Table 1.
Baseline characteristic of the study population and comparison groups
| Variable | Categories | First wave | Second wave | Total | p value |
|---|---|---|---|---|---|
| N = 884 (100.0%) | N = 1817 (100.0%) | N = 2701 (100.0%) | |||
| Sex | Female | 363 (41.1%) | 782 (43.0%) | 1145 (42.4%) | 0.330 |
| Male | 521 (58.9%) | 1035 (57.0%) | 1556 (57.6%) | ||
| Age | 18–39 | 71 (8.0%) | 147 (8.1%) | 218 (8.1%) | 0.001 |
| Grouped | 40–59 | 190 (21.5%) | 495 (27.2%) | 685 (25.4%) | |
| (years) | 60–79 | 350 (39.6%) | 724 (39.8%) | 1074 (39.8%) | |
| ≥ 80 | 273 (30.9%) | 451 (24.8%) | 724 (26.8%) | ||
| Ethnicity | White | 301 (34.0%) | 636 (35.0%) | 937 (34.7%) | < 0.001 |
| Asian | 145 (16.4%) | 346 (19.0%) | 491 (18.2%) | ||
| Black | 143 (16.2%) | 252 (13.9%) | 395 (14.6%) | ||
| Other | 147 (16.6%) | 491 (27.0%) | 638 (23.6%) | ||
| Unknown | 148 (16.7%) | 92 (5.1%) | 240 (8.9%) | ||
| Clinical | 1: Very fit | 94 (10.6%) | 102 (5.6%) | 196 (7.3%) | < 0.001 |
| Frailty | 2: Fit | 119 (13.5%) | 173 (9.5%) | 292 (10.8%) | |
| Score (CFS) | 3: Managing well | 217 (24.5%) | 685 (37.7%) | 902 (33.4%) | |
| 4: Vulnerable | 93 (10.5%) | 234 (12.9%) | 327 (12.1%) | ||
| 5: Mildly frail | 82 (9.3%) | 184 (10.1%) | 266 (9.8%) | ||
| 6: Moderately frail | 114 (12.9%) | 241 (13.3%) | 355 (13.1%) | ||
| 7–9: Severely frail | 164 (18.6%) | 197 (10.8%) | 361 (13.4%) | ||
| Missing | 1 (0.1%) | 1 (0.1%) | 2 (0.1%) | ||
| Charlson | 0 | 90 (10.2%) | 207 (11.4%) | 297 (11.0%) | 0.232 |
| Comorbidity | 1 | 82 (9.3%) | 209 (11.5%) | 291 (10.8%) | |
| Index (CCI) | 2 | 112 (12.7%) | 227 (12.5%) | 339 (12.6%) | |
| 3 | 102 (11.5%) | 248 (13.6%) | 350 (13.0%) | ||
| 4 | 132 (14.9%) | 237 (13.0%) | 369 (13.7%) | ||
| 5 | 127 (14.4%) | 222 (12.2%) | 349 (12.9%) | ||
| 6 | 104 (11.8%) | 194 (10.7%) | 298 (11.0%) | ||
| 7 | 59 (6.7%) | 130 (7.2%) | 189 (7.0%) | ||
| 8_over | 76 (8.6%) | 143 (7.9%) | 219 (8.1%) | ||
| BMI | < 18.5 | 49 (5.5%) | 80 (4.4%) | 129 (4.8%) | < 0.001 |
| Grouped | 18.5–24.9 | 258 (29.2%) | 527 (29.0%) | 785 (29.1%) | |
| (kg/m2) | 25–29.9 | 230 (26.0%) | 559 (30.8%) | 789 (29.2%) | |
| ≥ 30 | 206 (23.3%) | 528 (29.1%) | 734 (27.2%) | ||
| Missing | 141 (16.0%) | 123 (6.8%) | 264 (9.8%) | ||
| Symptomatic at admission | No | 50 (5.7%) | 361 (19.9%) | 411 (15.2%) | < 0.001 |
| Yes | 834 (94.3%) | 1456 (80.1%) | 2290 (84.8%) |
p value corresponds to the chi square test of independence