Nutritional outcomes following gastrostomy in children with cystic fibrosis

An emotional journey: caregiver experiences with gastrostomy tube decision-making for children with cystic fibrosis

BACKGROUND

Nutritional challenges are common in early CF care and stressful for caregivers of children with CF (cwCF) to navigate. Gastrostomy tube (G-tube) placement can improve weight gain, however the decision to proceed with placement is personalized and preference-sensitive. Little is known about the experiences of caregivers of cwCF and the G-tube decision-making process.

OBJECTIVES

The present study used a qualitative approach to explore the perceptions and experiences of caregivers of cwCF with G-tube introductions and recommendations, as well as factors influencing G-tube decision-making.

METHODS

Caregivers of cwCF aged ≤ 10 years completed audio-taped, semi-structured interviews describing their experiences with G-tube placement discussions. Interviews were transcribed and two independent researchers coded the transcripts and conducted content and thematic analysis using an inductive approach.

RESULTS

Participants included 43 caregivers, 84 % were mothers (36/43). CwCF had a mean age of 4 years (SD=2.6), 84 % were White (36/43), and 60 % reported weights below <50th percentile (26/43). All caregivers knew about G-tubes, 44 % (19/43) were recommended a G-tube and 35 % (15/43) had a G-tube placed. Major findings included descriptions of the stages of G-tube decision-making from a heads up, to the game plan, to making a first difficult decision and finally living with the decision to pursue G-tube placement.

CONCLUSION

G-tube decision-making is an emotional and personalized journey for caregivers of cwCF. Efforts to explore the values and priorities of caregivers is imperative to supporting families making difficult decisions in CF care.

Factors guiding gastrostomy tube decision-making for caregivers of children with cystic fibrosis: a scoping review protocol

INTRODUCTION

While ensuring appropriate growth is essential for all children, optimising nutritional status in children with cystic fibrosis (CF) is critical for improving health outcomes. Nutritional challenges in CF are multifactorial and malnutrition is common. While gastrostomy tubes (G-tubes) can improve weight status in individuals with CF, they also have common and chronic complications resulting in clinical equipoise. To date, factors influencing G-tube decision-making among caregivers of children with CF have not been systematically explored. This review aims to chart existing knowledge about caregivers' decisional needs related to G-tube placement, with a focus on caregivers of children with CF, as well as known medical and psychosocial benefits and risks of G-tube feedings in paediatric care.

METHODS AND ANALYSIS

This scoping review will follow the JBI methodological framework. We will include articles published between 1 January 1985 and 1 November 2023 in English and Spanish from MEDLINE (Ovid), Embase, CINAHL, PsycInfo, Cochrane Database of Systematic Reviews and Web of Science related to G-tube decision-making. Articles published in languages besides English and Spanish will be excluded. Articles will be screened for final eligibility and inclusion according to title and abstract, followed by full texts. Articles will be independently reviewed by two reviewers and any disagreements discussed with a third reviewer for consensus. We will map themes and concepts, and data extracted will be presented in tabular, diagrams and descriptive summaries.

ETHICS AND DISSEMINATION

As a form of secondary analysis, scoping reviews do not require ethics approval. This review will inform future research with caregivers involved in G-tube decision-making for children with CF. The final review will be submitted to a peer-reviewed scientific journal, disseminated at relevant academic conferences and will be shared with patients and clinicians.

TRIAL REGISTRATION NUMBER

Center for Open Science. https://osf.io/g4pdb.

Early life growth trajectories in cystic fibrosis are associated with lung function at age six

BACKGROUND

Higher growth percentiles are associated with more favorable lung function in cystic fibrosis (CF), prompting the creation of CF Foundation (CFF) nutritional guidelines.

OBJECTIVES

To describe early childhood growth trajectories within CF, to determine if growth trajectories are associated with differences in lung function at age six, and to identify factors that differ between trajectory groups.

METHODS

Retrospective cohort study of children diagnosed with CF and born 2000-2011 using the US CFF Patient Registry. Annualized growth parameters prior to age six were included in group-based trajectory modeling to identify unique early life growth trajectories. FEV1 percent predicted (FEV1pp) at age six was compared between trajectory groups using linear regression. Factors associated with group membership were identified using multinomial logistic regression.

RESULTS

6,809 children met inclusion criteria. Six discrete growth trajectories were identified, including three groups that began with growth parameters >50th percentile, termed: "always high", "gradual decliner", "rapid decliner", and three which began with growth parameters <50th percentile, termed: "rapid riser", "gradual riser", "always low". FEV1pp at age six was highest for the Always High trajectory. The Always Low trajectory was nearly 10% lower than the Always High trajectory. Sex, ethnicity, newborn screening and pancreatic function were associated with trajectory class membership.

CONCLUSIONS

Distinct early life growth trajectories were identified within CF. Trajectories that met CFF nutritional guideline recommendations were associated with higher FEV1pp at age six. CF care teams should continue to partner with families to encourage interventions to support optimal growth to improve lung function in CF.

Real food in enteral nutrition for chronically ill children: overview and practical clinical cases

BACKGROUND

Many feeding strategies may be used in chronically ill children on enteral nutrition. Interest is currently growing in real food-based enteral nutrition. A new tube feeding formula with real food ingredients is currently commercially available in Europe.

CASE REPORTS

By focusing on four clinical cases, this article illustrates the use of a tube feeding formula with real food ingredients in pediatric patients with various complex conditions. The formula contains a milk-based mixture of peas, green beans, peaches, carrots, and chicken, and provides 1.2 kcal/ml. It was offered under medical supervision and after full consideration of all feeding options.

CONCLUSIONS

Formula choice appears to be based on clinical experience and must be individualized to patients' characteristics and needs. Real food-containing formulas seem to improve tolerance and feeding outcomes as well as promote family inclusion and mealtime engagement, but further studies are warranted.

Transitioning From Nasogastric Feeding Tube to Gastrostomy Tube in Pediatric Patients: A Survey on Decision-Making and Practice

BACKGROUND

Tube feeding via nasogastric tubes (NGTs) and gastrostomy tubes (GTs) is a common practice for children unable to meet their nutrition needs by oral feeding alone. There is currently a lack of evidence-based guidance specific for the process of transitioning from an NGT to GT as a longer-term enteral access device. Uncertainty in the literature about feeding tube choices, practices, and transitions requires clinicians to draw on incomplete and sometimes conflicting evidence, personal experience, economic realities, and compassion to deliver supportive child-centered care.

METHODS

The ASPEN Enteral Nutrition Task Force Pediatric Work Group designed a survey to explore current practice of enteral access device safety and use among pediatric clinicians practicing in the US and Canada. The survey aimed to define time frames, parameters, and decision points to guide clinicians and families in the transition from NG to GT feeding.

RESULTS

258 clinicians, 55% practicing in an inpatient setting, 17% in-home patient setting, and 28% practicing in both inpatient and outpatient setting. 22% were physicians, 42% were dietitians, 32% were nurses or advanced practice nurses, 2% were pharmacists. The most common feeding tubes used were NGTs followed by GTs. Majority of respondents indicated that they did not have a specific timeline for when an NGT should be changed to a GT. Highest ranked patient factors or clinical considerations prior to recommending changing from an NGT to a GT were exceeding the duration for temporary feeding or the need for an extended duration of tube feeding. Highest physician barriers to GT placement were the reluctance for referral from primary care doctors for GT placement. Majority of respondents reported the use of NGTs for enteral access at home and that parents were taught how to place the NGTs for home use but without consistently being taught the use of pH paper to verify NGT tip location or being provided with the pH paper to perform this task at home.

CONCLUSIONS

This survey is the first step to address the knowledge gap surrounding feeding tube choices by ascertaining the current standard of practice regarding enteral access devices and appropriate timing of transitioning from NGT to GT feeding. The results highlight current practice variability and concerns. Information from the survey was used to formulate a decision tree to guide the transition of NGT to GT feeding that nutrition support professionals can use to advocate for best practices in their hospital and community settings.

Long-term use of tube feeding in children with cystic fibrosis: results from two Belgian CF centers

BACKGROUND

Enteral tube feeding (ETF) is often used in an attempt to optimize the nutritional status. The aim of this study was to observe the long term effect of ETF and to compare the start of ETF with the current European guidelines on nutrition care in CF.

METHOD

From all patients who received ETF (ETFp) between February 2000 and September 2016 in the Ghent University Hospital (GUH) or Brussels University Hospital (BUH), z-scores for body weight (W), height (H), growth velocity (GV) and BMI, FEV₁%, and FVC% were retrospectively collected from the patients' medical record, 3 years before and 5 years after the year of ETF initiation. Gender, age, and pancreatic status matched controls were selected from the GUH database.

RESULTS

All baseline (T0) measurements in ETFp were worse compared to controls. Only 11% of the controls had a Hz < -1.6 compared 58% of the ETFp. After the initiation of ETF a rapid weight gain was noted until the second year (T + 2:-1.9 (-2.8; -1.0) vs. T0:-2.7 (-3.2; -2.1) (p = 0.01) with a stabilization afterwards. A rapid GVz increase was noted at T + 1:1.0 (-0.8; 1.9) vs. T0:-1.5 (-2.0;-0.3). After the start of ETF until T + 3, a stabilization of FEV₁% was noted. However, compared to controls, it remained significantly lower (p < 0.05).

CONCLUSION

ETF as a nutritional intervention has its effect on weight, height, GV, and BMI. To our knowledge this is the first study that describes the evolution of growth in ETFp. The effect on GV argues for a faster introduction of ETF in malnourished children with CF.

Enteral tube feeding for cystic fibrosis

BACKGROUND

Enteral tube feeding is routinely used in many cystic fibrosis centres when oral dietary and supplement intake has failed to achieve an adequate nutritional status. The use of this method of feeding is assessed on an individual basis taking into consideration the patients age and clinical status. This is a final update of a previously published review.

OBJECTIVES

To examine the evidence that in people with cystic fibrosis, supplemental enteral tube feeding improves nutritional status, respiratory function, and quality of life without significant adverse effects.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also contacted the companies that market enteral feeds and reviewed their databases.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 10 July 2019.Date of the most recent hand search of PubMed: 26 October 2018.

SELECTION CRITERIA

All randomised controlled trials comparing supplemental enteral tube feeding for one month or longer with no specific intervention in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The searches identified 44 trials; however, none were eligible for inclusion in this review.

MAIN RESULTS

There are no trials included in this review.

AUTHORS' CONCLUSIONS

Supplemental enteral tube feeding is widely used throughout the world to improve nutritional status in people with cystic fibrosis. The methods mostly used, nasogastric or gastrostomy feeding, are expensive and may have a negative effect on self-esteem and body image. Reported use of enteral tube feeding suggests that it results in nutritional and respiratory improvement; but, efficacy has not been fully assessed by randomised controlled trials. It is acknowledged, however, that performing a randomised controlled trial would be difficult due to the ethics of withholding an intervention in a group of people whose nutritional status necessitates it.

Nutritional Outcome in Home Gastrostomy-Fed Children with Chronic Diseases

The aim of the study was to assess the anthropometric outcomes after gastrostomy tube (GT) placement in children with chronic diseases and the influence of primary diagnosis, age, and nutritional support. A longitudinal, multicenter, and prospective study was performed evaluating 65 children with GT feeding and chronic diseases (61.5% with neurological disease). Each child was evaluated three times (at baseline and at 6 and 12 months after GT placement) and the following data was collected: primary diagnosis, age at GT placement, anthropometry, and feeding regime. Repeated measures ANOVA were used to analyze the main effects (intra and intergroup) and the interactions effects on weight gain and linear growth at 6 and 12 months after GT placement. All patients significantly improved their body mass index (BMI)-for-age z-score (p < 0.001) and height-for-age z-score (p < 0.05) after 6 and 12-month of follow-up. BMI gain increased significantly the first 6 months, followed by a plateau, while height followed a linear trend. Children with GT placement before 18 months old experienced an accelerated growth rate during the first 6 months post-GT. This technique showed the effectiveness of GT placement improving nutritional status and growth catch up regardless of their primary diagnosis and the type of nutritional support.

Nutrition: Prevention and management of nutritional failure in Cystic Fibrosis

Close monitoring of nutritional status is critical to the overall health of a patient with CF. As part of routine CF care, measurement of weight and height (and calculation of weight/length or BMI as appropriate) should be performed and analyzed at each visit. Early recognition of nutritional risk is imperative and evaluation with a multidisciplinary team should be performed to assess for caloric intake, caloric malabsorption, and other causes of poor weight gain and growth. Many tools are available to use for intervention, including oral supplementation, behavioral interventions, medications, nutritional therapies, and enteral tube feeding.

Exercise capacity following a percutaneous endoscopic gastrostomy in a young female with cystic fibrosis: a case report

Cystic fibrosis (CF) is a genetic condition affecting the respiratory and gastrointestinal systems, with patients experiencing problems maintaining weight, especially during rapid growth periods such as puberty. The aim of this case report was to monitor the effect of gastrostomy insertion and implementation of overnight supplemental feeding upon clinical outcomes, including body mass index (BMI), lung function (FEV₁), and exercise‐related variables (maximal oxygen uptake [VO_2max] and ventilatory efficiency [V_E/VO₂]) in an 11‐year‐old female with CF. Combined incremental and supramaximal exercise testing to exhaustion was performed at four time points: 3 months prior to the procedure (T1), 2 days prior to (T2), 4 months (T3), and 1 year following the procedure (T4). Improvements following gastrostomy insertion were observed at the 1 year follow‐up with regards to BMI (+20%); whereas absolute VO_2max remained stable and lung function fluctuated throughout the period of observation. Declines in function with regards to body weight relative VO_2max (−16.3%) and oxygen uptake efficiency (+7.5%) were observed during this period. This case report is the first to consider exercise‐related clinical outcomes in assessing the effect of implementing gastrostomy feeding in CF. The varied direction and magnitude of the associations between variables shows that further investigations are required.

Enteral tube feeding for individuals with cystic fibrosis: Cystic Fibrosis Foundation evidence-informed guidelines

Nutrition is integral to the care of individuals with cystic fibrosis (CF). Better nutritional status is associated with improved pulmonary function. In some individuals with CF, enteral tube feeding can be useful in achieving optimal nutritional status. Current nutrition guidelines do not include detailed recommendations for enteral tube feeding. The Cystic Fibrosis Foundation convened an expert panel to develop enteral tube feeding recommendations based on a systematic review of the evidence and expert opinion. These guidelines address when to consider enteral tube feeding, assessment of confounding causes of poor nutrition in CF, preparation of the patient for placement of the enteral feeding tube, management of the tube after placement and education about enteral feeding. These recommendations are intended to guide the CF care team, individuals with CF, and their families through the enteral tube feeding process.

Nutrition and Growth in Cystic Fibrosis

Close attention to nutrition and growth is essential in caring for children with cystic fibrosis (CF). Growth and nutritional status should be monitored as part of routine CF care. Children with CF should achieve growth and nutritional status comparable with that of well-nourished children without CF. Children with CF are at risk for nutritional deficiencies. Optimal nutritional and growth status may be difficult to attain in this population given risk of insufficient caloric intake and likelihood of increased caloric expenditure. Various methods to attain optimal nutritional status may be used, including oral supplementation, behavioral treatment, pharmacotherapy, and enteral nutrition.

Clinical Practice Guidelines From the Cystic Fibrosis Foundation for Preschoolers With Cystic Fibrosis

Cystic fibrosis (CF) clinical care guidelines exist for the care of infants up to age 2 years and for individuals ≥6 years of age. An important gap exists for preschool children between the ages of 2 and 5 years. This period marks a time of growth and development that is critical to achieve optimal nutritional status and maintain lung health. Given that disease often progresses in a clinically silent manner, objective and sensitive tools that detect and track early disease are important in this age group. Several challenges exist that may impede the delivery of care for these children, including adherence to therapies. A multidisciplinary committee was convened by the CF Foundation to develop comprehensive evidence-based and consensus recommendations for the care of preschool children, ages 2 to 5 years, with CF. This document includes recommendations in the following areas: routine surveillance for pulmonary disease, therapeutics, and nutritional and gastrointestinal care.

Critical timing of gastrostomy insertion in a child with cystic fibrosis

Pulmonary exacerbations and malabsorption in children with cystic fibrosis (CF) can lead to faltering growth and poor weight gain. Children with a higher BMI (body mass index) show a slower decline in lung function. Our specialist CF centre has experienced a death following gastrostomy insertion in a young CF child, despite maximal medical intervention, which has made us reflect on our practice and the urgency with which we discuss the option for a gastrostomy to improve nutrition.

Clinical audit results in earlier nutritional intervention in malnourished children with cystic fibrosis with improved outcome

AIM

The association between nutritional status, pulmonary function and survival in cystic fibrosis (CF) is well established. A previous case series from the Royal Children's Hospital, Melbourne (RCH), demonstrated suboptimal referral practices and highlighted the importance of early nutritional interventions in children with CF. Various qualitative changes were made to our CF service, and this study assesses the effects of these practice changes timing of gastrostomy and clinical outcome in patients who underwent gastrostomy insertion.

METHOD

Clinical audit of all CF patients who had undergone gastrostomy insertion from 2002 to 2010 at Royal Children's Hospital. Clinical data, including nutritional parameters, respiratory function and survival, were collected at 2 years prior and 2 years post gastrostomy insertion. Data were compared with the previous study from 1989 to 1997.

RESULTS

Patients with CF who underwent gastrostomy insertion between 2002 and 2010 (n = 22) had higher weight-for-age scores (-1.5 ± 0.68 vs. -2.67 ± 1.06; P = 0.0001) and higher forced expiratory volume in 1 s (68% ± 22 vs. 52% ± 18.5; P = 0.006), compared with the cohort from 1989 to 1997 (n = 37). These differences were maintained at 2-year follow-up. Pseudomonas aeruginosa colonisation rate was 100% in 1989-1997 vs. 41% in 2002-2010; P = 0.0001. The 2-year survival post-gastrostomy insertion improved from 70% to 100%; P = 0.004.

CONCLUSION

Earlier referral of patients in the recent cohort resulted in sustained improvements in weight-for-age and lung function. Survival at 2 years post-procedure was significantly improved. This study confirms the value of clinical audits and subsequent re-evaluation of clinical services.

Enteral tube feeding for cystic fibrosis

BACKGROUND

Enteral tube feeding is routinely used in many cystic fibrosis centres when oral dietary and supplement intake has failed to achieve an adequate nutritional status. The use of this method of feeding is assessed on an individual basis taking into consideration the patients age and clinical status.

OBJECTIVES

To examine the evidence that in people with cystic fibrosis, supplemental enteral tube feeding improves nutritional status, respiratory function, and quality of life without significant adverse effects.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also contacted the companies that market enteral feeds and reviewed their databases.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 13 February 2015.Date of the most recent hand search of PubMed and conference abstract books: 13 February 2015.

SELECTION CRITERIA

All randomised controlled trials comparing supplemental enteral tube feeding for one month or longer with no specific intervention in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The searches identified 38 trials; however, none were eligible for inclusion in this review.

MAIN RESULTS

There are no trials included in this review.

AUTHORS' CONCLUSIONS

Supplemental enteral tube feeding is widely used throughout the world to improve nutritional status in people with cystic fibrosis. The methods mostly used, nasogastric or gastrostomy feeding, are expensive and may have a negative effect on self-esteem and body image. Reported use of enteral tube feeding suggests that it results in nutritional and respiratory improvement; but, efficacy has not been fully assessed by randomised controlled trials. It is acknowledged, however, that performing a randomised controlled trial would be difficult due to the ethics of withholding an intervention in a group of patients whose nutritional status necessitates it.

ESPGHAN position paper on management of percutaneous endoscopic gastrostomy in children and adolescents

OBJECTIVES

This European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) position statement provides a comprehensive guide for health care providers to manage percutaneous endoscopic gastrostomy tubes in a safe, effective, and appropriate way.

METHODS

Relevant literature from searches of PubMed, CINAHL, and recent guidelines was reviewed. In the absence of evidence, recommendations reflect the expert opinion of the authors. Final consensus was obtained by multiple e-mail exchange and during 3 face-to-face meetings of the gastroenterology committee of the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition.

RESULTS

Endoscopically placed gastrostomy devices are essential in the management of children with feeding and nutritional problems. The article focuses on practical issues such as indications and contraindications.

CONCLUSIONS

The decision to place an endoscopic gastrostomy has to be made by an appropriate multidisciplinary team, which then provides active follow-up and care for the child and the device.

Pancreatic enzyme replacement therapy dosing and nutritional outcomes in children with cystic fibrosis

OBJECTIVES

To utilize the Cystic Fibrosis Foundation Patient Registry to evaluate whether pancreatic enzyme dose is associated with better nutritional status as measured by average body mass index (BMI) percentile.

STUDY DESIGN

A retrospective analysis of the Cystic Fibrosis Foundation Patient Registry from 2005-2008 was performed. The final analysis included 42 561 patient visits from 14 482 patients 2-20 years of age taking pancreatic enzyme replacement therapy from 179 programs. Cystic fibrosis care programs were assigned to quartiles based on adjusted mean patient BMI percentiles. Differences in median lipase dose between programs in the highest and lowest BMI quartiles were examined using a mixed effects model that adjusted for individual patient BMI, age, race, ethnicity, forced expiratory volume in 1 second percent, acid-blocker use, presence of Pseudomonas aeruginosa, nutritional supplement use, growth hormone use, and diagnosis of cystic fibrosis-related diabetes.

RESULTS

A significant difference in median enzyme dose existed between the highest and lowest BMI quartiles. Multivariable analysis demonstrated the effect persisted after adjustment for covariates. Highest quartile programs had a median enzyme dose of 1755 lipase units/kg/meal compared with 1628 lipase units/kg/meal for lowest quartile programs.

CONCLUSION

Patients attending US cystic fibrosis programs achieving highest nutritional outcomes, measured by mean BMI percentile, have higher enzyme dosing than those attending programs at lower performance levels. Further randomized clinical trials are necessary to determine the role of enzyme dose in improving nutritional outcomes.

Gastrostomy in children with cystic fibrosis and portal hypertension

Children with cystic fibrosis-associated liver disease (CFALD) and portal hypertension may require supplemental feeding with gastrostomy; however, this could lead to the development of stomal varices. We assessed this risk and nutritional and pulmonary outcome in a series of 7 children with CFALD and portal hypertension. In 35.1 patient-years of follow-up, none developed stomal varices or had a gastrointestinal bleed attributable to a varix. There was significant improvement in nutrition and lung function 2 years postinsertion. We conclude that gastrostomy placement for poor nutrition in children with CFALD and portal hypertension is safe and contributes to improved nutritional and pulmonary outcome.

Enteral tube feeding for cystic fibrosis

BACKGROUND

Enteral tube feeding is routinely used in many cystic fibrosis centres when oral dietary and supplement intake has failed to achieve an adequate nutritional status. The use of this method of feeding is assessed on an individual basis taking into consideration the patients age and clinical status.

OBJECTIVES

To examine the evidence that in people with cystic fibrosis, supplemental enteral tube feeding improves nutritional status, respiratory function, and quality of life without significant adverse effects.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also contacted the companies that market enteral feeds and reviewed their databases.Date of the most recent search of the Group's Cystic Fibrosis Trials Register: 03 September 2012.Date of the most recent hand search of PubMed and conference abstract books: 15 June 2012.

SELECTION CRITERIA

All randomised controlled trials comparing supplemental enteral tube feeding for one month or longer with no specific intervention in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Thirty-one trials were identified by the searches; however, none were eligible for inclusion in this review.

MAIN RESULTS

There are no trials included in this review.

AUTHORS' CONCLUSIONS

Supplemental enteral tube feeding is widely used throughout the world to improve nutritional status in people with cystic fibrosis. The methods mostly used, nasogastric or gastrostomy feeding, are expensive and may have a negative effect on self-esteem and body image. Reported use of enteral tube feeding suggests that it results in nutritional and respiratory improvement; but, efficacy has not been fully assessed by randomised controlled trials. It is acknowledged, however, that performing a randomised controlled trial would be difficult due to the ethics of withholding an intervention in a group of patients whose nutritional status necessitates it.

Genetic modifiers of nutritional status in cystic fibrosis

BACKGROUND

Improved nutrition early in life is associated with better pulmonary function for patients with cystic fibrosis (CF). However, nutritional status is poorly correlated with the CFTR genotype.

OBJECTIVE

We investigated the extent to which modifier genes influence nutrition in children with CF.

DESIGN

BMI data were longitudinally collected from the CF Twin-Sibling Study and Cystic Fibrosis Foundation Patient Registry for twins and siblings from 2000 to 2010. A nutritional phenotype was derived for 1124 subjects by calculating the average BMI z score from 5-10 y of age (BMI-z(5to10)). The genetic contribution to the variation in BMI-z(5to10) (ie, heritability) was estimated by comparing the similarity of the phenotype in monozygous twins to that in dizygous twins and siblings. Linkage analysis identified potential modifier-gene loci.

RESULTS

The median BMI-z(5to10) was -0.07 (range: -3.89 to 2.30), which corresponded to the 47th CDC percentile. BMI-z(5to10) was negatively correlated with pancreatic insufficiency, history of meconium ileus, and female sex but positively correlated with later birth cohorts and lung function. Monozygous twins showed greater concordance for BMI-z(5to10) than did dizygous twins and siblings; heritability estimates from same-sex twin-only analyses ranged from 0.54 to 0.82. For 1010 subjects with pancreatic insufficiency, genome-wide significant linkage was identified on chromosomes 1p36.1 [log of odds (LOD): 5.3] and 5q14 (LOD: 5.1). These loci explained ≥16% and ≥15%, respectively, of the BMI variance.

CONCLUSIONS

The analysis of twins and siblings with CF indicates a prominent role for genes other than CFTR to BMI variation. Specifically, regions on chromosomes 1 and 5 appear to harbor genetic modifiers of substantial effect.