Most patients with RA will have a disease flare after undergoing total knee or hip arthroplasty but withdrawal of biologics is not a factor, a US study has found.

In a prospective study of 120 patients with RA undergoing TKA or THA, 63% of patients had flared by six weeks after the procedure.

The median time to flare after surgery was two weeks with a median severity of 7 (on a 1–10 scale), and a median duration of four to seven days.

The risk of flares was increased among patients with higher disease activity at baseline, but was not related to duration of disease. And while more patients who had flares used biologics, stopping the medications was not an independent risk factor for flares. Conversely, continuing on methotrextate was not protective against flares.

The findings highlighted the fact that many patients with RA still had significant disease activity when they underwent arthroplasty, contradicting the notion that long duration of disease led to a patient’s RA being “burnt out” according to the clinicians from Rockerfeller University, New York.

Writing in the Journal of Rheumatology, they noted that around 40% of patients with RA undergoing TKA were treated with biologics and 67% treated with non-biologic DMARDs at the time of referral for arthroplasty.

Current guidelines recommend discontinuation of biologics prior to arthroplasty to mitigate infection risk, and withdrawal was known to precipitate flares, they said.

But the study showed that flares were frequent and severe in many RA patients after arthroplasty, and might affect postoperative rehabilitation, they concluded.

“While our study cannot address flare effect on longterm outcomes, the evidence presented here suggests that medication management decisions are not independent risk factors for postoperative flares,” they wrote.

The researchers also noted that widespread use of biologics in RA had not decreased the use of arthroplasty findings, suggesting that RA was an ongoing disease over a lifetime, with symptoms and quality of life controlled by medications such as biologics.