Table 3 Multivariable linear and non-linear relationship between sUA and BMI stratified by gender, β (95% CI) of BMI (kg/m²)

Linear regression model, Per SD increase in BMI

 Crude model

6.11 (5.56, 6.66)

< 0.0001

5.03 (4.66, 5.40)

< 0.0001

5.47 (5.15, 5.78)

< 0.0001

 Model I

6.16 (5.60, 6.71)

< 0.0001

4.09 (3.71, 4.48)

< 0.0001

5.29 (4.97, 5.61)

< 0.0001

 Model II

4.71 (4.08, 5.35)

< 0.0001

3.03 (2.60, 3.46)

< 0.0001

3.80 (3.44, 4.17)

< 0.0001

Non-linear model, regression coefficients (β)

 Break point of BMI, kg/m² (K)

19.1

21.3

19.2

  < K

− 7.74 (− 14.7, − 0.75)

0.0301

− 2.70 (− 4.47, − 0.94)

0.0027

− 8.72 (− 12.4, − 5.06)

< 0.0001

  ≥ K

5.10 (4.44, 5.77)

< 0.0001

3.93 (3.42, 4.43)

< 0.0001

4.26 (3.87, 4.65)

< 0.0001

Difference of β-value between strata

12.8 (5.66, 20.0)

0.0005

6.63 (4.65, 8.61)

< 0.0001

13.0 (9.21, 16.8)

< 0.0001

 Predicted value of sUA at break point

308 (304, 312)

243 (240, 245)

267 (264, 270)

 P-value for likelihood ratio test

< 0.001

< 0.001

< 0.001