Introduction: There is evidence of positive relationships between cholesterol concentration and risk of cardiovascular diseases. However, higher mortality in patients with a low cholesterol level has been reported (the "cholesterol paradox").
Material and methods: Medical records of 34 191 inpatients between 2014 and 2016 were reviewed and the relationships between total (TC), low-density lipoprotein (LDL-C) and high-density lipoprotein (HDL-C) cholesterol and triglyceride blood concentrations and all-cause in-hospital death and readmission within 14 and 30 days and 1 year were determined in univariate and multivariate analyses.
Results: Patients with TC in the lower quartile and LDL-C < 70 mg/dl had greater risk of the outcomes measured than individuals with a TC level in the remaining quartiles and LDL-C ≥ 70 mg/dl. Moreover, patients with TC in the highest quartile, OR (95% CI): 0.36 (0.13-0.99), p < 0.05, and LDL-C ≥ 115 mg/dl, OR (95% CI): 0.53 (0.37-0.77), p < 0.05, had the lowest all-cause in-hospital mortality. However, multivariate analysis using logistic regression and a Cox proportional hazard model showed no significant influence of blood lipid levels on the occurrence of the outcomes measured.
Conclusions: A significant effect of a "cholesterol paradox" linking better prognosis with higher blood lipid concentration was found only in univariate analysis but, after adjustment for clinical characteristics in multivariate analysis, the plasma lipid level had a neutral influence on the occurrence of the measured outcomes. This suggests that a low cholesterol level should be interpreted as a biomarker of illness severity.
Keywords: cholesterol paradox; in-hospital mortality; lipids; readmission risk.