Inflammatory and blood gas markers of COVID-19 delirium compared to non-COVID-19 delirium: a cross-sectional study

Objectives We aimed to find the association of inflammation and respiratory failure with delirium in COVID-19 patients. We compare the inflammatory and arterial blood gas markers between patients with COVID-19 delirium and delirium in other medical disorders. Methods This cross-sectional study used the CHART-DEL, a validated research tool, to screen patients for delirium retrospectively from clinical notes. Inflammatory markers C-reactive protein (CRP) and white cell count (WBC), and the partial pressures of oxygen (PO2) and carbon dioxide (PCO2) were compared between patients with COVID-19 delirium and delirium in other medical disorders. Results In bivariate analysis, CRP (mg/L) was significantly higher in the COVID-19 group, (81.7 +/- 80.0 vs. 58.8 +/- 87.7, p = 0.04), and WBC (10(9)/L) was significantly lower (7.44 +/- 3.42 vs. 9.71 +/- 5.45, p = 0.04). The geometric mean of CRP in the COVID-19 group was 140% higher in multiple linear regression (95% CI = 7-439%, p = 0.03) with age and sex as covariates. There were no significant differences in pO(2) or pCO(2) across groups. Conclusion The association between higher CRP and COVID-19 in patients with delirium may suggest an inflammatory basis for delirium in COVID-19. Our findings may assist clinicians in establishing whether delirium is due to COVID-19, which may improve management and outcomes of infected patients.