Clarifying Potential Candidates for Extended Oral Antibiotic Prophylaxis: A Retrospective Analysis of Risk Factors...

Extended oral antibiotic prophylaxis (EOAP) has gained popularity after a study showed an 81% reduction in periprosthetic joint infection (PJI) among "high-risk" patients undergoing total joint arthroplasty (TJA). However, subsequent studies report inconsistent efficacy, particularly in revision TJA (rTJA) where PJI risk is higher. EOAP also conflicts with antibiotic stewardship principles. To optimize EOAP use, consensus on "high-risk" patients is needed. This study determined which preoperative comorbidities from the Inabathula comorbidities (IC) actually increase PJI risk in aseptic rTJA patients.

1995 consecutive aseptic rTJAs (1014 hips, 981 knees) met criteria for retrospective analysis. International Classification of Diseases-10 codes identified IC comorbidities, including autoimmune diseases, smoking, among others. Reoperations for PJI at 90 days and 1 year were recorded. Chi-squared/Fisher's exact tests analyzed associations between IC and PJI. Multivariable logistic regressions evaluated specific comorbidities' contributions to PJI risk.

502 (50%) revision hips and 580 (60%) revision knees had at least 1 IC. Having at least 1 IC did not significantly increase the risk of developing PJI for revision hips. Only body mass index >35 kg/m² (90-day RR = 3.5; P = .011; 1-year RR = 3.0; P = .014) and chronic kidney disease (90-day RR = 4.1; P = .016; 1-year RR = 4.0; P = .006) were the comorbidities significantly associated with developing PJI for revision hip cases. Meanwhile for knees, having at least 1 IC produced a 3.6x-fold increased relative risk for developing PJI at 1 year (P = .010). However, on multivariate analysis, diabetes mellitus was the only comorbidity significantly associated (90-day odds ratio = 3.5; 95% confidence interval [1.3-9.4]; 1-year odds ratio = 3.3; 95% confidence interval [1.4-7.7]) with developing PJI for revision knee cases. In hips and knees, having >3 IC comorbidities conferred the highest odds of PJI.

Although over half of rTJA patients meet IC and could be eligible for EOAP, very few comorbidities significantly confer increased PJI risk. Prospective EOAP studies should consider using indications that are stricter than the IC to avoid unnecessary antibiotic use.