Table 2 GEE model of baseline parameters associated with postoperative outcome measurements

Age

0.091

0.0572

0.114

0.006

0.0034

0.078

0.072

0.1626

0.659

Male (ref: female)

11.840

3.3015

< 0.001

0.344

0.1684

0.041

17.026

8.5286

0.046

BMI (ref: Obesity)

5.044

1.3288

< 0.001

0.161

0.0688

0.019

7.240

3.4619

0.036

 Underweight

1.629

1.6513

0.324

0.246

0.1075

0.022

3.208

4.8521

0.509

 Normal

-0.153

1.0699

0.886

-0.017

0.0531

0.753

0.558

2.3454

0.812

 Overweight

-1.568

1.4533

0.281

-0.099

0.0710

0.164

-3.600

4.1731

0.388

CCI

-1.104

0.3599

0.002

-0.028

0.0226

0.216

-0.901

0.9878

0.362

T-score (ref: Osteoporosis)

0.242

0.3797

0.524

0.042

0.0299

0.158

1.045

1.1945

0.381

 Normal

1.017

1.9484

0.602

-0.140

0.1294

0.278

-0.551

4.9836

0.912

 Low bone mass

0.483

1.1103

0.664

-0.006

0.0623

0.923

-0.260

2.6217

0.921

Spondylolisthesis

0.807

0.9214

0.381

0.002

0.0494

0.962

2.267

2.1974

0.302

Fusion levels (ref: 3-level)

 1-level

-3.287

2.1039

0.118

0.129

0.1076

0.230

-1.248

8.4883

0.883

 2-level

-1.211

1.8963

523

0.174

0.0957

0.068

-1.095

7.4262

0.883

Low HGS (ref: Normal HGS)

-2.551

0.9651

0.008

-0.142

0.0522

0.007

-5.784

2.7598

0.036

ASA (ref: ASA 3)

 1

1.709

1.7815

0.338

0.126

0.0996

0.206

4.877

4.5370

0.282

 2

-0.312

1.0828

0.74

-0.071

0.0677

0.296

-0.793

3.0051

0.792

Operation time

-0.002

0.0082

0.768

3.11E-5

0.0003

0.919

0.015

0.0280

0.580

Blood loss

-0.002

0.0016

0.126

1.70E-4

8.99E-5

0.059

-0.004

0.0060

0.501

Time (ref: Baseline)

 3 months

2.739

0.6436

< 0.001

0.060

0.0254

0.018

-4.728

2.0473

0.021

 6 months

3.753

0.7018

< 0.001

0.072

0.0248

0.004

-3.972

2.0754

0.056

 12 months

4.536

0.6100

< 0.001

0.086

0.0284

0.003

-2.608

1.8876

0.167