STUDY POPULATION
A detailed description of the population is shown in Table 1. Thirty-four children, 47% of female and 41% with deletion genetic subtype were included in this comparative study. Children belonged to one of the two groups, OT-exposed and non-exposed (17 children per group). These two groups were not statistical different regarding birth data, social status, family composition and schooling. In the whole group, median age was 3.8 years [3.0;4.3], BMI-Z-score was 0.08 [-1.79;6.31]. All children received GH treatment. All children were followed in dedicated PWS centers except for one OT-exposed child due to extreme poverty of the family with high social deprivation score.
Table 1
Characteristics of the population.
Variable | OT-exposed (n = 17) | Non-exposed (n = 17) | All (n = 34) |
Age (yrs) | 3.8 (3.1;4.2) | 3.8 (3.0;4.3) | 3.8 (3.0;4.3) |
Sex Female n (%) | 7 (41%) | 9 (53%) | 16 (47%) |
Genetics Deletion n (%) Non-deletion n (%) - mUPD n (%) - Imprinting defect n (%) | 6 (35%) 11 (65%) 9 (53%) 2 (12%) | 8 (47%) 9 (53%) 9 (53%) 0 | 14 (41%) 20 (59%) 18 (53%) 2 (6%) |
Auxological data - body composition Weight (kg) Weight (DS) Height (cm) Height (DS) BMI kg/m2 BMI (Z-score) BMI Z-score ≥ 2 Head circumference (cm) Head circumference (SDS) Body fat mass (%) Body lean mass (%) | 15.4 (12.2;28.4) 0.7 (-1;10,7) 98.5 (92.5;108) 0.8 (-1.2;3.9) 15.9 (14.1;26.3) 0.13 (-1.5;6.31) 2 (12%) 49 (46.5;53) (n = 16) -0.35 (-2.5;2.7) (n = 16) 22 (10;65) (n = 17) 75 (32;85) (n = 17) | 14.6 (13;19.6) 0.6 (-1.1;4.8) 96 (90.5;107) 0.5 (-1.4;4.3) 15.4 (13.8;21.7) -0.35 (-1.79;4.23) 2 (12%) 50 (48;52.5) (n = 17) -0.31 (-1.9;1.25) (n = 17) 24.5 (8;40) (n = 16) 71 (57;88) (n = 16) | 15.2 (12.2;28.4) 0.6 (-1.1;10.7) 97.9 (90.5;108) 0.6 (-1.4;4.3) 15.8 (13.8;26.3) 0.08 (-1.79;6.31) 4 (12%) 50 (46.5;53) (n = 33) -0.31 (-2.5;2.7) (n = 33) 22 (8;65) (n = 33) 73 (32;88) (n = 33) |
GH treatment % of treated Dose at start GH treatment (µg/kg/day) Current GH dose (µg/kg/day) Age at start GH treatment (months) % with at least 2 years of treatment | 100% 26 (15;41) 27.6 (15.2;41.4) 10.0 (7.2;12.4) 100% | 100% 25 (8;52) 28.6 (6.8;51.5) 13.2 (7.5;30.3) 94% | 100% 26 (8;52) 28.1 (6.8;51.5) 10.6 (7.2–30.3) 97% |
Psychosocial and family data Number of siblings Couple n (%) Schooling n (%) Social vulnerability score (EPICES)* | 0 (0;2) 12 (71%) 12 (71%) 16.6 (0;100) (n = 17) | 1 (0;3) 14 (82%) 14 (82%) 16.9 (0;73) (n = 16) | 1 (0;3) 26 (77%) 26 (77%) 16.6 (0;100) (n = 33) |
Birth data Term (WA) Premature birth n (%) Cesarean delivery n (%) Weight (SDS) Length (SDS) Nasogastric tube feeding (NGT) n (%) Duration of NGT (days) | 39 (30–41) 3 (18%) 9 (53%) (n = 17) -1.7 (-2.9;-0.3) (n = 17) -0.9 (-2.5;0) (n = 17) 15 (88%) 120 (14–195) | 39 (32–41) 3 (18%) 10 (59%) (n = 16) -1.7(-2.3;0) (n = 16) -1.0 (-2.6;0) n = 16) 13 (76%) 31 (2-210) | 39 (30;41) 6 (18%) 19 (56%) (n = 33) -1.7 (-2.3;0) (n = 33) -0.9 (-2.6;0) (n = 33) 28 (82%) 85 (2-210) |
Results are presented as n (%) or median (min-max) by groups and in all children. There was no statistical difference between the two groups regarding all the parameters of the table.
*The maximum score is 100, the cutoff of 30 was used to define social deprivation.
STUDY PROTOCOL
This single-center clinical trial compared the adaptive functioning, behavior and development, as well as feeding and social skills, endocrine, metabolic and safety issues, of 3- to 4-year-old PWS children who composed the 2 groups mentioned above. The OT-exposed group comprises 17 children who participated as infants in the OTBB2 study. The OTBB2 study was an open-label phase I/II escalating dose study with three groups of six infants with PWS, each group receiving the same dose which increased from group 1 to group 3 as described: OT 4 IU every other day, every day, twice a day for a total duration of treatment of 7 days. Children of the non-exposed group were aged-matched (with a maximum difference of plus or minus 3 months) with children of the OT-exposed. All children were admitted for a single 3-day visit in the Hospital hosting the French reference center for PWS in Toulouse. The complete study protocol is available at https://www.chu-toulouse.fr/IMG/pdf/final_protocole__ot2suite_v1.6_22032017-en.pdf and details of inclusion and exclusion criteria are detailed below.
Inclusion/Exclusion criteria
Among the 18 patients included in the OTBB2 study, one was lost to follow-up; the 17 remaining patients were included in this current study. One patient combining severe social economic deprivation regarding the EPICES score (> 50) and poverty, defined as extreme deprived conditions of life confirmed by the clinical team, was excluded of the Vineland socialization domain analysis because both conditions have a severe impact on care, social adaptive skills and behavior.
Outcomes and data collected
Adaptive functioning: the primary endpoint was the score in the communication domain of the Vineland adaptive behavior scale version II (VABS-II) (9). The VABS-II evaluates adaptive functioning in four domains: Communication, Socialization, Daily Living Skills and Motor Skills expressed in scores and categorized in adequate /moderately low /low. Age equivalent scores and standard scores (mean (M) = 100; standard deviation (SD) = 15) are provided for each domain. The other subscores of the VABS-II were analyzed as secondary endpoints as were the following evaluations.
Behavior: behavior was assessed with the Child Behavior Check List (CBCL) using its total T score and 14 subscores (10).
Feeding skills: a dynamic videofluoroscopy of swallowing (VFSS) was performed and scored with a chart including the analysis of the five phases of swallowing. Eating behavior was assessed by a questionnaire used in routine care in our center. It was completed by the pediatrician during an interview with the parents, with 5-point Likert scale responses (Supplementary Table 1).
Growth and development: children were measured and weighed during the study visit. Development was assessed by the Bayley Scale of Infant and Toddler Development version III (BSID-III), which included cognitive, receptive language, expressive language, fine motor, and gross motor scores (11).
Endocrine and metabolic evaluations: sampling for hormone and metabolic assays: Measurements of IGF-1, thyroid hormones, glycaemia, insulin and lipids were performed as routine evaluations. Plasma concentrations of acylated ghrelin (AG), unacylated ghrelin (UAG) and OT were measured as previously described (6). We then compared the ghrelin data with data from age-matched healthy controls from our previous studies (12, 13).
Brain connectivity analysis during resting state using functional MRI (fMRI): the children lay supine and were instructed to relax and keep their eyes closed, but not to sleep. fMRI preprocessing and statistical analyses are described in the supplementary methods. We chose to study the default mode network (DMN) which has frequently been studied and the orbitofrontal cortex network (superior, median and inferior) as in the OTBB2 study (6).
To reveal the areas where significant connectivity change occurred, we set up the threshold for the Statistical Maps at p < 0.005 voxel-wise and we used a threshold for cluster extent of P < 0.05 corrected for multiple comparisons across the whole brain.
Comorbidities: sleep disorders and orthopedic problems reported in children medical files were collected.
Evaluation of tolerance: tolerance was assessed by recording vital signs, physical examination sign, laboratory parameters and adverse events (AE);
Evaluation of social deprivation: the EPICES score (Evaluation of the Deprivation and Inequalities of Health in Healthcare Centers) is a self -questionnaire validated in France (14, 15) that evaluates the social deprivation of the family as defined by limited access to society’s resources due to poverty, discrimination, or other disadvantages. The score ranges from 0 to 100 with a threshold of > 30 defining social deprivation.
Statistical analysis
Comparisons between OT-exposed and non-exposed group were performed.
Results for all variables, including each item of the questionnaires, were summarized by group using descriptive statistics or frequency/percentage, as appropriate. A parametric approach (Student t-test) or a non-parametric approach (Mann-Whitney) according to the normality/non-normality distribution was used to compare groups. Subgroups statistical analysis was done using an analysis of variance (ANOVA). The model included group (treated vs. untreated) and age group (1st, 2nd, and 3rd terciles) as fixed effects.
Subgroup analysis was performed to explore the group effect within two levels of genetic diagnosis (deletion and non-deletion). When differences were found between the two genetics subtypes within OT-exposed vs non-exposed groups they were mentioned in the result section. Differences in the proportions of normal and abnormal patients, defined by thresholds, between the OT-exposed and non-exposed groups were analyzed using a Cochran-Mantel-Haenszel test with age group as the controlling factor.
Statistical analysis was performed using SAS® Enterprise Guide software, version 7.1 (SAS Institute, Cary, NC, US) and Stata version 11.2 (Stata Corp, College Station, TX). The statistical significance threshold was set at 0.05.