Significance of high C-reactive protein levels in pre-dialysis patients.
BACKGROUND
An elevated serum C-reactive protein (CRP) has been shown to be strongly predictive of morbidity and mortality in dialysis patients. However, the significance of high CRP levels in the pre-dialysis period has not been studied extensively. The aim of our study was to analyse the evolution of our pre-dialysis population according to their basal levels of CRP.


METHODS
A cohort of 66 pre-dialysis patients was followed for 1 year, after initial determination of serum CRP. The evolution of blood pressure (BP) control, CRP levels, nutritional data (body mass index, serum albumin, prealbumin, transferrin, cholesterol), proteinuria, calcium-phosphorus product, bicarbonate, haemoglobin (Hb), the weekly dose of erythropoietin (Epo)/kg body weight, and the Hb/Epo dose ratio were measured and compared between patients with high (>6 mg/l) or low (<6 mg/l) CRP levels at baseline. The decline in renal function, hospitalization, and death also were measured and compared between the two groups.


RESULTS
At baseline, 23 patients (35%) showed high (>6 mg/l) CRP levels. CRP was higher in patients with a previous history of cardiovascular disease (P<0.01), as well as in patients in whom ischaemic nephropathy or nephrosclerosis was the cause of end-stage renal disease (P<0.01). There were no differences between diabetic and non-diabetic patients. During the study period, patients with higher CRP levels at baseline maintained higher levels (P<0.001). During this period, these patients showed lower (P<0.05) albumin concentration, higher bicarbonate levels, lower Hb concentration, and lower Hb/Epo ratio and needed higher Epo doses. There were no differences in systolic BP, the degree of proteinuria, and the decline in renal function between groups; diastolic BP was lower in patients with high CRP levels. Hospitalization was higher (P<0.005) in this group. Only one patient died.


CONCLUSIONS
The prevalence of inflammation is high in pre-dialysis patients. High serum CRP levels predict a constant inflammatory state on follow-up. As occurs in dialysis patients, pre-dialysis inflammation predicts lower serum albumin concentration, poorer response to Epo, and a higher hospitalization rate. The decline in renal function does not seem to be related to the inflammatory state. Mortality was not affected on short-term follow-up.
Ortega
Olimpia
O
Department of Nephrology, Hospital Severo Ochoa, Leganés, Madrid, Spain. oortega@hsvo.insalud.es
Rodriguez
Isabel
I
Gallar
Paloma
P
Carreño
Agustín
A
Ortiz
Milagros
M
Espejo
Beatriz
B
Jimenez
Juana
J
Gutierrez
Magdalena
M
Oliet
Aniana
A
Vigil
Ana
A
D001639:Bicarbonates / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002097:C-Reactive Protein / Q000032:analysis*; D002784:Cholesterol / Q000097:blood; D015331:Cohort Studies; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000401:mortality / Q000628:therapy; D009017:Morbidity; D011237:Predictive Value of Tests; D011507:Proteinuria; D006435:Renal Dialysis / Q000009:adverse effects* / Q000401:mortality; D012680:Sensitivity and Specificity; D012709:Serum Albumin / Q000378:metabolism; D014168:Transferrin / Q000032:analysis
D001639:Bicarbonates; D015415:Biomarkers; D006454:Hemoglobins; D012709:Serum Albumin; D014168:Transferrin; D002097:C-Reactive Protein; D002784:Cholesterol