Is an elevated level of serum lipoprotein (a) a risk factor for cardiovascular disease in CAPD patients?

Cardiovascular disease (CVD) is the single most important cause of mortality in hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. An increased lipoprotein (a) [Lp(a)] level in HD patients is associated with CVD. However, Lp(a) levels in CAPD patients are controversial, and their association with CVD has not been established. In the present study, prevalent CAPD and HD patients [excluding those who were human immunodeficiency virus (HIV)-positive] attending the Long Island College Hospital from June, 1990 to July, 1995 underwent analysis of lipid profile including Lp(a). Total and low-density lipoprotein cholesterol, triglycerides, apolipoprotein (apo) A, and apo B were all significantly increased in CAPD patients compared to HD patients. Serum Lp(a) levels were also significantly higher in CAPD patients than in HD patients (51 +/- 32 vs 34 +/- 23 mg/dL, p < 0.001). CAPD patients who had a history of myocardial infarction (MI) or coronary artery disease (CAD) at enrollment had significantly higher Lp(a) levels compared to those who did not have a history of MI or CAD. CAPD patients who died of CVD had higher Lp(a) levels than patients who died of non-CVD causes. In the Cox model with backward stepwise selection, a history of CVD was associated with a significantly elevated relative risk (RR) of mortality (RR = 1.84, p = 0.014). Expected survival by all causes of mortality and by cardiac mortality was significantly shorter in patients with a history of CVD than in those without a history of CVD. Thus, elevated Lp(a) is related to increased CVD and therefore may contribute to increased mortality in CAPD patients.