Characterization of Potentially Unsafe Ambulatory Antibiotic Use and Associated Outcomes in an Adult Kidney Transplant Population.

Background: Antibiotics are frequently prescribed to kidney transplant (KTX) recipients in the outpatient setting, but there are limited data assessing the safety and outcomes associated with this practice.

Objective: The primary objective of this study was to describe ambulatory antibiotic prescribing in a large cohort of adult KTX recipients. The secondary objective was to assess the outcomes associated with potentially unsafe antibiotic use in this population.

Methods: National Veterans Health Administration data compiled between 2001 and 2010 were used to conduct a pharmacovigilance assessment of antibiotic prescribing, excluding intravenous agents, antifungals, antivirals, and prophylactic regimens. Multivariable Cox proportional hazard regression was used to determine the impact of safe and potentially unsafe antibiotic use on time to event for graft loss.

Results: Among 5130 KTX recipients and 30 127 patient-years of follow-up, 14 259 antibiotic courses were prescribed at a rate of 0.47 courses per patient-year. Transplant or nephrology providers prescribed 24.8% of courses. Overall, 608 courses (4.3%) in 311 patients (6.1%) were considered potentially unsafe for dosages in disagreement with recommended adjustments for renal function, interaction with immunosuppressive regimens, and other pertinent safety concerns. After adjusting for baseline characteristics, unsafe antibiotic use was associated with a 40% higher risk of graft loss (adjusted hazard ratio = 1.40; 95% CI = 1.03-1.89; P = 0.030) compared with safe use.

Conclusions And Relevance: Although unsafe antibiotic prescribing was uncommon, it was associated with increased risk of graft loss. Prospective research is needed to elucidate whether the driver of poor outcomes is the safety of the antibiotic prescription or fragmented care.