Prognostic Value of Plasma Myeloperoxidase in ESRD Patients

Background

Myeloperoxidase (MPO) has been suggested to have a role in atherosclerosis through its strong oxidative capacity. We hypothesized that MPO level may predict clinical outcomes in patients with end-stage renal disease receiving long-term peritoneal dialysis (PD) therapy.

Study Design

Prospective cohort study.

Setting & Participants

236 long-term PD patients were recruited from a single regional dialysis unit in Hong Kong between April 1999 and February 2001.

Predictor

Level of plasma MPO, analyzed using a sandwich enzyme-linked immunosorbent assay.

Outcome & Measurement

Mortality and fatal or nonfatal cardiovascular events at 3 years.

Results

The distribution of MPO levels was skewed with a median of 31.8 μg/L (25th-75th percentiles, 24.4-42.7). There were 69 deaths and 81 cardiovascular events. Adjusting for traditional and nontraditional risk factors and C-reactive protein, cardiac troponin T, and N-terminal pro-brain natriuretic peptide levels, a doubling in plasma MPO level was associated independently with a 46% (95% CI, 1.02-2.08; P = 0.04) and 60% (95% CI, 1.17-2.18; P = 0.003) increase in risks of mortality and cardiovascular events, respectively. Log₂MPO showed significant additional predictive value for mortality (P = 0.04) and cardiovascular events (P = 0.005) when included in Cox regression models consisting of clinical, demographic, dialysis, echocardiographic, and biochemical parameters, as well as C-reactive protein, cardiac troponin T, and N-terminal pro-brain natriuretic peptide levels.

Limitations

MPO was measured at a single time and did not reflect changes over time.

Conclusions

These data suggest that plasma MPO level has significant independent and additional prognostic value beyond the standard clinical, biochemical, and echocardiographic parameters and is useful for outcome stratification in long-term PD patients. MPO may be an important mediator of increased cardiovascular risk in patients with end-stage renal disease and warrants further investigation.

Index Words: Myeloperoxidase, end-stage renal disease, mortality, cardiovascular events, peritoneal dialysis