Table 3.
Demographic, clinical, and comparative data of a predefined subset of patients across the 3 COVID-19 variant waves.
| Variable | Wild-type, n (%)a | Delta, n (%)a | Omicron, n (%)a | Total, n (%)a | P value (3 group comparison) | P value (delta vs omicron) | |
|---|---|---|---|---|---|---|---|
| No. of patients | 618 | 231 | 465 | 1314 | |||
| Age, y median (IQR, range) | 45 (35-51, 19-89) | 70 (57-81, 20-98) | 66 (52-81, 20-99) | 52 (39-69, 19-99) | b | .039 | |
| Gender | Male | 560 (90.6) | 127 (55.0) | 230 (49.5) | 917 (69.8) | <.001 | .170 |
| Female | 58 (9.4) | 104 (45.0) | 235 (50.5) | 397 (30.2) | |||
| Race/ethnicity | Chinese | 123 (19.9) | 163 (70.6) | 296 (63.7) | 582 (44.3) | <.001 | .084 |
| Malay | 14 (2.3) | 24 (10.4) | 87 (18.7) | 125 (9.5) | |||
| Indian | 192 (31.1) | 25 (10.8) | 43 (9.2) | 260 (19.8) | |||
| White | 13 (2.1) | 2 (0.9) | 4 (0.9) | 19 (1.4) | |||
| Other | 276 (44.7) | 17 (7.4) | 35 (7.5) | 328 (25.0) | |||
| LOS, d median (IQR, range) | 8 (6-12, 5-99) | 13 (9-20, 4-91) | 9 (6-14, 1-137) | 9 (6-14, 1-137) | c | <.001 | |
| At least one comorbidity | 155 (25.1) | 99 (42.9) | 194 (41.7) | 448 (34.1) | <.001 | .775 | |
| Diabetes | 62 (10.0) | 36 (15.6) | 71 (15.3) | 169 (12.9) | .015 | .913 | |
| Heart disease (excluding IHD) | 8 (1.3) | 5 (2.2) | 17 (3.7) | 30 (2.3) | .036 | .290 | |
| Vascular disease on antiplatelets (including IHD, stroke, PVD) | 25 (4.0) | 55 (23.8) | 125 (26.9) | 205 (15.6) | <.001 | .383 | |
| Hypertension | 83 (13.4) | 36 (15.6) | 82 (17.6) | 201 (15.3) | .162 | .497 | |
| Kidney disease | 27 (4.4) | 31 (13.4) | 66 (14.2) | 124 (9.4) | <.001 | .781 | |
| Lung disease | 19 (3.1) | 6 (2.6) | 8 (1.7) | 33 (2.5) | .369 | .438 | |
| Readmission within 60 d | 10 (1.6) | 31 (13.4) | 100 (21.5) | 141 (10.7) | <.001 | .010 | |
| Severity of infection | Mild | 584 (94.5) | 148 (64.1) | 378 (81.3) | 1110 (84.5) | <.001 | <.001 |
| Moderate | 7 (1.1) | 42 (18.2) | 62 (13.3) | 111 (8.4) | <.001 | .091 | |
| Critical | 27 (4.4) | 41 (17.7) | 25 (5.4) | 93 (7.1) | <.001 | <.001 | |
| VTE prevention use | Total | 34 (5.5) | 71 (30.7) | 66 (14.2) | 171 (13.0) | <.001 | <.001 |
| Mild | 9 (1.5) | 19 (12.8) | 35 (9.3) | 63 (5.7) | <.001 | .224 | |
| Moderate | 0 (0) | 17 (40.5) | 15 (24.2) | 32 (28.8) | .044 | .078 | |
| Critical | 25 (92.6) | 35 (85.4) | 16 (64.0) | 76 (81.7) | .021 | .045 | |
P values were derived from the Pearson chi-squared test comparing proportions of categorical data and the Mann–Whitney U-test comparing distributions of age and LOS.
IHD, ischemic heart disease; LOS, length of stay; PVD, peripheral vascular disease; VTE, venous thromboembolism.
a
Unless otherwise specified.
b
Kruskal–Wallis test comparing age distribution: wild-type-omicron P < .001, wild-type-delta P < .001, delta-omicron P = .041 (adjusted P value).
c
Kruskal–Wallis test comparing the LOS distribution: wild-type-omicron P = .149, wild-type-delta P < .001, delta-omicron P < .001 (adjusted P value).