Low levels of IgM antibodies against phosphorylcholine are associated with fast carotid intima media thickness progression and cardiovascular risk in men.

Objective: Low levels of IgM anti-phosphorylcholine (anti-PC) increase the risk of cardiovascular events (CVE). Here we investigate the association of low anti-PC with the progression of carotid intima media thickness (C-IMT) and incidence of CVE in a large cohort of individuals at high risk of CVE, the IMPROVE, a prospective multicenter European study.

Methods: 3711 subjects (54-79 years) with at least three established cardiovascular risk factors were enrolled. Baseline serum levels of IgM anti-PC were measured by ELISA. Carotid ultrasound investigations were performed at baseline and after 15 and 30 months of follow-up. The risk of C-IMT progression and ischemic CVE associated with low anti-PC levels was tested by logistic regression and Cox regression analysis, respectively. Risk estimates were adjusted by center and conventional cardiovascular risk factors.

Results: 3670 study participants were included in the present analysis and 213 CVE were recorded during a 3 year follow up. Anti-PC levels (U/ml) were classified into quartiles [Q1≤ 40, Q2 >40-≤64, Q3 >64-≤102, Q4 >102]. In men, low levels of anti-PC (Q1) were associated with the highest (>90th) percentile of the fastest C-IMT progression, i.e. the segment showing the fastest progression over 30 months in the whole carotid tree, with an OR of 1.41 (95%CI, 1.02-1.9) and with an increased risk of CVE with a multivariable adjusted HR of 1.85 (95%CI, 1.1-3.1). No significant associations were found in women.

Conclusions: Low anti-PC levels increase the risk of CVE in men. This effect may be partly mediated by a fast C-IMT progression.