CHARACTERISTICS and OUTCOMES CHANGES in COVID-19 INPATIENTS: A COMPARISON of 4 WAVES

ABSTRACT

Background: Four Coronavirus disease 2019 (COVID-19) epidemic waves occurred in France between March 2020 and September 2021. These 4 waves had different intensities and anti severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) therapies including the extensive use of corticosteroids, monoclonal antibodies, high-flow nasal oxygenotherapy, and generalization of vaccination. This single-center retrospective study compared patients' characteristics and outcomes during these four waves. Methods: We retrospectively analyzed the data of all consecutive inpatients with proven COVID-19 (based on polymerase chain reaction (PCR) testing of nasopharyngeal swab sampling) in a French tertiary care hospital from March 1 to July 31, 2020 (wave 1), August 1 to December 31 (wave 2), January 1 to June 30, 2021 (wave 3), and August 1 to September 30, 2021 (wave 4). Differences in baseline characteristics and outcomes i.e., intensive care unit (ICU) hospitalization and deaths were assessed. A patient with healthcare-associated COVID-19 was defined by a positive PCR 48 h after admission. Continuous variables were compared using the Kruskal-Wallis test and categorical data by the Chi-square test (SAS 9.4 software). Results: During wave 1, 1939 patients were hospitalized at the HCC for COVID-19 816 (42.1%), 463 (23.9%) during wave 2, 572 (29.5%) during wave 3, and 88 (4.5%) during wave 4. Table 1 summarizes the patients' main clinical characteristics, baseline biological results, and outcome according to COVID-19 waves Results are presented in table 1 in the form n (%) [95% confidence interval], percentages are calculated for non missing values only. Wave 1 patients were hospitalized later after COVID-19 symptom onset, had more serious disease at baseline (higher temperature, more frequent need for oxygen, higher C-reactive protein and lactate dehydrogenase levels, and lower lymphocytes), and were more frequently hospitalized in the ICU. Wave 4 patients were younger. The highest death rates were found during the first 2 waves;17% vs. 15% in wave 3 and 4% in wave 4. A higher percentage of healthcare-associated COVID-19 was found in wave 2. Although the month of October was not included in the results, there was a marked decrease of cases and the lowest death rate during wave 4. Conclusion: Wave 1 patients were had more serious disease at baseline with the highest death and ICU hospitalization rates. Deaths were reduced during wave 3 and 4 with a marked decrease in the number of patients hospitalized during wave 4.