Table 4 Results of the multivariate Cox regression analysis comparing the converted categorical variables between two groups

Sex

 Female

 Male

297.490

137.133–645.360

5.695

< 0.001

Age (years)

 <30

 <39

3.000

1.744–5.159

1.099

< 0.001

 <53

7.637

4.425–13.179

2.033

< 0.001

 ≥53

6.974

3.831–12.697

1.942

< 0.001

Occupation

 Weight-Bearing

 Standing

1.155

0.748–1.784

0.144

0.515

 Seatting

7.617

4.754–12.206

2.030

< 0.001

Haemoglobin (g/L)

 ≥154.2

 <154.2

3.314

1.873–5.862

1.198

< 0.001

 <145.5

13.304

7.333–24.137

2.588

< 0.001

 <134

373.617

163.716-852.629

5.923

< 0.001

Duration of disease (months)

 <1

 <2.1

0.518

0.298–0.898

-0.658

0.019

 <3.9

0.835

0.470–1.486

-0.180

0.541

 ≥3.9

26.657

14.327–49.599

3.283

< 0.001

Aetiology

 Alcohol-induced

 Idiopathic

5.525

2.257–13.514

1.710

< 0.001

 Steroid-induced

4.852

1.587–9.265

1.352

0.478

The combined necrosis angle

 <72°

 <117°

3.203

1.475–6.953

1.164

0.003

 <168°

33.120

15.903–68.974

3.500

< 0.001

 ≥168°

1154.011

466.923-2852.166

7.051

< 0.001