Usefulness of Routine Laboratory Tests for Follow up of Patients Receiving Outpatient Parenteral Antimicrobial Therapy Run by Infectious Diseases Fellows

Abstract

Background: The infectious disease society of America (IDSA) recommends routine laboratory tests for all patients receiving outpatient parenteral antimicrobial therapy (OPAT) to monitor for adverse events. There are no data to support how often patients should take monitoring laboratory tests. In addition, the relevance of different laboratory tests commonly used for OPAT follow up is not clearly known. Methods: We conducted a retrospective observational cohort study over a 7-year study interval (1 January 2014 to 31 December 2021). Clinical data were obtained to identify the risk factors associated with abnormal laboratory tests and determine if abnormal laboratory tests led to antibiotic change or hospital readmission. Results: Two hundred and forty-six patients met the inclusion criteria for this study. In our multivariate analysis, the Charlson comorbidity index (CCI) of 0–4 (aOR 0.39, 95%Cl 0.18–0.86), the use of ceftriaxone without vancomycin (aOR 0.47, 95%Cl 0.24–0.91) and an OPAT duration of 2–4 weeks (aOR 0.47, 95%Cl 0.24–0.91) were associated with a lower risk of OPAT complications. A CCI of 5 or more (aOR 2.5, 95%Cl (1.1–5.7)) and an OPAT duration of 5 or more weeks (aOR 2.7, 95% Cl 1.3–5.6) were associated with a higher risk of OPAT complications. An abnormal complete metabolic panel or vancomycin levels, but not an abnormal complete blood count, were associated with antibiotic change or readmission. Conclusion: Patients with fewer comorbidities, ceftriaxone and short OPAT durations are at lower risk for OPAT complications. These patients could be followed with less frequent laboratory monitoring.

Serious Adverse Events and Laboratory Monitoring Regimens for Outpatient Parenteral Antimicrobial Therapy With Cefazolin and Ceftriaxone

“…Our results confirm previous studies regarding time to abnormal lab–associated OPAT-AEs [ 8 , 10 , 11 ]. Lam et al reported changing their institutional laboratory monitoring policy for patients receiving nonvancomycin OPAT to 1 set of labs at week 3 of therapy because they found that this corresponded to the highest-risk period for delayed-onset hypersensitivity reactions [ 11 ].…”

“…However, this study specifically assessed neutropenia and not other potential abnormal lab–associated OPAT-AEs. Additionally, Frisby et al confirmed that an OPAT duration of 2–4 weeks was associated with lower risk of OPAT-related complications [ 10 ]. However, they included antimicrobials with known higher incidence of AEs in comparison with beta-lactams.…”

“…Zukauckas et al reviewed OPAT patients prescribed beta-lactams and found that while 52% had abnormal laboratory findings, only 5.7% of these abnormal laboratory findings led to an antimicrobial therapy modification [ 8 ]. Beyond this work and a recent retrospective cohort study assessing laboratory monitoring for all antibiotics administered via OPAT [ 10 ], little is known about the cadence of laboratory monitoring necessary to prevent AEs in patients receiving beta-lactams via OPAT. As cefazolin and ceftriaxone comprise a large percentage of overall OPAT utilization, more rigorous and directed evaluation of the necessary monitoring for these agents would be valuable.…”