The Time Course of Serum C-Reactive Protein is More Predictive of Mortality than its Baseline Level in Peritoneal Dialysis Patients

Abstract

Several recent studies reported that a high baseline serum C-reactive protein (CRP) is a powerful predictor of mortality in dialysis patients. However, the acute-phase response is intermittent and not a continuous feature in an individual patient. The aim of this prospective study was to determine whether serial analysis of serum CRP during follow-up allows better prediction of mortality and echocardiographic cardiac disease than a single baseline measurement in peritoneal dialysis (PD) patients. 97 PD patients were monitored for 3 years from the beginning of the treatment. We evaluated the effect of demographic features, comorbidity, blood pressure, blood biochemistry, including CRP, residual renal function, and indices of dialysis adequacy, on mortality and left ventricular hypertrophy (LVH). Cox regression analysis using both the baseline and the averaged values of the study parameters was carried out to determine factors predicting mortality. Logistic regression analysis was performed to determine which factors were independently predictive for LVH and the type of time course of serum CRP. Baseline serum CRP was elevated in 29 patients (29.9%). While serum CRP exhibited a stable course (normal or high) in 55 patients (56.7%), it varied considerably over time in 42 patients (43.2%). In the Cox models, both the averaged serum CRP and the type of variability of CRP were predictors of mortality. On the contrary, baseline CRP did not affect adjusted survival. The averaged CRP was also an independent factor affecting LVH, but baseline CRP was not. Age, comorbidityindex, instilled dialysate glucose concentration, and Kt/V urea were independently associated with the type of time course of serum CRP. The averaged value of serum CRP is more predictive of prognosis compared to the baseline value in PD patients. Determining serum CRP on a regular basis may be helpful to detect early signs of tissue damage or asymptomatic inflammation.