-center HeartMate 3 cohort from July 2016 to July 2021 (n = 108) was utilized for this analysis. Cohort subjects with complete covariates for MPRS calculation (pectoralis muscle measures, Black race, creatinine, total bilirubin, body mass index, bridge to transplant status, and presence/absence of contrast) implanted after MPRS development were included. MPRS were calculated on each subject. Receiver operating characteristic curves were generated to test model discrimination at 30-day, 90-day, and 1-year mortality post-LVAD. Next, the performance of the 1-year post-LVAD outcome was compared to the HeartMate 3 survival risk score (HM3RS). RESULTS: The mean age was 58 (15 years), 80% (86/108) were male, and 26% (28/108) were destination therapy. The area under the curve (AUC) for the MPRS model to predict post-LVAD mortality was 0.73 at 30 days, 0.78 at 90 days, and 0.81 at 1 year. The AUC for the HM3RS for the 1-year outcome was 0.693. Each 1-unit point of the MPRS was associated with a significant increase in the hazard rate of death after LVAD (hazard ratio 2.1, 95% confidence interval 1.5-3.0, p < 0.0001). CONCLUSIONS: The MPRS had high performance in this prospective validation, particularly with respect to 90-day and 1-year post-LVAD mortality. Such a tool can provide additional information regarding risk stratification to aid informed decision-making.

Gut Microbiome Wellness Index 2 for Enhanced Health Status Prediction from Gut Microbiome Taxonomic Profiles.

Recent advancements in human gut microbiome research have revealed its crucial role in shaping innovative predictive healthcare applications. We introduce Gut Microbiome Wellness Index 2 (GMWI2), an advanced iteration of our original GMWI prototype, designed as a robust, disease-agnostic health status indicator based on gut microbiome taxonomic profiles. Our analysis involved pooling existing 8069 stool shotgun metagenome data across a global demographic landscape to effectively capture biological signals linking gut taxonomies to health. GMWI2 achieves a cross-validation balanced accuracy of 80% in distinguishing healthy (no disease) from non-healthy (diseased) individuals and surpasses 90% accuracy for samples with higher confidence (i.e., outside the "reject option"). The enhanced classification accuracy of GMWI2 outperforms both the original GMWI model and traditional species-level α-diversity indices, suggesting a more reliable tool for differentiating between healthy and non-healthy phenotypes using gut microbiome data. Furthermore, by reevaluating and reinterpreting previously published data, GMWI2 provides fresh insights into the established understanding of how diet, antibiotic exposure, and fecal microbiota transplantation influence gut health. Looking ahead, GMWI2 represents a timely pivotal tool for evaluating health based on an individual's unique gut microbial composition, paving the way for the early screening of adverse gut health shifts. GMWI2 is offered as an open-source command-line tool, ensuring it is both accessible to and adaptable for researchers interested in the translational applications of human gut microbiome science.

CT-derived psoas muscle area and density are associated with length of stay and discharge disposition after liver transplantation.

BACKGROUND & AIMS: Prolonged length of stay (LOS) and discharge disposition following liver transplantation are associated with postoperative complications and increased healthcare utilization. This study evaluated the relationship between CT-derived psoas muscle measurements and hospital LOS, intensive care unit (ICU) LOS, and discharge disposition after liver transplant. The psoas muscle was chosen given its ease of measurement with any radiological software. A secondary analysis assessed the relationship between the American Society for Parenteral and Enteral Nutrition and the Academy of Nutrition and Dietetics (ASPEN/AND) malnutrition diagnosis criteria and CT-derived psoas muscle measures. METHODS: CT-derived measures of psoas muscle density (mHU) and cross-sectional area at the level of the third lumbar vertebrae were obtained from preoperative CT scans of liver transplant recipients. Cross-sectional area measures were corrected for body size to generate a psoas area index variable (cm2/m2; PAI). RESULTS: Each 1-unit increase in PAI was associated with a reduced hospital LOS of 4 days (R2 = 0.07). Each 5-unit increase in mean Hounsfield units (mHU) was associated with a reduced hospital and ICU LOS of 5 and 1.6 days, respectively (R2 = 0.22 and 0.14, respectively). Mean PAI and mHU were higher in patients who discharged to home. PAI was reasonably identified through ASPEN/AND malnutrition criteria, but there was no difference in mHU between those with and without malnutrition. CONCLUSION: Measures of psoas density were associated with both hospital and ICU LOS and discharge disposition. PAI was associated with hospital LOS and discharge disposition. CT-derived measures of psoas density may be a valuable complement to preoperative liver transplant nutrition assessment using traditional ASPEN/AND malnutrition criteria.

Pulmonary Arterial Hypertension Patients Have a Proinflammatory Gut Microbiome and Altered Circulating Microbial Metabolites.

Rationale: Inflammation drives pulmonary arterial hypertension (PAH). Gut dysbiosis causes immune dysregulation and systemic inflammation by altering circulating microbial metabolites; however, little is known about gut dysbiosis and microbial metabolites in PAH. Objectives: To characterize the gut microbiome and microbial metabolites in patients with PAH. Methods: We performed 16S ribosomal RNA gene and shotgun metagenomics sequencing on stool from patients with PAH, family control subjects, and healthy control subjects. We measured markers of inflammation, gut permeability, and microbial metabolites in plasma from patients with PAH, family control subjects, and healthy control subjects. Measurements and Main Results: The gut microbiome was less diverse in patients with PAH. Shannon diversity index correlated with measures of pulmonary vascular disease but not with right ventricular function. Patients with PAH had a distinct gut microbial signature at the phylogenetic level, with fewer copies of gut microbial genes that produce antiinflammatory short-chain fatty acids (SCFAs) and secondary bile acids and lower relative abundances of species encoding these genes. Consistent with the gut microbial changes, patients with PAH had relatively lower plasma concentrations of SCFAs and secondary bile acids. Patients with PAH also had enrichment of species with the microbial genes that encoded the proinflammatory microbial metabolite trimethylamine. The changes in the gut microbiome and circulating microbial metabolites between patients with PAH and family control subjects were not as substantial as the differences between patients with PAH and healthy control subjects. Conclusions: Patients with PAH have proinflammatory gut dysbiosis, in which lower circulating SCFAs and secondary bile acids may facilitate pulmonary vascular disease. These findings support investigating modulation of the gut microbiome as a potential treatment for PAH.

Impact of diet on hydrogen sulfide production: implications for gut health.

PURPOSE OF REVIEW: Excessive hydrogen sulfide (H 2 S) production by the gut microbiota may contribute to the pathogenesis of multiple intestinal diseases, including colon cancer and ulcerative colitis. Therefore, understanding of dietary drivers of H 2 S production has potential implications for nutritional strategies to optimize gut health and treat intestinal diseases. RECENT FINDINGS: Recent studies support a positive relationship between dietary protein intake and H 2 S production. However, protein rarely exists in isolation in the diet, and dietary fiber intake could reduce H 2 S production in humans and animals, even with ∼30% of calories derived from protein. SUMMARY: These findings suggest that increased fiber intake may reduce H 2 S production irrespective of protein intake, enabling the ability to meet the metabolic demands of the illness while supporting gut health. Here we discuss two recent ulcerative colitis diet studies that illustrate this point.

Hormone Replacement Therapy Is Associated with Disease Activity Improvement among Post-Menopausal Women with Inflammatory Bowel Disease.

(1) Background: There are limited data available to guide clinical decision-making regarding the effects of hormone replacement therapy (HRT) in post-menopausal women with inflammatory bowel disease (IBD). In this study, we sought to characterize a population of post-menopausal women with IBD and to determine the effects of HRT on their disease activity. (2) Methods: A multicenter, retrospective, case-control cohort study of post-menopausal women with IBD was conducted. The physician global assessment (PGA) score was used to quantify disease activity. To control for the effects of menopause, IBD patients who had not undergone HRT were used as controls. (3) Results: There was a significant reduction in the frequency of PGA scores ≥2 post HRT treatment (p < 0.01). HRT treatment was associated with a 5.6× increase in the odds of post-HRT PGA score improvement compared to controls (OR 5.6; 95% CL 1.6, 19.7) in our univariate logistic regression analysis. (4) Conclusion: Post-menopausal IBD women who underwent HRT therapy showed an improvement in their disease symptoms following HRT compared to post-menopausal women without HRT therapy, who showed no change.

AGA Clinical Practice Guideline on Pharmacological Interventions for Adults With Obesity

Pharmacological management of obesity improves outcomes and decreases the risk of obesity-related complications. This American Gastroenterological Association guideline is intended to support practitioners in decisions about pharmacological interventions for overweight and obesity. A multidisciplinary panel of content experts and guideline methodologists used the Grading of Recommendations Assessment, Development and Evaluation framework to prioritize clinical questions, identify patient-centered outcomes, and conduct an evidence synthesis of the following agents: semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate extended-release (ER), naltrexone-bupropion ER, orlistat, phentermine, diethylpropion, and Gelesis100 oral superabsorbent hydrogel. The guideline panel used the evidence-to-decision framework to develop recommendations for the pharmacological management of obesity and provided implementation considerations for clinical practice. The guideline panel made 9 recommendations. The panel strongly recommended the use of pharmacotherapy in addition to lifestyle intervention in adults with overweight and obesity (body mass index ≥30 kg/m2, or ≥27 kg/m2 with weight-related complications) who have an inadequate response to lifestyle interventions. The panel suggested the use of semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate ER, and naltrexone-bupropion ER (based on moderate certainty evidence), and phentermine and diethylpropion (based on low certainty evidence), for long-term management of overweight and obesity. The guideline panel suggested against the use of orlistat. The panel identified the use of Gelesis100 oral superabsorbent hydrogel as a knowledge gap. In adults with overweight and obesity who have an inadequate response to lifestyle interventions alone, long-term pharmacological therapy is recommended, with multiple effective and safe treatment options.

AGA Clinical Practice Guideline on Pharmacological Interventions for Adults With Obesity.

BACKGROUND & AIMS: Pharmacological management of obesity improves outcomes and decreases the risk of obesity-related complications. This American Gastroenterological Association guideline is intended to support practitioners in decisions about pharmacological interventions for overweight and obesity. METHODS: A multidisciplinary panel of content experts and guideline methodologists used the Grading of Recommendations Assessment, Development and Evaluation framework to prioritize clinical questions, identify patient-centered outcomes, and conduct an evidence synthesis of the following agents: semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate extended-release (ER), naltrexone-bupropion ER, orlistat, phentermine, diethylpropion, and Gelesis100 oral superabsorbent hydrogel. The guideline panel used the evidence-to-decision framework to develop recommendations for the pharmacological management of obesity and provided implementation considerations for clinical practice. RESULTS: The guideline panel made 9 recommendations. The panel strongly recommended the use of pharmacotherapy in addition to lifestyle intervention in adults with overweight and obesity (body mass index ≥30 kg/m2, or ≥27 kg/m2 with weight-related complications) who have an inadequate response to lifestyle interventions. The panel suggested the use of semaglutide 2.4 mg, liraglutide 3.0 mg, phentermine-topiramate ER, and naltrexone-bupropion ER (based on moderate certainty evidence), and phentermine and diethylpropion (based on low certainty evidence), for long-term management of overweight and obesity. The guideline panel suggested against the use of orlistat. The panel identified the use of Gelesis100 oral superabsorbent hydrogel as a knowledge gap. CONCLUSIONS: In adults with overweight and obesity who have an inadequate response to lifestyle interventions alone, long-term pharmacological therapy is recommended, with multiple effective and safe treatment options.

Differential hydrogen sulfide production by a human cohort in response to animal- and plant-based diet interventions.

BACKGROUND: Hydrogen sulfide (H2S) is a toxic end-product of microbial fermentation produced in the colon that may play a role in the pathogenesis of several diseases, including ulcerative colitis and colon cancer. However, the effect of diet interventions on intestinal burden of H2S gas exposure remains poorly understood. OBJECTIVE: Determine the effect of short-term (1-week) plant- and animal-based eating patterns on ex vivo fecal H2S production in healthy human volunteers. METHODS: The study design was an open-label, cross-over diet study and diets were self-administered. Each participant consumed two interventional diets: 1) an animal-based, low fiber (i.e. western) diet and 2) a plant-based, high fiber diet, separated by a two-week washout period. Participants collected full stool samples at the end of each week, which were processed within 2 h of collection to capture H2S production. Microfluidic qPCR (MFQPCR) was used to simultaneously quantify multiple taxonomic and functional groups involved in sulfate reduction and the fecal microbiota was characterized through high-throughput DNA sequencing. RESULTS: Median H2S production was higher following the animal-based diet compared to the plant-based diet (p = 0.02; median difference 29 ppm/g, 95% CI 16-97). However, there was substantial individual variability and 2 of 11 individuals (18%) produced more H2S on the plant-based diet. Using the top and bottom quartiles of H2S percent change between animal- and plant-based diet weeks to define responders and non-responders, significant taxonomic differences were observed between the responder and non-responder cohorts. CONCLUSIONS: Here we report that substrate changes associated with a 1-week plant-based diet intervention resulted in lower ex vivo H2S production compared to a 1-week animal-based diet intervention in most healthy individuals. However, H2S responsiveness to diet was not uniform across the entire cohort, and potential H2S production enterotypes were characterized that may predict individualized H2S responsiveness to diet.

Pre-operative sarcopenia is predictive of recurrent gastrointestinal bleeding on left ventricular assist device support: A multicenter analysis.

INTRODUCTION: Whether pre left ventricular assist device (LVAD) sarcopenia is associated with higher incidence of gastrointestinal bleeding (GIB) on LVAD support remains unknown. METHODS: To study the association between preoperative sarcopenia and post LVAD GIB events, we performed a retrospective, multi-centered study including patients with chest CTs performed ≤ 3 months prior to LVAD implantation at the University of Minnesota (n = 143) and Houston Methodist Hospital (n = 133). To quantify sarcopenia, unilateral pectoralis muscle mass indexed to body surface area (PMI) and attenuation (approximated by mean Hounsfield units; PHUm) were measured on pre-operative chest CT scans. Negative binomial regression analyses were performed to determine the association between pectoralis muscle measures and number of GIB events to 2 years of LVAD support. RESULTS: The study cohort included 276 LVAD recipients with 43 % designated as bridge to transplant at the time of LVAD implantation. High pectoralis muscle mass and tissue attenuation were both protective against GIB events. Each 5 unit increase in PHUm was associated with an adjusted 19 % reduction in the incidence rate of GIB (95 % CI 7-29 %, p = 0.002). Each unit increase in PMI was associated with an adjusted 17 % reduction in the incidence of GIB (95 % CI 1- 29 %, p = 0.04). The models were adjusted for age, sex, INTERMACS profile, bridge to transplant status, creatinine, albumin and implanting center. CONCLUSION: Preoperative sarcopenia, as quantified by pectoralis muscle size and attenuation, was associated with the development of recurrent GI bleeding after LVAD implantation. These CT quantitative measures appear to predict not only early mortality but morbidity on LVAD as well.

Sarcopenia Is More Prevalent Among Inflammatory Bowel Disease Patients Undergoing Surgery and Predicts Progression to Surgery Among Medically Treated Patients.

BACKGROUND: Sarcopenia is common in inflammatory bowel disease (IBD); however, estimates of its prevalence and impact on clinical outcomes are variable. This study sought to compare the prevalence of sarcopenia in IBD patients starting new biologics vs patients undergoing IBD surgeries, and its association with common clinical predictors of nutritional status, adverse events, and clinical outcomes. METHODS: This was a multicenter retrospective cohort study of IBD patients who had a computed tomography (CT) scan within 6 months prior to new biologic initiation (medical cohort) or IBD surgery (surgery cohort). The lowest sex-specific quartile of the total psoas area index at the L3 level defined sarcopenia. Prevalence and predictors of sarcopenia, performance of common clinical nutritional markers, and association with adverse events and clinical outcomes at 1 year were determined. RESULTS: A total of 156 patients were included (48% medical cohort, 52% surgery cohort). Sarcopenia was more common in the surgery cohort (32% vs 16%; P < .02). In the medical cohort, sarcopenia predicted need for surgery at 1 year (odds ratio, 4.75; 95% confidence interval, 1.10-20.57; P = .04). Low albumin and body mass index (BMI) were associated with the presence of sarcopenia; however, 24% of sarcopenic patients had both normal BMI and albumin. CONCLUSIONS: Sarcopenia is more prevalent among IBD patients undergoing surgery and predicts the need for surgery in patients starting new biologic therapy. Low albumin and BMI were similar between cohorts, suggesting a unique role for sarcopenia as a relevant clinical marker of lean muscle mass depletion for surgically and medically treated IBD patients.

Sarcopenia is more common in inflammatory bowel disease surgery patients compared with medical patients, and predicts need for surgery in medical patients. Differences in skeletal muscle measurements compared with albumin and body mass index suggest that sarcopenia may be challenging to detect in routine clinical settings.

Ultrasound measurements of abdominal muscle thickness are associated with postmenstrual age at full oral feedings in preterm infants: A preliminary study.

BACKGROUND: A premature infant's discharge from the neonatal intensive care unit (NICU) is dependent on factors such as respiratory stability, adequate growth, and the ability to consume oral feeds. Once infants have achieved respiratory stability, a tool that can better predict age at discharge is desirable. Thus, we conducted a secondary data analysis to assess the association between ultrasound measurements of abdominal muscle thickness and postmenstrual age (PMA) at full oral feedings. METHODS: Forty-nine (n = 49) healthy, premature infants (mean gestational age = 32 weeks) were recruited from the NICU. Anthropometric measurements and ultrasound measurements of the rectus abdominis were conducted when infants were medically stable. Fat-free mass (FFM) was obtained using air displacement plethysmography. The relationship between ultrasound measurements of muscle thickness and PMA at full oral feedings was assessed using linear regression analysis. The relationship between FFM z-scores and PMA at full oral feedings was also assessed for comparison. RESULTS: When adjusting for gestational age at birth, PMA at measurement, days of positive pressure respiratory support, weight, and length, ultrasound measurements of abdominal muscle thickness were independently, negatively associated with PMA at full oral feedings (ß estimate: -0.71, P = .03). CONCLUSION: Preliminary results suggest infants with greater abdominal muscle thickness may reach full oral feedings at an earlier PMA (nearly 1 week per millimeter). Thus, ultrasound measurements of abdominal muscle thickness may be helpful in assessing readiness for discharge in healthy preterm infants. Further research is needed for development and validation of a prediction equation.

Heart Failure Severity Stratification Beyond INTERMACS Profiles: A Step Toward Optimal Left Ventricular Assist Device Timing.

The purpose of this analysis is to determine whether pectoralis muscle measures quantified on pre left ventricular assist device (LVAD) computerized tomography (CT) scans can identify subgroups of patients with differential disease severity within each Interagency Registry for Mechanical Circulatory Support (INTERMACS) profile. Patients with chest CTs performed ≤3 months before LVAD implantation at University of Minnesota (n = 143) and Houston Methodist Hospital (n = 133) were identified from the larger LVAD cohorts (University of Minnesota n = 353, Houston Methodist =278). Unilateral Pectoralis muscle mass indexed to body surface area and pectoralis muscle attenuation were measured on preoperative chest CT scans. Patients within each INTERMACS profile were separated into HIGH and LOW PEC muscle groups. Kaplan-Meier and multivariable cox regression analyses were performed to compare mortality among INTERMACS profiles by HIGH and LOW PEC muscle groups. INTERMACS 3 and 4 patients in the HIGH PEC groups had the highest survival on LVAD support (1 year survival 85% vs. 68%, log rank P = 0.0001). Being in this group was associated with a 60% reduction in the hazards rate (HR) of death after LVAD (adjusted HR 0.40, 95% confidence interval 0.25-0.62). Additionally, renal function deterioration in the year before LVAD was associated with lower INTERMACS profiles and lower measured pectoralis muscle tissue attenuation at the time of LVAD implantation. INTERMACS 3 and 4 patients with the highest pectoralis muscle measures had the best survival after LVAD. The association between renal function deterioration and sarcopenia suggests these muscle changes are progressive. Computerized tomography quantification of sarcopenia may help identify optimal LVAD implantation timing.

Can Ultrasound Measures of Muscle and Adipose Tissue Thickness Predict Body Composition of Premature Infants in the Neonatal Intensive Care Unit?

BACKGROUND: Premature infants are at risk for adverse metabolic and neurodevelopmental outcomes due to growth alterations in early infancy. Monitoring body composition by tracking gains in fat mass (FM) and fat-free mass (FFM) may assist clinicians in preventing obesity and metabolic disease while promoting optimal growth and development. A prospective, observational study was conducted to determine the ability of ultrasound (US) measurements of muscle and adipose tissue thickness to predict whole-body composition (FFM, FM, percent body fat [%BF]). METHODS: Sixty-three healthy premature infants were recruited from the University of Minnesota's Neonatal Intensive Care Unit. Anthropometric measurements, air displacement plethysmography, and US measurements of abdomen, biceps, and quadriceps muscle and of adipose tissue thickness were conducted when infants were medically stable. The relationship between US measurements and body composition was assessed using stepwise linear regression analysis. RESULTS: In linear regression analyses, biceps adipose and the sum of adipose thickness measurements were significant predictors of %BF, but prediction models had low R2 (0.17 and 0.16, respectively) and high root-mean-square error. US measurements of muscle thickness were not predictive of whole-body FFM. CONCLUSION: US measurements of muscle and adipose tissue thickness at the examined sites are not adequate surrogates for whole-body composition in preterm infants. Exploration of alternate measurement sites may improve predictive ability.

The Comparison of Segmental Multifrequency Bioelectrical Impedance Analysis and Dual-Energy X-ray Absorptiometry for Estimating Fat Free Mass and Percentage Body Fat in an Ambulatory Population.

BACKGROUND: Despite malnutrition being associated with increased mortality and morbidity, there continues to be great difficulty in defining criteria and implementing widespread screening. Tools used to diagnose decreased fat-free mass (FFM [sarcopenia]) should be easy to use, relatively inexpensive, and safe. Bioelectrical impedance analysis (BIA) has the potential to meet these criteria, but reliability across body mass index (BMI) classes is a concern. METHODS: A total of 176 healthy ambulatory participants (aged 18-65 years) were recruited equally (n = 44) in 4 BMI categories: (1) 18.5-24.9, (2) 25.0-29.9, (3) 30-34.9, and (4) ≥35.0. Participants were fasting overnight and had S-MFBIA (InBody 770) measurements the next morning, with DXA being performed subsequently within 30 minutes. RESULTS: The measurement (mean ± SD) for FFM with DXA was 52.8 ± 11.0, and BIA was 53.6 ± 11.0. Delta (S-MFBIA vs DXA) was 0.8 ± 2.2 (5% limits of agreement -3.5 to +5.2), and concordance correlation coefficient (CCC) was 0.98 (95% CI, 0.97-0.98). The measurements (mean ± SD) for PBF with DXA was 37.5 ± 10.6% and S-MFBIA was 36.6 ± 11.3%. Delta (S-MFBIA vs DXA) was -0.9 ± 2.6 (5% limits of agreement 6.0 to +4.2), and CCC was 0.97 (95% CI, 0.96-0.98). The CCC according to the 4 BMI groups for FFM and PBF was between 0.96-0.98 and 0.90-0.94, respectively. CONCLUSIONS: FFM and PBF measured by S-MFBIA had good agreement with DXA across all BMI categories measured in the current study of ambulatory participants.