Background/Purpose:   Studies have shown rheumatoid arthritis (RA) to be a risk factor for development of prosthetic joint infections (PJI) and for worse outcome from PJI compared to non-RA patients, but these findings may not be generalizable to the U.S. veterans. Thus, we aimed to evaluate the risk for recurrence of PJI in RA patients compared with non-RA patients among the veteran population.

Methods:   We conducted a retrospective cohort study of all patients admitted for a S. aureus PJI and undergoing surgical intervention between 2003 and 2010 at 123 Veterans Affairs Medical Centers (VAMCs). RA was the exposure of interest, identified using the ICD9 code 714.0, and the outcome was recurrent PJI. Co-variates studied were age, sex, methicillin resistance status of staphylococcal aureus, site of PJI, time to recurrence of PJI, co-morbidities (i.e., hypertension, diabetes, renal disease, Charlson comorbidity score), steroid use and the type of surgical intervention done for the index PJI. T-test was used to compare continuous variables; Chi-square or Fisher exact test was used to compare dichotomous variables among the RA and non-RA groups. Cox proportional hazards regression model was used to compare the time to recurrent PJI for the RA versus non-RA group.

Results:   Of the 731 veterans in our cohort who had a revision surgery for their first S.aureus PJI, 91 (12.4%) had RA. PJI patients with RA tended to be older than PJI patients without RA (mean years: 67.6 vs. 65.1, p=0.03). The two groups did not differ based on the time to their first PJI after arthroplasty. The RA patients had a significantly higher prevalence of hypertension. The prevalence of diabetes and renal disease and the Charlson Comorbidity score were similar among the two groups. RA patients tended to have a lower risk for recurrence of PJI compared with non-RA patients; however, this association was not statistically significant (HR=0.78, 95% CI 0.5-1.2, p=0.27). Infection with methicillin-resistant S.aureus (MRSA) carried an increased risk of recurrent PJI (HR=1.36, 95% CI 1.03-1.80) compared with MSSA. Two-stage exchange surgery was associated with a lower recurrence rate compared with debridement, antibiotics and implant retention (HR=0.35, 95% CI 0.23-0.53, p<0.001).

Conclusion:   : MRSA PJI and the type of surgical intervention were the main predictors of recurrent PJI in a national cohort of veterans with S. aureus PJI treated with surgical modality. Our study results are in keeping with reports that two-stage prosthesis revision offers the best chance for recurrence-free 2-year outcomes following PJI. In contrast, our results did not find RA to be a risk factor for worse disease outcome or increased PJI. The strength of our study is the identification of a large cohort of veterans with S. aureus PJI with a validated outcome of recurrence. The small number of female patients and the possible higher co-morbidity inherent in our cohort are limitations that affect the generalizability of our findings to non-veteran populations. To summarize, prior RA diagnosis was not associated with recurrence of S. aureus PJI compared with non-RA patients in the veteran population.  

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prosthetic-joint-infection-with-staphylococcus-aureus-recurrence-after-surgical-treatment-in-u-s-veterans-with-and-without-rheumatoid-arthritis/