Table A7.
Subgroup of 9618 patients who did not receive invasive critical care therapies (i.e. no invasive ventilation, renal replacement or extracorporeal membrane oxygenation) – baseline characteristics by category of percentage of critical care registered nurses (CCRN) in each ICU.
| <50 % CCRN |
50–75% CCRN |
>75% CCRN |
p value | |
|---|---|---|---|---|
| N = 1408 | N = 4398 | N = 3812 | ||
| Age in years | 63.0 (18.1) | 62.9 (17.7) | 63.4 (17.3) | 0.39 |
| Men | 785 (55.8%) | 2344 (53.3%) | 1950 (51.2%) | 0.01 |
| Source of admission to ICU | <0.001 | |||
| Operating theatre | 380 (27.0%) | 1385 (31.5%) | 1869 (49.0%) | |
| Emergency department | 699 (49.6%) | 1924 (43.7%) | 1000 (26.2%) | |
| Hospital ward | 250 (17.8%) | 816 (18.6%) | 648 (17.0%) | |
| Other hospital | 75 (5.3%) | 265 (6.0%) | 282 (7.4%) | |
| Other/unknown admission source | 4 (0.3%) | 8 (0.2%) | 13 (0.3%) | |
| Admission category | <0.001 | |||
| Emergency surgical admission | 190 (13.5%) | 637 (14.5%) | 552 (14.5%) | |
| Medical ICU admission | 1022 (72.6%) | 2986 (67.9%) | 1874 (49.2%) | |
| Planned ICU admission after elective surgery | 196 (13.9%) | 775 (17.6%) | 1386 (36.4%) | |
| ICU admission diagnosis | <0.001 | |||
| Cardiac medical diagnoses | 183 (13.0%) | 538 (12.2%) | 359 (9.4%) | |
| Respiratory medical diagnoses (excl. pneumonia) | 149 (10.6%) | 471 (10.7%) | 239 (6.3%) | |
| Sepsis and other infections (incl. pneumonia) | 279 (19.8%) | 875 (19.9%) | 575 (15.1%) | |
| Other medical diagnoses (incl. overdose) | 236 (16.8%) | 716 (16.3%) | 465 (12.2%) | |
| Cardiothoracic & vascular surgery | 72 (5.1%) | 308 (7.0%) | 362 (9.5%) | |
| Coronary artery bypass and/or valve surgery | 0 (0.0%) | 5 (0.1%) | 11 (0.3%) | |
| Gastro-intestinal surgery | 137 (9.7%) | 486 (11.1%) | 631 (16.6%) | |
| Neurological and neurosurgical diagnoses | 62 (4.4%) | 203 (4.6%) | 252 (6.6%) | |
| Orthopaedic surgery | 39 (2.8%) | 163 (3.7%) | 353 (9.3%) | |
| Trauma | 136 (9.7%) | 297 (6.8%) | 141 (3.7%) | |
| Other surgical diagnoses | 115 (8.2%) | 336 (7.6%) | 424 (11.1%) | |
| COVID-19 pneumonitis | 52 (3.7%) | 152 (3.5%) | 75 (2.0%) | <0.001 |
| Comorbidities and frailty | ||||
| Diabetes | 349 (24.8%) | 1171 (26.6%) | 814 (21.4%) | <0.001 |
| Chronic - cardiovascular | 115 (8.2%) | 292 (6.6%) | 290 (7.6%) | 0.09 |
| Chronic - respiratory | 137 (9.7%) | 467 (10.6%) | 230 (6.0%) | <0.001 |
| Chronic - dialysis dependent | 34 (2.4%) | 187 (4.3%) | 104 (2.7%) | <0.001 |
| Chronic - liver disease (cirrhosis) | 32 (2.3%) | 116 (2.6%) | 67 (1.8%) | 0.03 |
| Frailty category | <0.001 | |||
| Not frail (CFS1-3) | 824 (58.5%) | 2316 (52.7%) | 1454 (38.1%) | |
| Pre-frail (CFS 4,5) | 420 (29.8%) | 1342 (30.5%) | 958 (25.1%) | |
| Frail (CFS 6–8) | 131 (9.3%) | 389 (8.8%) | 214 (5.6%) | |
| Frailty unknown | 33 (2.3%) | 351 (8.0%) | 1186 (31.1%) | |
| Illness severity scores | ||||
| APACHE II scorea | 14.4 (6.4) | 14.6 (6.4) | 13.0 (6.2) | <0.001 |
| APACHE III scorea | 47.1 (20.5) | 49.4 (20.6) | 46.1 (19.2) | <0.001 |
| ANZROD percent (median IQR)b | 6.9 (12.5) | 7.4 (13.1) | 5.8 (11.8) | <0.001 |
| ANZROD percent (mean, SD)a | 2.1 (0.5–7.2) | 2.2 (0.6–7.4) | 1.3 (0.4–5.1) | <0.001 |
| Therapies provided in ICU | ||||
| Invasive ventilation | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | |
| Renal replacement therapy | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | |
| Extracorporeal membrane oxygenation | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | |
| Inotropes | 337 (24.2%) | 1282 (30.4%) | 762 (23.6%) | <0.001 |
| Hospital Classification | <0.001 | |||
| Public rural/regional (4 ICUs) | 594 (42%) | 887 (20%) | 145 (4%) | |
| Public metropolitan (6 ICUs) | 461 (33%) | 1639 (37%) | 469 (12%) | |
| Public tertiary (5 ICUs) | 346 (25%) | 1555 (35%) | 1406 (37%) | |
| Private (5 ICUs) | 7 (0%) | 317 (7%) | 1792 (47%) | |
| Primary outcome | ||||
| In-hospital mortality | 83 (5.9%) | 257 (5.8%) | 182 (4.8%) | 0.07 |
| Secondary outcomes | ||||
| In-ICU mortality | 43 (3.1%) | 132 (3.0%) | 67 (1.8%) | <0.001 |
| Delirium in ICU | 92 (7.5%) | 211 (5.8%) | 87 (3.4%) | <0.001 |
| Pressure injury developed in ICU | 5 (0.4%) | 14 (0.4%) | 7 (0.3%) | 0.75 |
| Duration of ICU stay (days) | 1.7 (0.9–3.1) | 1.7 (0.9–2.9) | 1.2 (0.8–2.2) | <0.001 |
| Ratio of observed to predicted length of ICU stay | 1.10 (0.64–1.91) | 1.02 (0.63–1.71) | 0.95 (0.64–1.50) | <0.001 |
| Duration of stay in hospital (days) | 6.3 (3.2–11.3) | 7.0 (3.9–12.7) | 7.0 (3.7–12.7) | <0.001 |
| After-hours discharge from ICUa | 348 (25.5%) | 960 (22.5%) | 461 (12.3%) | <0.001 |
APACHE, Acute Physiology and Chronic Health Evaluation; ANZROD, Australian & New Zealand Risk of Death; ICU, Intensive Care Unit. A vacant ICU bed is one that is not occupied by a patient but is available, equipped and can be staffed with 1:1 nursing ratio. A staffed ICU bed is equipped and can be staffed with 1:1 nursing ratio but may or may not be filled by a patient.
aData reported as mean (standard deviation).
bMedian (interquartile range); all other data reported as number (percentage).