Rheumatoid Arthritis Flares after Total Hip and Total Knee Arthroplasty: Outcomes at 1 year
Susan M. Goodman, MD,1,2 Serene Z. Mirza, BS,1 Edward F. DiCarlo, MD,1 Diyu Pearce-Fisher, BS,1 Meng Zhang, PhD,4 Bella Mehta, MBBS, MD,1,2 Laura T. Donlin, PhD,1,2 Vivian P. Bykerk, MD, FRCPC,1,2 Mark P. Figgie, MD,1,2 and Dana E. Orange, MD, MS1,3Hip Knee
Objective:
Most RA patients undergoing total hip(THA) and total knee arthroplasty(TKA) have active RA and report post-operative flares; whether RA disease activity or flares increase risk of worse pain and function scores 1 year later is unknown.
Methods:
RA patients were enrolled before THA/TKA. Patient Reported Outcomes (PROS) including Hip and Knee Osteoarthritis/disability and injury Outcome Scores (HOOS/KOOS) and MD assessments of disease characteristics and activity (DAS 28, CDAI) were collected before surgery. PROS were repeated at 1 year. Post-operative flares were identified using RA Flare Questionnaire weekly for 6 weeks, and defined by concordance between patient report plus MD assessment. We compared baseline characteristics and HOOS/KOOS scores using two-sample t-test/Wilcoxon rank-sum and Chi-squared/Fisher’s exact tests. We used multivariate linear and logistic regression to determine association of baseline characteristics, disease activity, and flares, with 1-year outcomes.
Results:
One-year HOOS/KOOS scores were available for 122 patients (56THA/66TKA). Although HOOS/KOOS pain was worse for patients who flared within six weeks of surgery; absolute improvement was not different. In multivariable models, baseline DAS28 predicted 1-year HOOS/KOOS pain and function; each 1 unit increase in DAS28 worsened 1-year pain by 2.41 (SE=1.05, p=.02) and 1-year function by 4.96 (SE=1.17, p=.0001). Post-operativeerative flares were not independent risk factors for pain or function scores.
Conclusion:
Higher disease activity increased risk of worse pain and function one year after arthroplasty, post-operative flares did not.
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