Association between atherogenic index of plasma and mortality of patients with sepsis: Evidence from a large population-based study based on the MIMIC-IV database and EICU-CRD database

Background The mortality of sepsis is alarmingly high. Identifying biomarkers capable of predicting the prognosis of sepsis patients is crucial for improving patient management. This study aimed to explore the association between the atherogenic index of plasma (AIP) and the mortality of sepsis. Methods This was a retrospective observational cohort study. Data of sepsis patients were obtained from the Medical Information Mart for Intensive Care-IV (MIMIC-IV V.2.2) database and EICU cooperative research database (EICU-CRD V.2.0). The exposure was AIP, which was calculated by the equation: log10 (triglycerides/high-density lipoprotein cholesterol) . The outcome was 168 hours mortality. Area under the receiver operating characteristic curves, multivariable logistics proportional regression analysis and restricted cubic spline regression were used to evaluate the association between the AIP and the mortality of sepsis. Machine learning algorithms was used to predict which factors may affect the short-term changes of AIP. The mediating effect of metabolism-related indicators were evaluated to investigate the potential mechanism of the associations between AIP and mortality. Results AIP was independently associated with an elevated risk of 168 hours mortality (OR: 1.242, 95%CI: 1.193-1.294, P - value<0.001) in the MIMIC group and (OR：1.198, 95%CI：1.118 - 1.285, P - value<0.001) in the EICU group. 168 hours mortality increased no-linearly with increasing AIP. Lactate (Lac), total bilirubin (TBIL) and serum creatinine (Cr) were the three strongest mediating factors, mediating 63.6%, 22% and 17.6% of the association of AIP with 168 hours mortality respectively. Conclusions Our study indicates that high AIP is associated with an increased 168 hour mortality in patients with sepsis. AIP may affect mortality in patients with sepsis through Lac metabolism and organ function.