Young adults with PIMD Polyhandicap in pediatric settings a situation more complex than problematic

This cross-sectional study is included in the prospective multicentric French national EVAL-PLH (EVALuation PoLyHandicap) cohort initiated in 2015 (clinical trial registration number NCT02400528 ). The general aim of the cohort is to study the impact of socioeconomic and environmental, epidemiologic determinants on the health status of the persons with PIMD/Polyhandicap. Data are collected every five years. The inclusion criteria for persons with PIMD/Polyhandicap in the cohort were as follows: age > 3 years at the time of inclusion (i.e. 2015– 2016); presenting with a combination of motor deficiency (tetraparesia, hemiparesis, paraplegia, extrapyramidal syndrome, cerebellar syndrome, and/or neuromuscular problems), severe to profound intellectual impairment (intelligence quotient IQ). Various French centers across different regions participated: four specialized inpatient rehabilitation centers providing long-term (days to months), high-level medical and paramedical physical rehabilitation, along with comprehensive preventive care; and eight residential facilities for inpatients and outpatients requiring less intensive medical care.The list and names of the centers are provided in Supplemental Material. All methods were performed in accordance with the relevant guidelines and regulations. The details of the study protocol were previously published 15 . In this cross-sectional study (2020 data), to address the study’s objectives, we distinguished two groups of adults aged 18–35 with PIMD/Polyhandicap, categorized according to their care setting: paediatric facilities (in- or outpatients under 18) versus adult facilities (in- or outpatients over 18). The following data were collected from the medical record of the persons with PIMD/Polyhandicap. Sociodemographics (age, sex); etiology nature (progressive vs. non-progressive, acquired vs. congenital), body mass index (BMI), pubertal status: (completed vs. not completed), autonomy status (FIM   = 20), mobility status (GMFCS III vs. IV-V), health severity based on the Polyhandicap Severity Scale (PSS), providing a global score (from 0 least to 129 most severe) and 2 subscores, the abilities score from 0 (best) to 60 (worse ability) and the comorbidities score (from 0 none to 69 more comorbidities/impairments) 16 , global health stability ( i. unstable for patients who meet at least one of the following criteria: recurrent pulmonary infections (≥ 5/yrs), drug-resistant epilepsia (≥ 4 seizures/month), ii. stable for patients who do not meet any of these criteria), occurrence of decompensation episodes during the last year (defined by an episode leading to admission to an acute care unit); number of medications (including laxatives, anti-convulsants agents, antalgics agents, psychotropics agents, antispastics agents, antidystonics agents, antibiotics, osteoporosis prevention, iron supplementation), medical devices (at least one versus none) including invasive mechanical ventilation, noninvasive mechanical ventilation, tracheostomy, nasogastric tube, gastrostomy, permanent urinary probe, cerebrospinal fluid derivation, and central venous catheter, reeducation devices (at least one versus none) including sitting devices, bed positioning orthesis, limb orthesis, and walking devices. We collected clinically relevant comorbidities and disorders based on established guidelines of the transition process related to children with severe motor and intellectual disabilities of the Conceptual Framework for Children with severe motor and intellectual disabilities 17 . The following comorbidities and disorders were recorded: Respiratory disorders: recurrent pulmonary infections (≥ 5/yrs) (yes/no), receiving oxygen daily (yes/no), muscle and tone disorders: involountary movement (yes/no), orthopedic disorders : cervical stiffness (yes/no), scoliosis with thoracic deformation (yes/no), limb deformation (yes/no), hip luxation (yes/no), digestive disorders : swallowing disorders (yes/no), enteral nutrition (yes/no), gastroesophageal reflux (yes/no), chronic constipation (yes/no), drug-resistant epilepsia (> = 4 seizures/month), urinary tract infections (at least one in the past year vs.none), bedsores versus none (yes/no), noisy behavioral disorders (at least one) of the following items: intermittent screaming, intermittent crying, agitation, self-aggressivity and hetero-aggressivity, sleep disorders (at least one) of the following items: short sleep, night wake up, and difficulties falling asleep, neuro-sensorial disorders: visual impairment (partial/complete blindness) and hearing impairment (partial/complete deafness). Nature of the usual care setting (specialized rehabilitation centers vs. residential facilities), documentation in the patient’s medical record of a specific transition consultation jointly organized or coordinated between the paediatric and adult care teams (yes/no), specialty of the patient’s institution referring clinician (general practitioner vs. (neuro)paediatrician /paediatrician practitioner), daily verticalization sessions (< 2 vs. ≥ 2 sessions /week), daily shower (Yes/No), outing outside (< 1 vs. ≥ 1/week), family visit (< 1 vs. ≥ 1/trimester), return home (< 1 vs. ≥ 1/trimester), and request of structure change (Yes/No). We collected data on the most relevant medical and paramedical specialties involved in the care of persons with PIMD/Polyhandicap: Consumption of medical care : number of consultations during the last year before the assessment were recorded for general practitioner, physical medicine rehabilitation, paediatrician, neurologist, orthopaedist, pneumologist, gastrologist, ophthalmologist, and gynaecologist (for girls-women). Consumption of paramedical care : monthly prescribed sessions (none vs. ≥ 1), the number of performed sessions, and the gap between the number of prescribed and performed sessions (< 3 vs. ≥ 3) were recorded for : physiotherapy, occupational therapy, psychomotor therapy, speech therapy, psychologist, educator, and dietary. Consumption of medical care : number of consultations during the last year before the assessment were recorded for general practitioner, physical medicine rehabilitation, paediatrician, neurologist, orthopaedist, pneumologist, gastrologist, ophthalmologist, and gynaecologist (for girls-women). Consumption of paramedical care : monthly prescribed sessions (none vs. ≥ 1), the number of performed sessions, and the gap between the number of prescribed and performed sessions (< 3 vs. ≥ 3) were recorded for : physiotherapy, occupational therapy, psychomotor therapy, speech therapy, psychologist, educator, and dietary. Regulatory monitoring was performed in accordance with French law, which requires the approval of the French ethics committee (Comité de Protection des Personnes Sud Méditerranée V (Ethics Committee Sud Méditerranée V), University Hospital of CIMIEZ, 20/10/2014, reference number 2014-A00953-44). In accordance with French law, a written informed consent form was obtained from all the parents or guardians of the persons (minors and adults) included in the study. Descriptive data were provided as numbers and percentages for qualitative variables, and as means and standard deviations for quantitative variables. Comparisons between persons in adult facilities and persons in paediatric facilities were performed using Student’s t tests or Mann–Whitney tests for continuous variables, and chi-square tests or Fisher exact tests for qualitative variables. Adjustment for unbalanced factors were made (dependency level and comorbidities score) using logistic regressions. Data were analysed by using SPSS 20.0 software.

A total of 204 persons with PIMD/Polyhandicap were aged between 18 and 35 years at 2020 assessment, with 67 (33%) of them who were care managed in paediatric facilities and 137 (67%) of them who were care managed in adult facilities. In comparison with the young adult care managed for in adult facilities, the young adults care managed for in paediatric facilities were significantly younger, had a lower body mass index, presented a less severe functional dependency status and a less severe health status (less comorbidities). All the details are provided in Table  1 . Table 1 General characteristics of the 18–35 years old persons with PIMD/Polyhandicap according to the care structure (adult or paediatric facilities). Persons cared for in adult facilities Persons cared for in paediatric facilities p-value MD N = 137 N = 67 M ± SD / N (%) M ± SD / N (%) Age 26.8 ± 4.5 21.6 ± 2.4  < 0.001 0 Sex Boys/Men 75 (54.7) 34 (50.7) 0.591 0 Girls/Women 62 (45.3) 33 (49.3) Aetiology nature Non-progressive 31 (27.0) 13 (29.5) 0.852 19 Progressive 83 (73.0) 38 (74.5) Acquired 49 (51.0) 18 (42) 0.361 32 Congenital 47 (49.0) 25 (58) BMI 19.3 ± 4.7 18.0 ± 3.0 0.035 37 Pubertal Not started/not completed 10 (8) 7 (14) 0.175 29 Completed 115 (92) 43 (86) Severe functional dependency FIM score < 20 77 (57.5) 25 (40) 0.020 7 Severe mobility dysfunction GMFCS IV-V 122 (89) 56 (83.6) 0.271 0 Severity (from PSS) Total score 60.0 ± 15.0 59.0 ± 15.2 0.763 21 Abilities score 42.4 ± 11.0 44.4 ± 11.5 0.255 6 Comorbidities score 17.3 ± 6.0 14.1 ± 5  < 0.001 16 Global health stability* Stable 94 (80) 57 (89) 0.107 22 Unstable 24 (20) 7 (11) Annual decompensation episode 0.7 ± 1.5 0.3 ± 0.6 0.097 34 Number of medications** 11.6 ± 4.8 11.4 ± 4.4 0.823 2 At least one medical devices*** 61 (45.2) 33 (50) 0.521 3 At least one reeducation devices**** 127 (93.4) 65 (97) 0.345 1 N numbers; % percent; MD missing data; M ± SD: mean ± standard deviation. BMI: body mass index; FIM: Functional Independency Measure; GMFCS: Gross Motor Function Classification System; PSS: Polyhandicap Severity Scale. *Unstable case: recurrent pulmonary infections and/or drug resistant epilepsy. **Medications: laxatives, anti-convulsants, antalgics, psychotropics, antispastics, antidystonics, antibiotics, osteoporosis prevention, iron supplementation. ***Medical devices: invasive mechanical ventilation, noninvasive mechanical ventilation, tracheostomy, nasogastric tube, gastrostomy, permanent urinary probe, cerebrospinal fluid derivation, and central venous catheter. ****Reeducation devices: sitting devices, bed positioning orthesis, limb orthesis, walking devices. Bold values: p-value < 0.05. General characteristics of the 18–35 years old persons with PIMD/Polyhandicap according to the care structure (adult or paediatric facilities). N numbers; % percent; MD missing data; M ± SD: mean ± standard deviation. BMI: body mass index; FIM: Functional Independency Measure; GMFCS: Gross Motor Function Classification System; PSS: Polyhandicap Severity Scale. *Unstable case: recurrent pulmonary infections and/or drug resistant epilepsy. **Medications: laxatives, anti-convulsants, antalgics, psychotropics, antispastics, antidystonics, antibiotics, osteoporosis prevention, iron supplementation. ***Medical devices: invasive mechanical ventilation, noninvasive mechanical ventilation, tracheostomy, nasogastric tube, gastrostomy, permanent urinary probe, cerebrospinal fluid derivation, and central venous catheter. ****Reeducation devices: sitting devices, bed positioning orthesis, limb orthesis, walking devices. Bold values: p-value < 0.05. Young adults in paediatric facilities also presented significantly lower proportions of digestive comorbidities (gastroesophageal reflux and chronic constipation) than those in structures adult facilities. The 2 groups did not differ for the other comorbidities and disorders. For details see Supplemental Table 1. Compared to young adults in care structures adult facilities, young adults with PIMD/Polyhandicap in paediatric facilities did not differ on the nature of the care structure (specialized rehabilitation centers or residential facilities), benefited of less transition consultation (35% vs. 81%), were less likely to be followed by a general practitioner, had more regular verticalization sessions (33% vs. 18%), had less daily shower (95% vs. 100%). The 2 groups did not differ for the frequency of outing outside and family visits. A higher proportion (73% vs. 48%) of adults with PIMD/Polyhandicap in paediatric facilities had regular home return. A majority (57%) of the adults cared for in paediatric facilities had a request for a structure change. All the details are provided in Table  2 . Table 2 Organization of the care according to the care structure (adult or paediatric facilities). Persons cared for in adult facilities Persons cared for in paediatric facilities p-value MD N = 137 N = 67 N (%) N (%) Care structure Spec. rehab. centers: 58 (42.3) 25 (38) 0.545 1 Residential facilities 79 (57.7) 41 (62) Transition consultation 92 (81) 16 (35)  < 0.001 44 Referring clinician General practitioner 100 (73) 32 (48)  < 0.001 0 (Neuro)-Paediatrician 37 (27) 35 (52.4) Verticalization  ≥ 2 sessions/week 24 (18) 22 (33) 0.016 2 Daily shower 136 (100) 62 (95.4) 0.033 3 Outings outside  ≥ 1/week 82 (61.7) 35 (61.4) 0.974 14 Family visit  ≥ 1/trimester 73 (64.6) 29 (54.7) 0.223 38 Return home  ≥ 1/trimester 50 (48) 41 (73) 0.002 44 Request of structure change 27 (21) 25 (56.8)  < 0.001 32 N numbers; % percent; MD missing data. Spec. rehab. centers: specialized rehabilitation centers. Bold values: p-value < 0.05. Organization of the care according to the care structure (adult or paediatric facilities). N numbers; % percent; MD missing data. Spec. rehab. centers: specialized rehabilitation centers. Bold values: p-value < 0.05. As dependency and comorbidity scores differed between the two groups, we present both unadjusted and adjusted results for healthcare consumption, with adjustments for dependency level (MIF) and comorbidity score (PSS). Before adjustment, compared to young adults care managed in adult facilities, the young adults care managed in paediatric facilities were more often been examined by a paediatrician, less often examined by a pneumologist practitioner, or a gynaecologist practitioner (restricted to women). When adjusted for dependency level (MIF) and comorbidity score (PSS), there were no significant differences between the two groups in access to paediatricians and pulmonologists. The 2 groups did not differ before and after adjustment on the annual consultation with general practitionner, physical and rehabilitation medicine, neurologist, orthopaedist, gastrologist and ophtalomlogist practitioners during the last year, including after adjustment for dependency level and comorbidity score. All the details are provided in Table  3 . Table 3 Medical care during the last year before assessment according to the care structure (adult or paediatric facilities). Persons cared for in adult facilities Persons cared for in paediatric facilities p1 p2 MD N = 137 N = 67 N (%) N (%) General practitioner None 66 (49.3) 35 (58.3) 0.242 0.213 10  >  = 1 68 (50.7) 25 (41.7) Physical medicine rehabilitation physician None 66 (53.2) 39 (61.9) 0.258 0.453 17  >  = 1 58 (46.8) 24 (38.1) Paediatrician None 107 (86.3) 45 (72.6) 0.023 0.119 18  >  = 1 17 (13.7) 17 (27.4) Neurologist None 89 (72.4) 43 (72.9) 0.941 0.860 22  >  = 1 34 (27.6) 16 (27.1) Orthopaedist None 97 (79.5) 45 (77.6) 0.768 0.528 24  >  = 1 25 (20.5) 13 (22.4) Pneumologist None 107 (87.0) 56 (98.2) 0.016 0.192 24  >  = 1 16 (13.0) 1 (1.8) Gastrologist None 114 (91.9) 53 (93.0) 1.000 0.830 23  >  = 1 10 (8.1) 4 (7.0) Ophtalmologist None 116 (93.5) 54 (94.7) 1.00 0.670 23  >  = 1 8 (6.5) 3 (5.3) Gynaecologist (only for girls-women) None 36 (70.6) 22 (95.7) 0.016 - 6  >  = 1 15 (29.4) 1 (4.3) N numbers; % percent; MD missing data. Bold values: p-value < 0.05. p1 unadjusted p-value; p2: adjusted p-value for dependency level (MIF) and comorbidities score (PSS). Medical care during the last year before assessment according to the care structure (adult or paediatric facilities). N numbers; % percent; MD missing data. Bold values: p-value < 0.05. p1 unadjusted p-value; p2: adjusted p-value for dependency level (MIF) and comorbidities score (PSS). Regarding the prescribed sessions of the various paramedical care, before adjustment, the 2 groups did not differ except for educator and dietary that were more often prescribed in adult facilities. Young adults cared for in paediatric facilities had less performed sessions for occupational therapy, educator, and dietary than those cared for in adult facilities. Ten percent of the young adults cared for in adult facilities had a gap (more than 3 sessions between prescribed and performed sessions) for occupational therapy while there was no gap in the other group.The 2 groups did not differ for (prescribed vs. not precribed sessions, performed sessions and gap between prescribed and performed sessions) for physiotherapy, psychomotor therapy, speech therapy and psychology sessions. After adjustment for dependency level (MIF) and comorbidity score (PSS), young adults cared for in paediatric facilities had less frequently prescribed sessions for educator sessions, higher performed sessions for physiotherapy and less performed sessions for educator, and dietary than those cared for in adult facilities. Almost nine percent of the young adults cared for in adult facilities had a gap (more than 3 sessions between prescribed and performed sessions) for educator sessions whereas no such gap was observed for other paramedical care. All the details are provided in Table  4 . Table 4 Paramedical care during the last month before assessment. Persons cared for in adults facilities Persons cared for in paediatric facilities p1 p2 MD N = 137 N = 67 N (%) N (%) Physiotherapy Prescribed sessions None 15 (11.9) 9 (13.6) 0.730 0.152 12  >  = 1 111 (88.1) 57 (86.4) Number of performed sessions m [IQR] 4 [4–12] 8 [4–17] 0.077  < 0.001 12 Gap prescribed-performed sessions    = 3 28 (22.2) 10 (15.2) Occupational Prescribed sessions None 49 (36.3) 28 (47.5) 0.144 0.238 10 Therapy  >  = 1 86 (63.7) 31 (52.5) Number of performed sessions m [IQR] 1 [0–4] 0.5 [0–2] 0.040 0.053 11 Gap prescribed-performed sessions    = 3 14 (10.4) 0 Psychomotor Prescribed sessions None 71 (55.5) 33 (54.1) 0.859 0.447 15 Therapy  >  = 1 57 (44.5) 28 (45.9) Number of performed sessions m [IQR] 0 [0–4] 0 [0–2] 0.908 0.827 14 Gap prescribed-performed sessions    = 3 6 (4.7) 1 (1.6) Speech Prescribed sessions None 115 (93.5) 59 (100) 0.055 - 22 Therapy  >  = 1 8 (6.5) 0 Number of performed sessions m [IQR] 0 [0–0] 0 [0–0] 0.159 - 21 Gap prescribed-performed sessions    = 3 4 (3.3) 0 Psychology Prescribed sessions None 58 (44.3) 28 (43.1) 0.874 0.943 8  >  = 1 73 (55.7) 37 (56.9) Number of performed sessions 0 [0–4] 0 [0–2] 0.228 0.092 9 Gap prescribed-performed sessions    = 3 3 (2.3) 6 (9.2) Special Prescribed sessions None 18 (14.0) 24 (42.1)    = 1 111 (86.0) 33 (57.9) Number of performed sessions m [IQR] 8 [2–30] 2 [0–4]  < 0.001 0.001 17 Gap prescribed-performed sessions    = 3 9 (7.0) 5 (8.8) Dietary Prescribed sessions None 34 (27.9) 30 (50.8) 0.002 0.488 23  >  = 1 88 (72.1) 29 (49.2) Number of performed sessions m [IQR] 1 [0–1] 0 [0–1] 0.005 0.876 23 Gap prescribed-performed sessions    = 3 0 0 N numbers; % percent; p p-value; MD missing data; m [IQR] median [interquartile range]. Bold values: p-value < 0.05. p1 unadjusted p-value; p2: adjusted p-value for dependency level (MIF). Paramedical care during the last month before assessment. N numbers; % percent; p p-value; MD missing data; m [IQR] median [interquartile range]. Bold values: p-value < 0.05. p1 unadjusted p-value; p2: adjusted p-value for dependency level (MIF).

This study focuses on the adults with PIMD/Polyhandicap that have not made their transition to adult facilities, rather than the transition process itself. Even if the transition process needs to be improved, the delay in transition is not prejudicial from the persons with PIMD/Polyhandicap perpective, although, it stresses the paediatric structures capabilities. The improvement of knowledge of the health characteristics of adults with PIMD/Polyhandicap according to the care structures (adult or children facilities) may help to identify avenues for optimization of the coordination between the two systems. The more childlike characteristics of adults cared for in paediatric facilities should encourage us to reflect on the optimal age of transition for adolescents with PIMD/Polyhandicap, which in our view should be later than 18 yrs.

The first finding of this study showed that a large part (one third) of the young people (18–35 years) with PIMD/Polyhandicap were still care managed for in paediatric facilities. This finding is in line with previous studies carried out in France 2 , 12 – 14 . One first explanation can be expressed. It is well known that there is a lack of places in adult structures and that there is heterogeneous availability across the national territory. To partially overcome this, in the 80 s, a French law allowed to prolong the stays of young adults with PIMD/Polyhandicap in paediatric structures 13 . It is now important to better quantify this point and thus be able to offer a more appropriate offer. But other explanations can be given. First of all, the reluctance of families is real. Parents can be apprehensive about switching to an adult facilities. Not only their child, but also them too, have developed trust with the team and the institution, and a change could cause instability or a decline in the quality of care provided (interviews from parents, unpublished data at this time). Likewise, the paediatric team may be also hesitant to transfer the patient, believing that their long-standing relationship with the child gives them greater legitimacy in understanding the patient’s needs and demands 18 , 19 . The transition consultation between paediatric and adult care teams, which is widely recommended by the expert groups 9 , 10 , seems to be a key element of transition process. Care providers and managers of care facilities for people with PIMD/Polyhandicap should ensure that a transition consultation is consistently offered to guide the transition process for these adolescents 20 , 21 . The study’s second finding revealed that, despite the high proportion of youth in paediatric settings, their health outcomes did not really differ from those of individuals care managed for in adult-focused institutions. The study found no substantial disparities between youth in paediatric care and those transitioned to adult structures regarding health severity, episodes of decompensation, medication requirements, or the use of medical and rehabilitative equipment. However, there are some observations to highlight. Compared to those who haven’t transitioned, patients in adult care facilities seem to present marginally higher dependency levels and a greater number of comorbidities. We can propose some hypotheses. First, one possible explanation is that patients who had transitioned to adult care were older, which may partly reflect natural age-related increases in dependency and comorbidities. The process of transitioning to adult care itself may also temporarily increase dependency or exacerbate existing health conditions. Second, it may be hypothesized that more complex cases with higher care needs are prioritized for transition to adult facilities, whereas less dependent patients or those with delayed puberty may remain in paediatric care for a longer period 22 . This hypothesis aligns with the Canadian Paediatric Society’s recommendations for improving the transition to adult care for youth with complex health needs, which emphasize that more flexible age cut-offs—based on developmental readiness rather than chronological age—are preferable 23 . Taken together, these findings suggest that individuals with PIMD/Polyhandicap often transition to adult care well beyond the standard age of 18. The third major finding revealed by this study is that the structure of the care environment does not seem to be associated with the consistency of medical care. As a result, both groups have similar access to key specialties involved in the care of persons with PIMD/Polyhandicap, such as physical medicine and rehabilitation, neurology, and orthopedics. This contrasts with earlier studies that highlight how the care and follow-up of adults with chronic neurological conditions (including mental or developmental disorders) are less multidisciplinary and specialized in adult facilities compared to paediatric ones 4 , 10 , 17 , 24 . Nevertheless, integrating paediatric preventive strategies into adult care remains crucial for optimizing health outcomes, particularly regarding preventive measures and educational issues (such as scoliosis, epilepsy, and digestive disorders) 25 – 27 . Lastly, the fact that girls and women in paediatric settings have less access to gynecologists is a real concern. Regular gynecological follow-up remains essential for these young women for identifying potential hormonal disorders, endometriosis, screening for gynecological cancers and other gynecological conditions that may emerge during this period of hormonal maturation 28 , 29 . Concerning paramedical care, young adults receiving care in facilities dedicated to adults had access to less educational care, while individualized and intensive educative favor progression in persons with PIMD/Polyhandicap 30 – 32 . They also had restricted access to physiotherapy interventions, particularly verticalization sessions, which are recognized for their benefits in reducing bone fragility, improving digestive and respiratory function, and enhancing social interaction 33 . These gaps may exacerbate motor and cognitive deficits, possibly reflecting a greater focus on educational care in paediatric settings compared with adult services. Young adults experience no difference in the frequency of outings and family visits based on whether they are cared for in a children’s or an adult’s facility. Home visits are less frequent for adults cared for in facilities dedicated to adults compared to those in paediatric settings, possibly because their parents are older or live farther away. This reduced frequency may have important implications, as studies in other contexts suggest that more frequent home visits are associated with better developmental outcomes, likely because regular visits or weekend stays with parents and relatives help maintain attachment bonds, provide familiar routines, and offer a stimulating and supportive environment 34 . To our knowledge, this is the first study to investigate the health and care profiles of young adults with PIMD/Polyhandicap who remain in paediatric settings, suggesting that delayed transition is not detrimental from their perspective, although it places significant strain on paediatric service capacity; nevertheless, further studies are needed. Several limitations should be considered when interpreting these findings. First, the cross-sectional design precludes establishing causal relationships; results should thus be interpreted as associations only. While age-group comparisons offer valuable insights, they cannot capture longitudinal patterns or individual trajectories—further studies using longitudinal designs and larger samples are needed to elucidate how health characteristics evolve over time and to better document the transition process to adult care structures. Second, complementary qualitative studies would provide deeper insights into barriers and facilitators. And finally, this study should be replicated in a non–COVID-19 context. Because the 2020 data were collected during the COVID-19 pandemic, changes in healthcare organization, staff absenteeism, and safety guidelines may have affected access to care and support, including medical, paramedical, and educational services, which may have influenced the results observed in this study.

Profound Intellectual Multiple Disability (PIMD)/Polyhandicap is defined by the Ithaca European Reference Network for congenital malformations and rare intellectual disabilities, as a complex disability condition occurring in an immature brain, leading to profound intellectual disabilities, sensory impairments and severe motor disabilities, manifesting in the inability to move independently. These persons are dependent on human and technical assistance 1 . Persons with PIMD/Polyhandicap requires lifelong care that provides both the specific medical care required (management of episodes of decompensation and comorbidities, and preventive care) and also addresses the social and educational dimension, in order to offer them a coherent, adapted, and integrative life project. The French health system allows these persons to benefit from two main care management modalities according to their health severity status: specialized rehabilitation centers offering a high level of medical and paramedical physical rehabilitation and residential facilities offering a high level of psychosocial education. Within these two modalities, there are units dedicated to adult populations and units dedicated to paediatric populations 1 , 2 . Thanks to advances in medical management, a large majority of children with PIMD/Polyhandicap now reach adulthood and their survival has been estimated to exceed 50 years. 3 , which raises the importance of addressing their adult care needs and the process of moving from child-centered to adult-oriented healthcare systems. It is known that this period, called transition process from paediatric to adult care, can be associated with a deterioration in the health status of adolescents with chronic diseases, particularly for Children with Special Care Needs 4 – 7 . The transition process is defined as the « purposeful, planned movement of adolescents and young adults with chronic physical and medical conditions from child-centered to adults-oriented healthcare systems » 8 . To facilitate the transition process for Children with Special Health Care Needs, the French Society of Physical Medicine and Rehabilitation (SOFMER) has endorsed a consensus statement with guidelines stressing the importance of a paired transition consultation combining paediatrician and adult physician, a transition coordinator, a written transition program, and an adapted offer of care for adults (part-time, sequential, etc.) 9 . In spite of these recommendations, the transition process of Children with Special Health Care Needs remains suboptimal 4 , 10 , 11 . Over the past twenty years, various French studies pointed that 7% of young adults (≥ 18 years old) with disabilities were not care managed in a structure dedicated to their age 12 , 13 , and this proportion being higher (11%) for persons with PIMD/Polyhandicap 2 , 12 – 14 . This raises the question of whether or not transiting to adult structures affects the health outcomes for adolescents and young adults with PIMD/Polyhandicap. The aims of this study were to assess whether the profile of young adults in paediatric care differ from those in adult care on health characteristics, care organizations, and healthcare consumption.

Supplementary Information 1. Supplementary Information 2. Supplementary Information 1. Supplementary Information 2.