The magnitude of multimorbidity in childhood: a global systematic review

BACKGROUND: Childhood multimorbidity, defined as the co-occurrence of two or more chronic conditions, is an emerging yet underexplored global health concern. Unlike adult multimorbidity, which is predominantly linked to ageing, childhood multimorbidity affects critical developmental phases, impacting physical, cognitive, and emotional well-being. Despite increasing recognition, its prevalence, correlates, and long-term implications remain inadequately understood. OBJECTIVES: This systematic review aims to synthesize existing evidence on the prevalence, correlates, and outcomes of childhood multimorbidity in the general paediatric population. METHODS: A comprehensive search was conducted across PubMed, EMBASE, Web of Science, and CINAHL (EBSCO) to identify observational studies published up to May 31, 2024. Studies were included if they reported multimorbidity prevalence among children aged 0-18 years. Owing to high heterogeneity across studies, a meta-analysis was not performed, and the results were synthesized narratively. RESULTS: Nine studies, covering diverse paediatric populations, met the inclusion criteria. The individual study prevalence varied widely, ranging from 1.26% to 17.04%, reflecting differences in chronic conditions, multimorbidity definitions, study designs, and data sources. The key correlates included socioeconomic disadvantage, early-life factors (e.g., preterm birth), and poly-victimization. The co-occurrence of physical and mental health conditions commonly affects health-related quality of life (HRQOL), healthcare utilization, and educational performance. CONCLUSIONS: Childhood multimorbidity poses significant health and social challenges, necessitating integrated care approaches and standardized definitions for cross-study comparability. Preventive strategies targeting social determinants and early-life interventions are crucial to mitigate its long-term burden. Future research should focus on longitudinal studies to explore progression and inform targeted interventions. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42024601137.