Comparison of body composition assessment methods in pediatric intestinal failure

Air Displacement Plethysmography is an Accurate and Feasible Noninvasive Measure of Fat-Free Mass in Children With Intestinal Failure

BACKGROUND

The nutritional status of children with intestinal failure (IF) can be difficult to determine using body weight and currently available anthropometric techniques. Air displacement plethysmography (ADP) is a noninvasive measure of whole-body composition that measures body mass and volume, with a calculation of percent body fat (%BF) and fat-free mass (FFM) that may be useful during the provision of specialized nutrition.

OBJECTIVES

To evaluate the validity and feasibility of measuring body composition in children with IF using ADP compared with deuterium dilution (DD), as well as secondarily with other measures of body composition, namely bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DXA), and four-site skinfold anthropometry.

METHODS

We conducted a prospective cohort study of 18 children recruited through the Center for Advanced Intestinal Rehabilitation at Boston Children's Hospital. Patients 2-17 years of age with IF dependent on parenteral nutrition (PN) for more than 90 days were included. Spearman rank correlation and Bland-Altman limits of agreement (LOA) analysis were used to compare ADP to 4 alternative measures of body composition.

RESULTS

Eighteen children with IF, median age 7.1 [interquartile range (IQR) 5.4-9.3] years, 9 female (50%), and median residual bowel length 31 (IQR 22-85) cm were enrolled. Median PN energy intake was 46 (IQR 39-49) kcal/kg/day. Incomplete bladder emptying lead to invalid measures of DD in 4 subjects. Spearman correlation coefficients for %BF were low to moderate between ADP and DD ( r = 0.29), DXA ( r = 0.62), BIA ( r = 0.50), and skinfold ( r = 0.40). Correlations for FFM were high between ADP and these other measures (range 0.95-0.98). Comparing ADP with DD and skinfold measures, Bland-Altman analysis showed small mean bias (-1.9 and +1.5 kg) and acceptable 95% LOA ranges (10.7 and 22.9 kg), respectively, with larger bias (-10.7 and -7.7 kg) and LOA ranges (38.7 and 45.2 kg) compared to DXA and BIA. %BF by ADP and skinfold thickness were moderately correlated ( r = 0.43) with low bias (-0.2%) but very wide LOA (25.7%).

CONCLUSIONS

Body composition via ADP is feasible and valid in children with IF as a measure of FFM but appears less suitable for the measurement of %BF. The technique holds promise as a noninvasive measure of body composition to assess the efficacy of nutritional, medical, and surgical interventions.

Assessment of body composition in pediatric intestinal failure: A comparison study

BACKGROUND

The objective of the study was to compare bioelectrical impedance analysis (BIA) and skinfolds with dual energy x-ray absorptiometry (DXA) in the assessment of body composition of children with intestinal failure. DXA is the reference method for body composition assessment in clinical settings.

METHODS

Children aged 1-18 years with intestinal failure whohave DXA as part of routine clinical monitoring were eligible. BIA measured total body water on the same day as DXA. Skinfold measurements were taken at four sites: triceps, biceps, subscapular, and suprailiac. Percentage of fat mass (%FM) and fat-free mass (%FFM) were derived from resistance and reactance measured by BIA by using age-specific equations. Percentage of FM was calculated from skinfold measures by using age-specific equations. Data on patient characteristics, intestinal failure-related factors, and feeding method were collected. Paired t test examined differences in %FM and %FFM and Bland-Altman analysis determined the agreement between BIA, skinfolds, and DXA. Marginal linear model assessed the effect of age, sex, and feeding method on the difference in body composition obtained between DXA and BIA and between DXA and skinfolds.

RESULTS

Sixty-eight children with intestinal failure, mean age 8.9 ± 4.2 years, were studied. There was no difference between %FFM and %FM obtained by DXA and BIA (P = 0.26), with a mean bias (95% CI) of -0.69 (-1.9 to 0.5) for %FFM. Sex and age were individually and jointly associated with the bias observed between DXA and BIA (P < 0.05). Skinfold and DXA measurements were significantly different (P < 0.05).

CONCLUSIONS

BIA is an acceptable clinical tool for assessing body composition in pediatric intestinal failure.

Frequency and impact of enteric hyperoxaluria in pediatric short bowel syndrome: a retrospective single centre study

Objectives

The survival of pediatric patients with short bowel syndrome has improved in recent years. Enteric hyperoxaluria as a pathophysiological consequence has been hardly addressed so far. It can be associated with nephrolithiasis, nephrocalcinosis or even renal insufficiency. We assessed the prevalence of hyperoxaluria and its pathogenic consequences in a retrospective single centre study over the last 12 years.

Methods

We conducted an internal database search for all pediatric patients suffering from short bowel syndrome treated from 2010 to 2022 in the department of pediatric gastroenterology as well as the pediatric nephrology and dialysis unit. Out of 56 patients identified, 26 patients were analysed for etiology of short bowel syndrome, renal excretion of oxalate (24/26), remaining short bowel and large intestinal length as well as further clinical parameters such as eGFR, nephrocalcinosis/urinary stone formation or stool frequency.

Results

Hyperoxaluria was detected in 14/26 patients (54%). Nephrocalcinosis was present in four patients. Out of these four patients, hyperoxaluria could be proven (21% of all hyperoxaluric patients) in three cases, one hyperoxaluric patient had nephrolithiasis (7%). In one patient hyperoxaluria lead to end stage renal disease. We found that 80% of patients with volvulus developed enteric hyperoxaluria. None of the investigated factors had an effect on oxalate excretion.

Conclusion

Enteric hyperoxaluria is a relevant pathophysiological finding in patients with short bowel syndrome occurring in about 50% of our cohort with multiple pathogenic complications. Regular screening for hyperoxaluria may be implemented in medical care for patients with short bowel syndrome. If necessary, prophylaxis, e.g., dietary advice or metaphylaxis should be initiated.

Normal anthropometry does not equal normal body composition in pediatric intestinal failure

BACKGROUND

Published reports on abnormal body composition in pediatric patients with intestinal failure have been in patients with poor growth. The goal of the current study is to report the body composition of normally growing patients with intestinal failure.

METHODS

Children 8-18 years old with a dual-energy x-ray absorptiometry (DXA) between January 1, 2013, and July 15, 2018, were included in the study. Data were retrospectively collected from the medical charts and included demographics, residual bowel anatomy, nutrition support, height, and weight. DXA data, including total body less head bone mineral density (BMD), fat mass (FM), and fat-free mass (FFM), were collected and compared with published literature controls matched for age and sex.

RESULTS

Thirty-four children met inclusion criteria. Mean age at the time of DXA was 9.6 ± 1.8 years. Weight- and height-for-age z-scores were -0.4 ± 0.9 and -0.5 ± 1.0, respectively. Mean BMD z-score was -1.0 ± 1.3. Twenty-six percent of patients (n = 9) had reduced BMD. Patients with intestinal failure had higher FM (P = .02) and lower FFM (P = .02) compared with controls.

CONCLUSIONS

These data show that, despite reference range z-scores for height and weight, children with intestinal failure are at risk for abnormal body composition. Body composition should be routinely measured in children with intestinal failure to direct nutrition interventions.

Nutrition in Pediatric Extracorporeal Membrane Oxygenation: A Narrative Review

Extracorporeal membrane oxygenation (ECMO) support is increasingly utilized in quaternary pediatric intensive care units. Metabolic derangements and altered nutritional requirements are common in critically ill children supported on ECMO. However, there remains no consensus on the optimal approach to the prescription of nutrition in these patients. This narrative review aims to summarize the current medical literature on various aspects of nutrition support in pediatric patients on ECMO. These include: (1) nutritional adequacy, (2) pros and cons of feeding on ECMO, (3) enteral vs. parenteral nutrition, and (4) proposed recommendations and future directions for research in this area.

Assessing the reliability of FTIR spectroscopy measurements and validity of bioelectrical impedance analysis as a surrogate measure of body composition among children and adolescents aged 8-19 years attending schools in Kampala, Uganda

Background

Accurate measurement of body composition in children and adolescents is important as the quantities of fat and fat-free mass have implications for health risk. The objectives of the present study were: to determine the reliability of Fourier Transform Infrared spectroscopy (FTIR) measurements and; compare the Fat Mass (FM), Fat Free Mass (FFM) and body fat percentage (%BF) values determined by bioelectrical impedance analysis (BIA) to those determined by deuterium dilution method (DDM) to identify correlations and agreement between the two methods.

Methods

A cross-sectional study was conducted among 203 children and adolescents aged 8–19 years attending schools in Kampala city, Uganda. Pearson product-moment correlation at 5% significance level was considered for assessing correlations. Bland Altman analysis was used to examine the agreement between of FTIR measurements and between estimates by DDM and BIA.. Reliability of measurements was determined by Cronbach’s alpha.

Results

There was good agreement between the in vivo D₂O saliva enrichment measurements at 3 and 4 h among the studied age groups based on Bland-Altman plots. Cronbach’s alpha revealed that measurements of D₂O saliva enrichment had very good reliability. For children and young adolescents, DDM and BIA gave similar estimates of FFM, FM, and %BF. Among older adolescents, BIA significantly over-estimated FFM and significantly under-estimated FM and %BF compared to estimates by DDM. The correlation between FFM, FM and %BF estimates by DDM and BIA was high and significant among young and older adolescents and for FFM among children.

Conclusions

Reliability of the FTIR spectroscopy measurements was very good among the studied population. BIA is suitable for assessing body composition among children (8–9 years) and young adolescents (10–14 years) but not among older adolescents (15–19 years) in Uganda. The body composition measurements of older adolescents determined by DDM can be predicted using those provided by BIA using population-specific regression equations.

Comprehensive nutritional and metabolic assessment in patients with spinal muscular atrophy: Opportunity for an individualized approach

Optimal nutrition support is recommended for patients with spinal muscular atrophy (SMA). In a prospective study, we performed comprehensive nutritional assessments with the aim to guide best nutritional strategies for patients with SMA types II and III. We recorded a) anthropometry; b) macro- and micronutrient intakes; c) measured resting energy expenditure by indirect calorimetry; and d) body composition including dual X-ray absorptiometry. We enrolled a cohort of 21 patients aged 3 to 36 years of which 13 were female; 19 had SMA type II and 2 had SMA type III. The body mass index z-score ranged from -3 to 2.4. Forty-five percent of the cohort was either underfed or overfed, based on the difference between actual energy intake and measured resting energy expenditure. Vitamin D, E, K, folate and calcium intakes were low in a majority of the cohort. Forty-five percent of the cohort was either hypometabolic or hypermetabolic. Fat mass index (kg/m²) was significantly higher and lean body mass index (kg/m²) was significantly lower in the study cohort compared to population normalized values. Bone mineral density was low in 13 of 17 patients. In summary, we have described the prevalence of malnutrition, suboptimal feeding and alterations in body composition in children with SMA. A comprehensive nutritional assessment could guide individualized nutrition therapy in this vulnerable population.

Body Composition in Children with Chronic Illness: Accuracy of Bedside Assessment Techniques

OBJECTIVE

To evaluate the accuracy of estimated fat mass and fat-free mass from bedside methods compared with reference methods in children with chronic illnesses.

STUDY DESIGN

Fat mass and fat-free mass values were obtained by skinfold, bioelectrical impedance analysis (BIA), dual-energy x-ray absorptiometry (DXA), and deuterium dilution method in children with spinal muscular atrophy, intestinal failure, and post hematopoietic stem cell transplantation (HSCT). Spearman's correlation and agreement analyses were performed between (1) fat mass values estimated by skinfold equations and by DXA and (2) fat-free mass values estimated by BIA equations and by DXA and deuterium dilution methods. Limits of agreement between estimating and reference methods within ±20% were deemed clinically acceptable.

RESULTS

Fat mass and fat-free mass values from 90 measurements in 56 patients, 55% male, and median age of 11.6 years were analyzed. Correlation coefficients between the skinfold-estimated fat mass values and DXA were 0.93-0.94 and between BIA-estimated fat-free mass values and DXA were 0.92-0.97. Limits of agreement between estimated and DXA values of fat mass and fat-free mass were greater than ±20% for all equations. Correlation coefficients between estimated fat-free mass values and deuterium dilution method in 35 encounters were 0.87-0.91, and limits of agreement were greater than ±20%.

CONCLUSION

Estimated body composition values derived from skinfold and BIA may not be reliable in children with chronic illnesses. An accurate noninvasive method to estimate body composition in this cohort is desirable.

Body composition estimation in children and adolescents by bioelectrical impedance analysis: A systematic review

BACKGROUND

Bioelectrical impedance analysis (BIA) has commonly been used to assess the body composition of children and adolescents. BIA validation studies have found distinct correlation values with reference methods.

OBJECTIVES

To assess the reproducibility, correlation and mean differences in body composition estimated by BIA and reference methods, we systematically reviewed the literature in the pediatric population.

METHOD

The search for articles was conducted in March 2016 and was limited to articles published from 2005 to 2015 in the PubMed, Embase, EBSCO, Web of Science, Scopus and SciELO databases. Two reviewers independently performed data selection and extraction of studies that investigated the BIA validity, responsiveness, reliability and/or measurement error (reproducibility) to estimate body composition in children and adolescents with an average age ≤ 18 years.

RESULTS

The search produced 48 articles. Almost perfect reproducibility was found in the body fat percentage estimated by BIA, and there was almost perfect correlation between the BIA ratings and reference methods for fat mass and fat-free mass. Regarding component estimates, BIA underestimated the fat mass in both sexes.

CONCLUSIONS

The body fat percentage estimated by BIA exhibited almost perfect reproducibility. The fat mass and fat-free mass estimated by BIA correlated almost perfectly with the reference methods in both sexes. BIA underestimated the fat mass in both sexes.

Protein Requirements of the Critically Ill Pediatric Patient

This article includes a review of protein needs in children during health and illness, as well as a detailed discussion of protein metabolism, including nitrogen balance during critical illness, and assessment and prescription/delivery of protein to critically ill children. The determination of protein requirements in children has been difficult and challenging. The protein needs in healthy children should be based on the amount needed to ensure adequate growth during infancy and childhood. Compared with adults, children require a continuous supply of nutrients to maintain growth. The protein requirement is expressed in average requirements and dietary reference intake, which represents values that cover the needs of 97.5% of the population. Critically ill children have an increased protein turnover due to an increase in whole-body protein synthesis and breakdown with protein degradation leading to loss of lean body mass (LBM) and development of growth failure, malnutrition, and worse clinical outcomes. The results of protein balance studies in critically ill children indicate higher protein needs, with infants and younger children requiring higher intakes per body weight compared with older children. Monitoring the side effects of increased protein intake should be performed. Recent studies found a survival benefit in critically ill children who received a higher percentage of prescribed energy and protein goal by the enteral route. Future randomized studies should evaluate the effect of protein dosing in different age groups on patient outcomes, including LBM, muscle structure and function, duration of mechanical ventilation, intensive care unit and hospital length of stay, and mortality.

Nutritional Status and Nutrient Intake Challenges in Children With Spinal Muscular Atrophy

BACKGROUND

Nutrition is recognized as a core component of multidisciplinary care for patients with spinal muscular atrophy, but specific nutritional challenges in this population are not well described. We aimed to describe the nutritional status and nutrient intake in children with spinal muscular atrophy.

METHODS

We performed a retrospective medical record review of prospectively collected data from children with spinal muscular atrophy followed at a multidisciplinary clinic at a tertiary referral center. We collected data including clinical parameters; anthropometrics, including weight, height, and body mass index (BMI); and 24-hour dietary intake records in all children followed in the clinic. Available data were found in records from the dietitian as part of a standard evaluation process, and additional clinical data were acquired from patient medical records. Subjects were classified based on spinal muscular atrophy type, and nutritional intake data were compared with dietary reference intakes for gender and age. Z-scores were calculated for weight for age (WAZ), height for age, and BMI (BMIZ) using the World Health Organization AnthroPlus software with appropriate World Health Organization reference growth standards. Subjects were classified as malnourished if their WAZ was <-2 or >+2. Anthropometric measurements were obtained at first visit and at a follow-up visit at an average of a 3-year interval between the clinic visits. A decline of more than 0.5 WAZ over this period was defined a priori as significant nutritional deterioration.

RESULTS

We analyzed data from 60 subjects, 26 (43%) female, with median age 5.5 years (interquartile range 2 years to 12 years). The cohort consisted of children with spinal muscular atrophy type 1 (28 %), type 2 (45 %), and type 3 (27 %). At the first clinic visit, nine (15%) patients were malnourished. Thirteen (23%) subjects had a significant decline in WAZ from -0.35 (-1.31 to 0.58) to -1.04 (-2.15 to 0.02) at follow-up after approximately 3 years. A third of these subjects were already malnourished at first visit. A significant decline in BMIZ was noted in 47% of the cohort, and the prevalence of severe malnutrition (BMIZ < -3) increased from 2% to 17% after 3 years. In children receiving specialized enteral nutrition via a feeding tube, overfeeding was recorded in 29% and underfeeding was recorded in 35%. Suboptimal vitamin D intake was recorded in 35% of patients with enteral feeding device.

CONCLUSIONS

Malnutrition was prevalent in children with spinal muscular atrophy, and nearly half the cohort demonstrated nutritional deterioration over time. Energy, protein, and vitamin D intakes were inadequate in a majority of the cohort. Underfeeding was highly prevalent, but overfeeding was also present in a third of the enterally fed cohort. Future studies describing optimal nutrient requirements and body composition variables in this group are required.

Resonant cavity perturbation: a promising new method for the assessment of total body water in children

The accurate measurement of total body water (TBW) in children has important clinical and nutritional applications. Resonant cavity perturbation (RCP) is a new method for estimating TBW. This method measures the dielectric properties of the body which are related to body water. For RCP measurements, each subject lay supine on a bed inside a screened room which acts as a resonant cavity. A network analyser measures the frequencies of two low-order cavity resonances of the room, with electric-field vectors that were respectively vertical and horizontal, the resonant frequency shifts relative to the empty room are then derived. These frequency shifts correlates with TBW. The aims of this present study were to (a) develop TBW(RCP) predictive equations for children using TBWdil as the criterion method, (b) cross-validate the derived equations, (c) determine precision of the TBW(RCP) method, and (d) compare the criterion method TBWdil with three methods of estimating TBW: RCP, MFBIS and anthropometry.Predictive equations, independent of sex, were developed with linear regression in a group of 36 children. The relationship between combined RCP frequency shifts and TBWdilution had an r2  =  0.90 and standard error of the estimate (SEE)  =1.42 kg. Multiple regression analysis, that included a term for body mass index, only had a small effect on r2  =  0.93 and SEE  =  1.25 kg. In vivo TBW precision for the vertical, horizontal and combined frequency modes ranged from 0.7 to 3.4%. Bland-Altman analysis indicated close agreement between the criterion method TBWdil and the three other methods of TBW estimation. Mean differences were TBW(RCP(2))  =  0.01  ±  /-  1.34 kg, TBW(MFBIS)  =  0.45  ±  /-  1.35 kg, TBWAnthropometry  =  0.29  ±  /-  1.29 kg.Currently the RCP method does not significantly improve the prediction of TBW compared to MFBIS and anthropometry in this initial study. However the derived equation was independent of sex and body size had only a small effect.

Necrotizing Enterocolitis and Central Line Associated Blood Stream Infection Are Predictors of Growth Outcomes in Infants with Short Bowel Syndrome

OBJECTIVES

To describe the natural history of growth patterns and nutritional support in a cohort of infants with short bowel syndrome (SBS), and to characterize risk factors for suboptimal growth.

STUDY DESIGN

A retrospective chart review of 51 infants with SBS followed by our intestinal rehabilitation program. Weight and length data were converted to age, sex, and gestational age-standardized weight-for-age z-scores (WAZ) and length-for-age z-scores (LAZ).

RESULTS

Median (IQR) age at enrollment was 8.3 (0.9-14.6) weeks, and follow-up duration was 10 (8-13) months, including both inpatient and outpatient visits. Both WAZ and LAZ followed a U-shaped curve, with median for newborns (WAZ = -0.28; LAZ = -0.41), a nadir at age 6 months (-2.38 and -2.18), and near recovery by age 1 year (-0.72 and -0.76). Using multivariable regression analysis, diagnosis of necrotizing enterocolitis was independently associated with significant decrements of WAZ (-0.76 ± 0.32; P = .02) and LAZ (-1.24 ± 0.32; P = .0001). ≥ 2 central line-associated bloodstream infections was also independently associated with decreases in WAZ (-0.95 ± 0.33; P = .004) and LAZ (-0.86 ± 0.32; P = .007).

CONCLUSION

In a cohort of infants with SBS, we observed a unique pattern of somatic growth, with concomitant deceleration of both WAZ and LAZ and near recovery by 1 year. Inflammatory conditions (necrotizing enterocolitis and central line-associated bloodstream infections) represent potentially modifiable risk factors for suboptimal somatic growth.

Impact of Individualized Diet Intervention on Body Composition and Respiratory Variables in Children With Respiratory Insufficiency: A Pilot Intervention Study

OBJECTIVES

Diet modification may improve body composition and respiratory variables in children with respiratory insufficiency. Our objective was to examine the effect of an individualized diet intervention on changes in weight, lean body mass, minute ventilation, and volumetric CO2 production in children dependent on long-term mechanical ventilatory support.

DESIGN

Prospective, open-labeled interventional study.

SETTING

Study subjects' homes.

PATIENTS

Children, 1 month to 17 years old, dependent on at least 12 hr/d of transtracheal mechanical ventilatory support.

INTERVENTIONS

Twelve weeks of an individualized diet modified to deliver energy at 90-110% of measured energy expenditure and protein intake per age-based guidelines.

MEASUREMENTS AND MAIN RESULTS

During a multidisciplinary home visit, we obtained baseline values of height and weight, lean body mass percent by bioelectrical impedance analysis, actual energy and protein intake by food record, and measured energy expenditure by indirect calorimetry. An individualized diet was then prescribed to optimize energy and protein intake. After 12 weeks on this interventional diet, we evaluated changes in weight, height, lean body mass percent, minute ventilation, and volumetric CO2 production. Sixteen subjects, mean age 9.3 years (SD, 4.9), eight male, completed the study. For the diet intervention, a majority of subjects required a change in energy and protein prescription. The mean percentage of energy delivered as carbohydrate was significantly decreased, 51.7% at baseline versus 48.2% at follow-up, p = 0.009. Mean height and weight increased on the modified diet. Mean lean body mass percent increased from 58.3% to 61.8%. Minute ventilation was significantly lower (0.18 L/min/kg vs 0.15 L/min/kg; p = 0.04), and we observed a trend toward lower volumetric CO2 production (5.4 mL/min/kg vs 5.3 mL/min/kg; p = 0.06) after 12 weeks on the interventional diet.

CONCLUSIONS

Individualized diet modification is feasible and associated with a significant decrease in minute ventilation, a trend toward significant reduction in CO2 production, and improved body composition in children on long-term mechanical ventilation. Optimization of respiratory variables and lean body mass by diet modification may benefit children with respiratory insufficiency in the ICU.

Metabolic assessment and individualized nutrition in children dependent on mechanical ventilation at home

OBJECTIVE

To evaluate the nutritional and metabolic status and body composition of children on long-term mechanical ventilation using a home-based model.

STUDY DESIGN

Children on home mechanical ventilation, for at least 12 hours a day, were eligible. We performed anthropometry, bioelectrical impedance analysis (BIA), actual energy intake (AEI), and indirect calorimetry in the subject's home. Agreement between measured energy expenditure (MEE) from indirect calorimetry, and estimated energy expenditure by the Schofield equation and a novel volumetric carbon dioxide production-based equation was examined. Agreement between fat mass estimates from anthropometry and BIA was examined and compared with population norms.

RESULTS

We enrolled 20 children, 11 (55%) male; mean age 8.4 years (SD 4.8). Mean weight for age z-score was -0.26 (SD 1.48); 9/20 had z-scores <-1 or >+1. Thirteen were underfed (AEI:MEE <90%) or overfed (AEI:MEE >110%); 11 of 19 had protein intake that was less than recommended by guidelines. Fifteen subjects were hypo- or hypermetabolic. Mean (SD) fat mass % was 33.6% (8.6) by anthropometry, which was significantly greater than matched population norms (mean 23.0%, SD 6.1, P < .001). The estimated energy expenditure by a volumetric carbon dioxide production-based equation was in stronger agreement with the MEE than the Schofield equation (mean bias 0.06%, limits -15.98% to 16.16% vs mean bias -1.31%, limits -74.3% to 72%, respectively). BIA and anthropometric fat mass values were not in agreement.

CONCLUSION

A majority of children on home ventilation are characterized by malnutrition, altered metabolic status, and suboptimal macronutrient intake, in particular low protein intake. A multidisciplinary home-based model facilitates individualized energy and protein delivery and may improve outcomes in this cohort.