WASHINGTON – Low bone mineral density and the presence of vertebral fractures in patients with rheumatoid arthritis not only signal the likely presence of osteoporosis but also appear to signal increased cardiovascular disease risk, according to findings from a cross-sectional study.*
The findings suggest that dual-energy x-ray absorptiometry (DEXA) scans commonly performed in rheumatoid arthritis (RA) patients to assess for osteoporosis could also serve as an assessment of cardiovascular disease risk, Dr. Ausaf Mohammad reported at the annual meeting of the American College of Rheumatology.
Of 603 patients from a convenience sample of adults who met 1987 ACR criteria for RA classification, 230 had at least one documented cardiovascular disease event, and those patients, compared with patients without a cardiovascular disease event, had significantly lower total hip and lumbar spine bone mineral density, and were four times as likely to have osteoporosis (60% vs. 15%) and twice as likely to have a vertebral fracture (24% vs. 12%), said Dr. Mohammad of Galway (Ireland) University Hospitals.
Low bone mineral density and the presence of vertebral fractures were independently associated with cardiovascular disease after adjustment for age, sex, smoking, hypertension, diabetes, and hypercholesterolemia. These measures outperformed traditional risk factors and RA disease activity scores for predicting cardiovascular disease.*
For example, the age- and sex-adjusted odds ratios for osteoporosis and vertebral fractures in those with cardiovascular disease were 2.70 and 2.67; the odds ratios for diabetes mellitus, smoking history, hypertension, hyperlipidemia, C-reactive protein, and Disease Activity Score (DAS-28) indicative of active RA were 1.61, 1.18, 1.58, 1.02, 1.73, and 1.63, respectively.
Patients in the RA cohort included 446 women and 157 men over age 40 years (mean, 56 years) who had a prior DEXA scan with vertebral fracture assessment available for analysis. The scans were evaluated by blinded musculoskeletal radiologists, and osteoporosis diagnoses were made using World Health Organization DEXA criteria; 32% of patients had osteoporosis by bone mineral density criteria, and 13% had one or more vertebral fractures on vertebral fracture assessment.
Cardiovascular events in the cohort included myocardial infarction in 45 patients, stent in 145, heart failure in 33, and stroke in 7.
The findings are of note given that traditional risk factors for cardiovascular disease tend to underperform in patients with RA, and that cardiovascular disease remains the leading cause of mortality in this population, Dr. Mohammad said.
"The risk of cardiovascular disease rises shortly after onset of arthritis, but does not precede it, and the risk appears similar to what is seen in non-RA subjects with diabetes and non-RA subjects who are 5-10 years older, so this tells us we are looking at a very high-risk population," he said.
However, despite a similar distribution in RA and non-RA patients, risk factors for cardiovascular disease "behave differently" in RA patients, and multiple studies have shown that methods for assessing risk, such as the Framingham risk score, underestimate risk in those with RA.
Indeed, the Framingham risk score did not differ significantly between those with and without cardiovascular disease events in the current study, Dr. Mohammad said, adding: "This poses a significant challenge. Therefore we need better markers and better prediction tools."
It appears, based on these findings, that bone mineral density could serve as such a marker, and that DEXA scans could be a good prediction tool, he said.
Since RA patients are also at increased risk for osteoporosis and fractures, many are already referred for DEXA scans.
"So DEXA may provide an opportunity to assess RA subjects at the time of osteoporosis for cardiovascular disease without the need for additional testing," he said.
Although this study has inherent limitations associated with its cross-sectional design, it does have several strengths, including the large cohort size and the fact that participating radiologists were blinded to patient status. Also, the findings are in keeping with those from multiple prior studies in non-RA populations, demonstrating strong associations between osteoporosis and cardiovascular disease, he added, noting that the findings underscore a need for interventions to reduce cardiovascular disease risk in RA patients with osteoporosis.
Dr. Mohammad reported having no relevant financial disclosures.
*Correction: 12/04/2012: An earlier version of this story misstated Dr. Mohammad's findings.