Association between time-of-day plasma lipid measurements and acute kidney injury in critically ill patients: A retrospective cohort study.

BACKGROUND

This study aimed to evaluate the association between time-of-day differences in blood lipids and acute kidney injury (AKI) in critically ill patients.

METHODS

This study enrolled 3,227 ICU patients. AKI was defined according to the KDIGO 2012 criteria. Cox regression, restricted cubic splines, Kaplan-Meier analysis, and stratified interaction analysis were used to assess the association between daytime/nighttime levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides and AKI.

RESULTS

Each 1 mg/dL increase in HDL-C was associated with a 0.5% decrease in AKI risk [HR 0.995, 95% CI 0.993-0.998, P < 0.001]. Each 1 mg/dL increase in triglyceride was associated with a 0.1% increase in AKI risk [HR 1.001, 95% CI 1.000-1.001, P = 0.004]. LDL-C exhibited an L-shaped nonlinear relationship with AKI. At or below 47 mg/dL (daytime), 58 mg/dL (nighttime), and 48 mg/dL (overall), lower LDL-C was associated with higher AKI risk, whereas above these thresholds, LDL-C was no longer associated with AKI risk [daytime: HR 0.977, 95% CI 0.964-0.991, P < 0.001; nighttime: HR 0.992, 95% CI 0.985-0.998, P = 0.009; overall: HR 0.987, 95% CI 0.980-0.994, P < 0.001].

CONCLUSION

Higher HDL-C levels were consistently associated with lower AKI incidence within 28 days after ICU admission. Higher nighttime and overall triglyceride levels were associated with higher AKI incidence. An L-shaped nonlinear relationship was observed between LDL-C and AKI risk, with thresholds at 47 mg/dL (daytime), 58 mg/dL (nighttime), and 48 mg/dL (overall). These findings highlight a complex relationship between lipid metabolism and renal outcomes in critically ill patients and warrant confirmation through prospective studies.