Table 3: Multiple stepwise regression and principal component regression of Ln(ACR) and related factors.

Standard error

Standard regression coefficient

Constant

1.914

0.429

4.466

<0.001

Principal Component

1.038

0.052

0.592

20.031

<0.001

UA

0.004

0.001

0.164

6.210

<0.001

BUN

0.207

0.045

0.125

4.552

<0.001

Duration

0.027

0.008

0.091

3.572

<0.001

eGFR

−0.008

0.004

−0.139

−5.356

<0.001

TG

0.114

0.032

0.094

3.603

<0.001

25(OH)VD_{3}

−0.017

0.007

−0.058

−2.292

=0.022

LDL

0.113

0.050

0.057

2.240

=0.025

Since the values of HIF-1α, VEGF, vWF, and IGF-1 were correlated, their unique principal component was substituted for them in the model and the principal component = 0.803 HIF-1α + 0.864 VEGF + 0.929 IGF-1 + 0.725 vWf (HIF-1α: hypoxia-inducible factor-1α; VEGF: vascular endothelial growth factor; IGF-1: insulin-like growth factor-1; vWf: von Willebrand factor). In the formula, each variable was no longer the original variable but standardized variable and the coefficients before the standardized variables represented the correlation coefficients of principal component and the corresponding original variables. Since only one principal component was extracted among the four serum factors and the correlation coefficients were all close to 1, it showed that the four factors were highly correlated and the component could almost contain all the information of the four variables. UA: uric acid; BUN: blood urea nitrogen; eGFR: estimated glomerular filtration rate; TG: triglyceride; 25(OH)VD_{3}: 25-hydroxy vitamin D_{3}; LDL: low-density lipoprotein.