NEW YORK (Reuters Health) Dec 25 - Hypothyroid rheumatoid arthritis (RA) patients have worse cardiovascular risk profiles - reflected by a higher prevalence of metabolic syndrome -- than those with normal thyroid function, new research shows.
Based on the findings, these patients should be getting more intensive cardiovascular risk management, Dr. H. G. Raterman of VU University Medical Center in Amsterdam and colleagues conclude.
RA itself increases cardiovascular disease (CVD) risk, the researchers note, while recent studies suggest hypothyroidism may further boost CVD risk in RA patients.
To investigate whether thyroid function was related specifically to metabolic syndrome, Dr. Raterman and colleagues looked at 257 patients taking part in a study of CVD and CVD risk factors in RA. Twenty-one, or 8.2%, were hypothyroid.
Among the hypothyroid patients, 43% had metabolic syndrome, as defined by the National Cholesterol Education Program Third Adult Treatment Panel criteria, compared to 20% of euthyroid RA patients. After adjusting for age and gender, hypothyroidism increased the likelihood of having metabolic syndrome 3.5-fold.
Hypothyroid patients were also significantly more likely to have low HDL cholesterol.
There was no significant difference in Framingham risk score between hypothyroid and euthyroid patients overall. But when the researchers looked separately at women, the association was significant; 10-year CVD risk for female hypothyroid patients was 13%, compared to 9% for those with normal thyroid function.
While inflammation could help explain the relationship, the researchers note, accounting for inflammatory activity didn't reduce the increased risk of metabolic syndrome seen in hypothyroid patients, "suggesting that additional mechanisms are involved."
Microvascular dysfunction could be a factor as well, they add.
"A key message of the present study is that in daily clinical practice, particularly in RA patients with hypothyroidism, the metabolic syndrome requires more attention, because the metabolic syndrome reflects an increased, but theoretically modifiable, cardiovascular risk," the researchers write. "Relatively simple lifestyle and/or pharmacological interventions may prevent future CVD in this group of patients with an already enhanced background risk of CVD."
Ann Rheum Dis 2010;69:39-42.