Table 1.
Baseline characteristics of the whole intensive care cohort, non-polypharmacy cohort, and polypharmacy cohort. See Supplementary Table S2 in the Supplementary material for more detailed characteristics of the full, non-polypharmacy, and polypharmacy cohorts. IQR, inter-quartile range.
| Whole cohort |
No polypharmacy cohort |
Polypharmacy cohort |
P-value | |
|---|---|---|---|---|
| (n=23 844) | (n=16 706) | (n=7138) | ||
| Patient characteristics | ||||
| Female, n (%) | 10 166 (42.6) | 6590 (39.4) | 3576 (50.1) | <0.001 |
| Age at admission to ICU, yr, median (IQR) | 62 (47–72) | 59 (44–70) | 66 (55–75) | <0.001 |
| Scottish Index of Multiple Deprivation, n (%) | <0.001 | |||
| First quartile (most deprived) | 6174 (25.9) | 4127 (24.7) | 2047 (28.7) | |
| Second quartile | 5402 (22.7) | 3591 (21.5) | 1811 (25.4) | |
| Third quartile | 4741 (19.9) | 3259 (19.5) | 1482 (20.8) | |
| Fourth quartile | 4194 (17.6) | 3099 (18.6) | 1095 (15.3) | |
| Fifth quartile (least deprived) | 3311 (13.9) | 2616 (15.7) | 695 (9.7) | |
| Remoteness of residence, n (%) | 0.073 | |||
| Urban area | 15 944 (66.9) | 11 202 (67.1) | 4742 (66.4) | |
| Accessible | 5456 (22.9) | 3813 (22.8) | 1643 (23.0) | |
| Remote | 1001 (4.2) | 698 (4.2) | 303 (4.2) | |
| Very remote | 855 (3.6) | 557 (3.3) | 298 (4.2) | |
| Indices of pre-existing patient health | ||||
| Unplanned inpatient admissions in the year before index stay, n (%) | <0.001 | |||
| 0 | 16 206 (68.0) | 12,299 (73.6) | 3907 (54.7) | |
| 1 | 4705 (19.7) | 2967 (17.8) | 1738 (24.3) | |
| 2 or more | 2933 (12.3) | 1440 (8.6) | 1493 (20.9) | |
| Count of Charlson comorbidities, n (%) | <0.001 | |||
| 0 | 9983 (41.9) | 8183 (49.0) | 1800 (25.2) | |
| 1 | 7468 (31.3) | 5336 (31.9) | 2132 (29.9) | |
| 2 | 3673 (15.4) | 2109 (12.6) | 1564 (21.9) | |
| 3 or more | 2720 (11.4) | 1078 (6.5) | 1642 (23.0) | |
| Indices of critical illness severity | ||||
| Type of admission to ICU | 0.009 | |||
| Elective surgery | 8630 (36.2) | 6124 (36.7) | 2506 (35.1) | |
| Emergency surgery | 4807 (20.2) | 3394 (20.3) | 1413 (19.8) | |
| Non-operative | 10 222 (42.9) | 7055 (42.2) | 3167 (44.4) | |
| APACHE II score at admission to ICU, median (IQR) | 15 (11–19) | 14 (10–19) | 16 (12–21) | <0.001 |
| Acute physiology score at admission to ICU, median (IQR | 10 (7–15) | 10 (7–15) | 11 (8–16) | <0.001 |
| Outcomes | ||||
| Length of ICU stay, days, median (IQR) | 1 (0–4) | 1 (0–4) | 2 (1–4) | <0.001 |
| Length of index hospital stay, days, median (IQR) | 13 (7–27) | 12 (7–25) | 15 (8–29) | <0.001 |
| Readmission outcome at 1 yr | <0.001 | |||
| Emergency readmission | 9685 (40.6) | 5985 (35.8) | 3700 (51.8) | |
| Alive with no readmission | 13 687 (57.4) | 10 444 (62.5) | 3243 (45.4) | |
| Died with no readmission | 472 (2.0) | 277 (1.7) | 195 (2.7) | |
| Mortality at 1 yr | 1963 (8.2) | 1140 (6.8) | 823 (11.5) | <0.001 |
| Time until death (days, median+quartiles) | 153 (69, 248) | 158 (75, 252) | 144 (61, 244) | 0.024 |
| Prescribing | ||||
| Average monthly dispensed items (median+quartiles) | 3 (1, 5) | 1 (0, 3) | 7 (6, 10) | <0.001 |
| Total distinct items in past 12 months (median+quartiles) | 9 (5, 15) | 7 (3, 10) | 17 (13, 22) | <0.001 |