Risk of Treatment Failure in Outpatient Parenteral Antimicrobial Therapy from an Academic Medical Center in Kentucky

Background Outpatient parenteral antimicrobial therapy (OPAT) has many benefits, yet factors contributing to treatment failure are not well understood. This study aimed to identify risk factors for OPAT failure by comparing successful patients to those failing therapy. Methods Adult patients referred and discharged to receive OPAT in the home from August 2019 and May 2021 were included. Patients were excluded if they received OPAT at a nonhome location or had creatinine clearance less than 30 mL/min. Patient demographics, as well as admission-related information, were collected. The primary composite outcome was OPAT failure defined as infection nonresolution or new infection, medication modification, or hospital readmission. Bivariate followed by multivariate analysis was used to identify factors that increased a patient's risk of failing therapy. Additional analysis examined predictors of loss to follow-up. Results Of the 823 patients included, 588 (71.4%) successfully completed therapy with 195 (23.7%) experiencing failure. Forty (4.9%) patients were lost to follow-up. Of the failures, 109 (55.9%) experienced readmission, 63 (32.3%) experienced new or persistent infection, and 23 (11.8%) required therapy modification. Factors associated with failure included infection with vancomycin-resistant Enterococcus (odds ratio [OR]: 4.42, 95% confidence interval [CI] [1.01-19.29]), oxazolidinone treatment (OR: 4.92, 95% CI [1.90-12.82]), and increasing numbers of infusions (OR: 1.16, 95% CI [1.04-1.30]). Patients living further from the clinic were more likely to be lost to follow-up. Conclusions Simplifying home-based antimicrobial regimens may improve OPAT outcomes. Early identification of risk factors for OPAT treatment failure and loss to follow-up can optimize patient management and reduce adverse outcomes.