Clinical and Biochemical Characteristics of COVID-19 Patients During the Delta-Omicron Wave with Risk Assessment of Adverse Outcomes.

Objective: To compare clinical and biochemical characteristics of hospitalised COVID-19 patients and risk assessment of disease outcomes Study Design: Descriptive study. Place and Duration of the Study: Department of Pathology, Dow International Medical College and Sindh Infectious Diseases Hospital and Research Centre, from January to March 2022 Methodology: SARS CoV-2 PCR-positive hospitalised patients were enrolled. Delta or omicron variants infected patients were followed till the last recorded event of hospitalisation. After a detailed history, clinical and biochemical profiles were recorded during the hospitalisation. Length of hospitalisation, ICU admission and in-hospital mortality were taken as outcomes and odd ratios were calculated.

Results: During the study period, omicron was the predominant SARS CoV-2 variant. Omicron-infected patient were older (67 vs. 62 years) and had a significantly shorter duration between appearance of symptoms and hospitalisation (5 vs. 8 days), when compared with the delta patients. Median values of LDH, ferritin and TLC were significantly higher in delta patients (p<0.05). Delta infected patients have a 3.9 times more risk of prolonged hospital stay. In patients with increased TLC, the risk of prolonged hospitalisation and ICU admission was found 16% and 23%, respectively. However, the aOR for ICU admission and in- Hospital mortality were not found significant for the delta and omicron-infected patients.

Conclusion: The clinical course and biochemical profiles are diverse in delta and omicron patients. Hospitalised patients with omicron infection exhibit shorter stays. High values of TLC are found associated with an increased risk of longer hospital stay and ICU admissions.

Key Words: COVID-19, Delta variant, Omicron variant, Hospitalised patients, Outcomes, In-hospital mortality, Biochemical markers, Clinical severity.