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. 2018 Jul 5;13(7):e0199610. doi: 10.1371/journal.pone.0199610

Table 3. Multiple linear regression analysis to explain the relationship between gas exchange values and variables considered.

Variables Regression model Fitted regression model
Dependent Independent VIF EC SE t- value p-value AR2 p-value EC SE t- value p-value AR2 p-value
PaO2PRE Sex (M) 1.257 -4.239 1.84 -2.291 0.024 0.138 <0.001 -4.287 1.83 -2.339 0.021 0.145 <0.001
Age 1.044 0.025 0.09 -0.260 0.794 - - - -
BMI 1.117 -0.426 0.14 -2.899 0.004 -0.420 0.14 -2.906 0.004
Leptin 1.318 -0.148 0.06 -2.292 0.024 -0.147 0.06 -2.295 0.023
PaO2POST Sex (M) 1.257 -5.115 2.379 -2.149 0.0338 0.037 0.089 -5.885 2.098 -2.804 0.0059 0.058 0.006
Age 1.044 0.004 0.128 -0.036 0.971 - - - -
BMI 1.117 -0.103 0.189 -0.547 0.585 - - - -
Leptin 1.318 0.057 0.083 0.687 0.493 - - - -
PaCO2PRE Sex (M) 1.257 1.539 0.856 1.798 0.074 0.128 <0.001 1.423 0.767 1.856 0.066 0.136 <0.001
Age 1.044 0.131 0.046 2.845 0.006 0.130 0.045 2.848 0.005
BMI 1.117 0.191 0.068 2.816 0.005 0.197 0.065 3.033 0.003
Leptin 1.318 0.009 0.029 0.310 0.757 - - - -
PaCO2POST Sex (M) 1.257 0.778 1.138 0.683 0.496 -0.017 0.712 - - - - - -
Age 1.044 -0.006 0.061 -0.105 0.916 - - - -
BMI 1.117 0.045 0.090 0.498 0.619 - - - -
Leptin 1.318 -0.032 0.040 -0.812 0.418 - - - -

Multiple linear regression analysis was performed to explain the relationship between one dependent normally distributed variable (gas exchange parameters) and independent normally distributed variables (sex, age, BMI, and serum leptin). Multicollinearity was not detected using variance inflation factors. Using the Akaike information criterion, backward/forward stepwise regression analysis was then performed to choose the best model. BMI, body mass index; EC, estimate coefficient; PaCO2POST, postoperative arterial partial pressure of carbon dioxide (PaCO2); PaCO2PRE, preoperative PaCO2; ΔPaCO2, PaCO2POST minus PaCO2PRE; PaO2POST, postoperative arterial partial pressure of oxygen (PaO2); PaO2PRE, preoperative PaO2; ΔPaO2, PaO2POST minus PaO2Pre; SE, standard error; VIF, variance inflation factor.