Risk factors for treatment failure in late acute periprosthetic joint infection in patients with rheumatoid arthritis treated with surgical debridement - a case-control study

Background: Patients with rheumatoid arthritis (RA) with late acute periprosthetic joint infections (PJIs) treated with surgical debridement, antibiotics, and implant retention (DAIR) have a high failure rate. We conducted a case-control study to identify risk factors for DAIR failure in this specific patient population. Methods: Data from an international multicenter retrospective observational study were used. Late acute PJI was defined as a sudden and acute onset of PJI symptoms occurring more than 3 months after implantation in a previously asymptomatic joint. Cases with RA were matched with cases without RA based on the affected joint. A multivariate Cox regression, stratified for RA, was used to identify risk factors and calculate hazard ratios (HRs) for failure. Subgroup analysis was done to explore the role of immunosuppressive therapy. Results: A total of 40 patients with RA and 80 control patients without RA were included. The use or continuation of immunosuppressive drugs was not associated with a higher failure rate. No significant association was found between the duration of symptoms, causative microorganisms, and therapy failure. Bacteremia was an independent predictor for treatment failure (HR of 1.972; 95 % confidence interval, CI, of 1.088-3.573; $p$ $=$ 0.025), and the exchange of modular components was associated with a lower risk of treatment failure (HR of 0.491; 95 % CI of 0.259-0.931; $p=0.029$ ). Conclusion: In patients with RA and a late acute PJI treated with DAIR, bacteremia is an important predictor of treatment failure. Exchanging the modular components seems to be especially important in this patient group and is associated with a lower failure rate.