Leucocytosis and outcomes in older ICU patients after ischaemic stroke: a binational multicentre cohort study
Je Min Suh, Jerry Lim, Kyle Williams, Steven Lin, Nattaya Raykateeraroj, Fawaz Prem Navaz, David Pilcher, Dong-Kyu Lee, Laurence WeinbergBackground
White blood cell count (WCC) is a recognised prognostic and systemic inflammatory marker in ischaemic stroke, with higher counts associated with increased tissue damage, secondary complications and mortality. However, its value in the very elderly remains unclear despite the increased burden of ischaemic stroke with age. We aimed to investigate the association between admission WCC and mortality and length of stay (LOS) among nonagenarians and centenarians admitted to intensive care unit (ICU) with ischaemic stroke.
Methods
We conducted a binational retrospective cohort study of patients aged ≥90 years admitted to an Australian or New Zealand ICU with ischaemic stroke between 2010 and 2024, using data from the Australian and New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation. Multivariable regression assessed associations between WCC, analysed as a continuous and categorical variable, and all clinical outcomes. Logistic regression evaluated ICU and in-hospital mortality, and linear regression assessed ICU and hospital LOS.
Results
615 nonagenarian and centenarian patients with ischaemic stroke were included: 444 (72%) with normal WCC (4–11×10⁹/L), 7 (1%) with leucopenia (<4×10⁹/L) and 164 (27%) with leucocytosis (>11×10⁹/L). Compared with a normal WCC, leucocytosis was an independent predictor of ICU mortality (adjusted odds ratio 2.33, 95% CI 1.11 to 4.96, p=0.026) and hospital mortality (aOR 2.01, 95% CI 1.29 to 3.13, p=0.002). Each one-unit WCC increase was associated with higher ICU mortality (aOR 1.21, 95% CI 1.03 to 1.41; p=0.018) and hospital mortality (aOR 1.11, 95% CI 1.02 to 1.21; p=0.015). Additionally, leucocytosis was associated with a 15% longer ICU stay (exp 1.15, 95% CI 1.00 to 1.32, p=0.043), but not hospital LOS.
Conclusion
Early leucocytosis was independently associated with both increased mortality and ICU LOS in nonagenarians and centenarian patients admitted to ICU with ischaemic stroke, supporting its use as a readily available prognostic biomarker to inform risk stratification and decision-making.