Background: Outpatient parenteral antimicrobial therapy (OPAT) has become standard of care for numerous severe infections, including osteomyelitis, endocarditis, and bacteremia. Intravenous (IV) beta-lactam therapy is often employed given favorable tolerability profiles. However, beta-lactam-induced neutropenia (BLIN) is a serious complication frequently encountered in the home infusion setting. The mechanism of BLIN is still not well understood. Risk factors from previous studies include high doses and extended treatment durations along with suggestion of IV push administration.
Purpose: The first study aim is to compare BLIN incidence between IV push and intermittent infusion administration among home infusion patients. The second study aim is to evaluate other BLIN risk factors along with Fairview Home Infusion pharmacists’ treatment monitoring and managing adverse drug events. As the healthcare landscape continues to evolve, this exciting area of research represents a critical opportunity for pharmacists to demonstrate their value in the future of home health and transitions of care.
Methods: The proposed study is a single-center, retrospective cohort study of home infusion patients treated with ceftriaxone, cefepime, or cefazolin and seen within the M Health Fairview system between 7/1/2017 and 7/1/2022. These three beta lactams were selected based on incidence of prescribing, adequate volumes of both IV push and infusions, and previously observed rates of neutropenia. Patient-specific risk factors for BLIN will be identified via linear regression analysis. Pharmacist interventions will be categorized and quantified using descriptive statistics.
Results: Table 2. Patient Characteristics at Baseline
Patient grouping patients (n) Age (yr) Baseline ANC ANC Change Total Duration Mean StdDev Mean StdDev Mean StdDev Mean StdDev
Grand Total 225 57 16 8.54 5.14 -3.92 4.88 30.13 11.69
Table 1. primary endpoint preliminary results – incidence of neutropenia in cefazolin patients by route of administration
Route non-neutropenic neutropenic Percent P-value
Infusion (n=46) 42 4 8.7% 0.057
IV Push (n=179) 175 4 2.2%
Grand Total 217 8 3.6%
One-sided P value calculated via Fisher’s Exact Test. NA
Discussion: In an interim analysis, incidence of neutropenia was low (3.6%) and higher for the infusion group (8.7%), which is not statistically significant (one-sided p=0.057). The observed overall incidence of 3.6% is in line with previously literature. Most of the observed neutropenic events occur late in treatment courses. These events often occur after 4 weeks of treatment and some have been observed several days after discontinuation. One confounder to note is age, with a mean of 69 in the infusion group and 54 of the IV push group. This gap is largely due to institutional protocol, whereby Medicare patients are protocolized to receive CADD pumps as opposed to the otherwise more common syringe for IV push. These older Medicare patients make up a substantial portion of the infusion arm of this study. NA
Conclusions: The ability to draw conclusions from this data is limited at this time by a small number of neutropenic events reflected by incomplete data collection. Older age may serve as a significant confounder in the primary analysis. Further explorations of confounders and independent risk factors will be explored via linear regression analysis. This represents critical data in the OPAT space, which will serve to guide antimicrobial selection and route of administration based on patient specific factors. In this way, we hope to optimize home infusion care and better understand this mysterious adverse reaction.NA