Long-term mortality in different COVID-19 variants: 18-month follow-up

Abstract

The viral infection and pandemic of coronavirus infection 2019 (COVID-19) was characterized not only by high morbidity and in-hospital mortality, but also by an increase in the mortality of patients after hospital discharge. At the same time, differences were noted in hospitalization rate, the number of complications and mortality of patients, and mortality rate between different pandemic waves from 2020 to 2023.Aim. To compare the 18-month post-hospital mortality rate of patients between three COVID-19 variants (Alpha, Delta and Omicron).Material and methods. In this prospective, single-center, non-randomized continuous study, 2400 medical records of patients with the Alpha variant (2020), 1826 with the Delta variant (2021) and 997 with the Omicron variant (2022) were analyzed. The end point was all-cause mortality during the follow-up period.Results. There were following differences in clinical and demographic characteristics in the context of COVID-19 strains: more women were hospitalized in the Delta and Omicron waves; in the Omicron wave, patients were older. Also, comorbid patients were more common with the Delta and Omicron variants than with the Alpha (in chronic obstructive pulmonary disease, hypertension and heart failure), but chronic kidney disease was more common with the Alpha and Omicron variants. The groups differed significantly in mortality, with the maximum being with Delta and the minimum with Omicron, and the maximum mortality with Delta was observed in the first 90 days after discharge. Between 12 and 18 months, survival estimates decreased most for patients hospitalized in the Delta wave, which is determined by the risk of long-term cardiovascular consequences.Conclusion. Clinical and demographic differences between patients with different COVID-19 variants, as well as a significant difference in the mortality rate of patients of different waves, emphasize the importance of a personalized approach to treatment and long-term post-hospital monitoring.