Extended Oral Antibiotic Prophylaxis and Periprosthetic Joint Infection-Free Survivorship After Primary Total Hip Arthroplasty.

Background: Several studies have presented findings in favor of using extended oral antibiotic (EOA) prophylaxis to reduce periprosthetic joint infection (PJI) after primary total hip arthroplasty (THA) in patients at high risk for infection. To date, there is a paucity of evidence examining this topic from large retrospective databases. This study explored 90-day complication rates and 2-year PJI-free survivorship in a large cohort of patients receiving EOA prophylaxis after primary THA. Methods: A large national database was used to identify patients undergoing primary THA from 2009 to 2022. Patients receiving 7-14 days of EOA were identified and propensity score-matched based on comorbidities to controls not receiving EOA and subsequently stratified into any-risk, high-risk, and standard-risk cohorts based on infection-related risk factors. Complication rates at 90 days were examined, and 2-year PJI-free survivorship was assessed employing Kaplan-Meier curves and Cox regression analysis further adjusting for comorbidity status. Results: A total of 4153 patients receiving EOA prophylaxis after THA were identified. Of those patients, 2154 (52%) were considered high risk for PJI, while 1999 (48%) were considered standard risk. Significant reduction in hazards of PJI with administration of EOA was not seen at 90 days (any-risk: hazard risk [HR]: 0.75, 95% confidence interval [CI]: 0.42-1.35, Conclusions: No significant increase in PJI-free survivorship at 90 days, 1 year, or 2 years was seen with EOA prophylaxis following primary THA. Reported PJI rates were low across all cohorts, irrespective of baseline risk. Further evidence is needed to adjudicate the efficacy of EOA prophylaxis after THA in addition to possible risks and appropriate indications for use.