Study researcher Gabriel Chodick, MD, called the risk reduction "important and meaningful," but he says more research is needed to confirm the association.
"It would certainly be premature to suggest taking statins to prevent rheumatoid arthritis," he tells WebMD. "But one important message is that people who have been prescribed them should adhere to treatment. Right now about 75% of people who begin taking statins stop within two years."
There is also a suggestion that statins reduce systemic inflammation and may be protective against RA and other chronic inflammatory diseases.
Several studies have suggested a role for statins in slowing the progression of disease among patients with rheumatoid arthritis, but others failed to find a protective benefit for statin use.
In the newly published study, Chodick and colleagues examined data on 1.8 million members of Israel's Maccabi Healthcare Services HMO. Between 1998 and 2007, 2,578 new cases of rheumatoid arthritis were identified in this group.
The analysis revealed that patients who took statins for at least eight years during the decade-long study period were roughly 40% less likely to develop rheumatoid arthritis than people who did not take statins at all or who took them less persistently.
A more modest 15% reduction in osteoarthritis risk was seen in persistent statin users. Like rheumatoid arthritis, osteoarthritis is a chronic, degenerative joint disease. But it is not driven by inflammation, so statin use is not as likely to affect its development or progression.
The study appears in the September issue of the journal PLoS Medicine.