| Quadratic function between body mass index and mortality risk in septic patients：a retrospective study based on MIMIC-III database |
| 投稿时间：2021-06-19 修订日期：2022-02-23 Click here to download the full text |
| Citation of this paper:王雨婷.脓毒症患者病死率与体重指数的二次函数关系：基于MIMIC-III数据库的回顾性研究[J].中国临床医学,0,(): |
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| Abstract:Purpose: The study aimed to explore the impact of body mass index (BMI) on clinical outcomes in septic patients.
Methods: The MIMIC-III database was employed for the study. Subjects meeting the inclusion and exclusion criteria were eligible for the study. They were randomly divided into a training set and a validation set. Patients in training set were divided into survivor group and non-survivor group based on whether died during their stay in hospital. Retrospectively analysis was operated to analyze the factors predicting death. This study hypothesized that BMI followed a U-shaped relationship with fatality risk, a quadratic form function was assumed for model specification. Multivariable logistic regression was used to adjust for the factors. The study aims to construct a regression model and estimate the coefficients for the quadratic and linear term of BMI. Likelihood Ratio Test was used to test the model. Goodness-of-fit test of the fitted model was examined by using Pearson χ2 test after logistic regression. The analysis of marginal effect and graphical examination were performed to show the relationship between BMI and the fatality outcome, and how the effect of BMI status changed with different levels of significant interaction terms. Finally, the training set is used to verify the regression model internally, and the verification set is used to verify the regression model externally.
Results: 5120 septic patients met the criteria of this study. 3120 were randomly included in the training set and 2000 in the validation set. The training-set-fitted multivariable model supported the hypothesis that the effect of BMI on fatality risk was in quadratic form. Likelihood Ratio Test for the model was significant (LRχ2 = 425.37, P<0.001). Goodness-of-fit test of the model was well fitted (Pearson χ2=3043.32, P= 0.807). The lowest of fatality risk was at a BMI value of approximately 37Kg/m2. There was significant interaction between BMI and SOFA score (P<0.001), BMI and Elixhauser comorbidity index (P<0.001). The marginal effect analysis indicated that the inflection point of the quadratic function shifted to the left with the increase of SOFA score and Elixhauser's complication index, and the U-shaped curve presented a J-shaped curve. The regression model's area under the ROC curve verified internally in the training set was 0.75, and the area under the ROC curve verified externally in the verification set was 0.72, and the difference between the two was not statistically significant (P>0.05).
Conclusions: In ICU sepsis patients, the fatality risk and BMI showed a U-shaped quadratic function relationship, and there was a BMI inflection point corresponding to the lowest fatality risk. BMI lower than the inflection point and BMI higher than the inflection point both increased fatality risk. The U-shaped relationship weakened and the inflection point shifted to the left as the disease severity increased and the complications increased. The relationship between fatality risk and body mass index was J-shaped. |
| keywords:body mass index sepsis obesity paradox severity of illness score |
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