Patients with the most severe cases of rheumatoid arthritis are more likely to suffer flares after knee or hip replacement surgery, a new study finds, and it doesn’t seem to matter whether they stop taking biologics before their operation.

“We found that the majority of patients had active disease at the time of surgery, contrary to prior statements that RA patients have inactive disease at the time they go for hip or knee replacement. In fact, the majority – 65% of the patients – reported a flare of RA within 6 weeks of surgery,” lead author Susan M. Goodman, MD , of Cornell University and the Hospital for Special Surgery, New York, said in an interview. “Surprisingly, although more of the flaring patients were taking potent biologics that had been withheld preoperatively, the major risk factor for flares was their baseline disease activity.”

The study appeared online March 15 in the Journal of Rheumatology .

According to Dr. Goodman, the researchers launched the study to better understand how medical decisions prior to joint replacement surgery affect the progress of RA afterward.

In terms of continuing RA drug treatment, she said, “the decision really hinges on the risk of infection versus the risk of flare, and we didn’t know the usual course of events for these patients.”

In addition, she said, “many doctors incorrectly think that the majority of patients with RA have ‘burnt-out’ or inactive disease at the time of hip or knee replacement surgery.”

For the study, the researchers prospectively followed 120 patients who were to undergo joint replacement surgery. (The researchers initially approached 354 patients, of whom 169 declined to participate. Another 65 were dropped from the study for various reasons, including 42 who did not sufficiently fill out questionnaires and were deleted from the final analysis.)

The researchers tracked the patients before surgery and for 6 weeks after surgery. A majority of the patients were female (83%) and white (81%), with a mean age of 62 and a median RA symptom duration of 15 years. A total of 44% underwent hip replacement surgery while the rest underwent knee replacement surgery. Just over half of the patients were taking biologics, which were stopped prior to surgery, while glucocorticoids and methotrexate were usually continued.

Just under two-thirds of the patients flared within the first 6 weeks after surgery. The researchers didn’t find any connection between the flares and stopping biologics or using methotrexate. They did, however, link higher baseline RA activity to postsurgery flaring (odds ratio, 2.11; P = .015).

Dr. Goodman said that she and her colleagues continue to collect data to better understand flares and the link to disease severity. “The long-term implications of this are not yet known. We would like to know the effect on long-term functional outcome and complication rate.”

The National Institutes of Health, the Weill Cornell Clinical Translational Science Center, and the Block Family Foundation supported the study. Dr. Goodman disclosed receiving research funding from Novartis and Roche.

SOURCE: Goodman S et al. J Rheumatol. 2018 Mar 15. doi: 10.3899/jrheum.170366