What Do We Now Know About Pediatric Chronic and Complex Critical Illness?

In 2023, a Pediatric Critical Care Medicine (PCCM) scoping review focused on the potential challenges and gaps in the definition of pediatric “chronic critical illness” (CCI) (1). The investigators studied 67 articles published before March 2021 and showed a core problem being faced by practitioners working in this field. That is, the definitions of CCI in the literature were: 1) inconsistent; 2) subjective, and often “anchored” on different ideas of patient complexity; and 3) heterogeneous regarding chronicity of PICU admission duration, such as ≥ 14 or ≥ 28 days. As a conclusion, the authors called for some work on “a consensus definition...to advance this emerging and important area of pediatric critical care research.” In fact, the authors thought that without such work, our specialty would be unable to carry out significant, collaborative health services research on the epidemiology and outcomes of CCI. The editorial that accompanied the scoping review (2) took a broader perspective, and discussed whether the definition should be a matter of operationalizing the statement “I know it when I see it?” Another approach would be to use views of all stakeholders, including children living with increasingly complex needs and vulnerabilities. The question is whether in late 2025, we are any further forward in this work. I have therefore used this month’s Editor’s Notes to consider highlights in recent research on CCI since 2023. Specifically, the developments in diagnosis and epidemiology, new knowledge about coordination of clinical practice, and reports describing improvements in family communications. DIAGNOSIS AND EPIDEMIOLOGY The diagnosis and epidemiology of “medical complexity” has been explored in a few reports published between 2023−2025. Two large, multicenter patient databases held in the United States have been central to a better understanding of the scale of patient need (i.e., the Virtual Pediatric Systems Database [VPS, LLC] of PICU admissions and the Pediatric Health Information System [PHIS] administrative database of children’s hospitals and PICU admission) (3). For example, the 2017−2019 VPS database was used to test clinical differences and the degree of overlap between two definitions of complex medical conditions (4). (These two organ system definitions were the “Complex Chronic Condition” [CCC] and the “Pediatric Medical Complexity Algorithm” [PMCA]). In a test population of 291,583 pediatric patients younger than 21 years, from 131 PICUs across the United States, the investigators found that the CCC and PMCA definitions identified distinct subpopulations, with only “fair” agreement between the two. Even so, from an epidemiological perspective, 77.7% of the total cohort met at least one definition of medical complexity. Similarly, the PHIS database was used as a window to understand national epidemiology of complex medical conditions but, here, the authors were interested in two patient subgroups admitted to the PICU (5,6). One study used the 2011−2022 PHIS dataset of 65,740 adolescent patients and young adults (age ≥ 15 years) with respiratory failure (5) and found that half of these patients had a CCC according to the schema from the Agency for Healthcare Research and Quality (7). Another study used the 2016−2021 PHIS dataset of 6,511 patients aged 5−18 years undergoing elective spinal fusion surgery with one or more CCC (6) (in this instance, CCC was defined as an underlying neuromuscular or genetic disorder, including hypotonic/myopathic and hypertonic/spastic condition (8,9)) and found that around 6.7% of these patients were technology-dependent with an established preoperative tracheostomy. Besides these reports using national databases to highlight epidemiology, there is also a PROSPERO (Prospective Register of Systematic Reviews, CRD42024529649) registered protocol for a systematic review of nomenclature and outcomes of children with “complex critical illness” reported in the PICU literature from 2014−2024 (10). The authors aim to use the review as a basis for consensus definition, which may unify our approach to terminology and resolve the breadth of terms such as: complex critical illness, CCC, prolonged PICU admission, PMCA, severe or CCI, severe neurologic impairment, and technology-dependent children. COORDINATING CLINICAL PRACTICE Between 2023−2025, there were four studies that covered the care of children with CCC in the PICU (11−14). One study reviewed nutrition support (11), and another study examined the significant interaction between patients with CCC and their need for mechanical ventilation ≥ 3 days (12). Two other studies aimed to help clinicians coordinate care for children and families dealing with CCI and complex care needs. First, a systematic review of literature published up to May 2023 assessed the effectiveness of comprehensive care programs for children with medical complexity (13). These cases were defined as those having: 1) a chronic illness; 2) functional limitations; 3) increased health and other service needs; and 4) increased healthcare costs. Here, comprehensive healthcare was viewed as the coordination of services that, potentially, required co‐management of patients by specialists and specialist teams in various hospital and community settings. The authors identified four reports (total of 912 children) and concluded “…comprehensive care may make little or no difference to overall healthcare costs…” The second item appeared in the PICU literature and was a report about operationalizing expert and parent continuity in the PICU by the Lucile Packard Foundation PICU Continuity Panel in 2023 (14). The panel endorsed 17 consensus statements in various aspects of continuity, including eligibility criteria, initiation, standard responsibilities, and resources needed for implementing and sustaining prolonged care. However, the quality of evidence for the statements was low to very low. FAMILY COMMUNICATIONS In the United States, there is literature that shows patient family use of a language other than English has significant association with outcomes (15). Is this an issue of disparity in access, or timing of communications with parents and children, or even the form of parental decision-making (16)? Additionally, thinking of communications with parents and caregivers of children with medical complexity, are we providing the necessary social supports (17); and, what about the unique challenges in mental health and emotional and psychological support for adolescents and young adults with CCC (18). In this context, a scoping review in August 2025 aimed at guiding family meetings for hospitalized children with medical complexity (19). The authors found common components of these meetings in 21 studies, and the main ones included addressing specific tasks (e.g., identifying the need for a meeting) and having goals to communication (e.g., assessing and supporting understanding). As an example of goals of care discussions, one single-center retrospective study focused on children with complex medical conditions with at least one CCC and one hospitalization in 2021 (20). The authors found that out of 1,235 cases, goals of care discussions occurred in 22%, and 70% of these discussions occurred in the PICU. In fact, 78% of goals of care discussions occurred within 6 months of death. In this context, there are an additional three recent studies about end-of-life issues and needs in families of children with complex medical conditions. First, there is lack of ethical resources available for families as they approach difficult decision-making in their child with medical complexity and CCI (21). Second, as demonstrated in an electronic survey of 218 parents of children with medical complexity (carried out 2022−2023), parents experience ethical challenges and consequently they are at risk of distress (22). Last, in a follow-up survey of 114 bereaved parents of children with CCC who were managed during terminal care, 2006−2015, nearly one in five experienced “great economic hardship” (23). The authors concluded that this higher economic burden needed additional supportive and preventative measures. NEW RESEARCH IN COMPLEX-CHRONIC CRITICAL ILLNESS In summary, this Editor’s Notes item highlights advances in PICU research since the 2023 scoping review about the potential challenges and gaps in knowledge when defining pediatric CCI (1). These new studies on coordinating clinical practice and family communications in complex-chronic critical illness add to PCCM’s theme focused on family-centered care (24) and show us what we know now. Even so, we need to know more, and the Journal welcomes research from all disciplines involved with supporting and improving care for children with chronic medical complexity in the PICU.