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.