Clinical Outcomes of Piperacillin/Tazobactam Treatment in Outpatient Parenteral Antimicrobial Therapy (OPAT) Programs: Comparison of Two Models of Opat Care

<b>Objectives</b>: Piperacillin/tazobactam (P/T) is a broad-spectrum β-lactam antibiotic frequently used in outpatient parenteral antimicrobial therapy programs (OPAT). We aim to compare the clinical outcomes of P/T treatment in two models of OPAT care in order to maximize the utilization of health resources. <b>Material and methods</b>: We conducted a prospective observational study with retrospective analysis of a cohort of patients treated with P/T delivered every 24 or 48 h in an OPAT program. The primary outcomes were treatment failure during the OPAT episode and 30 day treatment failure. A bivariate and multivariate logistic regression model was built. A two-sided <i>p</i> < 0.05 was considered statistically significant. <b>Results</b>: Between 2012 and 2022, 247 patients were treated with P/T. Treatment was delivered daily in 176 patients (Group 24) and every two days in 71 patients (Group 48). The rate of treatment failure during OPAT in Group 24 and Group 48 was 12.4% (<i>n</i> = 22) and 5.6% (<i>n</i> = 4), respectively (<i>p</i> = 0.112); and the rate of treatment failure 30 days after OPAT treatment end was 18.2% (<i>n</i> = 32) and 21.1% (<i>n</i> = 15) in Group 24 and Group 48, respectively (<i>p</i> = 0.594). Treatment every 24 or 48 h was not associated with higher treatment failure during OPAT or 30 days after finishing OPAT in either bivariate or multivariate analysis. <b>Conclusions</b>: P/T administration in OPAT programs being replaced every two days is feasible without an increase in treatment failure, relapse, or mortality compared to daily drug replacement. These findings should motivate further research to facilitate the implementation of this novel delivery strategy in OPAT programs.