Comparison of growth status of patients with cystic fibrosis between the United States and Canada

Physiologically-based pharmacokinetic modeling of the drug-drug interaction between ivacaftor and lefamulin in cystic fibrosis patients

Lefamulin is being evaluated as a treatment for bacterial exacerbations in cystic fibrosis (CF). Ivacaftor is approved for the treatment of patients with CF. Lefamulin is a moderate CYP3A inhibitor and co-administration with ivacaftor may result in a drug-drug interaction (DDI). A CF population was built based on literature using the Simcyp Simulator. A previously developed and validated physiologically-based pharmacokinetic (PBPK) model for ivacaftor was used. A PBPK model for lefamulin was developed and verified. Predicted concentrations and pharmacokinetic (PK) parameters for both ivacaftor and lefamulin in healthy subjects and patients with CF were in reasonable agreement with observed data (within 1.4-fold, majority within 1.25-fold). The lefamulin model as a CYP3A4 perpetrator was validated using a different Ki value for oral (p.o.) and intravenous (i.v.) routes. The simulated changes in area under the curve of ivacaftor in patients with CF when co-administered with p.o. and i.v. lefamulin were weak-to-moderate. The predicted change in ivacaftor PK when co-administered with oral lefamulin was less than observed between ivacaftor and fluconazole. These results suggest a low liability for a DDI between lefamulin and ivacaftor in patients with CF.

Nutrition in Cystic Fibrosis—Some Notes on the Fat Recommendations

Nutrition is important in cystic fibrosis (CF) because the disease is associated with a higher energy consumption, special nutritional deficiencies, and malabsorption mainly related to pancreatic insufficiency. The clinical course with deterioration of lung function has been shown to relate to nutrition. Despite general recommendation of high energy intake, the clinical deterioration is difficult to restrain suggesting that special needs have not been identified and specified. It is well-known that the CF phenotype is associated with lipid abnormalities, especially in the essential or conditionally essential fatty acids. This review will concentrate on the qualitative aspects of fat metabolism, which has mainly been neglected in dietary fat recommendations focusing on fat quantity. For more than 60 years it has been known and confirmed that the patients have a deficiency of linoleic acid, an n-6 essential fatty acid of importance for membrane structure and function. The ratio between arachidonic acid and docosahexaenoic acid, conditionally essential fatty acids of the n-6 and n-3 series, respectively, is often increased. The recently discovered relations between the CFTR modulators and lipid metabolism raise new interests in this field and together with new technology provide possibilities to specify further specify personalized therapy.

The Exocrine Pancreas in Cystic Fibrosis in the Era of CFTR Modulation: A Mini Review

Cystic fibrosis (CF) is a common disorder of autosomal recessive inheritance, that once conferred a life expectancy of only a few months. Over recent years, significant advances have been made to CF therapeutic approaches, changing the face of the disease, and facilitating the partial restoration of pancreatic function. This mini review summarizes the current landscape of exocrine pancreatic management in CF and explores areas for future direction and development.

Obesity in cystic fibrosis

The prevalence of obesity in patients with cystic fibrosis (CF) is increasing and around one-third of adults with CF are now overweight or obese. The causes of excess weight gain in CF are likely multifactorial, including: adherence to the high-fat legacy diet, reduced exercise tolerance, therapeutic advances, and general population trends. Increased weight has generally been considered favorable in CF, correlating with improved pulmonary function and survival. While the optimal BMI for overall health in CF is unknown, most studies demonstrate minimal improvement in pulmonary function when BMI exceeds 30 kg/m2. Dyslipidemia and cardiovascular disease are important co-morbidities of obesity in the general population, but are uncommon in CF. In people with CF, obesity is associated with hypertension and higher cholesterol levels. With longer life expectancy and rising obesity rates, there may be an increase in cardiovascular disease among people with CF in coming years. Overweight CF patients are more likely to be insulin resistant, taking on features of type 2 diabetes. Treating obesity in people with CF requires carefully weighing the metabolic risks of overnutrition with the impact of low or falling BMI on lung function. This article describes current knowledge on the epidemiology, causes, consequence, and treatment of obesity in people with CF.

A G542X cystic fibrosis mouse model for examining nonsense mutation directed therapies

Nonsense mutations are present in 10% of patients with CF, produce a premature termination codon in CFTR mRNA causing early termination of translation, and lead to lack of CFTR function. There are no currently available animal models which contain a nonsense mutation in the endogenous Cftr locus that can be utilized to test nonsense mutation therapies. In this study, we create a CF mouse model carrying the G542X nonsense mutation in Cftr using CRISPR/Cas9 gene editing. The G542X mouse model has reduced Cftr mRNA levels, demonstrates absence of CFTR function, and displays characteristic manifestations of CF mice such as reduced growth and intestinal obstruction. Importantly, CFTR restoration is observed in G542X intestinal organoids treated with G418, an aminoglycoside with translational readthrough capabilities. The G542X mouse model provides an invaluable resource for the identification of potential therapies of CF nonsense mutations as well as the assessment of in vivo effectiveness of these potential therapies targeting nonsense mutations.

Kcnn4 is a modifier gene of intestinal cystic fibrosis preventing lethality in the Cftr-F508del mouse

Nearly 70% of cystic fibrosis (CF) patients bear the phenylalanine-508 deletion but disease severity differs greatly, and is not explained by the existence of different mutations in compound heterozygous. Studies demonstrated that genes other than CFTR relate to intestinal disease in humans and CF-mouse. Kcnn4, the gene encoding the calcium-activated potassium channel KCa3.1, important for intestinal secretion, is present in a locus linked with occurrence of intestinal CF-disease in mice and humans. We reasoned that it might be a CF-modifier gene and bred a CF-mouse with Kcnn4 silencing, finding that lethality was almost abolished. Silencing of Kcnn4 did not improve intestinal secretory functions, but rather corrected increased circulating TNF-α level and reduced intestinal mast cell increase. Given the importance of mast cells in intestinal disease additional double mutant CF-animals were tested, one lacking mast cells (C-kitW-sh/W-sh) and Stat6-/- to block IgE production. While mast cell depletion had no effect, silencing Stat6 significantly reduced lethality. Our results show that Kcnn4 is an intestinal CF modifier gene partially acting through a STAT6-dependent mechanism.

Growth deficits in cystic fibrosis mice begin in utero prior to IGF-1 reduction

Growth deficits are common in cystic fibrosis (CF), but their cause is complex, with contributions from exocrine pancreatic insufficiency, pulmonary complications, gastrointestinal obstructions, and endocrine abnormalities. The CF mouse model displays similar growth impairment despite exocrine pancreatic function and in the absence of chronic pulmonary infection. The high incidence of intestinal obstruction in the CF mouse has been suggested to significantly contribute to the observed growth deficits. Previous studies by our group have shown that restoration of the cystic fibrosis transmembrane conductance regulator (CFTR) in the intestinal epithelium prevents intestinal obstruction but does not improve growth. In this study, we further investigate growth deficits in CF and gut-corrected CF mice by assessing insulin-like growth factor 1 (IGF-1). IGF-1 levels were significantly decreased in CF and gut-corrected CF adult mice compared to wildtype littermates and were highly correlated with weight. Interestingly, perinatal IGF-1 levels were not significantly different between CF and wildtype littermates, even though growth deficits in CF mice could be detected late in gestation. Since CFTR has been suggested to play a role in water and nutrient exchange in the placenta through its interaction with aquaporins, we analyzed placental aquaporin expression in late-gestation CF and control littermates. While significant differences were observed in Aquaporin 9 expression in CF placentas in late gestation, there was no evidence of placental fluid exchange differences between CF and control littermates. The results from this study indicate that decreased IGF-1 levels are highly correlated with growth in CF mice, independent of CF intestinal obstruction. However, the perinatal growth deficits that are observed in CF mice are not due to decreased IGF-1 levels or differences in placenta-mediated fluid exchange. Further investigation is necessary to understand the etiology of early growth deficits in CF, as growth has been shown to be a significant factor in disease outcomes.

Growth Deficiency in Cystic Fibrosis Is Observable at Birth and Predictive of Early Pulmonary Function

INTRODUCTION

Cystic fibrosis (CF) is a complex disease that includes both pulmonary and gastrointestinal challenges, resulting in decreased weight. Pulmonary symptoms of CF are extremely variable. Greater body mass at an early age is associated with improved pulmonary function, but it is unknown at what age weight becomes predictive of pulmonary disease severity. The purpose of this study was to investigate the relationship between birth weight and pulmonary function in CF.

METHODS

Birth weight and pulmonary data were obtained. Linear regressions were used to examine the relationship between these two variables. A one-tailed t-test was used to compare birth weights between CF patients and the national average.

RESULTS

Birth weight was significantly lower in babies with CF and correlated with pulmonary disease at ages 6 and 10 years but not with age at which Pseudomonas aeruginosa colonization was observed.

DISCUSSION

These data suggest that CF growth deficiency has prenatal origins. Early nutritional intervention for babies with CF and a low birth weight is warranted to maximize pulmonary potential.

Growth and the Growth Hormone-Insulin Like Growth Factor 1 Axis in Children With Chronic Inflammation: Current Evidence, Gaps in Knowledge, and Future Directions

Growth failure is frequently encountered in children with chronic inflammatory conditions like juvenile idiopathic arthritis, inflammatory bowel disease, and cystic fibrosis. Delayed puberty and attenuated pubertal growth spurt are often seen during adolescence. The underlying inflammatory state mediated by proinflammatory cytokines, prolonged use of glucocorticoid, and suboptimal nutrition contribute to growth failure and pubertal abnormalities. These factors can impair growth by their effects on the GH-IGF axis and also directly at the level of the growth plate via alterations in chondrogenesis and local growth factor signaling. Recent studies on the impact of cytokines and glucocorticoid on the growth plate further advanced our understanding of growth failure in chronic disease and provided a biological rationale of growth promotion. Targeting cytokines using biological therapy may lead to improvement of growth in some of these children, but approximately one-third continue to grow slowly. There is increasing evidence that the use of relatively high-dose recombinant human GH may lead to partial catch-up growth in chronic inflammatory conditions, although long-term follow-up data are currently limited. In this review, we comprehensively review the growth abnormalities in children with juvenile idiopathic arthritis, inflammatory bowel disease, and cystic fibrosis, systemic abnormalities of the GH-IGF axis, and growth plate perturbations. We also systematically reviewed all the current published studies of recombinant human GH in these conditions and discussed the role of recombinant human IGF-1.

A standardized approach to estimating survival statistics for population-based cystic fibrosis registry cohorts

OBJECTIVES

Our objective was to quantify the effect of different statistical techniques, inclusion/exclusion criteria, and missing data on the predicted median survival age.

STUDY DESIGN AND SETTING

Using the Canadian cystic fibrosis registry (CCFR), the median age of survival was calculated using both the Cox proportional hazards (PH) and the life-table methods. Through simulations, we examined how the median age of survival would change when: (1) patients were excluded, (2) death dates were inaccurate, (3) patients were lost to follow-up, (4) entire years with no clinic visits were excluded even if the​ patient had a visit in subsequent years, and (5) censoring patients at their date of transplant. Simulations were run assuming 5-35% of data were affected by each scenario.

RESULTS

Over the period 2009-2013, there were 4,666 individuals in the CCFR with 240 deaths. The observed median age of survival calculated by the Cox PH method was 50.9 [95% confidence interval (CI): 47.4, 54.3] and 50.5 from the life-table method (95% CI: 47.5, 53.5). Censoring patients at their transplant date overestimated the median age of survival by 7.2 years (58.1; 95% CI: 53.3, 64.7). Simulations determined that by missing just 15% of deaths, the median age of survival can be overestimated by 3.5 years (54.4; 95% CI: 54.2, 56.1), and having 25% of patients lost to follow-up can underestimate the median age of survival by 3.3 years (47.6; 95% CI: 46.8, 47.7).

CONCLUSION

We present several recommendations to assist national cystic fibrosis registries in calculating and reporting the median age of survival in a standardized fashion. It is imperative to state the statistical method used as well as the proportion lost to follow-up and the treatment of missing data and transplanted patients. Registries must be diligent in their data collection as incomplete data can lead to overestimation and underestimation of survival.

Changes in Mineral Micronutrient Status During and After Pulmonary Exacerbation in Adults With Cystic Fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) may be at risk for micronutrient depletion, particularly during periods of illness and infection. The purpose of this study was to investigate serum micronutrient status over time in adults with CF initially hospitalized with a pulmonary exacerbation.

MATERIALS AND METHODS

This was an ancillary study of a multicenter trial investigating the role of high-dose vitamin D supplementation in 24 adults with CF (mean age, 29.6 ± 7.3 years). We measured serum concentrations of copper (Cu), iron (Fe), calcium (Ca), magnesium (Mg), potassium (K), and sulfur (S) in subjects at the beginning of a pulmonary exacerbation and again at 3 months.

RESULTS

Serum concentrations of Cu, Fe, and Ca were significantly lower at baseline compared with 3 months following the pulmonary exacerbation (Cu: baseline, 1.5 ± 0.6 vs 3 months, 1.6 ± 0.6 µg/mL, P = .027; Fe: 0.8 ± 0.3 vs 1.3 ± 1.1 µg/mL, P = .026; Ca: 9.7 ± 0.8 vs 10.8 ± 2.0 mg/dL, P = .024). Serum concentrations of K, Mg, and S did not change over time (K: baseline, 4.9 ± 0.3 vs 3 months, 5.1 ± 0.5 mEq/L; Mg: 1.8 ± 0.2 vs 2.0 ± 0.3 mg/dL; S: 1288.6 ± 343 vs 1309.9 ± 290 µg/mL; P > .05 for all).

CONCLUSION

Serum concentrations of Cu, Fe, and Ca increased significantly several months following recovery from acute pulmonary exacerbation in adults with CF. This may reflect decreased inflammation, improved food intake, and/or increased absorption following recovery.

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.

Update of faecal markers of inflammation in children with cystic fibrosis

There is evidence of intestinal inflammation in patients with CF. Intestinal inflammation may negatively impact the nutritional status of patient with CF, which adversely affects pulmonary function and survival. This paper provides an up-to-date review of intestinal inflammation in CF and an evaluation of utility of two specific faecal inflammatory markers (S100A12 and calprotectin).

Cystic fibrosis growth retardation is not correlated with loss of Cftr in the intestinal epithelium

Maldigestion due to exocrine pancreatic insufficiency leads to intestinal malabsorption and consequent malnutrition, a mechanism proposed to cause growth retardation associated with cystic fibrosis (CF). However, although enzyme replacement therapy combined with increased caloric intake improves weight gain, the effect on stature is not significant, suggesting that growth retardation has a more complex etiology. Mouse models of CF support this, since these animals do not experience exocrine pancreatic insufficiency yet are growth impaired. Cftr absence from the intestinal epithelium has been suggested as a primary source of growth retardation in CF mice, a concept we directly tested by generating mouse models with Cftr selectively inactivated or restored in intestinal epithelium. The relationship between growth and functional characteristics of the intestines, including transepithelial electrophysiology, incidence of intestinal obstruction, and histopathology, were assessed. Absence of Cftr exclusively from intestinal epithelium resulted in loss of cAMP-stimulated short-circuit current, goblet cell hyperplasia, and occurrence of intestinal obstructions but only slight and transient impaired growth. In contrast, specifically restoring Cftr to the intestinal epithelium resulted in restoration of ion transport and completely protected against obstruction and histopathological anomalies, but growth was indistinguishable from CF mice. These results indicate that absence of Cftr in the intestinal epithelium is an important contributor to the intestinal obstruction phenotype in CF but does not correlate with the observed growth reduction in CF.

CREON (Pancrelipase Delayed-Release Capsules) for the treatment of exocrine pancreatic insufficiency

Exocrine pancreatic insufficiency (EPI) is associated with conditions including cystic fibrosis (CF), chronic pancreatitis (CP), and pancreatic surgery (PS). The symptoms include maldigestion, malnutrition, weight loss, flatulence, and steatorrhea. Pancreatic enzyme replacement therapy (PERT) is the standard treatment for EPI; it is regulated in many countries and most recently in the USA following a US FDA mandate for all PERT manufacturers to submit new drug applications. Pancrelipase delayed-release capsules (CREON®, Abbott, Marietta, GA, USA) have been available in Europe since 1984 and in the USA since 1987; a new formulation was the first PERT to gain approval in the USA in 2009. The efficacy and safety of CREON have been demonstrated in double-blind, randomized, placebo-controlled trials in patients with CF aged ≥7 years and in patients with CP or post-PS. The data consistently demonstrate significantly better fat and nitrogen absorption with CREON versus placebo, and improvements in clinical symptoms, stool frequency, and body weight. Additionally, efficacy and safety of CREON have been shown in open-label studies in young children with CF (aged 1 month to 6 years), with control of fat malabsorption and control of clinical symptoms. The most commonly reported adverse events (AEs) with PERT are gastrointestinal disorders and allergic skin reactions. In clinical studies, CREON was well tolerated with very few withdrawals due to AEs and a low frequency of AEs judged treatment related, regardless of patient age. To further support the known safety profile of PERT, all manufacturers are required to investigate risk factors for fibrosing colonopathy, a rare gastrointestinal complication of CF, and the theoretical risk of viral transmission from porcine-derived PERT products. Together, the clinical study data and wealth of clinical experience suggest that CREON is effective and safe in patients with EPI regardless of etiology, with a very favorable risk-benefit profile.

Management of pancreatic exocrine insufficiency: Australasian Pancreatic Club recommendations

Pancreatic exocrine insufficiency (PEI) occurs when the amounts of enzymes secreted into the duodenum in response to a meal are insufficient to maintain normal digestive processes. The main clinical consequence of PEI is fat maldigestion and malabsorption, resulting in steatorrhoea. Pancreatic exocrine function is commonly assessed by conducting a 3-day faecal fat test and by measuring levels of faecal elastase-1 and serum trypsinogen. Pancreatic enzyme replacement therapy is the mainstay of treatment for PEI. In adults, the initial recommended dose of pancreatic enzymes is 25,000 units of lipase per meal, titrating up to a maximum of 80,000 units of lipase per meal. In infants and children, the initial recommended dose of pancreatic enzymes is 500 units of lipase per gram of dietary fat; the maximum daily dose should not exceed 10,000 units of lipase per kilogram of bodyweight. Oral pancreatic enzymes should be taken with meals to ensure adequate mixing with the chyme. Adjunct therapy with acid-suppressing agents may be useful in patients who continue to experience symptoms of PEI despite high-dose enzyme therapy. A dietitian experienced in treating PEI should be involved in patient management. Dietary fat restriction is not recommended for patients with PEI. Patients with PEI should be encouraged to consume small, frequent meals and to abstain from alcohol. Medium-chain triglycerides do not provide any clear nutritional advantage over long-chain triglycerides, but can be trialled in patients who fail to gain or to maintain adequate bodyweight in order to increase energy intake.

Nutritional considerations in patients with cystic fibrosis

Nutritional status is strongly associated with pulmonary function and survival in cystic fibrosis patients. Attainment of a normal growth pattern in childhood and maintenance of adequate nutritional status in adulthood represent major goals of multidisciplinary cystic fibrosis centers. International guidelines on energy intake requirements, pancreatic enzyme-replacement therapy and fat-soluble vitamin supplementation are of utmost importance in daily practice. The present review summarizes the most up-to-date information on early nutritional management in newly diagnosed patients and evaluates the benefits of aggressive nutritional support, assessment of nutritional status, recommendations for nutrition-related management in pancreatic-insufficient patients and the possible therapeutic impact of fat intake modulation upon inflammatory status.

Pulmonary outcome differences in U.S. and French cystic fibrosis cohorts diagnosed through newborn screening

BACKGROUND

A comparison of the longitudinal progression of lung disease in cystic fibrosis patients identified through newborn screening (NBS) in cohorts located in two different countries has never been performed and was the primary objective of this study.

METHODS

The study included 56 patients in Brittany diagnosed through NBS between 1989 and 1994 and 69 similar patients in Wisconsin between 1985 and 1994. The onset and progression of lung disease was radiographically quantified using the Wisconsin Chest X-ray (WCXR) scoring system. A single pediatric pulmonologist blinded to all identifiers scored the films.

RESULTS

Generalized estimating equation analyses adjusted for age, genotype, sex, pancreatic insufficiency, and meconium ileus showed worse WCXR scores in Brittany patients compared to Wisconsin patients (average score difference=4.48; p<0.001). Percent predicted FEV1 was also worse among Brittany patients (p<0.001).

CONCLUSIONS

The finding of milder radiographically-quantified lung disease using the WCXR scoring system, as well as better FEV1 values, may be explained by variations in nutrition, environmental exposures, or healthcare delivery.

Growth assessment of paediatric patients with CF comparing different auxologic indicators: A multicentre Italian study

OBJECTIVES

To evaluate growth in Italian patients with cystic fibrosis (CF).

PATIENTS AND METHODS

A multicentre cross-sectional study was carried out on patients with CF attending Italian reference centres. Anthropometric data were evaluated using the Centers for Disease Control and Prevention 2000 reference data. Nutritional failure was defined as height-for-age percentile (HAP) <5th (all patients); weight-for-length percentile (WLP) <10th (patients <2 years); body mass index percentile (BMIp) <15th (patients between 2 and 18 years). The risk of malnutrition (defined as HAP, WLP, and BMIp <25th) and the proportion of patients below the "BMIp goal" (BMIp > or =50th) were also evaluated. Nutritional status was evaluated in the whole population and in relation to age, sex, pancreatic insufficiency, meconium ileus, and lung function.

RESULTS

A total of 892 patients with CF (50.7% males, mean age 9.2 years, range 0.1-18 years) were enrolled. The proportion of children with HAP <5th, WLP<10th and BMIp<15th was 12.2%. 12.9%, 20.9%, respectively, and 54.4% did not fulfill the BMIp > or =50th goal. HAP <25th identified the highest proportion of children at risk of malnutrition, whereas BMIp <15th identified the highest proportion of children with nutritional failure. Whatever the criterion used to define malnutrition, the highest proportion of children with nutritional failure was found in adolescence (11-18 years). z scores for height, weight, and BMI were significantly associated with pancreatic status and lung function. Differences among centres for the auxologic parameters were not significant, except for BMIp.

CONCLUSIONS

Nutritional failure is present in a minority of Italian patients with CF, particularly during adolescence. Different auxologic indicators should be used for identifying children at risk for or with actual malnutrition.

Growth and nutritional status in children and adolescents with cystic fibrosis

BACKGROUND

Growth retardation, delayed puberty and malnutrition are frequently observed in children suffering from cystic fibrosis.

AIM

The aim of this study was to estimate growth and nutritional status in children with cystic fibrosis on the basis of body proportions and body mass index.

SUBJECTS AND METHODS

Anthropometric data were collected from the medical histories of 62 patients treated in three cystic fibrosis treatment centers in Poland. Anthropometric parameters were expressed in terms of standard deviations away from age-specific and sex-specific reference means reported for the population of Poland. Two-way analysis of variance was used to determine whether the type of cystic fibrosis transmembrane conductance regulator (CFTR) mutation is correlated with age at the time of diagnosis and with body proportions.

RESULTS

The type of mutation was significantly correlated with height, weight and transverse chest width. Growth retardation was greater in subjects diagnosed before they were 3 years old than in subjects diagnosed later. The children had infantile body proportions. Their legs were short and their trunks were long in comparison to their height. Almost 40% of the subjects suffered from malnourishment.

CONCLUSION

Further study is needed to determine how growth in children with cystic fibrosis is affected by clinical practice and socio-economic factors.

Intestinal phenotype of variable-weight cystic fibrosis knockout mice

Cystic fibrosis (CF) transmembrane conductance regulator (Cftr) knockout mice present the clinical features of low body weight and intestinal disease permitting an assessment of the interrelatedness of these phenotypes in a controlled environment. To identify intestinal alterations that are affected by body weight in CF mice, the histological phenotypes of crypt-villus axis height, goblet cell hyperplasia, mast cell infiltrate, crypt cell proliferation, and apoptosis were measured in a population of 12-wk-old (C57BL/6 x BALB/cJ) F2 Cftr(tm1UNC) and non-CF mice presenting a range of body weight. In addition, cardiac blood samples were assessed, and gene expression profiling of the ileum was completed. Crypt-villus axis height decreased with increasing body weight in CF but not control mice. Intestinal crypts from CF mice had fewer apoptotic cells, per unit length, than did non-CF mice, and normalized cell proliferation was similar to control levels. Goblet cell hyperplasia and mast cell infiltration were increased in the CF intestine and identified to be independent of body weight. Blood triglyceride levels were found to be significantly lower in CF mice than in control mice but were not dependent on CF mouse weight. By expression profiling, genes of DNA replication and lipid metabolism were among those altered in CF mice relative to non-CF controls, and no differences in gene expression were measured between samples from CF mice in the 25th and 75th percentile for weight. In this CF mouse model, crypt elongation, due to an expanded proliferative zone and decreased apoptosis, was identified to be dependent on body weight.

Nutrition and Lung Disease in Cystic Fibrosis

Among patients who have cystic fibrosis (CF), lung disease is a significant contributor to morbidity. From a clinical perspective, the link between malnutrition and lung dysfunction in CF is well established; however, the causal relationship remains unclear. Nutritional intervention for CF patients is predicated on the hypothesis that improved nutritional status improves pulmonary function. Which interventions will be of most value and have sustained gains is not completely clear from the available data. Taking into account that several factors condition the deficits that lead to malnutrition in CF, multidisciplinary interventions are likely to give the best results. More research is needed to better dissect the nutritional factors involved in lung disease and to identify effective and safe interventions through systematic controlled trials.

Evaluation of body mass index percentiles for assessment of malnutrition in children with cystic fibrosis

OBJECTIVE

To compare the performance of recently released body mass index percentiles (BMIp) with standard anthropometric indexes, including height-for-age percentile (HAP), weight-for-age percentile (WAP) and percent ideal body weight (%IBW), as measures for nutritional failure in children with cystic fibrosis (CF).

DESIGN

Cross-sectional analysis of growth and lung function data from 4577 children with CF reported to the German CF quality assurance (CFQA) project from 1995 to 2004.

RESULTS

Frequency distribution of HAP (mean+/-s.d.: male 30.0+/-27.5; female 31.3+/-27.4) and WAP (male 28.9+/-27.0; female 29.6+/-26.7) were skewed, with significant numbers of patients below the fifth percentiles of a healthy reference population. However, because deficits occurred in both measures simultaneously, mean %IBW (male 97.0+/-12.1; female 98.1+/-12.3) assumed subjects weight close to the nominal weight-for-height at all ages. In contrast, mean BMIp was markedly reduced (male 35.7+/-27.9; female 35.6+/-27.2) and steadily declined with age. Ideal weight-for-age was significantly lower when predicted by %IBW compared with BMIp method, particularly in subjects with shorter-than-average stature. Consequently, less CF children were identified with nutritional failure according to %IBW method (male 20.5%; female 22.7%) compared with BMIp method (male 30.4%; female 28.7%). The clinical relevance of these findings was confirmed by stronger correlation of BMIp with impaired %forced expiratory volume/s, a marker for disease progression in CF.

CONCLUSION

BMIp predicts nutritional failure more sensitively and accurately than conventional anthropometric indexes, at least in children with CF. Screening of CF patients by BMIp could provide an early warning sign and allow for timely therapeutic intervention.

Insulin-like growth factor-1, leptin, body composition, and clinical status interactions in children with cystic fibrosis

BACKGROUND/AIMS

Children with cystic fibrosis (CF) are of increased risk of reduced fat body mass (FBM) and lean body mass (LBM). Serum concentrations of insulin-like growth factor-1 (IGF-1)and leptin could be markers of LBM and/or FBM depletion. To evaluate the relationships between disease activity, body composition, IGF-1 and leptin concentrations in CF children.

METHODS

A cross-sectional study with 26 CF children aged 5.0-15.5 years and 33 healthy controls, mean age 9.4 years. Body composition was evaluated by dual-energy X-ray absorptiometry. Fasting blood samples were analyzed for leptin, IGF-1 and IGFBP-3.

RESULTS

FBM standard deviation score (SDS; CF boys -0.02 +/- 0.88 vs. 0.78 +/- 0.65, p < 0.01; CF girls -0.37 +/- 1.15 vs. 0.70 +/- 0.97, p < 0.05), leptin concentration (CF boys 2.07 +/- 0.79 vs. 3.07 +/- 1.28 ng/ml, p < 0.05; CF girls 2.71 +/- 0.86 vs. 5.00 +/- 2.95 ng/ml, p < 0.05) and IGF-1SDS (CF boys -1.43 +/- 1.50 vs. -0.32 +/- 0.88, p < 0.05; CF girls -0.66 +/- 1.66 vs. 0.64 +/- 0.57, p < 0.01) were lower in CF children compared to controls. Shwachman score was the strongest predictor of lean body mass (R = 0.63). Leptin levels explain 60% of the variability in FBM.

CONCLUSION

Serum concentrations of IGF-1 and leptin are decreased in children with CF and are associated with clinical conditions and body composition.

Dietary and circulating polyunsaturated fatty acids in cystic fibrosis: are they related to clinical outcomes?

OBJECTIVE

To assess the relationship between dietary intakes, plasma phospholipid (PL) fatty acid profile and clinical parameters in children with cystic fibrosis (CF) in comparison to healthy controls.

PATIENTS AND METHODS

A cross-sectional survey including 37 patients with CF (ages 8.0 +/- 2.9 yrs) and a reference group of 68 healthy children (ages 8.0 +/- 0.7 yrs) was carried out by means of a food-frequency questionnaire. At enrollment, all subjects underwent blood sampling for plasma PL fatty acids (FA). In CF patients, pulmonary function tests (forced expiratory volume in 1 second and forced vital capacity), anthropometric measurements and the Shwachman score were also determined.

RESULTS

In CF patients, mean z score for weight and height (-0.35 +/- 1.16 and -0.28 +/- 0.99) were lower than controls (0.83 +/- 1.73 and 0.55 +/- 1.11, respectively). Patients with CF showed higher energy intakes (110 +/- 43 kcal/d) compared with controls (75 +/- 22 kcal/d; P < 0.0001), with higher intake of total (saturated and monounsaturated) fats and lower intake of polyunsaturated FA (3.9 +/- 1.0% of total macronutrient intake vs 4.3 +/- 1.2%, P = 0.05). In CF patients, plasma and PL levels of linoleic and docosahexaenoic acids were lower, whereas those of arachidonic acid were similar compared with controls. The Shwachman score showed significant positive associations with plasma PL levels of arachidonic acid and total n-6 long-chain FA (r = 0.32, P = 0.05, and r = 0.35, P = 0.03, respectively).

CONCLUSIONS

The data give suggestions that fat intake and CF-associated biomechanisms are bound in a vicious circle, concurring to create the clinical and biochemical picture of CF. The quantity and quality of fat supplementation in CF need careful attention to balance the fat supply with polyunsaturated FA.

Clinical outcome of cystic fibrosis presenting with or without meconium ileus: a matched cohort study

OBJECTIVE

This matched case-control study compared the nutritional and the pulmonary long-term outcomes of cystic fibrosis (CF) patients presenting a history of meconium ileus (MI) with early-diagnosed symptomatic CF without MI (non-MI).

MATERIAL AND METHOD

Twenty-six patients with CF treated for MI between 1980 and 1997 have been matched for sex, birth date, and earliest CF symptomatic diagnosis for the children with non-MI CF. Clinical characteristics, genotype and complications were evaluated as well as the progression of the CF disease from infancy to 15 years old by nutritional status (z score weight, z score height), pulmonary function tests (PFTs) (FVC and FEV1), and Pseudomonas aeruginosa acquisition.

RESULTS

Median duration of the follow-up was 12.5 years (range, 10-17 years). Genotype identification showed no significant difference. Further on, the rate of complications and the occurrence of chronic P. aeruginosa colonization did not differ. At age of 15 years (n = 13), nutritional status and PFTs did not demonstrate any significant difference.

CONCLUSION

These results suggest that adequate initial nutritional and medical management of MI allows further similar nutritional status and PFTs compared with other early-diagnosed symptomatic CF patients. In this study, MI did not represent an additional risk factor for the patient's life.

Comparative analysis of Cystic Fibrosis Registry data from the UK with USA, France and Australasia

BACKGROUND

Using the UK Cystic Fibrosis Database, we analysed the health of the UK CF paediatric population (UKPP) in terms of their biographical, clinical and infection status and compared outcomes with the US, French and Australasian CF Registries.

METHODS

UKPP data were collected for 2,673 patients aged less than 18 years in 2001 and used as a reference base for comparison with the most recent equivalent CF Registry reports.

RESULTS

Although differences exist between National CF Registries, all record similar demographic factors and key outcomes. Where plausible comparisons can be made, we report that the UKPP had the oldest median age (15.0 years), the Australasian population had the lowest median age at diagnosis (1.8 months). Approximately, double the expected number of UKPP patients (23% and 19%, respectively) fall below the 10th centile for height and weight with similar outcomes in Australasia. UKPP and French populations had similar proportions with FEV1 >80% predicted (53% and 54%, respectively).

CONCLUSION

Each Registry's data systems have developed independently providing a first step towards international comparisons. Standardisation of data collection criteria and definition for national CF Registries is required and we propose a standardised minimum data set, which would facilitate data integration as part of a global Registry for CF.

Short-term protein intake and stimulation of protein synthesis in stunted children with cystic fibrosis

BACKGROUND

Stunted children with cystic fibrosis (CF) have less net protein anabolism than do children without CF, and the result is retarded growth in the CF patients. It is not known whether protein intake above that recommended by the Cystic Fibrosis Foundation would further stimulate whole-body protein synthesis.

OBJECTIVE

We studied the effects of 3 amounts of protein intake on whole-body protein synthesis and breakdown by using isotopic infusion of [1-(13)C]valine and [(15)N(2)]urea in children with stable CF who required tube feeding.

DESIGN

In 8 pediatric CF patients, we administered 3 randomly allocated isocaloric diets with normal (NP), intermediate (IP), and high (HP) amounts of protein (1.5, 3, and 5 g . kg(-1) . d(-1), respectively) by continuous drip feeding during a 4-d period at 6-wk intervals. Each patient acted as his or her own control. On the fourth day of feeding, whole-body protein synthesis and breakdown were measured.

RESULTS

Protein synthesis was significantly higher in the HP group (x +/- SEM: 1.78 +/- 0.07 micromol . kg(-1) . min(-1)) than in the IP (1.57 +/- 0.08 micromol . kg(-1) . min(-1); P=0.001) and NP (1.37 +/- 0.07 micromol . kg(-1) . min(-1); P < 0.001) groups. There were no significant differences in protein breakdown. Net retention of nitrogen was significantly higher in the HP group (12.93 +/- 1.42 micromol . kg(-1) . min(-1)) than in the IP (7.61 +/- 1.40 micromol . kg(-1) . min(-1); P=0.01) and HP (2.48 +/- 0.20 micromol . kg(-1) . min(-1); P < 0.001) groups.

CONCLUSION

In stunted children with CF requiring tube feeding, the highest stimulation of whole-body protein synthesis was achieved with a short-term dietary protein intake of 5 g . kg(-1) . d(-1).

Association of nutritional status and pulmonary function in children with cystic fibrosis

PURPOSE OF REVIEW

Multiple studies have shown that nutritional status is a strong predictor of morbidity and mortality in patients with cystic fibrosis (CF). Since CF is characterized by progressive lung disease, it could be argued that the underlying lung disease is what determines the nutritional failure seen in most patients. This review will summarize the data available from studies that have attempted to better define this relation and also present a review of the possible mechanisms involved taken from both observational and interventional studies.

RECENT FINDINGS

Longitudinal studies with sufficiently large follow-up times have demonstrated that young underweight patients have worst pulmonary function outcomes. More importantly, these studies concur in that the yearly change in growth parameters has a significant effect on the rate at which pulmonary function develops. Although the mechanisms behind this important association are yet unclear, there is some suggestion from interventional studies that the accrual of lean body mass is the factor that is involved in the preservation of lung function.

SUMMARY

Nutritional status strongly influences pulmonary health among CF patients. Therefore, aggressive nutritional support aiming at achieving normal growth patterns should lead to adequate development of lung function and maintenance of pulmonary health. However, more research is required with long-term longitudinal studies to better identify the most critical nutritional characteristics influencing this process as well as the most effective nutritional interventions.

Azithromycin for improving pulmonary function in cystic fibrosis

OBJECTIVE

To review the literature concerning the use of azithromycin in the treatment of patients with cystic fibrosis (CF).

DATA SOURCES

A search of MEDLINE (1966-April 2004), Embase (1980-April 2004), and International Pharmaceutical Abstracts (1971-April 2004) was performed. Search terms included cystic fibrosis, macrolide, and azithromycin.

DATA SYNTHESIS

Four studies have been performed in 7-185 patients (children and adults) over a 3- to 6-month period. The azithromycin dosage ranged from 250 mg 3 times weekly to 500 mg daily. The trials reported an improvement in percent predicted forced expiratory volume ranging from 2.95% to 6.2% in patients treated with azithromycin compared with those receiving placebo.

CONCLUSIONS

Azithromycin appeared to improve pulmonary function in adults and older children with CF and was well tolerated when administered for 6 months. Further research is needed to determine an optimal dosage regimen, duration of treatment, effects on quality of life, and cost-effectiveness of azithromycin therapy.

Relationship between nutritional status and lung function in cystic fibrosis: cross sectional and longitudinal analyses from the German CF quality assurance (CFQA) project

BACKGROUND

The German cystic fibrosis (CF) quality assurance (CFQA) project is a patient registry for CF which was founded in 1995. Relevant clinical and laboratory data, respiratory function test results, complications, and CF treatments are entered into the database once a year for each patient. Using the database, a study was undertaken to elucidate the relationship between nutrition and lung function in a large patient cohort by cross sectional and longitudinal analysis.

METHODS

A cohort of 3298 patients above 2 years of age was analysed. Patients were grouped according to the presence or absence of malnutrition (wasting and/or stunting). Cross sectional and longitudinal analyses over 2 and 3 years including mixed model analyses were performed.

RESULTS

The prevalence of abnormal weight for height (<90% predicted) increased with age from 19% in children aged <6 years to 38% in adults with CF. Patients with malnutrition had significantly lower mean values of vital capacity, arterial oxygen tension (PO(2)), and forced expiratory volume in 1 second (FEV(1)) and higher serum IgG (p<0.05). Pseudomonas aeruginosa infection was also associated with decreased pulmonary function. Malnourished adolescents aged 12-18 years experienced a serious decline in FEV(1) of about 20% predicted, whereas mean FEV(1) values remained stable at above 80% predicted in adolescents of normal weight. Longitudinal follow up showed that malnourished patients of all ages and those with P aeruginosa infection had significantly worse lung function than their normally nourished counterparts and a greater yearly loss of FEV(1) % predicted. During 1 year of observation adolescents who experienced a >5% predicted decrease in weight for height had a concomitant mean loss of FEV(1) of 16.5% predicted during that year, whereas patients who gained relative weight had a parallel increase in FEV(1) of 2.1% predicted.

CONCLUSIONS

These data emphasise the close relationship between nutrition, lung function, and clinical course in CF. Normal body weight and absence of P aeruginosa infection was associated with better preservation of lung function.

Stature as a prognostic factor in cystic fibrosis survival

OBJECTIVE/DESIGN

This study provides a longitudinal analysis of the National Cystic Fibrosis Patient Registry to determine if height-for-age percentile would be a useful predictor of survival.

SUBJECTS

All patients were selected from the national registry (n = 19,000) maintained by the Cystic Fibrosis Foundation's 115 accredited Cystic Fibrosis Care Centers in the United States. Inclusion in our analysis required that subjects were born between 1980 and 1989; had a minimum of 4 records each; the subject was alive at age 7; and the subject had a recorded height measurement at age 7 to 8 (n = 2,773).

STATISTICAL ANALYSIS

The Cox proportional hazards model was used to compare height-for-age with survival. We recorded whether a subject was less than the 5th National Center for Health Statistics (NCHS) percentile at age 5 and then in a separate analysis at age 7. Cohort effect was coded as "1" if they were born before 1982 and "0" otherwise.

RESULTS

Stature is a significant prognostic indicator of survival. The relative hazard associated with height below the 5th NCHS percentile for age was significant for both males and females. In males at age 5 the relative hazard was 2.9, [95% confidence interval (CI) 1.23, 6.91; P < .02] and at age 7 it was 6.3 (95% CI 2.1, 18.8; P < .001). The relative hazard in females at age 5 was 4.3 (95% CI 2.4, 7.3; P < .0001) and at age 7 was 5.8 (95% CI 2.5, 13.1; P < .0001).

APPLICATION

These highly significant relative hazard values strongly suggest that shorter patients are much more likely to die before taller patients. The dietetic professional should consider using height-for-age as an effective screening tool to identify patients at risk. Based on these data, short stature should not be considered benign to patients with cystic fibrosis. The CF team, clinicians, family, and patients need work together to maximize linear growth through medical and nutritional intervention.

Prospective evaluation of growth, nutritional status, and body composition in children with cystic fibrosis

BACKGROUND

Several cross-sectional studies have shown improvement in the growth of children with cystic fibrosis (CF) because of increased awareness of and more comprehensive care of their special nutritional needs. However, longitudinal data on the nutritional status of these children are rare.

OBJECTIVE

The objective was to compare changes in growth, body composition, and nutritional status between children with and without CF.

DESIGN

This was a prospective 3-y cohort study of 25 children aged 5-10 y with CF, mild pulmonary disease, and pancreatic insufficiency and of 26 healthy control children. Three methods were used to assess body composition: measurements of skinfold thickness, total body water by deuterium oxide, and total-body electrical conductivity. Growth and body-composition changes over time were analyzed by a longitudinal mixed-effects model.

RESULTS

Over the 3 y of the study, the statural growth of the boys with CF was slower than that of the control subjects (P = 0.004). The same divergence over time between the boys with and without CF was observed for fat-free mass assessed by skinfold-thickness measurements and total body water (P = 0.008 and 0.02, respectively) and for fat mass assessed by skinfold-thickness measurements and total-body electrical conductivity (P = 0.009 and 0.001, respectively). The differences in the pattern of changes in growth and body composition were less striking for girls.

CONCLUSIONS

Despite comprehensive care, the growth of boys with CF was impaired on the basis of height, fat-free mass, and fat mass, when observed longitudinally. Caution should be used when interpreting cross-sectional measurements because they often do not detect suboptimal growth.

Cystic fibrosis: nutritional status and micronutrients

Recent studies have focused on the current dietary intake of cystic fibrosis patients, the impact of nutritional support on both the nutritional status and clinical outcome variables, and the effects on the nutritional status of antibiotic therapy and surgical treatment of meconium ileus. In addition to weight and height, skinfold measurements, bioelectrical impedance analysis and dual energy X-ray absorptiometry have been employed for the determination of nutritional status. A proton pump inhibitor has been used successfully along with pancreatic enzymes for the improvement of fat absorption. Attention has been paid to resting energy expenditure during pulmonary exacerbations, to vitamin K function in bone mineralization and to risk factors for low bone mineral density in cystic fibrosis. The relationships between glutathione and nutritional status have been studied, along with possible interactions with albumin, a potent antioxidant. Finally, a beneficial effect of docosahexaenoic acid on cystic fibrosis pathology has been suggested, but this requires further critical evaluation.

A prospective study of body composition changes in children with cystic fibrosis

Recent cross-sectional studies of children with cystic fibrosis (CF) have shown an improvement in their growth with improved nutritional status, but there are only a few longitudinal studies in this population. A four-year prospective study was conducted in 25 children with CF and 26 controls, ages 5 to 10 years at baseline, to describe changes in body composition using three independent methods of assessment: skinfold thickness, total body water by deuterium dilution, and total body electrical conductivity (TOBEC). The statural growth of the boys with CF was slower than that of the control boys. Using different methods, the fat-free mass and fat-mass increases were shown to be slower in boys with CF than in controls. These differences were less significant in girls. Despite comprehensive care, the growth of boys with CF may still not be optimal, as observed longitudinally.