October 31, 2019
2 min read

High RA disease activity increases risk for pain one year after arthroplasty

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Susan M. Goodman

Higher rheumatoid arthritis disease activity at the time of total hip or knee arthroplasty is associated with an increased risk for worse pain and function 1 year following the operation, according to data published in Arthritis Care & Research.

“Patients with rheumatoid arthritis continue to undergo total hip and total knee replacement to lessen pain and improve function due to advanced arthritis of the knee and hip, despite the overall improved outcomes associated with the increased use of potent disease modifying drugs and biologics,” Susan M. Goodman, MD, of the Hospital for Special Surgery and Weill Cornell Medical College, told Healio Rheumatology. “However, patients with RA may not achieve the same outcomes in gain of function, and are at higher risk for complications including prosthetic joint infection or hip dislocation.”

“We have been concerned that withholding potent DMARDs or biologics to decrease infection risk might increase the risk of flares, and have previously shown that flares in the six weeks after surgery were linked to high disease activity at the time of surgery, and not withholding medications,” she added.

To determine whether RA disease activity or flares increase the risk for worse pain and function 1 year following total knee or hip arthroplasty, Goodman and colleagues conducted a prospective observational cohort study of patients at a single, high-volume tertiary care center for musculoskeletal disease. The researchers recruited adult patients with RA prior to surgery. Among the 315 participants who initially gave consent, 129 were lost to follow-up and 64 had not yet reached the 1-year exam at the time of the researchers’ analysis, leaving 122 patients for final consideration.

Higher RA disease activity at the time of total hip or knee arthroplasty is associated with an increased risk for worse pain and function 1 year following the operation, according to data.
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The researchers collected patient reported outcomes, including Hip and Knee Osteoarthritis/disability and injury Outcome Scores (HOOS/KOOS), as well as physician assessments of disease characteristics and activity, specifically DAS28 and CDAI, at baseline prior to surgery. Later, participants answered a questionnaire on RA status and disease flare each week for 6 consecutive weeks following surgery. Flares were defined by an agreement between patient reports and physician assessment. Patient-report outcomes were again assessed at 1 year.

The researchers compared baseline characteristics and scores using twosample ttest/Wilcoxon ranksum and Chisquared/Fisher's exact tests. In addition, they used multivariate linear and logistic regression to find the association between baseline data and one-year outcomes.

According to the researchers, HOOS/KOOS pain was reportedly worse for patients who experienced flares within 6 weeks of surgery. However, absolute improvement did not differ between those who experienced flares and those who did not. In their multivariable models, the researchers found that baseline DAS28 predicted 1year HOOS/KOOS pain and function. Each one-unit increase in DAS28 worsened 1-year pain by 2.41 based on HOOS/KOOS (SE = 1.05; P = .02), as well as 1-year function by 4.96 (SE = 1.17; P = .0001). Postoperative flares were not found to be independent risk factors for pain or function.

“We have demonstrated that higher disease activity, but not acute post-op flares, is linked to less gain in pain relief and function one year after total hip and total knee replacement surgery,” Goodman said. “High BMI was also associated with worse outcomes at 1 year, but the magnitude of the effect was not large.”

“Both disease activity and BMI are modifiable, and the majority of patients with RA have moderate to high disease activity at the time of arthroplasty,” she added. “Future efforts are needed to determine whether pre-arthroplasty medical management should include efforts to control disease activity and weight, and whether these interventions might improve long term pain and function.” – by Jason Laday

Disclosure: The researchers report no relevant financial disclosures.