Association of Vaccination Status, Clinical and Laboratory Parameters with Mortality in COVID-19 Patients Admitted to the Intensive Care Unit: A Single-Center Retrospective Study

Objective: To evaluate the association between second-dose vaccination status, clinical characteristics, treatment modalities, and laboratory parameters with intensive care unit (ICU) mortality among patients with COVID-19 who had received at least one dose of vaccination.Methods: This single-center retrospective cohort study included 100 consecutive adults with RT-PCR-confirmed COVID-19 admitted to the COVID-19 ICU between March 11, 2021, and August 23, 2021, who had received at least one vaccine dose. Demographic, clinical, treatment-related, and laboratory data were obtained from medical records and hospital information systems. The primary outcome was ICU mortality. Variables associated with mortality were evaluated using univariate and multivariable logistic regression analyses, and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.Results: Among the 100 patients included in the study, 49% died during ICU follow-up. The rate of receiving a second vaccine dose was significantly higher among survivors (78.4% vs. 61.2%, p=0.048). Invasive mechanical ventilation (IMV) was markedly more frequent in non-survivors (95.9% vs. 3.9%, p<0.001), whereas dexmedetomidine use was significantly more common among survivors (66.7% vs. 6.1%, p<0.001). Non-survivors had significantly higher ferritin, troponin, and myoglobin levels and lower platelet counts (all p<0.05). In univariate logistic regression analysis, dexmedetomidine use was associated with lower odds of mortality (OR: 0.03, 95% CI: 0.008–0.120, p<0.001), whereas IMV was strongly associated with increased mortality (OR: 24.46, 95% CI: 6.28–95.27, p<0.001). Higher log-transformed troponin (OR: 1.49, 95% CI: 1.15–1.92, p=0.002) and ferritin levels (OR: 1.67, 95% CI: 1.16–2.38, p=0.006) were associated with increased mortality. In multivariable analysis, dexmedetomidine use remained independently associated with lower mortality (OR: 0.03, 95% CI: 0.007–0.14, p<0.001), while higher ferritin levels remained independently associated with increased mortality risk (OR: 1.83, 95% CI: 1.09–3.07, p=0.022).Conclusion: Among vaccinated COVID-19 patients admitted to the ICU, mortality was associated with IMV requirement and elevated inflammatory and cardiac biomarkers. Dexmedetomidine use and ferritin levels remained independently associated with mortality after adjustment. These findings suggest that integrating clinical characteristics and routinely available laboratory parameters into patient assessment may improve risk stratification in critically ill COVID-19 patients.