Renal characteristics, resource utilisation and hospital outcomes during entire hospitalisation by trajectories of AKI in all cohort
| Variables | All subjects (N=355 678) | AKI (N=54 212, 15%) | Persistent AKI without renal recovery (N=14 122, 4%) | Persistent AKI with renal recovery (N=8590, 2%) | Rapidly reversed AKI (N=31 500, 9%) | No AKI (N=301 466, 85%) |
| Renal characteristics during entire hospitalisation | ||||||
| Worst AKI staging, n (%) | ||||||
| Stage 1 | 36 258 (10) | 36 258 (67)* | 5210 (37)*†‡ | 4176 (49)*† | 26 872 (85)* | 0 (0) |
| Stage 2 | 9551 (3) | 9551 (18)* | 3762 (27)*†‡ | 2492 (29)*† | 3297 (10)* | 0 (0) |
| Stage 3 | 8403 (2) | 8403 (16)* | 5150 (36)*†‡ | 1922 (22)*† | 1331 (4)* | 0 (0) |
| Stage three without RRT | 6351 (2) | 6351 (12)* | 3384 (24)*†‡ | 1646 (19)*† | 1321 (4)* | 0 (0) |
| Stage three with RRT | 2052 (1) | 2052 (4)* | 1766 (13)*†‡ | 276 (3)† | 10 (0)* | 0 (0) |
| AKI duration, days, median (IQR) | 2 (1–4) | 2 (1–4) | 5 (3–9) b‡ | 4 (3–7) | 1 (1–2) | NA |
| Recurrent AKI, n (%) | 6466 (2) | 6466 (12)* | 2173 (15)*†‡ | 1957 (23)*† | 2336 (7)* | 0 (0) |
| No renal recovery at discharge/death, n (%) | 22 240 (6) | 22 240 (41)* | 14 122 (100)*†‡ | 0 (0)† | 8118 (26)* | 0 (0) |
| Resource utilisation during entire hospitalisation | ||||||
| Hospital days, median (IQR) | 3 (1–6) | 7 (4–14)* | 8 (4–15)*†‡ | 14 (8–24)*† | 6 (3–10)* | 2 (1–5) |
| Admission to ICU, n (%) | 78 769 (22) | 27 711 (51)* | 8573 (61)*†‡ | 5860 (68)*† | 13 278 (42)* | 51 058 (17) |
| Days in ICU, median (IQR) | 4 (2–7) | 6 (3–12)* | 6 (3–13)*†‡ | 9 (5–18)*† | 5 (3–9)* | 3 (–5) |
| Mechanical ventilation, n (%) | 23 286 (7) | 11 876 (22)* | 4779 (34)*† | 2876 (33)*† | 4221 (13)* | 11 410 (4) |
| Mechanical ventilation calendar days, median (IQR) | 3 (2–6) | 4 (2–9)* | 4 (2–9)*†‡ | 5 (2–12)*† | 3 (2–7)* | 2 (1–4) |
| Vasopressor or inotropes used, n (%) | 55 415 (16) | 17 261 (32)* | 6016 (43)*† | 3781 (44)*† | 7464 (24)* | 38 154 (13) |
| Hospital disposition, n (%) | ||||||
| Hospital mortality | 7799 (2) | 4974 (9)* | 3918 (28)*†‡ | 376 (4)*† | 680 (2)* | 2825 (1) |
| Another hospital, LTAC, SNF, Hospice | 34 092 (10) | 10 028 (18)* | 3011 (21)*†‡ | 2494 (29)*† | 4523 (14)* | 24 064 (8) |
| Home/rehab | 313 787 (88) | 39 210 (72)* | 7193 (51)*†‡ | 5720 (67)*† | 26 297 (83)* | 274 577 (91) |
| 30-day outcomes (among survivors), n (%) | 347 879 | 49 238 (14) | 10 204 (3) | 8214 (2) | 30 820 (9) | 298 641 (86) |
| Death in 30 days of discharge | 4934 (1) | 1776 (4)* | 570 (6)*† | 418 (5)*† | 788 (3)* | 3158 (1) |
| Trajectory group for encounter with readmission within 30 days of discharge | 83 592 (24) | 12 748 (26)* | 2528 (25)‡ | 2381 (29)*† | 7839 (25)* | 70 844 (24) |
| Persistent AKI with no renal recovery | 2764 (3) | 1297 (10)* | 536 (21)*†‡ | 223 (9)*† | 538 (7)* | 1467 (2) |
| Persistent AKI with renal recovery | 2118 (3) | 933 (7)* | 231 (9)*† | 239 (10)*† | 463 (6)* | 1185 (2) |
| Rapidly reversed AKI | 7505 (9) | 2504 (20)* | 502 (20)* | 448 (19)* | 1554 (20)* | 5001 (7) |
| No AKI | 59 164 (71) | 7096 (56)* | 1100 (44)*†‡ | 1337 (56)*† | 4659 (59)* | 52 068 (73) |
| Unknown | 12 041 (14) | 918 (7) | 159 (6)*† | 134 (6)*† | 625 (8)* | 11 123 (16) |
| Other complications during entire hospitalisation | ||||||
| Venous thromboembolism, n (%) | 15 755 (4) | 5180 (10)* | 1589 (11)*†‡ | 1290 (15)*† | 2301 (7)* | 10 575 (4) |
| Sepsis, n (%) | 29 836 (8) | 13 995 (26)* | 5102 (36)*†‡ | 3275 (38)*† | 5618 (18)* | 15 841 (5) |
| Cardiovascular complication, n (%) | 31 780 (9) | 15 229 (28)* | 5553 (39)*† | 3469 (40)*† | 6207 (20)* | 16 551 (5) |
| Thirty-day mortality, n (%) | 11 082 (3) | 5655 (10)* | 3962 (28)*†‡ | 506 (6)*† | 1187 (4)* | 5427 (2) |
| One-year mortality, n (%) | 34 687 (10) | 12 570 (23)* | 5802 (41)*†‡ | 2054 (24)*† | 4714 (15)* | 22 117 (7) |
| Three-year mortality, n (%) | 49 144 (14) | 15 703 (29)* | 6414 (45)*†‡ | 2669 (31)*† | 6620 (21)* | 33 441 (11) |
*P<0.05 compared with rapidly no AKI.
†P<0.05 compared with rapidly reversed AKI.
‡P<0.05 compared with persistent AKI with renal recovery.
AKI, acute kidney injury; ICU, intensive care unit; LTAC, long-term acute care hospital; NA, not applicable; RRT, renal replacement therapy; SNF, skilled nursing facility.