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Table 2 Cohort characteristics

From: Acute kidney injury as an independent risk factor for unplanned 90-day hospital readmissions

  90 day readmission or death (%) 90 day readmission free survival (%) baseline impairment Univariable odds ratio (95% CI)
N 3065   13388    
 Age (median, IQR) 74 (62–83) 69 (55–79) 1.20 (/10 years) (1.17–1.23)
 Male sex 1372 (44.8) 5770 (43.1) ()) 1.07 (0.99–1.16)
 Residential care 277 (9.0) 471 (3.5) 2.72 (2.34–3.18)
 Deprived (highest quintile) 298 (9.7) 1088 (8.1) 1.22 (1.06–1.39)
 Rural (settlement <3000) 735 (24.0) 3720 (27.8) 0.82 (0.75–0.90)
Admission context
 No admissions past yeara 1896 (61.9) 10461 (78.1) 1.38 (/admission) (1.34–1.43)
  1 admission past year 593 (19.3) 1872 (14.0)   
  2 admissions past year 244 (8.0) 620 (4.6)   
  3+ admissions past year 332 (10.8) 435 (3.2)   
 Length of stay (median, IQR) 7 (2–16) 3 (1–9) 1.05 (/7 days) (1.04–1.06)
  Emergency admission 2326 (75.9) 7760 (58.0) 2.28 (2.09–2.50)
  Medical ward admission 1889 (61.6) 6570 (49.1) 1.67 (1.54–1.81)
  Intensive care admission 98 (3.2) 366 (2.7) 1.18 (0.94–1.47)
Renal function
 No AKI 2154 (70.3) 11676 (87.2) (reference group)  
 AKI stage 1 528 (17.2) 1190 (8.9) 2.41 (2.15–2.69)
 AKI stage 2 233 (7.6) 341 (2.5) 3.70 (3.12–4.40)
 AKI stage 3 150 (4.9) 181 (1.4) 4.49 (3.60–5.60)
 No prior AKI episodesa 2526 (82.4) 12188 (91.0) 1.71 (/episode) (1.58–1.85)
  1 prior AKI episode 414 (13.5) 1000 (7.5)   
  2+ prior AKI episodes 125 (4.1) 200 (1.5)   
Baseline eGFR (median, IQR)a 63 (48–83) 66 (52–87) 0.94 (/10 ml/min/1.73 m2) (0.93–0.96)
 Baseline eGFR 0–29 213 (6.9) 502 (3.7)   
 Baseline eGFR 30–44 423 (13.8) 1461 (10.9)   
 Baseline eGFR 45–59 713 (23.3) 3309 (24.7)   
 Baseline eGFR ≥60 1716 (56.0) 8116 (60.6)   
Discharge creatinine 20% > baseline 520 (17.0) 1167 (8.7) 2.14 (1.91–2.39)
Comorbidity
 Cancer 410 (13.4) 973 (7.3) 1.97 (1.74–2.23)
 Cardiac failure 317 (10.3) 592 (4.4) 2.49 (2.16–2.88)
 Cerebrovascular disease 231 (7.5) 580 (4.3) 1.80 (1.54–2.11)
 Dementia 96 (3.1) 163 (1.2) 2.62 (2.03–3.39)
 Diabetes 336 (11.0) 776 (5.8) 2.00 (1.75–2.29)
 Hemiplegia 28 (0.9) 71 (0.5) 1.73 (1.11–2.68)
 Liver disease 59 (1.9) 156 (1.2) 1.66 (1.23–2.25)
 Myocardial infarction 257 (8.4) 638 (4.8) 1.83 (1.57–2.13)
 Peptic ulcer disease 81 (2.6) 278 (2.1) 1.28 (1.00–1.64)
 Peripheral vascular disease 162 (5.3) 452 (3.4) 1.60 (1.33–1.92)
 Pulmonary disease 346 (11.3) 704 (5.3) 2.29 (2.00–2.62)
 Rheumatic disease 82 (2.7) 289 (2.2) 1.25 (0.97–1.60)
  1. Abbreviations: AKI acute kidney injury, CI confidence interval, eGFR estimated glomerular filtration rate, IQR inter-quartile range
  2. aModelled here linearly per 10 ml/min/1.73 m2 increase and reported in categories for clarity