Table 3 Subgroup analyses stratified by fracture location for factors independently associated with the preoperative DVT

Femoral neck fracture

 Time from injury to DUS (increment of each day)

1.20 (1.10–1.30)

< 0.001

 Age (increment of each year)

1.09 (1.02–1.15)

0.006

 LDH (> 250 U/L)

1.89 (1.23–2.91)

0.004

 Sodium (< 137 mmol/L)

2.35 (1.27–5.67)

0.008

Intertrochanteric fracture (versus femoral neck fracture)

 Time from injury to DUS (increment of each day)

1.42 (1.25–1.62)

< 0.001

 Gender (male versus female)

2.36 (1.27–6.02)

0.013

 WBC (> 10 * 10⁹/L)

0.55 (0.29–1.07)

0.076

 HCT (> upper limit)

4.27 (1.31–13.14)

0.002