Table 4.
The 28-day mortality rates during periods with the dominance of particular SARS-CoV-2 variants.
| Parameters | Pre-Delta 1 March 2020–30 June 2021 |
Delta 1 July 2021–31 December 2021 |
Delta vs. Pre-Delta | Omicron 1 January 2022–30 June 2022 |
Omicron vs. Delta |
|---|---|---|---|---|---|
| Overall 28-day mortality 1, n (%) | 761/7371 (10.3) | 359/2699 (13.3) |
p < 0.001 (χ2 = 14.0) |
119/1220 (9.8) |
p = 0.005 (χ2 = 7.8) |
| Age-related mortality (years), n/N (%) | |||||
| <60 | 69/3542 (1.9) | 37/1260 (2.9) |
p = 0.04 (χ2 = 4.0) |
9/512 (1.7) |
p > 0.05 (χ2 = 1.9) |
| 60–80 | 426/3118 (13.7) | 199/1062 (18.7) |
p < 0.001 (χ2 = 11.6) |
49/390 (12.6) |
p = 0.02 (χ2 = 5.6) |
| >80 | 340/1082 (31.4) | 254/607 (41.8) |
p < 0.001 (χ2 = 8.7) |
74/316 (23.4) |
p < 0.001 (χ2 = 15.4) |
| Mortality in subpopulations most at risk of death, n/N (%) | |||||
| SpO2 < 91% | 561/2429 (23.1) | 333/1074 (31.0) |
p < 0.001 (χ2 = 14.2) |
74/292 (25.3) |
p > 0.05 (χ2 = 2.0) |
| Age >80 years +SpO2 < 91% +hypertension |
164/359 (45.7) | 131/221 (59.3) |
p > 0.05 (χ2 = 3.2) |
26/82 (31.7) |
p = 0.01 (χ2 = 6.4) |
| Age > 80 years +SpO2 < 91% +COPD 2 |
16/40 (40.0) | 17/31 (54.8) |
p > 0.05 (χ2 = 0.6) |
7/17 (41.2) |
p > 0.05 (χ2 = 0.3) |
| Age > 80 years +SpO2 < 91% +diabetes |
69/150 (46.0) | 70/96 (72.9) |
p = 0.03 (χ2 = 4.7) |
19/40 (47.5) |
p > 0.05 (χ2 = 1.8) |
| Age > 80 years +SpO2 < 91% +neoplasm |
24/41 (58.5) | 13/21 (61.9) |
p > 0.05 (χ2 = 0.02) |
9/14 (64.3) |
p > 0.05 (χ2 = 0.01) |
| Age > 80 years +SpO2 < 91% +CIHD 3 |
81/153 (52.9) | 53/82 (64.6) |
p > 0.05 (χ2 = 0.8) |
13/31 (41.9) |
p > 0.05 (χ2 = 1.3) |
1 Only data confirmed for 28 days of observation from the start of hospitalization were included; 2 chronic obstructive pulmonary disease; 3 chronic ischemic heart disease.