Study participants with high blood pressure, diabetes or high cholesterol – all well-known risk factors for kidney disease (independent of RA) – were also more likely to have reduced kidney function.

Having kidney disease can be especially bad news for RA patients since it further increases the risk for heart disease, says Dr. Matteson. Rheumatoid Arthritis patients already have a heart disease risk that’s higher than average. “Having kidney dysfunction is strongly associated with developing heart disease and other cardiovascular diseases, and ultimately those cardiovascular diseases are associated with morbidities [illnesses] and even early mortality [death].”

David Pisetsky, MD, professor of medicine at Duke University in Durham, N.C., says, “This is an excellent study by a top group of experts in the epidemiology of RA.” He says he was not surprised by the results. Doctors who treat patients with RA know this, in general. “Some increase in kidney disease is not unexpected in patients with RA who have a systemic inflammatory disease and are at increased risk of cardiovascular disease.”

But he points out that rheumatoid arthritis treatment has evolved in the last 20 years. “This study may not reflect current trends given the availability of more effective treatment approaches that reduce disease activity better,” he says. Those include the more widespread use of disease-modifying antirheumatic drugs (DMARDs) and biologics, as well as treat-to-target strategies to achieve low disease activity.

The increase in kidney disease risk is “certainly worth highlighting, but if anything, it just tells people the importance of overall good health,” says Dr. Pisetsky. “My take on it is: Treat RA well, get disease activity under control, recognize there’s cardiovascular risk, get hypertension under control, get diabetes under control, get people to lose weight, get people to exercise more. If you have you an inflammatory disease, you have to focus on overall health and recognize it’s not just a joint disease.”

Dr. Matteson says both patients and doctors can take steps to guard against kidney disease. “I think that the first thing is to be aware that the patients are actually at higher risk and to be especially attentive to doing the things that we already know are important in reducing the risk. That includes managing blood pressure, avoiding drugs that are toxic to the kidneys like NSAIDS [nonsteroidal anti-inflammatory drugs, such as ibuprofen and naproxen]. And for us in rheumatology, it means we should do everything we can to get the inflammatory disease under control.”

RA patients should have their kidney function tested regularly. “There’s not a strict regimen or schedule for doing kidney tests in patients with RA – and whether there should be is a question that the study raises,” says Dr. Matteson.