Effects of disease activity on lipoprotein levels in patients with early arthritis: can oxidized LDL cholesterol explain the lipid paradox theory?

BACKGROUND: An increased risk of cardiovascular (CV) complications has been described in patients with rheumatoid arthritis (RA). It is the result of the combined effect of classic CV risk factors and others that are specific to the disease. METHODS: We assessed data from 448 early arthritis (EA) patients: 79% women, age (median [p25-p75]) at onset: 55 [44–67] years and disease duration at study entry 5 [3–8] months; and 72% fulfilled the 1987 RA criteria at 2 years of follow-up. Rheumatoid factor was positive in 54% of patients and anti-citrullinated peptide antibodies in 50%. The follow-up of patients ranged from 2 to 5 years with more than 1400 visits with lipoprotein measurements available (mean 2.5 visits/patient). Demographic- and disease-related variables were systematically recorded. Total cholesterol (TC), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C) levels were obtained from routine laboratory tests. Oxidized-LDL (oxLDL-C) levels were assessed using a commercial ELISA kit. We fitted population-averaged models nested by patient and visit to determine the effect of independent variables on serum levels of TC, its fractions, and oxLDL-C. RESULTS: After adjustment for several confounders, high-disease activity was significantly associated with decreased TC, HDL-C, and LDL-C levels and increased oxLDL-C levels. Standardized coefficients showed that the effect of disease activity was greater on oxLDL-C and HDL-C. Interestingly, we observed that those patients with lower levels of LDL-C showed higher oxLDL-C/LDL-C ratios. CONCLUSIONS: High-disease activity in EA patients results in changes in the HDL-C and oxLDL-C levels, which in turn may contribute to the increased risk of CV disease observed in these patients.