Table 3 Summary statistics and comparison between readmitted and non-readmitted patients: Healthcare utilisation and index hospital admission

Prior healthcare utilisation

 Increasing number of previous admissions^b

Zero = 3223 (93.9%)

Zero = 230 (91.6%)

0.234

One = 116 (3.4%)

One = 10 (4.0%)

Two = 50 (1.5%)

Two = 4 (1.6%)

 ≥ Three = 45 (1.3%)

 ≥ Three = 7 (2.8%)

 Number of prior ED presentations (12 months)^b

Zero = 3298 (96.0%)

Zero = 234 (93.2%)

0.083

One = 81 (2.4%)

One = 11 (4.4%)

 ≥ Two = 55 (1.6%)

 ≥ Two = 6 (2.4%)

 Historical knee procedures^b

Zero = 1234 (35.9%)

Zero = 82 (32.7%)

 < 0.001

One = 1324 (38.6%)

One = 77 (30.7%)

Two = 760 (22.1%)

Two = 51 (20.3%)

 ≥ Three = 116 (3.4%)

 ≥ Three = 41 (16.3%)

Variables related to index hospital admission

 In-hospital complication (any) during index admission^a

477 (13.9%)

76 (30.3%)

 < 0.001

 ICU/HDU admission during index admission^b

Zero = 3303 (96.2%)

Zero = 237 (94.4%)

0.109

One = 64 (1.9%)

One = 4 (1.6%)

 ≥ Two = 67 (2.0%)

Two = 10 (4.0%)

 Return to theatre during index admission^b

10 (29.1%)

6 (2.4%)

 < 0.001

 Length of stay in days, mean (SD)^a

8.993 (4.4)

11.283 (8.9)

 < 0.001

 Duration of operation in minutes, mean (SD)^b

119.796 (34.5)

120.928 (36.3)

0.632

 Wound class (not clean)^b

7 (20.4%)

0

1

 Transfusion during surgery in number of packed red blood cells, mean (SD)^a

Zero = 3110 (90.6%)

Zero = 212 (84.5%)

 < 0.001

One = 63 (1.8%)

One = 5 (1.0%)

Two = 206 (6.0%)

Two = 21 (8.4%)

 ≥ Three = 55 (1.6%)

 ≥ Three = 13 (5.2%)