CHICAGO (Reuters) - Rheumatoid arthritis nearly doubles the risk of having a heart attack within the first 10 years of diagnosis, Swedish researchers said on Saturday.
The research, to be presented this week at the American College of Rheumatology's annual meeting in San Francisco, confirms that rheumatoid arthritis raises the risk of heart attacks and suggests this risk begins early on in the disease.
About 20 million people worldwide have rheumatoid arthritis, an autoimmune disease caused when the body confuses healthy tissues for foreign substances and attacks itself.
The disease causes pain, stiffness and swelling in multiple joints, and inflammation can develop in other organs as well.
Other studies have suggested that RA raises heart risks.
But the study by Marie Gunnarsson, a graduate student at the Karolinska Institutet in Stockholm, Sweden, wanted to take the research a step further by seeing how quickly these risks can rise.
She used data on 7,954 patients in Sweden who were newly diagnosed with RA and matched them with 38,913 people in the general population.
The two groups were followed for over 10 years, and researchers collected information on heart attacks, heart-related deaths and deaths from other causes.
After adjusting for high blood pressure and diabetes, they found that before their RA diagnosis, people were no more likely than others to have a heart attack. But after their diagnosis, their heart risks rose steadily.
During their first decade with the disease, the RA patients had nearly double the number of heart attacks and deaths caused by heart attacks.
"The fact that there is no increased risk prior to RA diagnosis suggests that there is something in the RA disease itself, such as inflammatory processes, that lead to this increased risk," Gunnarsson said in a statement.
She said measures to reduce inflammation may help reduce the heart risks in this population, as well. Inflammation has long been linked with heart disease and heart attack risk.
Editing by Maggie Fox and Philip Barbara