THE UREMIC DYSLIPIDEMIA - A CROSS-SECTIONAL AND LONGITUDINAL-STUDY

Patients on maintenance hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) exhibit numerous disturbances of serum lipids and apoproteins that may contribute to their high cardiovascular mortality. Cross-sectional studies have found that lipid levels are inversely related to time on dialysis. However, it is not known whether this association is the result of the attrition of hyperlipidemic patients or a decrease in lipid levels over time in all patients. Additionally, few studies have investigated the effect of dialysis modality on the lipoprotein disturbances of uremia adjusting for the confounding influences of demographics, or nutritional and endocrine status. To address these issues, we undertook a cross-sectional and longitudinal study of lipids, apoproteins, and atherogenic risk ratios in patients maintained on HD and CAPD. Patients were enrolled in annual cohorts from 1987 to 1990 and monitored until 1991. A total of 196 HD and 77 CAPD patients were studied. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), apoprotein (apo) A-I, and apo e were measured on enrollment and remeasured annually in survivors through 1990. Using multivariate methods, we examined the relationship of the lipids, apoproteins, their respective ratios, and their changes over time, to a broad range of clinical factors and to mortality. Compared with HD patients, CAPD patients had significantly higher TC, apo A-I, and apo B, and a significantly lower apo A-I/apo B ratio. Serum albumin correlated directly with TC and apo B and inversely with apo A-I/apo B. For patients with normal serum albumin (≥3.5 g/dL [35 g/L]), CAPD patients had a significantly higher TC/HDL-C than HD patients; otherwise the ratios were similar for CAPD and HD. Independent influences on lipoprotein levels in HD and CAPD patients were also demonstrated for race, gender, and diabetes, but not for parathyroid hormone (PTH) levels. For both dialysis modalities, patients who died had significantly lower TC and apo B, and significantly higher apo A-I/apo B throughout their entire courses compared with survivors. In the subset of patients followed longitudinally for 2 or more years, apo e tended to decrease with time, but TC, HDL-C, and apo A-I were stable. The longitudinal changes in lipoproteins did not correlate with outcome or other factors. In conclusion, CAPD patients have more atherogenic lipoprotein profiles than HD patients. Improved visceral protein nutritional status, as defined by serum albumin level, is associated with hyperlipidemia and, especially for CAPD, worsened atherogenic risk ratios. However, the potential risk associated with hyperlipidemia is far outweighed by the increased overall mortality of dialysis patients with lower lipid levels and, presumably, poorer nutritional status. © 1992, National Kidney Foundation, Inc.. All rights reserved.