Association Between Serum High-Density Lipoprotein Cholesterol Concentration and Mortality in Critically Ill Patients: A Retrospective Cohort Study

Abstract Background This research aims to explore the association between serum high-density lipoprotein cholesterol (HDL-C) and mortality in patients who are critically ill. MethodsThis was a retrospective cohort study. Data were extracted from an online database named ‘Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC III)’. 3384 patients were included, 967 septic patients and 1380 patients with acute kidney injury (AKI) were screened from all the patients included. The association between HDL-C and hospital mortality in all patients, septic patients and AKI patients was evaluated using HDL-C as a design variable.Results Serum HDL-C (42.4±18.0 VS 45.0±15.2, P<0.001) concentration was significantly lower for non-survivors than survivors. An arc-shaped relationship between HDL-C and mortality was found for the whole group of patients and the AKI subgroup of patients with inflection point at around 30mg/dL; for septic patients, this relationship became ‘U’-shaped with inflection points at around 30mg/dL and 60mg/dL, respectively. Low HDL-C was associated with increased hospital and ICU mortality, longer ICU length of stay (LOS) and hospital LOS compared with medium HDL-C level for all included patients (p<0.01, all) while the differences between high HDL-C and medium HDL-C group were statistically nonsignificant. Similar patterns were found among AKI subgroup of patients. For the sepsis subgroup, low HDL-C group also showed higher hospital and ICU mortality rate (p<0.001, p=0.002, respectively); however, low HDL-C group did not show longer ICU LOS or hospital LOS. Multivariate logistic regression models showed only low HDL-C(<30mg/dL) were associated with increased hospital mortality in all three models(model 1 OR: 1.44, 95% CI 1.05 to 1.97, p=0.022 ; model 2 OR: 1.51, 95% CI 1.01 to 2.27, p=0.044; model 3 OR: 1.69, 95% CI 1.15 to 2.49, p=0.007). In all three models, age, mechanical ventilation use, Sequential Organ Failure Assessment (SOFA) score and Elixhauser comorbidity score were positively associated with mortality.Conclusions Low HDL-C is associated with increased mortality in patients who are critically ill.