The interplay between inflammation, lipids and cardiovascular risk in rheumatoid arthritis: why ratios may be better

There is abundant evidence that patients with rheumatoid arthritis (RA) are at elevated cardiovascular (CV) risk. The contribution of lipids in general is well recognised, but is as yet unclear in inflammatory diseases such as RA in part because inflammation appears inversely associated with lipid levels in RA.

The CARRE study is a cohort study of 353 randomly selected RA outpatients followed since their enrollment in 2001-2002. We used data from this cohort to (i) evaluate the relationship at baseline between lipid levels [total cholesterol (TC), high-density lipoprotein (HDL)-cholesterol and the TC:HDLc ratio] and inflammation [by means of C-reactive protein (CRP)]; and (ii) determine the association of baseline TC and TC:HDLc ratio with incident (fatal and non-fatal) CV events.

C-reactive protein correlated negatively with TC (r = -0.184, p = 0.002), more so with HDLc (r = -0.327, p = 0.001) and therefore positively with TC:HDLc ratio (r = 0.204, p = 0.001). These associations were most evident when CRP exceeded 10 mg/l. Furthermore, the TC:HDLc ratio, but not TC, was positively related to event risk, again most marked in those with elevated CRP.

Our observations support use of TC:HDLc ratio rather than TC alone in assessing cardiovascular risk in RA patients, especially in those with high inflammatory activity.