CO₂ combining power and outcomes in patients with acute ischaemic stroke or transient ischaemic attack

The clinical significance of carbon dioxide combining power (CO₂CP) in ischaemic cerebrovascular disease is not well established, and the role of CO₂CP in the prognosis of acute ischaemic stroke (AIS) or transient ischaemic attack (TIA) has not been reported. The objective of the study was to investigate the associations between CO₂CP and clinical outcomes in patients with AIS or TIA.

Data were derived from the China National Stroke Registry III. Patients were classified into five groups by quintiles of CO₂CP levels and three groups according to the normal range of CO₂CP (23-29 mmol/L). Multivariable Cox and logistic regressions were adopted to explore the associations of CO₂CP levels with all-cause death and poor functional outcomes (modified Rankin Scale (mRS) 3-6/2-6) at 3 months and 1 year.

Among 9531 patients included in the study, the median (IQR) CO₂CP was 24.9 (23.0-27.0) mmol/L. After adjustment for potential confounders, patients in the first CO₂CP quintile (21.1-23.3 mmol/L) had higher risk of all-cause death and poor functional outcomes (mRS score of 3-6/2-6) (HR or OR with 95% CI 2.37 (1.32 to 4.25), 1.49 (1.20 to 1.83) and 1.21 (1.03 to 1.42), respectively) compared with those in the fourth quintile. Similar results were found for outcomes at 1 year. Furthermore, all associations were also significant when CO₂CP was <23 mmol/L compared with CO₂CP of 23-29 mmol/L.

Decreased CO₂CP was associated with high risk of all-cause death and poor functional outcomes in patients with AIS or TIA.