Body composition assessed by the 4-component model and association with lung function in 6-12-y-old children with cystic fibrosis

Body composition and respiratory outcomes in children: a population-based prospective cohort study

BACKGROUND

Body composition might influence lung function and asthma in children, but its longitudinal relations are unclear. We aimed to identify critical periods for body composition changes during childhood and adolescence in relation to respiratory outcomes in adolescents.

METHODS

In a population-based prospective cohort study, we measured body mass index, fat mass index (FMI), lean mass index (LMI) and the ratio of android fat mass divided by gynoid fat mass (A/G ratio) by dual-energy X-ray absorptiometry at 6, 10 and 13 years. At 13 years, lung function was measured by spirometry, and current asthma was assessed by questionnaire.

RESULTS

Most prominently and consistently, higher FMI and A/G ratio at age 13 years were associated with lower forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) and forced expiratory flow after exhaling 75% of FVC (FEF75) (range Z-score difference -0.13 (95% CI -0.16 to -0.10) to -0.08 (95% CI -0.11 to -0.05) per SD score increase), and higher LMI at all ages was associated with higher FEF75 (range Z-score difference 0.05 (95% CI 0.01 to 0.08) to 0.09 (95% CI 0.06 to 0.13)). Between the ages of 6 and 13 years, normal to high FMI and A/G ratio were associated with lower FEV1/FVC and FEF75 (range Z-score difference -0.20 (95% CI -0.30 to -0.10) to -0.17 (95% CI -0.28 to -0.06)) and high to high LMI with higher FEF75 (range Z-score difference0.32 (95% CI 0.23 to 0.41)). Body composition changes were not associated with asthma.

CONCLUSION

Adolescents with higher total and abdominal fat indices may have impaired lung function, while those with a higher lean mass during childhood and adolescence may have better small airway function. Public health measures should focus on a healthy body composition in adolescents to minimise respiratory morbidity.

Centile reference chart for resting metabolic rate through the life course

OBJECTIVE

Reference centile charts are widely used for the assessment of growth and have progressed from describing height and weight to include body composition variables such as fat and lean mass. Here, we present centile charts for an index of resting energy expenditure (REE) or metabolic rate, adjusted for lean mass versus age, including both children and adults across the life course.

DESIGN, PARTICIPANTS AND INTERVENTION

Measurements of REE by indirect calorimetry and body composition using dual-energy X-ray absorptiometry were made in 411 healthy children and adults (age range 6-64 years) and serially in a patient with resistance to thyroid hormone α (RTHα) between age 15 and 21 years during thyroxine therapy.

SETTING

NIHR Cambridge Clinical Research Facility, UK.

RESULTS

The centile chart indicates substantial variability, with the REE index ranging between 0.41 and 0.59 units at age 6 years, and 0.28 and 0.40 units at age 25 years (2nd and 98th centile, respectively). The 50th centile of the index ranged from 0.49 units (age 6 years) to 0.34 units (age 25 years). Over 6 years, the REE index of the patient with RTHα varied from 0.35 units (25th centile) to 0.28 units (<2nd centile), depending on changes in lean mass and adherence to treatment.

CONCLUSION

We have developed a reference centile chart for an index of resting metabolic rate in childhood and adults, and shown its clinical utility in assessing response to therapy of an endocrine disorder during a patient's transition from childhood to adult.

Evaluation of anthropometry as an alternative to DXA as predictor of low bone mineral density in children and adolescents with cystic fibrosis

BACKGROUND & AIMS

Low bone mineral density (BMD) for age in people with Cystic Fibrosis (CF) is associated with worse nutritional status. The aim of this study is to assess body composition by anthropometry as a predictor of BMD in people with CF.

METHODS

Multicenter cross-sectional study with 39 people aged 5 and 20 years with CF. BMD was assessed by dual energy x-ray emission (DXA) in the incidence of the total body less head (TBLH) and the TBLH Z-score (Z-TBLH) was calculated, adjusted by sex, age, height and ethnicity. Anthropometry was assessed by weight, height, mid-upper arm circumference (MUAC) and triceps skinfold (TSF). Arm muscle area (AMA) and Body Mass Index (BMI) were calculated. Lean mass (LM), fat mass (FM) and free-fat mass (FFM) were identified by DXA. The molecular analysis method by sequencing was used to identify and classify the participants regarding the presence of the F508del pathogenic variant of the CFTR gene. Statistical models of simple and multiple linear regression were created to establish the predictive power of Z-TBLH in the variables.

RESULTS

Average age of the participants was 13.31 ± 3.86 years, 59% of whom were male. They showed more LM (30.97 Kg ± 11.29) than females (23 Kg ± 6.73). 20 of 30 participants (66.7%) had at least copy of F508del. Among the multiple models, adjusted by height, age and sex, it found BMI (R² = 0.367), Weight (R² = 0.220), AMA (R² = 0.338) as significant predictors of Z-TBLH. The final model composed of AMA, TSF and Age (p = 0.001; R² = 0.381) had AMA and Age as significant predictors. AMA was associated with an increase in the BMD Z-score in the participants studied. 66.7% of genetically tested participants had the F508del pathogenic variant. The presence of the F508del variant was associated with worse nutritional status.

CONCLUSION

A statistical model composed of the values of AMA, TSF and Age can predict Z-TBLH, as well as anthropometric variables Weight, or BMI, or AMA associated with height, age and sex, in children and adolescents aged 5-20 years old, of both sexes. Anthropometric markers, as they are easy and relatively inexpensive to obtain, it is a promising alternative to the use of DXA in predicting BMD in these people with CF.

Academy of Nutrition and Dietetics: 2020 Cystic Fibrosis Evidence Analysis Center Evidence-Based Nutrition Practice Guideline

The Academy of Nutrition and Dietetics Evidence Analysis Center conducted a systematic review of the literature to develop an evidence-based practice guideline for primary nutrition issues in cystic fibrosis (CF). This guideline is designed to complement and build upon existing evidence-based CF nutrition guidelines. The objective of this guideline was to provide recommendations for registered dietitian nutritionists in the United States delivering medical nutrition therapy to individuals with CF and their families that fill gaps in current evidence-based guidelines on topics that are crucial in order to improve health and prevent disease progression. This guideline provides 28 nutrition recommendations to guide medical nutrition therapy, including nutrition screening, nutrition assessment, and dietary intake. For topics outside the scope of this guideline, practitioners are referred to external, evidence-based recommendations. The CF landscape is evolving rapidly with breakthroughs in cystic fibrosis transmembrane regulator modulators changing CF at a cellular level. Medical nutrition therapy for individuals with CF from infancy through advanced age requires novel and individualized approaches. The Academy Evidence Analysis Library CF guidelines provide a framework for expanding upon current knowledge to determine effective nutrition strategies for individuals with CF through long and healthy futures.

Growth, Body Composition, and Lung Function in Prepubertal Children with Cystic Fibrosis Diagnosed by Newborn Screening

BACKGROUND

Children with cystic fibrosis (CF) are at risk of altered body composition (BC). Newborn screening (NBS) may lead to improved BC outcomes. We investigated BC and its relationship with lung function in prepubertal children diagnosed with CF by NBS. Secondary aims explored predictors of fat-free mass (FFM) and lung function.

METHODS

Thirty-seven screened (non-meconium ileus) children with CF (20 boys) born 2007-2012 had a dual-energy x-ray absorptiometry scan at 5-8 years to determine whole-body (WB) and appendicular BC. Anthropometry was performed and routine spirometry recorded. Results were converted to z-scores, height-adjusted (fat mass index [FMI] and FFM index [FFMI]) and compared with population mean values. Predictors of forced expiratory volume in 1 second (FEV₁ ) were assessed using linear regression.

RESULTS

Height, body mass index (BMI), and FEV₁ were within normal limits, however, weight and BC were significantly low compared with reference data (weight, P = .03; WB FMI, P = .001; WB FFMI, P = .009). Gender differences were detected, with lower appendicular BC in boys and lower weight, BMI, and BC in girls. The association between FEV₁ and WB FFMI (r = 0.38; P = .02) was stronger than with BMI (r = 0.29; P = .08). WB FFMI was the only significant predictor of FEV₁ in a multivariable model (95% CI, 0.11-0.99; P = .016).

CONCLUSION

In this NBS CF population, gender differences in growth and BC were apparent despite preserved lung function. These results support BC assessment in prepubertal children, particularly girls, with an opportunity to direct interventions to optimize FFM.

Childhood Body Composition Trajectories and Adolescent Lung Function. Findings from the ALSPAC study

Rationale: Body composition changes throughout life may explain the inconsistent associations reported between body mass index and lung function in children. Objectives: To assess the associations of body weight and composition trajectories from 7 to 15 years with lung function at 15 years and lung function growth between 8 and 15 years. Methods: Sex-specific body mass index, lean body mass index, and fat mass index trajectories were developed using Group-Based Trajectory Modeling on data collected at least twice between 7 and 15 years from 6,964 children (49% boys) in the UK Avon Longitudinal Study of Parents and Children birth cohort. Associations of these trajectories with post-bronchodilation lung function parameters at 15 years and with lung function growth rates from 8 to 15 years were assessed using multivariable linear regression models, stratified by sex, in a subgroup with lung function data (n = 3,575). Measurements and Main Results: For all body mass measures we identified parallel trajectories that increased with age. There was no consistent evidence of an association between the body mass index trajectories and lung function measures. Higher lean body mass index trajectories were associated with higher levels and growth rates of FVC, FEV1, and forced expiratory flow, midexpiratory phase in both sexes (e.g., boys in the highest lean body mass index trajectory had on average a 0.62 L [95% confidence interval, 0.44-0.79; P trend < 0.0001] higher FVC at 15 yr than boys in the lowest trajectory). Increasing fat mass index trajectories were associated with lower levels and growth rates of FEV1 and forced expiratory flow, midexpiratory phase only in boys and lower levels of FEV1/FVC in both sexes. Conclusions: Higher lean body mass during childhood and adolescence is consistently associated with higher lung function at 15 years in both sexes, whereas higher fat mass is associated with lower levels of only some lung function parameters.

Body composition and lung function in children with cystic fibrosis and meconium ileus

The aim of this study was to explore whether history of meconium ileus (MI) at birth in children and adolescents with cystic fibrosis (CF) adversely affects body composition and lung function in later life. Data of children and adolescents with CF who underwent spirometry and DXA as part of their routine care were analyzed. Associations between MI (explanatory variable) and areal bone mineral density (total body less head-TBLH aBMD), lean tissue mass (LTM), and fat mass (FM) (outcomes) were assessed using general linear models. Potential relationships of TBLH aBMD, LTM, and FM with FEV₁ (additional outcome) were also explored. One hundred and one subjects with CF (mean age 14 ± 3 years) were included, 19 (18.8%) of whom had history of MI. Negative associations were demonstrated between history of MI and FEV₁ (P = 0.04), TBLH aBMD (P = 0.03), and FM (P < 0.01) but not between history of MI and LTM (P = 0.07) after adjustment for other variables. Lung function was positively associated with TBLH aBMD (P < 0.01) and LTM (P = 0.02) but not with FM (P = 0.20).

CONCLUSION

Among children and adolescents with CF, those with history of MI have lower bone mineral density, FM, and lung function. What is Known: • Among children and adolescents with cystic fibrosis, those with history of meconium ileus in the neonatal period are at risk of having lower body mass index percentile and FEV ₁ percent predicted. What is New: • Children and adolescents with cystic fibrosis and history of meconium ileus have decreased bone mineral density and fat mass compared to patients without such history. • Lower lung function in children with MI coexists with suboptimal bone mineral density.

Body composition and lung function in cystic fibrosis and their association with adiposity and normal-weight obesity

OBJECTIVES

This study aimed to evaluate the relationship between lung function and body composition in cystic fibrosis (CF) and examine the presence of normal-weight obesity (NWO), a high body fat percentage with a normal body mass index (BMI), in this population.

METHODS

In a pilot, cross-sectional study, 32 subjects with CF and a reference group of 20 adults without CF underwent body composition analysis with air displacement plethysmography. NWO was defined as a BMI <25 kg/m(2) and body fat >30% (for women) or >23% (for men). Lung function in subjects with CF was determined by the percentage of predicted forced expiratory volume in 1 s (FEV1% predicted).

RESULTS

Despite lower BMI and fat-free mass index (P < 0.01), fat mass index and percent body fat did not differ between subjects with CF and the reference group. Among subjects with CF, FEV1% predicted was positively associated with fat-free mass index (β = 6.31 ± 2.93, P = 0.04) and inversely associated with fat mass index (β = -6.44 ± 2.93, P = 0.04), after adjusting for age, sex, and BMI. Ten subjects with CF (31%) had NWO, which corresponded with lower fat-free mass index and FEV1% predicted compared with overweight subjects (P = 0.006 and 0.004, respectively).

CONCLUSIONS

Excess adiposity, particularly in the form of NWO, was inversely associated with lung function in CF. Larger prospective studies should be undertaken to confirm these findings and determine the long-term metabolic and clinical consequences of excess adiposity in CF. As the lifespan of individuals with CF increases, nutrition screening protocols, which primarily rely on BMI, may require reassessment.

Body composition in young female eating-disorder patients with severe weight loss and controls: evidence from the four-component model and evaluation of DXA

Background/Objectives:

Whether fat-free mass (FFM) and its components are depleted in eating-disorder (ED) patients is uncertain. Dual energy X-ray absorptiometry (DXA) is widely used to assess body composition in pediatric ED patients; however, its accuracy in underweight populations remains unknown. We aimed (1) to assess body composition of young females with ED involving substantial weight loss, relative to healthy controls using the four-component (4C) model, and (2) to explore the validity of DXA body composition assessment in ED patients.

Subjects/Methods:

Body composition of 13 females with ED and 117 controls, aged 10–18 years, was investigated using the 4C model. Accuracy of DXA for estimation of FFM and fat mass (FM) was tested using the approach of Bland and Altman.

Results:

Adjusting for age, height and pubertal stage, ED patients had significantly lower whole-body FM, FFM, protein mass (PM) and mineral mass (MM) compared with controls. Trunk and limb FM and limb lean soft tissue were significantly lower in ED patients. However, no significant difference in the hydration of FFM was detected. Compared with the 4C model, DXA overestimated FM by 5±36% and underestimated FFM by 1±9% in ED patients.

Conclusion:

Our study confirms that ED patients are depleted not only in FM but also in FFM, PM and MM. DXA has limitations for estimating body composition in individual young female ED patients.

Lung transplantation in patients with cystic fibrosis: special focus to infection and comorbidities

Despite advances in medical care, patients with cystic fibrosis still face limited life expectancy. The most common cause of death remains respiratory failure. End-stage cystic fibrosis can be treated with lung transplantation and is the third most common reason for which the procedure is performed. Outcomes for cystic fibrosis are better than most other lung diseases, but remain limited (5-year survival 60%). For patients with advanced disease lung transplantation appears to improve survival. Outcomes for patients with Burkholderia cepacia remain poor, although they are better for patients with certain genomovars. Controversy exists about Mycobacterium abscessus infection and appropriateness for transplant. More information is also becoming available for comorbidities, including diabetes and pulmonary hypertension among others. Extra-corporeal membrane oxygenation is used more frequently for end-stage disease as a bridge to lung transplantation and will likely be used more in the future.

Body composition and pulmonary function in cystic fibrosis

BACKGROUND

Lower body mass index (BMI) is associated with worse pulmonary function in cystic fibrosis (CF).

HYPOTHESIS

lean body mass (LBM) is more strongly associated with pulmonary function than BMI is.

METHODS

Anthropometrics, body composition by dual x-ray absorptiometry, and pulmonary function were determined in pancreatic insufficient CF (PI-CF) youth. Sex and age-adjusted Z-scores (BMI-Z, LBMI-Z, FMI-Z) were generated for CF and controls. (1) Associations of BMI-Z with LBMI-Z and FMI-Z and (2) age-adjusted associations of BMI-Z, LBMI-Z, and FMI-Z with FEV1%-predicted were tested.

RESULTS

Two hundred eight PI-CF subjects had lower BMI-Z, LBMI-Z, and FMI-Z compared to 390 controls. BMI-Z was associated with lower LBMI-Z (p < 0.0001) in PI-CF. In females, LBMI-Z and BMI-Z were positively associated with FEV1%-predicted; this relationship did not persist for FMI-Z after adjustment for LBMI-Z. In males, only LBMI-Z and BMI-Z were associated with FEV1%-predicted.

CONCLUSION

In PI-CF youth, deficits in LBM were apparent. At lower BMI percentiles, BMI may not accurately depict LBM in PI-CF. In under-nourished PI-CF youth, this preservation of FM in preference to LBM is relevant since LBMI-Z, but not FMI-Z, is positively associated with FEV1%-predicted. Lean body mass index is more strongly associated with lung function compared to BMI, especially in the under-nourished child and adolescent with PI-CF.

Body-composition reference data for simple and reference techniques and a 4-component model: a new UK reference child

BACKGROUND

A routine pediatric clinical assessment of body composition is increasingly recommended but has long been hampered by the following 2 factors: a lack of appropriate techniques and a lack of reference data with which to interpret individual measurements. Several techniques have become available, but reference data are needed.

OBJECTIVE

We aimed to provide body-composition reference data for use in clinical practice and research.

DESIGN

Body composition was measured by using a gold standard 4-component model, along with various widely used reference and bedside methods, in a large, representative sample of British children aged from 4 to ≥20 y. Measurements were made of anthropometric variables (weight, height, 4 skinfold thicknesses, and waist girth), dual-energy X-ray absorptiometry, body density, bioelectrical impedance, and total body water, and 4-component fat and fat-free masses were calculated. Reference charts and SD scores (SDSs) were constructed for each outcome by using the lambda-mu-sigma method. The same outcomes were generated for the fat-free mass index and fat mass index.

RESULTS

Body-composition growth charts and SDSs for 5-20 y were based on a final sample of 533 individuals. Correlations between SDSs by using different techniques were ≥0.68 for adiposity outcomes and ≥0.80 for fat-free mass outcomes.

CONCLUSIONS

These comprehensive reference data for pediatric body composition can be used across a variety of techniques. Together with advances in measurement technologies, the data should greatly enhance the ability of clinicians to assess and monitor body composition in routine clinical practice and should facilitate the use of body-composition measurements in research studies.

Measures of body habitus are associated with lung function in adults with cystic fibrosis: a population-based study

BACKGROUND

Body habitus differences may explain some of the variation in lung function between individuals with cystic fibrosis (CF). We tested the hypothesis that measures of lean muscle mass and obesity are independently associated with lung function in CF.

METHODS

Cross-sectional study design using UK CF registry data from 2096 clinically stable adults.

RESULTS

Serum creatinine and BMI were positively and independently associated with FEV1 and FVC. One standard deviation increment in serum creatinine was associated with an FEV1 increase of 171ml (95% confidence intervals CI: +116 to +227ml) in males and 90ml (95% CI: +46 to +133ml) in females. Compared to the reference group of 20-24.9kg/m(2), those with a BMI<20kg/m(2) had lower FEV1 with values of -642ml (95%CI: -784 to -500ml) for males and -468ml (95%CI: -564 to -372ml) for females.

CONCLUSIONS

Prospective studies and controlled trials are required to ascertain if these associations have therapeutic potential in modifying disease progression.