Despite a similar relationship between lipid levels and cardiovascular disease risk in patients with or without rheumatoid arthritis, people with RA have an almost two-fold increased risk of having a major cardiovascular event, research shows.

The findings confirm that existing CV risk calculators are suboptimal for patients with RA and that improved methods of measuring risk in this population are needed, say the study authors from the Brigham and Women’s Hospital in Boston. They also show that there may be potential benefit in considering both LDL-C and HDL-C levels when estimating CV risk in RA, according to Dr. Katherine P. Liao and her associates from Brigham and Women’s Hospital, Boston (Arthritis & Rheumatology 2015; [doi: 10.1002/art.39165]).

While there have been many studies examining the relationship between low density lipoprotein cholesterol levels (LDL-C) and CV risk, only one study described the relationship between high density lipoprotein cholesterol levels (HDL-C) with CV risk among RA patients. It found higher levels of HDL-C were associated with lower CV risk in people with RA, consistent with the general population. “[This] suggests that HDL-C levels may provide important information for estimating CV risk independent of LDL-C,” according to Dr. Liao and her associates.

To assess the relationship between LDL-C and HDL-C with CV risk in RA patients compared with the general population, the researchers compared 16,085 RA patients with 48,499 matched controls without RA from the United Healthcare database. In line with other studies the researchers found evidence of the “lipid paradox” – where low and high LDL-C levels confer a similar CV risk – in both groups.

Looking at HDL-C levels, the risk of a major cardiovascular event (MACE) was highest among patients with lower levels compared with higher levels in both RA and non-RA subjects. For example subjects in the highest quintile had a 55% lower risk for MACE (hazard ratio, 0.45; 95% confidence interval, 0.48-0.72) compared with the lowest quintile after adjusting for CV risk factors. However,in a model that included both LDL-C and HDL-C levels, patients with RA had an elevated risk of MACE (HR 1.7; 95% CI, 1.5-1.9) independent of LDL-C levels.

“This magnitude of increased CV risk is similar to studies published a decade ago, suggesting that current practice and new RA therapies have not closed the gap between CV risk in RA compared to non-RA,” the researchers wrote. The finding also highlighted the potential benefit of considering both LDL-C and HDL-C levels when estimating CV risk in RA,” they said. One potential explanation for the independent significant association between HDL-C levels and CV-risk was that HDL-C levels appeared to remain relatively stable throughout changes in inflammation and may correlate better than LDL-C for CV risk, they suggested.

Overall the findings supported the notion that LDL-C levels may be a suboptimal measure for CV risk assessment in RA and demonstrated the need for improved methods for CV risk assessment, they said. The TransAtlantic cardiovascular risk calculator is under development to address this “major need in optimizing care for RA patients,” they added.