Admission ionised calcium disturbances and adverse outcomes in paediatric major trauma: a UK multicentre retrospective cohort study.

BACKGROUND: Calcium disturbances are increasingly recognised as detrimental in adult trauma patients; both ionised hypocalcaemia (iHypoCa) and ionised hypercalcaemia (iHyperCa) are associated with increased mortality. Paediatric data is limited and heterogeneous, with suggestions that iHypoCa may be associated with haemodynamic instability and increased treatment requirements. No paediatric studies have explored the effect of iHyperCa. OBJECTIVES: To examine the association between admission ionised calcium (iCa) disturbances and hypotension, treatment requirements, poor functional outcome and mortality in paediatric major trauma. METHODS: A multicentre retrospective cohort study across 13 sites in the United Kingdom (2016-2023). Children aged <16 years with major trauma (Injury Severity Score≥15) and an admission iCa measurement were included. Calcium levels were categorised as iHypoCa (iCa<1.16 mmol/L), ionised normocalcaemia (iCa≥1.16 mmol/L-1.29 mmol/L) and iHyperCa (iCa≥1.30 mmol/L). The primary outcome was hypotension in the Emergency Department. Secondary outcomes included treatment requirements within 24 hours, poor functional outcome at 30 days (Glasgow Outcome Scale≤4), and 24-hour and 30-day mortality. Multivariable logistic regression adjusted for injury severity, age categories, mechanism and sex. RESULTS: Among 517 children, 102/517 (19.7%) had iHypoCa and 72/517 (13.9%) iHyperCa on admission. iHypoCa was associated with hypotension and coagulation abnormalities on univariable analysis but was not independently associated with treatment requirements, poor functional outcome or mortality after adjustment. In contrast, iHyperCa was associated with a high-risk phenotype and was independently associated with poor functional outcome (OR 2.52, 95% CI 1.45 to 4.35), 24-hour mortality (OR 19.33, 95% CI 6.95 to 53.69) and 30-day mortality (OR 9.07, 95% CI 4.92 to 16.72). CONCLUSIONS: Admission calcium disturbances are prevalent in paediatric major trauma. These findings support contextual interpretation of calcium levels, the need for caution with empiric calcium administration in injured children and highlight the potential value of admission iHyperCa as a marker of physiological stress in injured children.