Safety of prolonged outpatient courses of intravenous antibiotics: a prospective cohort study

Objectives: The perceived need for prolonged intravenous antibiotic courses has become a major driver behind the growth of outpatient parenteral antimicrobial therapy (OPAT) services. Several recent randomized controlled trials demonstrate noninferiority of an early switch to oral therapy and highlight the need to accurately quantify harms associated with OPAT.

Methods: We conducted a 10-year prospective cohort study in a tertiary hospital OPAT service. Adults admitted to the service between 1 June 2009 and 30 June 2019 who received an intravenous antimicrobial agent were included. Adverse events (AEs) attributable to intravenous antibiotics or intravenous access were recorded in a prospectively maintained database and analyzed.

Results: There were 4160 admissions (median length of stay: 20 days) and a total of 88 432 patient-days of observation; 135 patients (3.3% of admissions) experienced at least one major AE (1.54 per 1000 patient-days; 95% CI, 1.29-1.82). The risk of a major AE peaked in the second week of OPAT admission, with acute kidney injury (43 of 136; 32%) and severe cytopenia (42 of 136; 31%) being the most common. At least one minor AE occurred in 38.3% of admissions (1592 of 4160; 26.4 per 1000 patient-days; 95% CI, 25.4-27.5), with central venous catheter-related complications accounting for 71% of AEs (1658 of 2338).

Discussion: The incidence of major AEs during long courses of intravenous antibiotics is low, peaking in week 2 and tailing off thereafter. These results should inform decisions concerning the choice of intravenous versus oral antimicrobials.