Comparison of clinical and metabolic characteristics between case group and control group
Compared with the control group, the age, FPG,UA,TG, TC, LDL-c, BUN and Cr levels in the case group were increased, while the HDL-c level was decreased (P < 0.001). NAFLD in the case group was 573 (44.9%) and that in the control group was 378 (20.2%). The difference was statistically significant (χ2 = 219.609, P < 0.001), as shown in Table 1.
Table 1
Comparison of clinical and metabolic characteristics between case group and control group(x̅±s,%)
variable
|
Case group (1277 cases)
|
Control group (1277 cases)
|
t/χ2 value
|
P value
|
Age (years)
|
50.55 ± 11.19
|
43.46 ± 11.16
|
17.479
|
0.000
|
UA (umol/L)
|
403.1 ± 95.50
|
364.92 ± 87.42
|
11.402
|
0.000
|
BUN(mmol/L)
|
4.72 ± 1.26
|
4.53 ± 1.19
|
4.398
|
0.000
|
Cr (umol/L)
|
82.42 ± 19.05
|
77.82 ± 16.50
|
7.019
|
0.000
|
TG (mmol/L)
|
2.16 ± 1.44
|
1.64 ± 1.13
|
10.840
|
0.000
|
TC (mmol/L)
|
4.96 ± 0.83
|
4.6 ± 0.80
|
10.427
|
0.000
|
LDL-c (mmol/L)
|
3.35 ± 0.80
|
3.1 ± 0.76
|
7.724
|
0.000
|
HDL-c (mmol/L)
|
1.17 ± 0.31
|
1.2 ± 0.29
|
-4.410
|
0.000
|
FPG (mmol/L)
|
5.82 ± 1.44
|
5.3 ± 0.93
|
10.646
|
0.000
|
NAFLD(cases)(%༉
|
573(44.9)
|
378(20.2)
|
219.609
|
0.000
|
Note: UA: uric acid; bun: urea nitrogen; Cr: creatinine; TG: triglyceride; TC: total cholesterol; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; FPG: fasting blood glucose; NAFLD: nonalcoholic fatty liverdisease. |
Building Classification Tree Model
Using CRT classification tree method to construct hypertension model of overweight and obese physical examination population, the overweight and obese hypertension patients were assigned as 1, and the overweight and obese people without hypertension were assigned as 0.Taking gender,age,UA,TC,TG,HDL-c,LDL-c,BUN,Cr,FPG,NAFLD as independent variables, overweight and obesity hypertension as dependent variables, a classification tree model was established by CRT method to screen the risk factors. After pruning the tree to avoid over fitting, the classification tree model includes 5 layers, 17 nodes and 9 Final nodes. Classification tree model showed that NAFLD, FPG, age, TG, UA and LDL-c were risk factors for overweight and obese hypertension, as shown in Fig. 1.
Logistic Regression Model
Before the logistic regression analysis, in order to make the data closer to clinical application, we inquired the critical value of the latest medical guidelines of each specialty in each influencing factor, and divided them into two groups according to the critical value as the standard. The value above the critical value of pathological significance of continuous variables was assigned as 1, and the value below the critical value was 0. The age cut-off value was 51.5 years old, greater than 51, 5-year-old was assigned as 1, less than or equal to 51.5-year-old was assigned as 0, as shown in Table 2. Single factor Logistic regression model was constructed by taking overweight and obesity hypertension as dependent variables and influencing factors as independent variables.The results showed that NAFLD,FPG,age,TG,TC,LDL-c,UA,Cr and gender (male) were risk factors for overweight and obese hypertension, and high HDL-c was for overweight and obese hypertension The protective factor of pressure (P < 0.01). After controlling the confounding factors, the results showed that NAFLD,FPG,age,TG,LDL-c,UA,Cr were the risk factors of overweight and obese hypertension (P < 0.05 or P < 0.01), as shown in Table 3.
Table 2
main variables and assignment of influencing factors of overweight and obesity hypertension
variable
|
assignment
|
overweight and obesity hypertension
|
No = 0,Yes = 1
|
Age (years)
|
≤ 51.5 = 0,༞51.5 = 1
|
Gender
|
Male = 0,Female = 1
|
NAFLD
|
No = 0,Yes = 1
|
UA(µmol/L)
|
Female: <360 = 0;≥360 = 1
|
|
Male: <420 = 0;≥420 = 1
|
FPG(mmol /L)
|
<6.1 = 0;≥6.1 = 2
|
TG( mmol /L)
|
<2.26 = 0;≥2.26 = 1
|
TC(mmol/L)
|
<6.22 = 0;≥6.22 = 1
|
LDL-c (mmol/L)
|
<4.14 = 0;≥4.14 = 1
|
HDL-c (mmol/L)
|
<1.04 = 0;≥1.04 = 1
|
High BUN(mmol/L)
|
<7.1 = 0;≥7.1 = 1
|
High Cr(µmol/L)
|
Female: <97 = 0;≥97 = 1
|
|
Male: <106 = 0;≥106 = 1
|
Table 3
The results of univariate and multivariate logistic regression analysis on the influencing factors of overweight and obesity hypertension and the results of logistic regression multiplication analysis of interactive influencing factors
|
|
Single factor analysis
|
P value
|
Multivariate analysis
|
P value
|
OR value(95%CI)
|
|
OR value(95%CI)
|
|
Female
|
-
+
|
1
|
|
1
|
|
1.395(1.196–1.626)
|
0.000
|
1.120(0.939–1.336)
|
0.208
|
TG
|
-
+
|
1
2.140(1.816–2.523)
|
0.000
|
1
1.376(1.125–1.684)
|
0.002
|
TC
|
-
+
|
1
2.023(1.447–2.827)
|
0.000
|
1
1.212(0.791–1.858)
|
0.378
|
LDL-c
|
-
+
|
1
1.831(1.468–2.284)
|
0.000
|
1
1.414(1.066–1.876)
|
0.016
|
HDL-c
|
-
+
|
1
0.718(0.616–0.836)
|
0.000
|
1
1.025(0.850–1.235)
|
0.798
|
UA
|
-
+
|
1
1.999(1.725–2.317)
|
0.000
|
1
1.540(1.305–1.817)
|
0.000
|
Cr
|
-
+
|
1
2.512(1.807–3.492)
|
0.000
|
1
1.725(1.203–2.275)
|
0.003
|
BUN
|
-
+
|
1
1.455(0.975–2.172)
|
1.455
|
1
0.925(0.588–1.455)
|
0.735
|
Age (years)
|
≤ 51.5
> 51.5
|
1
|
|
1
|
|
2.968(2.553–3.451)
|
0.000
|
2.575(2.190–3.029)
|
0.000
|
NAFLD
|
-
+
|
1
3.219(2.749–3.769)
|
0.000
|
1
2.489(2.095–2.958)
|
0.000
|
FPG
|
-
+
|
1
3.162(2.562–3.902)
|
0.000
|
1
2.103(1.679–2.635)
|
0.000
|
NAFLD
|
FPG
|
|
|
|
|
-
|
-
|
1.000
|
0.000
|
1.000
|
0.000
|
+
|
-
|
3.219(2.749–3.769)
|
0.000
|
2.489(2.095–2.958)
|
0.000
|
-
|
+
|
3.162(2.562–3.902)
|
0.000
|
2.103(1.679–2.635)
|
0.000
|
+
|
+
|
4.452(3.330–5.950)
|
0.000
|
3.023(2.225–4.106)
|
0.000
|
Note: UA: uric acid; bun: urea nitrogen; Cr: creatinine; TG: triglyceride; TC: total cholesterol; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; FPG: fasting blood glucose; NAFLD: nonalcoholic fatty liverdisease. |
Bp Neural Network Model
BP neural network was used to construct the hypertension model of overweight and obesity population. 11 research variables were assigned and included into the neural network model to form the input neuron. Whether or not suffering from overweight and obesity hypertension was taken as the output neuron to construct the standardized BP model. Its structure is: input layer (22 neurons), 1 hidden layer (7 neurons), and output layer (2 neurons). The importance of each dependent variable to the model was normalized as shown in Fig. 2, NAFLD > FPG > age > CR > TG > UA > BUN > LDL-c > gender > TC > HDL-c, as shown in Fig. 2.
Comparison Of Screening Effects Of Three Models
According to the predictive variables obtained from the three models as test variables, the ROC curve was drawn with overweight and obesity hypertension as state variables. The Youden index, sensitivity, specificity and area under curve (AUC) were 39.20%,61.63%,77.58% and 0.721, respectively. The Youden index, sensitivity, specificity and AUC of logistic regression model were 37.02%,76.59%,60.44% and 0.734, respectively. The Youden index of ROC curve of BP neural network model was 34.85%, sensitivity was 82.85%, specificity was 52.00%, AUC value was 0.733. There was no significant difference in pairwise comparison between the three models (P > 0.05), indicating that there was no significant difference between the three models, see Fig. 3, Table 4,Table 5.
Table 4
Comparison of screening parameters of logistic regression model, classification tree model and BP neural network model
parameter
|
Logistic regression model
|
Classification tree model
|
BP Neural network model
|
Susceptibility %
|
76.59
|
61.63
|
82.85
|
Specificity %
|
60.44
|
77.58
|
52.00
|
AUC %
|
0.734
|
0.721
|
0.733
|
Youden index %
|
37.02
|
39.20
|
34.85
|
Table 5
pairwise comparison of logistic regression model, classification tree model and BP neural network model
parameter
|
Logistic regression model and classification tree model
|
Classification tree model and BP neural network model
|
BP neural network model and logistic regression model
|
Differences between areas
|
0.0131
|
0.0117
|
0.00140
|
95% confidence interval
|
-0.0112-0.0375
|
-0.0126-0.0360
|
-0.00333-0.00612
|
Z statistics
|
1.056
|
0.944
|
0.580
|
P
|
0.2911
|
0.3451
|
0.5616
|
Logistic Regression Multiplication Model
Classification tree model CRT showed that the interaction between NAFLD and FPG and age was closely related to overweight and obese hypertension. Through the verification in logistic regression, (odds ratio, OR)was used to represent the disease risk, P < 0.05, indicating that there was a multiplicative interaction between NAFLD and FPG, as shown in Table 3.