Abstract
BACKGROUND AND AIMS: The relationship between dyslipidemia and mortality varies by age, with an inverse association observed in the oldest age groups. There is limited research examining lipid profiles' correlation with short-term mortality risk in older adults. This study aimed to investigate associations of lipid profiles and lipid ratios with 28-day mortality risk in non-surgical older patients with critical illnesses. METHODS: A retrospective cohort study was conducted with non-surgical older patients with critical illness who were admitted to the ICU of Shanghai East Hospital between January 2022 and November 2024. All data were collected via the hospitalization information system. Elastic network models were used to select covariates and Cox proportional hazards models were constructed to examine the association of lipid profiles and lipid ratios with 28-day mortality risk. Restricted cubic splines were used to test for non-linear relationships. Subgroup analyses were performed based on median age and gender. RESULTS: The median age of study's participants was 75 years, 35.91% of whom were female. Those who died within 28 days were more likely to receive dopamine, norepinephrine and mechanical ventilation than survivors. Adjusted models indicated that LDLC (HR = 0.82, 95% CI: 0.69 to 0.97), lbLDLC (HR = 0.79, 95% CI: 0.63 to 0.98), sdLDLC (HR = 0.44, 95% CI: 0.24 to 0.83), LDLC/HDLC (HR = 0.85, 95% CI: 0.73 to 1.00), and sdLDLC/HDLC (HR = 0.63, 95% CI: 0.40 to 1.00) were associated with decreased 28-day mortality risk. However, no non-linear associations were detected. In younger older adults (age < 75 years), TC, non HDLC, remanent C, TC/HDLC and remanent C/HDLC were related to increased short-term mortality risk. In very old adults, TC, LDLC, lbLDLC, sdLDLC, non HDLC, TC/ HDLC, LDLC/HDLC, lbLDLC/HDLC, and sdLDLC/HDLC were associated with lower 28-day mortality risk. In women, only lower sdLDLC was associated with increased short-term mortality risk. CONCLUSION: Lower levels of LDLC and its subtypes (lbLDLC, sdLDLC) were associated with increased 28-day mortality risk, particularly in patients aged ≥ 75 years and women. Conversely, elevated residual cholesterol levels correlated with higher mortality in younger older adults (< 75 years). These findings underscore the need for age- and sex-specific lipid management strategies in older patients with critical illnesses.