Table 3 Univariable analysis of predictors of blood loss following total knee arthroplasty

Age

10.4 (2.3–18.6)

0.01

−3.4 (−8.9 to 2.0)

0.22

0.14 (−0.08 to 0.37)

0.21

Female gender

140.5 (−12 to 293)

0.07

93.6 (−2.1 to 189.3)

0.06

−0.001 (−4.3 to 4.3)

0.99

BMI

3.1 (−13.5 to 19.8)

0.7

9.1 (−1.0 to 19.1)

0.08

−0.38 (−0.83 to 0.07)

0.09

Surgeon

220.3 (71.6 to 369.1)

0.004

317 (253 to 382)

<0.001

−4.90 (−9.08 to −0.72)

0.02

Heart rate

1.35 (−5.3 to 7.95)

0.7

3.9 (−0.7 to 8.5)

0.10

0.02 (−0.17 to 0.22)

0.81

Systolic BP

3.3 (−0.06 to 6.7)

0.054

−1.0 (−3.8 to 1.7)

0.46

0.06 (−0.03 to 0.16)

0.18

Anaesthetic type (reference category is general anaesthetic alone)

 Spinal

−108.57 (−952 to 734.9)

0.80

−393 (−829 to 44)

0.08

−23 (−62 to 16)

0.24

 Regional

45 (−921.28– 1011.28)

0.93

154 (−144 to 452)

0.31

−18 (−15 to 52)

0.46

 General + regional

−250 (−1161.02 to 661.02)

0.59

−162 (−369 to 46)

0.13

−14 (−34 to 6)

0.17

 Spinal + regional

−210 (−0.46 to 568.10)

0.57

−210 (−417 to −4)

0.05

−16 (−36 to 4)

0.12

 General + spinal + regional

−166.11 (−965.67 to 633.45)

0.68

−361 (−622 to −99)

0.01

−25 (−47 to −2)

0.03

Operative time

1.19 (−1.36 to 3.74)

0.36

−5.3 (−7.3 to –3.2)

<0.001

0.02 (−0.06 –0.11)

0.61

Medication (reference category is rivaroxaban alone)

NA

 Low-molecular-weight heparin

−312 (−387 to −237)

<0.001

−11 (−22 to 16)

0.06

 Warfarin

−205 (−378 to −32.6)

0.02

−10 (−33 to 14)

0.41

 Aspirin

−332 (−505 to −159)

<0.001

−6 (−13 to 25)

0.56

 Aspirin + Rivaroxaban

97 (−40 to 235)

0.16

17 (−7 to 39)

0.16

 Aspirin + LMWH

−287 (−414 to −160)

<0.001

−1 (−22 to 20)

0.92