One Disease But Different Outcomes: A Comparative Study of Characteristics and Outcomes of COVID-19 ICU Patients in the 2 Waves

ABSTRACT

Introduction: The 1st wave of COVID-19 spread rapidly affecting most countries globally in a short duration. Many countries suffered the 2nd wave of COVID-19 infection, months after the 1st wave, largely driven by viral mutants with high transmissibility and reduced susceptibility to neutralising antibodies (1-3). Despite COVID-19 being the common etiology, the two waves have significant differences impacting both current understanding and future planning of the impact of COVID-19. This study from a tertiary ICU is a comparative analysis focusing on the cardinal differences in COVID-19 ICU patients between the two waves, with respect to baseline demographics, clinical features, disease severity, and outcomes. Materials and methods: Retrospective data was collected from the medical records of all patients with COVID-19 disease admitted to the intensive care unit (ICU) in the 1st and 2nd wave of the pandemic. COVID-19 disease was confirmed by means of a positive RT-PCR or a rapid antigen test (RAT) on a nasopharyngeal swab or respiratory sample. Baseline demographic and clinical data, disease severity, and outcomes were analysed. Results: 419 patients (74.9% males) were admitted to the ICU between July and December 2020 and 206 (65% males) patients between April and June 2021. The mean age of patients admitted in the 1st wave was 59.84 ± 13.7 (mean ± SD) years and the 2nd wave was 55.31 ± 14.9 years (p = 0.038). The duration from symptom onset to admission (Median, IQR) was 5 days (3, 7) for the 1st wave and 5 days (3, 8) for the 2nd wave. 74.5% (312/419) of the patients in the 1st wave and 64.5% (129/206) in the 2nd wave had one or more comorbidities (p = 0.05). The median CRP values were 83.0 mg% (IQR 31.45, 159.7) for the 1st wave and 93.0 mg% (IQR 48.0, 141.0) for the 2nd wave, respectively, statistically not significant. 31.8% (131/412) of the ICU patients in the 1st wave and 52.3% (103/196) in the 2nd wave required mechanical ventilator support (p < 0.05). The overall ICU mortality was 32.1% (134/418) for the 1st and 52.5% (104/198) for the 2nd wave (p value?). Conclusion: There is a significant difference between the 2 waves in age, comorbidities, and mortality, likely related to viral mutants, vaccination policies, and social mobility dynamics.