Abstract
Rationale & Objective
Patients with chronic kidney disease (CKD) have dysfunctional high-density lipoprotein (HDL) particles that lack cardioprotective properties; altered lipid composition may be associated with these changes. To investigate HDL lipids as potential cardiovascular risk factors in CKD, we tested the associations of HDL ceramides, sphingomyelins, and phosphatidylcholines with mortality.
Study Design
We leveraged data from a longitudinal prospective cohort of participants with CKD.
Setting & Participants
We included participants aged greater than 21 years with CKD, excluding those on maintenance dialysis or with prior kidney transplant.
Exposure
HDL particles were isolated using density gradient ultracentrifugation. We quantified the relative abundance of HDL ceramides, sphingomyelins, and phosphatidylcholines via liquid chromatography tandem mass spectrometry (LC-MS/MS).
Outcomes
Our primary outcome was all-cause mortality.
Analytical Approach
We tested associations using Cox regressions adjusted for demographics, comorbid conditions, laboratory values, medication use, and highly correlated lipids with opposed effects, controlling for multiple comparisons with false discovery rates (FDR).
Results
There were 168 deaths over a median follow-up of 6.12 years (interquartile range, 3.71-9.32). After adjustment, relative abundance of HDL ceramides (HR, 1.22 per standard deviation; 95% CI, 1.06-1.39), sphingomyelins with long fatty acids (HR, 1.44; 95% CI, 1.05-1.98), and saturated and monounsaturated phosphatidylcholines (HR, 1.22; 95% CI, 1.06-1.41) were significantly associated with increased risk of all-cause mortality (FDR < 5%).
Limitations
We were unable to test associations with cardiovascular disease given limited power. HDL lipidomics may not reflect plasma lipidomics. LC-MS/MS is unable to differentiate between glucosylceramides and galactosylceramides. The cohort was comprised of research volunteers in the Seattle area with CKD.
Conclusions
Greater relative HDL abundance of 3 classes of lipids was associated with higher risk of all-cause mortality in CKD; sphingomyelins with very long fatty acids were associated with a lower risk. Altered lipid composition of HDL particles may be a novel cardiovascular risk factor in CKD.
Plain-Language Summary
Patients with chronic kidney disease have abnormal high-density lipoprotein (HDL) particles that lack the beneficial properties associated with these particles in patients with normal kidney function. To investigate if small lipid molecules found on the surface of HDL might be associated with these changes, we tested the associations of lipid molecules found on HDL with death among patients with chronic kidney disease. We found that several lipid molecules found on the surface of HDL were associated with increased risk of death among these patients. These findings suggest that lipid molecules may be risk factors for death among patients with chronic kidney disease.
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