The researchers identified more than 1,100 serious infections requiring hospitalization within the first 12 months of starting any kind of therapy; 53 percent involved skin or soft tissue infections or pneumonia.

But when researchers compared the infection rate of anti-TNF users to the infection rate of those who used non-biologic medications, such as hydroxychloroquine, or Plaquenil, and leflunomide, or Arava, they found no significant difference.

There was one exception: RA patients taking infliximab, or Remicade, had a higher infection rate than those on etanercept, or Enbrel, and adalimumab, or Humira. “Remicade had a significant association between risk of infection, but we didn’t see anything with other anti-TNF drugs,” says Dr. Grijalva, noting that they don’t know why.  

Additionally, among patients with RA and psoriasis/spondyloarthropathies, the simultaneous use of corticosteroids at the start of therapy was associated with an increased risk of serious infection, regardless of the treatment regimen (anti-TNF vs. non-biologic); the higher the corticosteroid dose, the higher the risk of infection.

“I think these results should reassure patients and providers that we did not observe that these biologics increase the risk of serious infections when compared with other, non-biologic regimens,” Dr. Grijalva explains.

But some researchers say the study isn’t the final word on anti-TNF infection risk because of the high drop-out rate of study patients.

“I think the study was well done, but a lot of people starting on anti-TNFs dropped out of treatment, so the follow-up was not comprehensive,” says David T. Felson, MD, a professor of medicine and epidemiology at the Boston University School of Medicine, who wrote an editorial accompanying the study. “They might have missed a heightened infection risk because those people weren’t taking the drugs for long enough.”

Dr. Felson says it’s important to figure out why there is conflicting research on this topic, but he thinks that’s more of a research matter than a clinical one at this point.

“I do think some people are scared to start [biologics] and I think the message isn’t all black and white. There is a risk to starting them,” Dr. Felson says. “I would say it’s right to be concerned – but not right to be overwhelmed with concern.”

Dr. Felson says patients who have previously had infections or are at a higher risk because of their age might want to be particularly mindful of this issue. But for most patients, he says, “Being so scared you don’t feel comfortable starting medicine that might help you is not good. I have a lot of patients on anti-TNFs. They are very effective and the infection risk in most patients is by no means overwhelming.”