Association between C-reactive protein and clinical outcomes in peritoneal dialysis patients

An elevated level of C-reactive protein (CRP), which is a marker of inflammation, is a risk factor for morbidity and mortality in the general population and in dialysis patients. Recently, the relationship between inflammation and nutrition status has received much attention. Serum prealbumin is a highly sensitive marker of nutrition and survival in dialysis patients. The objective of the present study was to evaluate the prognostic value and clinical correlates of CRP in peritoneal dialysis (PD) patients. Using retrospective chart review, we collected demographic, clinical, and laboratory data on 66 PD patients for the period June 2001 to January 2005. High-sensitivity CRP (hs-CRP) levels were measured in a subgroup of 32 patients starting in May 2003. Over the study period, prealbumin and CRP were assayed serially by the immunoturbidimetric method. Mean age (+/- standard deviation) of the patients was 55 +/- 15 years, and 73% were African American. Mean and median enrollment CRP were 15.2 +/- 24 mg/L (range: 4.2 - 149.5 mg/L) and 6.45 mg/L respectively. Mean and median enrollment hs-CRP were 15.3 +/- 23.5 mg/L (range: 0.2 - 96 mg/L) and 6.55 mg/L respectively. Enrollment CRP was elevated (215 mg/L) in 29% of the patients, and hs-CRP was elevated (> or = mg/L) in 63% of the patients. Enrollment CRP was strongly correlated with hs-CRP (r = 0.7, p < 0.0001). The presence of diabetes (22 mg/L vs. 7.8 mg/L, p = 0.02), infection and inflammatory conditions (44.9 mg/L vs. 11.6 mg/L, p = 0.001), and lower levels of markers of nutrition such as prealbumin (r = -0.47, p < 0.0001) and creatinine (r = 0.35, p = 0.006) were associated with a higher level of CRP. Enrollment hs-CRP was a significant predictor of mortality in PD patients (relative risk = 1.044, p = 0.023). The observed cumulative survival (Kaplan-Meier) of patients with hs-CRP <15 mg/L was significantly better (p = 0.007) than was the survival of patients with a hs-CRP > or =15 mg/L. In a multivariate regression analysis, serum prealbumin was the best and only significant predictor of CRP level (beta = -0.37, p = 0.005). Elevated CRP was associated with infection and inflammation. Therefore, routine testing of hs-CRP in PD patients should be considered.