Objective: To investigate the relationship between inflammatory processes and atherosclerosis in uraemic patients on chronic dialysis.
Design: A cross-sectional study in 138 dialysis patients (92 on haemodialysis and 46 on continuous ambulatory peritoneal dialysis).
Methods: Serum C-reactive protein (CRP), IgG anti-Chlamydia pneumoniae antibodies, lipoprotein (a), fibrinogen and plasma homocysteine as well as the intima-media thickness and the number of atherosclerotic plaques of the carotid arteries (by Echo-Colour-Doppler) were measured in each patient.
Results: One hundred and eight patients had at least one plaque and 26 had more than six plaques. Serum CRP was above the upper limit of the normal range (5 mg/l) in 85 of 138 patients (62%). IgG anti-Chlamydia pneumoniae antibodies were detectable in 64% of patients (high level in 24%, intermediate in 33% and low in 7%) and undetectable in the remaining 36% of patients. In a multiple regression model age (β = 0.35), serum CRP (β = 0.23), plasma homocysteine (β = 0.19), duration of dialysis (β = 0.19) and pulse pressure (β = 0.18) were independent predictors of intima-media thickness (R = 0.54, P < 0.0001). Similarly, age (β = 0.33), serum CRP (β = 0.29), plasma homocysteine (β = 0.20) and serum albumin (β = -0.18) were independent correlates of the number of atherosclerotic plaques (R = 0.55, P < 0.0001). Furthermore, in smokers, the interaction serum CRP-IgG anti-Chlamydia pneumoniae antibodies was the stronger independent predictor (β = 0.43, P = 0.0001) of the number of atherosclerotic plaques while no such relationship (P = 0.73) was found in non-smokers.
Conclusions: In patients on chronic dialysis treatment CRP is independently associated to carotid atherosclerosis and appears at least in part to be explained by IgG anti-Chlamydia pneumoniae antibodies level. These data lend support to the hypothesis that inflammation plays a role in the pathogenesis of atherosclerosis in these patients.