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    Why Do Some Patients with Rheumatoid Arthritis Have Worse Outcomes After TJA?

    In patients with rheumatoid arthritis (RA), higher disease activity — not postoperative flares — increases the risk of pain and poor function 1 year after total hip arthroplasty (THA) or total knee arthroplasty (TKA), according to a study in Arthritis Care & Research from researchers at Hospital for Special Surgery (HSS).

    “What we found was that at 1 year, those patients who had active disease were not as likely to do well, but the flares themselves didn’t really contribute to pain or poor function,” said lead study author Susan Goodman, MD, a rheumatologist at HSS. “I think this study gives us an idea that in RA, disease activity is really the bad actor when it comes to hip and knee replacement outcomes.”

    Dr. Goodman and colleagues conducted the study after noticing that outcomes of THA and TKA aren’t consistently as good for patients with RA as for patients without RA. Most RA patients undergoing THA and TKA have active RA and report postoperative flares, but whether RA disease activity or flares increased the risk of higher pain and lower function scores 1 year later was unknown. Understanding the reason for poor pain and function scores in RA patients can help optimize postoperative care.

    “One of the things we were suspicious of given the high likelihood of having a flare of RA after hip or knee replacement was that maybe those patients who flared couldn’t complete their physical therapy and wouldn’t be able to advance as quickly, leading to worse outcomes,” Dr. Goodman said.

    Their prospective observational cohort study evaluated outcomes in patients with RA who underwent THA or TKA at HSS from November 2014 through April 2018. At baseline, the researchers obtained a full set of clinical data on the state of a patient’s disease to assess severity and activity of disease. Patient-reported outcome measures were collected prior to surgery and were repeated at 1 year and included the Hip and Knee Osteoarthritis/Disability and Injury Outcomes Scores (HOOS/KOOS) and physician assessments of disease characteristics and activity (DAS28, CDAI). Each week for 6 consecutive weeks postoperatively, participants answered a questionnaire that addressed RA status and whether patients were experiencing a disease flare. The final analysis included 122 patients, 56 undergoing THA and 66 undergoing TKA.

    The researchers found that although HOOS/KOOS pain was worse for patients who flared within 6 weeks of surgery, absolute improvement was not different. In multivariable models, baseline DAS28 (a measure of disease activity), predicted 1-year HOOS/KOOS pain and function, with each 1 unit increase in DAS28 worsening 1-year pain by 2.41 and 1-year function by 4.96 (P=0.0001). High BMI also increased the risk of worse function. Postoperative flares were not independent risk factors for pain or function scores.

    Dr. Goodman said that patients with RA should anticipate a significant improvement in pain and function if they THA or TKA and that clinicians should target patients with higher disease activity for extra attention, such as increased physical therapy. She said that part of being an optimal candidate for surgery should include having less active disease.

    “One of the problems we have found is that many patients have longstanding active disease and have been on multiple different medications,” Dr. Goodman said. “It is not like getting a patient with new onset disease into low disease activity or remission; this is much more challenging.”

    Source

    Goodman SM, Mirza SZ, DiCarlo EF, et al. Rheumatoid Arthritis Flares After Total Hip and Total Knee Arthroplasty: Outcomes at One Year. Arthritis Care Res. 2020;72(7):925-932.