RATES OF PERIPROSTHETIC JOINT INFECTION FOLLOWING ASEPTIC REVISION TOTAL HIP ARTHROPLASTY ARE NOT REDUCED WITH EXTENDED ORAL ANTIBIOTIC PROPHYLAXIS

INTRODUCTION & AIMS Use of extended oral antibiotic prophylaxis (EOAP) following total hip arthroplasty (THA) has increased despite mixed evidence and no national guidelines. Since revision THA (rTHA) carries increased periprosthetic joint infection (PJI) risk, EOAP use in this setting is particularly relevant. We evaluated postoperative infectious outcomes following rTHA with and without EOAP. METHODS Patients undergoing initial aseptic rTHA were identified in the 2010-2023 Q1 PearlDiver database. Those who received EOAP, defined as postoperative oral antibiotic use >1 day and <2 weeks, were identified. To avoid antibiotic prescriptions for other indications, patients with non-hip infections during the first postoperative week were excluded. EOAP patients were matched 1:4 to controls based on age, sex, and Elixhauser Comorbidity Index (ECI). Median follow-up was 3.74 years in the EOA cohort, and 5.66 years in the no-EOA cohort. Other comorbidities controlled for as covariates included: smoking, BMI≥35kg/m2, chronic kidney disease, autoimmune conditions, and diabetes. The primary endpoint was PJI, with time-to-event analysis performed using Cox regression. Outcomes were assessed at sequential intervals through five-years. Rates of other postoperative infections, emergency department visits and hospital readmissions occurring between 7-90 days were evaluated using multivariable regression. Significance defined as P<0.05. RESULTS After matching, 2,195 EOAP patients were compared to 8,745 control patients. EOAP was not associated with reduced hazard of PJI following 90 days (Hazard ratio [HR]=0.95), 6 months (HR=1.01), 1 year (HR=0.98), 2 years (HR=1.02), or 5 years (HR=0.97) postoperatively (all p>0.05). EOAP patients had lower adjusted odds of experiencing a urinary tract infection (UTI, odds ratio [OR]=0.70, p=0.015) and readmission (OR=0.74, p<0.001) between 7-90 days, without increased odds of C. difficile colitis. CONCLUSION EOAP following aseptic rTHA was not associated with reduced risk of PJI over 5 years. Nonetheless, its use correlated with lower odds of UTI and readmission, suggesting possible alternate short-term benefits