Treatment of pediatric heterozygous familial hypercholesterolemia 7 years after the EAS recommendations: Real-world results from a large French cohort.

BACKGROUND: Heterozygous familial hypercholesterolemia (HeFH) predisposes to premature cardiovascular diseases. Since 2015, the European Atherosclerosis Society has advocated initiation of statins at 8-10 years of age and a low-density lipoprotein cholesterol (LDL-C) target of <135 mg/dL. Longitudinal data from large databases on pharmacological management of pediatric HeFH are lacking. OBJECTIVE: Here, we describe treatment patterns and LDL-C goal attainment in pediatric HeFH using longitudinal real-world data. METHODS: This was a retrospective and prospective multicenter cohort study (2015-2021) of children with HeFH, diagnosed genetically or clinically, aged <18 years, and followed up in the National French Registry of FH (REFERCHOL). Data on the study population as well as treatment patterns and outcomes are summarized as mean±SD. RESULTS: We analyzed the data of 674 HeFH children (age at last visit: 13.1 ± 3.6 years; 82.0 % ≥10 years; 52.5 % females) who were followed up for a mean of 2.8 ± 3.5 years. Initiation of lipid-lowering therapy was on average at 11.8 ± 3.0 years of age for a duration of 2.5 ± 2.8 years. At the last visit, among patients eligible for treatment (573), 36 % were not treated, 57.1 % received statins alone, 6.4 % statins with ezetimibe, and 0.2 % ezetimibe alone. LDL-C was 266±51 mg/dL before treatment and 147±54 mg/dL at the last visit (-44.7 %) in treated patients. Regarding statins, 3.3 %, 65.1 %, and 31.6 % of patients received high-, moderate-, and low-intensity statins, respectively. Overall, 59 % of children on statin therapy alone and 35.1 % on bitherapy did not achieve the LDL-C goal; fewer patients in the older age group did not reach the treatment goal. CONCLUSION: Pediatric patients with FH followed up in specialist lipid clinics in France receive late treatment, undertreatment, or suboptimal treatment and half of them do not reach the therapeutic LDL-C goal. Finding a more efficient framework for linking scientific evidence to clinical practice is needed.

Hyperphagia and impulsivity: use of self-administered Dykens' and in-house impulsivity questionnaires to characterize eating behaviors in children with severe and early-onset obesity.

BACKGROUND: The determinants of early-onset obesity (< 6 years) are not completely elucidated, however eating behavior has a central role. To date no study has explored eating behavior in children with severe, early-onset obesity. Self-administered questionnaire data from these children were examined to evaluate eating behavior and the etiology of early-onset obesity. METHODS: Children with severe, early-onset obesity (body mass index [BMI] > International Obesity Task Force [IOTF] 30) of different etiologies (hypothalamic obesity [HO], intellectual disability with obesity [IDO], common polygenic obesity [CO]) were prospectively included. BMI history and responses from the Dykens' Hyperphagia Questionnaire and an in-house Impulsivity Questionnaire at first visit were compared between groups. RESULTS: This cohort of 75 children (39 girls; mean age ± standard deviation [SD] 10.8 ± 4.4 years) had severe, early-onset obesity at an age of 3.8 ± 2.7 years, with a BMI Z-score of 4.9 ± 1.5. BMI history varied between the 3 groups, with earlier severe obesity in the HO group versus 2 other groups (BMI > IOTF40 at 3.4 ± 1.6 vs. 4.6 ± 1.6 and 8.4 ± 4.1 years for the IDO and CO groups, respectively [P < 0.01]). Absence of adiposity rebound was more prevalent in the HO group (87% vs. 63% and 33% for the IDO and CO groups, respectively [P < 0.01]). The Dykens' mean total score for the cohort was 22.1 ± 7.2 with no significant between-group differences. Hyperphagia (Dykens' score > 19) and impulsivity (score > 7) were found in 50 (67%) and 11 children (15%), respectively, with no difference between the HO, IDO and CO groups regarding the number of patients with hyperphagia (10 [67%], 14 [74%], and 26 [63%] children, respectively) or impulsivity (2 [13%], 1 [7%], and 8 [19%] children, respectively). Children with food impulsivity had significantly higher total and severity scores on the Dykens' Questionnaire versus those without impulsivity. CONCLUSION: The Dykens' and Impulsivity questionnaires can help diagnose severe hyperphagia with/without food impulsivity in children with early-onset obesity, regardless of disease origin. Their systematic use can allow more targeted management of food access control in clinical practice and monitor the evolution of eating behavior in the case of innovative therapeutic targeting hyperphagia.

Bariatric procedures including Roux-en-Y gastric bypass in French adolescents.

INTRODUCTION: In France, approximately 100 obese adolescents undergo a bariatric procedure every year. To date, only data from laparoscopic adjustable gastric banding (LAGB) or sleeve gastrectomy (SG) have been published. Our objective was to report the outcomes of a series of French obese adolescents who underwent a Roux-en-Y gastric bypass (RYGB). METHODS: We included all obese adolescents aged 13-19 years who underwent RYGB in our department from 2008 with at least 2 years of follow-up after surgery. We analyzed the course of the anthropometric data, comorbidities, and subsequent adverse events. RESULTS: Starting in September 2008, out of 93 obese adolescents who requested bariatric surgery, 39 (35%) underwent a bariatric procedure. From these adolescents, 2-year follow-up data were available for 26 patients who had a RYGB. At the time of surgery, the mean patient age was 17.4 years (standard deviation [SD]=1.4) and the body mass index (BMI) was 52.0 kg/m² (SD=7.8). One patient was lost to follow-up. At 2 years after surgery,  the mean BMI was 35.7 kg/m² (SD=9.4) with a mean decrease in BMI of 31.9% (SD=11.6). Comorbidities improved for most of the patients: high blood pressure (2/2) and pseudotumor cerebri (1/1) were cured after surgery, and dyslipidemia improved globally. The complications observed were anemia, abdominal pain requiring celioscopy (n = 2), and oxalic nephrolithiasis. CONCLUSION: Only one third of the obese adolescents requesting bariatric surgery were operated on. Our series including exclusively obese adolescents who underwent an RYGB presents the results of this technique on weight loss and comorbidities; mechanical and nutritional complications remain uncommon. These results are similar to those obtained in studies of adult patients.

Prevalence and Etiologies of Renal and Urinary Manifestations in a Large Cohort of Children With Inflammatory Bowel Disease.

BACKGROUND AND OBJECTIVES: Renal and/or urinary manifestations (RUM) have been reported in pediatric patients with inflammatory bowel disease (IBD) but their incidence is unknown. The aims of this study were to assess the prevalence and causes of these manifestations in children with IBD and determine the causal link with 5-aminosalicylic acid (5-ASA) treatment. METHODS: A retrospective observational study was performed with children with diagnosis of IBD. All children with RUM during follow-up and/or impaired renal function [estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m 2 ] were identified. RESULTS: Of 228 included patients, 9 (3.9%) had a RUM during follow-up [follow-up: 5 years (1-12 years)] at a median age of 16 years (8-17 years). It concerned 7 of 171 patients with Crohn disease and 2 of 57 with ulcerative colitis. Seven patients were taking 5-ASA at the time of the RUM. Only 1 of them had an iatrogenic renal complication related to this treatment. Patients with RUM had a more severe disease with increased anti-tumor necrosis factor-α use ( P = 0.031), more abscesses ( P = 0.003), and a higher rate of digestive surgery ( P = 0.04). For the whole cohort, a significant decrease in eGFR was found during follow-up (121 vs 107 mL/min/1.73 m 2 , P < 0.001). At the end of follow-up, 38 of 202 (19%) patients had an eGFR < 90 mL/min/1.73 m 2 . CONCLUSION: In children with IBD, RUM can occur, independently of treatment with 5-ASA. During follow-up, a significant decrease in eGFR was observed. We suggest monitoring renal function in all patients with IBD.

Factors Predicting Statin Initiation During Childhood in Familial Hypercholesterolemia: Importance of Genetic Diagnosis.

OBJECTIVE: To identify childhood and parental factors associated with initiation of statin therapy in children with heterozygous familial hypercholesterolemia (HeFH), including underlying genetic diagnosis or parental premature atherosclerotic cardiovascular disease (ASCVD). STUDY DESIGN: This multicenter cohort study included 245 HeFH child-parent pairs from the REFERCHOL national register (2014-2020). Demographic and clinical characteristics at the last visit were collected. Vascular disease in parents was defined as a history of ASCVD, and/or a coronary artery calcium score >100, and/or stenosis of >50% in at least carotid artery. Statistical analyses included descriptive analysis, logistic regression for univariate and multivariate effects of statins, and a sensitivity analysis combining the characteristics of children and parents. RESULTS: Among the 245 children in the study cohort, 135 (58%), with a mean age of 14 ± 3 years, were treated with a statin. In multivariable analysis, the predictive childhood factors associated with statin treatment were genetic diagnosis (OR, 2.5; 95% CI, 1.3 to 4.9; P = .01), older age (OR, 4.4; 95% CI, 1.8-10.6; P = .01), more than 2 visits (OR, 2.36; 95% CI, 1.18-4.73; P = .015), and longer duration of follow-up (OR, 1.3; 95% CI, 1.1-1.6; P < .001). The predictive parental factor associated with childhood treatment was the presence of vascular disease (OR, 2.4; 95% CI, 1.0-5.7; P = .04). CONCLUSIONS: HeFH confirmed by DNA testing during childhood and a history of vascular disease in parents were independently associated with statin treatment in children with HeFH. Genetic diagnosis may be useful for cardiovascular prevention in children.

Mental health of adolescents after bariatric surgery: A textual analysis.

Mental health after bariatric surgery during adolescence has been little explored. This is a sensitive period in terms of self-image on which bariatric surgery could have negative effects because of the rapid and significant changes in morphology it induces. Previous studies have explored mental effects using questionnaires and only related to psychopathological disorders. The objective of our study was to complement these studies by exploring, via in-depth interviews, the adolescents' views on changes after bariatric surgery at psychological as well as socio-emotional levels. Fourteen adolescents with obesity were recruited in a French hospital 6-43 months after surgery. They participated in one-on-one interviews lasting an average of 45 minutes. A lexical analysis (using ALCESTE software© ) of their speech highlighted the most positive effects, particularly in terms of social relationships, physical activities, self-esteem and reduced stigma, along with less positive effects in terms of eating behaviour and skin. In terms of clinical implications, this study confirmed the value of bariatric surgery for adolescents at psychological and social levels and its contribution to their mental health. However, it also highlighted the importance of pre- and post-operative support.

Estimation of the Burden of Iron Deficiency Anemia in France from Iron Intake: Methodological Approach.

: Dietary iron deficiency (ID) is the first nutritional deficiency in the world, in terms of disability adjusted life years (DALY). This nutritional deficiency may lead to anemia, especially among children, adolescents, and adult women. The aim of this study was to build an original probabilistic model to quantitatively assess the ID, the iron deficiency anemia (IDA) and the subsequent health burden in France expressed in DALY, per age class and gender. The model considered the distribution of absorbed iron intake, the iron requirement distribution established by the European Food Safety Authority and the iron status in France. Uncertainty due to lack of data and variability due to biological diversity were taken into account and separated using a second-order Monte Carlo procedure. A total of 1290 (95% CI = 1230-1350) IDA cases corresponding to 16 (95% CI = 11-20) DALY were estimated per 100,000 individuals per year. The major contributors to IDA burden were menstruating females aged from 25 to 44 years old. Then, a consumption scenario was built with ground beef as intake, an increase in red meat consumption to 100 g/d would not eliminate entirely the IDA burden. The quantitative methodology applied here for France could be reused for other populations.

Intermediate-Term Efficacy and Tolerance of Statins in Children.

OBJECTIVES: To evaluate the intermediate-term efficacy and tolerance of statins in children and adolescents with familial hypercholesterolemia. STUDY DESIGN: A total of 131 children or adolescents treated with statins for familial hypercholesterolemia were prospectively included. The efficacy of treatment was established by the percentage of children who achieved low density lipoprotein-cholesterol (LDL-C) levels <160 mg/dL during treatment. Treatment tolerance was evaluated by the occurrence of clinical or laboratory side effects, regularity of increases in height and weight, and pubertal development. RESULTS: The median duration of treatment with statins was 4 years. A median decrease of 32% in LDL-C levels was observed (P < .0001). The therapeutic target (LDL-C <160 mg/dL) was achieved in 67% of cases. Increases in height and weight and sexual maturation were not affected by the treatment. Minor side effects were reported for 24 (18.4%) patients including 3 cases of a clinically asymptomatic increase in creatine phosphokinase (CPK) levels, 2 cases of an increase in CPK levels with muscular symptoms, 14 cases of myalgia without an increase in CPK levels, 3 cases of abdominal pain, 1 case of dysuria, and 1 case of diffuse pain. None of these side effects led to the discontinuation of statin therapy, although a change of statin was required in 7 cases. This new statin was tolerated in all cases. No patients had abnormal liver function during treatment. CONCLUSIONS: The results of this large cohort confirm the intermediate-term safety and efficacy of statin therapy in children with familial hypercholesterolemia.

[Familial hypercholesterolemia in children and adolescents]. / Hypercholestérolémie familiale chez l'enfant et l'adolescent.

Familial hypercholesterolemia in children and adolescents. Familial hypercholesterolemia is a common genetic disease. The dominant autosomal heterozygous form is most common in relation to the pathogenic mutation of a single gene responsible for a significant rise in LDL-cholesterol levels in childhood. In the absence of treatment, this abnormality exposes to a risk of early cardiovascular diseases in men and women. This pathology is totally asymptomatic in childhood. A lipid check-up should be proposed in case of a familial history of early cardiovascular diseases or severe dyslipidemia, if a mutation is already known in parents or if familial history is unknown. The diagnosis is suspected if LDL-cholesterol is > 1,6 g/L. A genetic assessment will be proposed according to family history and evolution. Management begins in childhood with the initial introduction of specific dietary measures. However, these are often insufficient requiring statin therapy from the age of 8.

Hypercholestérolémie familiale chez l'enfant et l'adolescent. L'hypercholestérolémie familiale est une maladie génétique fréquente. La forme hétérozygote autosomique dominante est la plus courante en rapport avec la mutation pathogène d'un seul gène responsable d'une élévation importante des taux du LDL-cholestérol dès l'enfance. Cette anomalie, en l'absence de prise en charge, expose à un risque d'accidents cardiovasculaires précoces chez l'homme et la femme. Cette pathologie est totalement asymptomatique dans l'enfance. Un dépistage par un bilan lipidique doit donc être proposé en cas d'antécédents familiaux d'hypercholestérolémie importante, de pathologies cardiovasculaires précoces, d'une mutation responsable d'une hypercholestérolémie familiale connue chez un des parents ou en cas d'antécédents familiaux inconnus. Le diagnostic est suspecté si le LDL-cholestérol est supérieur à 1,6 g/L. Une étude génétique est alors proposée selon l'histoire familiale et l'évolution. La prise en charge initiale se fait dès l'enfance avec la mise en place de mesures diététiques spécifiques. Celles-ci sont cependant souvent insuffisantes, nécessitant l'instauration d'un traitement par statines à partir de l'âge de 8 ans.

Ultrasonography and Computed Tomographic Manifestations of Abdominal Sarcoidosis in Children.

OBJECTIVES: Sarcoidosis is a multisystem, granulomatous inflammatory disease affecting both pediatric and adult patients. So far in children, very few radiological descriptions of abdominal sarcoidosis manifestations have been reported. The present study describes the frequency and the appearance of abdominal radiologic manifestations in pediatric patients with histologically proven sarcoidosis. METHODS: We reviewed retrospectively all of the radiological examinations of 22 patients ages 1 to 15 years at diagnosis with proven sarcoidosis evaluated in a university pediatric hospital between 1994 and 2014. The locations of biopsies and the angiotensin-converting enzyme level were reported. The size, shape, and parenchymal homogeneity of the liver and spleen, the presence of abdominal lymph nodes, and abnormalities of the gastrointestinal tract were tabulated. RESULTS: The study included 22 children (mean age: 9.9 ±â€Š2.8 years). The liver was the most frequent location of biopsy (12/22), even without radiological involvement. Abdominal manifestations were present in 11 of 22 children with sarcoidosis. Hepatomegaly was the most frequent abnormality, reported in 8 of 11 cases either homogeneous (n = 7) or nodular (n = 1). Homogeneous lymph node enlargement was noted in 6 of 11 cases and splenomegaly in 4 of 11 cases. No calcification was observed. All patients with initial abdominal sarcoidosis had simultaneous thoracic involvement. CONCLUSIONS: Abdominal manifestations in children sarcoidosis are frequent but often nonspecific. Nodular hepatosplenomegaly is rare. All of our patients with abdominal abnormalities had a more specific associated thoracic involvement. Awareness of this association could assist the clinicians in assessing the initial diagnosis of abdominal sarcoidosis in children.

Global molecular analysis and APOE mutations in a cohort of autosomal dominant hypercholesterolemia patients in France.

Autosomal dominant hypercholesterolemia (ADH) is a human disorder characterized phenotypically by isolated high-cholesterol levels. Mutations in the low density lipoprotein receptor (LDLR), APOB, and proprotein convertase subtilisin/kexin type 9 (PCSK9) genes are well known to be associated with the disease. To characterize the genetic background associated with ADH in France, the three ADH-associated genes were sequenced in a cohort of 120 children and 109 adult patients. Fifty-one percent of the cohort had a possible deleterious variant in LDLR, 3.1% in APOB, and 1.7% in PCSK9. We identified 18 new variants in LDLR and 2 in PCSK9. Three LDLR variants, including two newly identified, were studied by minigene reporter assay confirming the predicted effects on splicing. Additionally, as recently an in-frame deletion in the APOE gene was found to be linked to ADH, the sequencing of this latter gene was performed in patients without a deleterious variant in the three former genes. An APOE variant was identified in three patients with isolated severe hypercholesterolemia giving a frequency of 1.3% in the cohort. Therefore, even though LDLR mutations are the major cause of ADH with a large mutation spectrum, APOE variants were found to be significantly associated with the disease. Furthermore, using structural analysis and modeling, the identified APOE sequence changes were predicted to impact protein function.

Seven novel deleterious LEPR mutations found in early-onset obesity: a ΔExon6-8 shared by subjects from Reunion Island, France, suggests a founder effect.

CONTEXT: Infrequent mutations have been reported in the leptin receptor (LEPR) gene in humans with morbid obesity and endocrine disorders. However LEPR mutations are rarely examined in large populations from different ethnicities in a given country. OBJECTIVE: We estimated the prevalence of LEPR mutations in French patients with severe obesity and evaluated mutated patients' phenotype. DESIGN AND PATIENTS: We sequenced the LEPR gene in 535 morbidly obese French participants. We conducted clinical investigations to determine whether individuals with a novel shared mutation display particular characteristics relative to obesity history, body composition, hormonal functions, and the outcome of bariatric surgery. RESULTS: We identified 12 patients with a novel LEPR mutation (p.C604G, p.L786P, p.H800_N831del, p.Y422H, p.T711NfsX18, p.535-1G>A, p.P166CfsX7). Six unrelated subjects were carriers of the p.P166CfsX7 mutation leading to deletion overlapping exons 6 to 8. All subjects originated from Reunion Island (France). Their clinical features (severe early-onset obesity, food impulsivity, and hypogonadotropic hypogonadism) did not differ from other new LEPR mutation carriers. Results concerning weight loss surgery were inconsistent in homozygous LEPR mutation carriers. Heterozygous LEPR mutation carriers exhibited variable severity of obesity and no endocrine abnormality. CONCLUSION: Among seven newly discovered LEPR mutations in this French obese population, we identified a LEPR frameshift mutation shared by six subjects from Reunion Island. This observation suggests a founder effect in this Indian Ocean island with high prevalence of obesity and supports a recommendation for systematic screening for this mutation in morbidly obese subjects in this population.

Genetic characterization of congenital tufting enteropathy: epcam associated phenotype and involvement of SPINT2 in the syndromic form.

Congenital tufting enteropathy (CTE) is a rare and severe enteropathy recently ascribed to mutations in the epcam gene. Here we establish SPINT2, previously ascribed to congenital sodium diarrhea, as a second gene associated with CTE and report molecular and immunohistochemistry data in 57 CTE patients. Inclusion criteria were early onset diarrhea and intestinal insufficiency with the typical histological CTE abnormalities. The clinical phenotype was registered, the entire coding regions of epcam and SPINT2 sequenced, and immunostaining of EpCAM and SPINT2 performed on intestinal biopsies. An epcam mutation was involved in 41 patients (73 %) who mainly displayed isolated digestive symptoms. Mutations severely affected gene expression since the EpCAM signal on intestinal tissues was either undetectable or low and irregular. Twelve other patients (21 %) carried mutations in SPINT2, and were phenotypically characterized by systematic association with keratitis (p < 10(-4)) and, for half of them, with choanal atresia (p < 10(-4)). Dependency on parenteral nutrition (PN) was comparable in patients with epcam or SPINT2 mutations, but the frequent epcam mutation c.556-14A>G (abnormal splicing) was significantly associated with a better outcome (p = 0.032) with milder PN dependency to weaning in some cases. Finally, four patients (7 %) with isolated digestive symptoms had no detectable epcam or SPINT2 mutation. Two candidate genes, Elf3 and Claudin7, were excluded from this population. Our study allows us to separate CTE patients into at least three genetic classes, each with specific phenotypes. The genetics approach raises the question of the distinction between two congenital enteropathies. Our findings should help improve the diagnosis of CTE, guide toward strategies of long-term PN management, and limit indications for intestinal transplantation to life-threatening PN complications.

Programming towards childhood obesity.

There is now considerable evidence that a constitutional susceptibility to fat gain is necessary for children to become obese under the pressure of an obesogenic environment; this is the programming towards obesity. The role of genetics in this programming is dominant. Besides the rare monogenic recessive forms of obesity secondary to mutations in genes involved in the hypothalamic appetite control pathways, obesity linked to mutations in melanocortin 3 and 4 receptors are more frequent due to their dominant mode of transmission. Predisposition to common obesity is polygenic and involves a network of genes; nevertheless, more research is required to elucidate their exact role. Fetal and perhaps early postnatal programming is also possible. Under- and overnutrition, diabetes, and maternal smoking during pregnancy were shown to promote later obesity and may affect the central body weight regulatory system during fetal development. The role of early postnatal factors such as formula-feeding rather than breastfeeding, excess in n-6 polyunsaturated fatty acids or protein intakes, and excessive weight gain early in life is more questionable and needs further investigation. Taking into consideration that childhood obesity is a programmed disease should modify its clinical management. Childhood obesity should no longer be considered as the result of inappropriate eating habits and/or excessive inactivity in order to relieve the obese children's discrimination and their parents' guilt. Since treatment of obese children requires a substantial motivation to continuously fight against the programmed excessive drive to eat, it seems wiser to wait for children to be old enough, thus more motivated, to initiate energy restriction. Moreover, with the great majority of children being not predisposed to obesity, prevention strategies should not be addressed to the whole pediatric population but targeted to those children at risk. Improvement of knowledge on programming towards obesity is essential to develop more promising therapeutic and preventive approaches.

Intractable diarrhea with tufting enteropathy: a favorable outcome is possible.

BACKGROUND AND OBJECTIVE: Tufting enteropathy (TE) is a congenital abnormality of intestinal mucosa development characterized by severe intestinal failure requiring parenteral nutrition (PN) and, in some cases, small bowel transplantation. A few patients have had a more favorable outcome. The objective of this study was to evaluate possible correlations between histological lesion severity in duodenal biopsies and clinical outcomes in children with TE. PATIENTS AND METHODS: We retrospectively reviewed the records of patients diagnosed with TE between 1993 and 2003 at our institution based on intractable neonatal-onset diarrhea with prolonged dependence on PN and duodenal biopsy findings of villous atrophy, epithelial dysplasia with enterocyte dedifferentiation and disorganization (tufting) of the surface epithelium, and crypt abnormalities. The histological lesions were assessed semiquantitatively and compared with the clinical outcomes including dependence on PN. RESULTS: Seven children, all from consanguineous parents, were studied for a median of 6.5 years. Three were permanently weaned off PN and experienced normal growth without nutritional assistance. Initial biopsies in all 3 children showed severe diffuse histological lesions. At weaning off PN, 2 of these 3 patients had persistent, although less diffuse, histological lesions. CONCLUSIONS: Progressive weaning off PN is possible in some children with TE. In our experience, this favorable outcome was not predicted by histological lesion severity, although the lesions improved in some patients. New biomarkers for identifying the histological lesions and predicting the outcome would be useful.

Nutritional status is an important predictor of diaphragm strength in young patients with cystic fibrosis.

BACKGROUND: The effect of nutritional status and lung disease progression on diaphragm strength in young patients with cystic fibrosis remains unclear. OBJECTIVE: The aim of this study was to investigate the effect of nutritional status and airway obstruction on diaphragm strength. DESIGN: Twitch transdiaphragmatic pressure (Tw Pdi) obtained by bilateral anterior magnetic phrenic nerve stimulation, body mass index (BMI) z score, fat mass, fat-free mass (FFM), arm muscle circumference (AMC), forced expiratory volume in 1 s (FEV(1)), and functional residual capacity (FRC) were measured in 20 patients aged 15.1 +/- 2.8 y (x +/- SD). Values were expressed as a percentage of predicted values. RESULTS: Mean (+/-SD) Tw Pdi was 24.3 +/- 5.5 cm H(2)O. Univariate regression analysis showed positive correlations between Tw Pdi and nutrition scores (BMI z score: r = 0.63, P = 0.003; FFM: r = 0.47, P = 0.04; AMC: r = 0.45, P = 0.04), airway obstruction (FEV(1): r = 0.68, P = 0.001), and arterial oxygen partial pressure (r = 0.68, P = 0.001). Negative correlations were observed between Tw Pdi and dynamic hyperinflation (FRC: r = -0.65, P = 0.005) and arterial carbon dioxide pressure (r = -0.50, P = 0.03). Furthermore, stepwise regression analysis showed that Tw Pdi correlated with BMI z score (r = 0.75, P = 0.0002) and FEV(1) (r = 0.69, P = 0.001). CONCLUSIONS: Diaphragm strength is relatively well preserved in young patients with cystic fibrosis. However, the strength of the diaphragm decreases with the progression of malnutrition and airway obstruction.