The association of lipid levels with mortality in patients on chronic peritoneal dialysis

Background. The role of traditional risk factors, including plasma lipids, in the pathogenesis of cardiovascular (CV) disease in chronic dialysis patients is unclear. Previous studies have suggested that lower serum total cholesterol (TC) is associated with higher mortality in patients on chronic haemodialysis (HD). Whether this relationship is specific to the HD population or is common to the uraemic state is unclear. The present study evaluated the association of serum TC and triglycerides with clinical outcomes in chronic peritoneal dialysis (PD) patients. Methods. Data of 1053 PD patients from the United States Renal Data System (USRDS) prospective Dialysis Morbidity and Mortality Study Wave 2 were examined. Cox regression was used to evaluate the relationship between lipid levels and mortality. Results. Patients with TC levels <= 125 mg/dl (3.24 mmol/l) had a statistically significant increased risk of an all-cause mortality, including those taking or not taking lipid-modifying medications, compared with the reference of 176-225 mg/dl (4.54-5.83 mmol/l). In stratified analysis, this association was demonstrated in patients with serum albumin > 3.0 g/dl (30 g/l), but not with albumin <= 3.0 g/dl. Compared with patients with triglyceride levels of 201-300 mg/dl (2.27-3.39 mmol/l), a statistically significant reduction of all-cause, but not CV, mortality was observed in patients with triglyceride levels of 101-200 mg/dl (1.14-2.26 mmol/l), as well as in the subgroup with serum albumin levels < 3.0 g/dl (30 g/l) and triglycerides of <= 100 mg/dl (1.13 mmol/l) and 101-200 mg/dl (1.14-2.26 mmol/l). Conclusions. While confounding factors and causal pathways have not been clearly identified, aggressive lowering of plasma cholesterol in PD patients is not supported by this study, however, treatment of hypertriglyceridaemia may be warranted with triglyceride levels > 200 mg/dl (2.26 mmol/l).