Outcome measures in Angelman syndrome.

BACKGROUND: Angelman syndrome (AS) is a rare neurodevelopmental disorder characterized by severe intellectual disability, little to no expressive speech, visual and motor problems, emotional/behavioral challenges, and a tendency towards hyperphagia and weight gain. The characteristics of AS make it difficult to measure these children's functioning with standard clinical tests. Feasible outcome measures are needed to measure current functioning and change over time, in clinical practice and clinical trials. AIM: Our first aim is to assess the feasibility of several functional tests. We target domains of neurocognitive functioning and physical growth using the following measurement methods: eye-tracking, functional Near-Infrared Spectroscopy (fNIRS), indirect calorimetry, bio-impedance analysis (BIA), and BOD POD (air-displacement plethysmography). Our second aim is to explore the results of the above measures, in order to better understand the AS phenotype. METHODS: The study sample consisted of 28 children with AS aged 2-18 years. We defined an outcome measure as feasible when (1) at least 70% of participants successfully finished the measurement and (2) at least 60% of those participants had acceptable data quality. Adaptations to the test procedure and reasons for early termination were noted. Parents rated acceptability and importance and were invited to make recommendations to increase feasibility. The results of the measures were explored. RESULTS: Outcome measures obtained with eye-tracking and BOD POD met the definition of feasibility, while fNIRS, indirect calorimetry, and BIA did not. The most important reasons for early termination of measurements were showing signs of protest, inability to sit still and poor/no calibration (eye-tracking specific). Post-calibration was often applied to obtain valid eye-tracking results. Parents rated the BOD POD als most acceptable and fNIRS as least acceptable for their child. All outcome measures were rated to be important. Exploratory results indicated longer reaction times to high salient visual stimuli (eye-tracking) as well as high body fat percentage (BOD POD). CONCLUSIONS: Eye-tracking and BOD POD are feasible measurement methods for children with AS. Eye-tracking was successfully used to assess visual orienting functions in the current study and (with some practical adaptations) can potentially be used to assess other outcomes as well. BOD POD was successfully used to examine body composition. TRIAL REGISTRATION: Registered d.d. 23-04-2020 under number 'NL8550' in the Dutch Trial Register: https://onderzoekmetmensen.nl/en/trial/23075.

Challenges in body composition assessment using air-displacement plethysmography by BOD POD in pediatric and young adult patients.

BACKGROUND & AIMS: Air-Displacement-Plethysmography (ADP) by BOD POD is widely used for body fat assessment in children. Although validated in healthy subjects, studies about use in pediatric patients are lacking. We evaluated user experience and usability of ADP measurements with the BOD POD system in healthy children and pediatric and young adult patients. METHODS: Using the experiences of seven cohort studies, which included healthy children and patients aged 2-22 years, we retrospectively evaluated the user experience with the User Experience Questionnaire (UEQ) (n = 13) and interviews (n = 7). Technical performance was studied using the quality control data collected by the ADP-system. RESULTS: From 2016 to 2022, 1606 measurements were scheduled. BOD POD was mostly rated 'user-friendly', with a generally neutral evaluation on all scales of the UEQ. However, questionable reliability and validity of the results were frequently (86%) reported. We found a high technical failure-rate of the device, predominantly in stability (17%) and accuracy of the measurement (12%), especially in the 'pediatric option' for children aged <6 years. Measurement failure-rate was 38%, mostly due to subject's fear or device failure, especially in young and lean children, and in children with physical and/or intellectual disabilities. CONCLUSION: We conclude that ADP by BOD POD in children and young adults is non-invasive and user-friendly. However, in specific pediatric populations, BOD POD has several limitations and high (technical) failure-rates, especially in young children with aberrant body composition. We recommend caution when interpreting body composition results of pediatric patients as assessed with BOD POD using the current default settings.

Clinical evaluation of an evidence-based method based on food characteristics to adjust pancreatic enzyme supplements dose in cystic fibrosis.

BACKGROUND: Patients with cystic fibrosis (CF) and pancreatic insufficiency need pancreatic enzyme replacement therapy (PERT) for dietary lipids digestion. There is limited evidence for recommending the adequate PERT dose for every meal, and controlling steatorrhea remains a challenge. This study aimed to evaluate a new PERT dosing method supported by a self-management mobile-app. METHODS: Children with CF recruited from 6 European centres were instructed to use the app, including an algorithm for optimal PERT dosing based on in vitro digestion studies for every type of food. At baseline, a 24h self-selected diet was registered in the app, and usual PERT doses were taken by the patient. After 1 month, the same diet was followed, but PERT doses were indicated by the app. Change in faecal fat and coefficient of fat absorption (CFA) were determined. RESULTS: 58 patients (median age 8.1 years) participated. Baseline fat absorption was high: median CFA 96.9%, median 2.4g faecal fat). After intervention CFA did not significantly change, but range of PERT doses was reduced: interquartile ranges narrowing from 1447-3070 at baseline to 1783-2495 LU/g fat when using the app. Patients with a low baseline fat absorption (CFA<90%, n=12) experienced significant improvement in CFA after adhering to the recommended PERT dose (from 86.3 to 94.0%, p=0.031). CONCLUSION: the use of a novel evidence-based PERT dosing method, based on in vitro fat digestion studies incorporating food characteristics, was effective in increasing CFA in patients with poor baseline fat absorption and could safely be implemented in clinical practice.