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Table 2 Cox proportional hazards regression model showing the association of variables with collapse-free survival

From: Nomogram to predict collapse-free survival after core decompression of nontraumatic osteonecrosis of the femoral head

Variable Univariate analysis Multivariate analysis
HR (95% CI) P value HR (95% CI) P value
Factors selected
 Symptom
  Delayed onset of symptom 1 (reference) NA 1 (reference) NA
  Acute onset of symptom 3.28(1.26–8.58) 0.015 2.78(1.03–7.48) 0.043
  Asymptomatic 1.73(0.70–4.25) 0.230 2.26(0.918–5.58) 0.076
 Necrotic location
  A/B 1 (reference) NA 1 (reference) NA
  C1/C2 8.94(3.20–25.03) < 0.001 3.67(1.20–11.27) 0.023
 Necrotic angle
  < 200° 1 (reference) NA 1 (reference) NA
  200–249° 3.62(1.24–10.62) 0.019 2.67(0.87–8.25) 0.087
  250–299° 11.62(4.30–31.37) < 0.001 5.08(1.73–14.93) 0.003
  > 299° 16.36(5.64–47.48) < 0.001 9.96(3.23–30.70) < 0.001
 BME before CD
  No 1 (reference) NA 1 (reference) NA
  Yes 3.09(1.65–5.77) < 0.001 2.03(1.02–4.02) 0.042
Factors not selected
 Age (years) 1.00(0.96–1.03) 0.913 NA NA
Gender
  Female 1 (reference) NA NA NA
  Male 0.81(0.34–1.91) 0.626 NA NA
 Body mass index (kg/m2) 1.04(0.97–1.13) 0.285 NA NA
 Etiology
  Alcohol abuse 1 (reference) NA NA NA
  Corticosteroid use 1.17(0.54–2.54) 0.700 NA NA
  Idiopathic 0.67(0.26–1.72) 0.401 NA NA
 Ficat classification
  Stage I 1 (reference) NA NA NA
  Stage IIA 1.27(0.45–3.55) 0.649 NA NA
 ARCO classification
  IA 0.32(0.08–1.34) 0.117 NA NA
  IB 0.20(0.05–0.86) 0.031 NA NA
  IC 0.00(0.00–0.00) 0.977 NA NA
  IIA 0.06(0.02–0.17) < 0.001 NA NA
  IIB 0.23(0.11–0.48) < 0.001 NA NA
  IIC 1 (reference) NA NA NA
 Bone grafting (no. of hips)
  No 1 (reference) NA NA NA
  Yes 0.65(0.35–1.22) 0.177 NA NA
 Triglyceride 1.08(0.85–1.37) 0.536 NA NA
 Total cholesterol 0.84(0.60–1.17) 0.304 NA NA
 White blood cell 0.97(0.83–1.14) 0.699 NA NA
 Hemoglobin 0.99(0.98–1.01) 0.425 NA NA
 Platelet 1.00(0.99–1.01) 0.642 NA NA
 Antithrombin III 1.00(0.98–1.03) 0.852 NA NA
  1. BME, bone marrow edema; CD, core decompression; ARCO, Association Research Circulation Osseous classification; HR, hazard ratio; NA, not applicable