Influence of Antibiotic Exposure Intensity on the Risk of Clostridioides difficile Infection

Area of Science:

• Infectious Diseases
• Antimicrobial Stewardship
• Health Services Research

Background:

• Antibiotics are a primary risk factor for Clostridioides difficile infection (CDI).
• Measuring the impact of antimicrobial stewardship on CDI requires a granular assessment of antibiotic therapy intensity.
• Traditional metrics like days of therapy (DOT) may not fully capture the varying risk of CDI associated with different antibiotic agents and treatment durations.

Purpose of the Study:

• To evaluate the association between antibiotic therapy intensity, measured by the antibiotic spectrum index (ASI), and hospital-associated CDI (HA-CDI).
• To determine if ASI provides a more granular measure of risk compared to DOT for informing antimicrobial stewardship interventions.

Main Methods:

• Retrospective cohort study of 35,457 inpatient encounters from January 2018 to March 2020.
• Utilized a marginal Poisson regression model to assess the independent association between ASI and HA-CDI.
• Calculated adjusted relative risks for HA-CDI per unit increase in ASI per antibiotic day.

Main Results:

• Sixty-eight percent of patients received at least one antibiotic.
• An incidence rate of 4.1 HA-CDI cases per 10,000 patient-days was observed.
• Each unit increase in ASI per antibiotic day was independently associated with a 1.09 times higher risk of HA-CDI (Relative Risk = 1.09; 95% CI: 1.06-1.13).

Conclusions:

• The antibiotic spectrum index (ASI) is strongly associated with hospital-associated CDI.
• ASI offers a more granular measure of antibiotic exposure than DOT.
• ASI can be a valuable tool for evaluating the effectiveness of antibiotic stewardship programs in reducing HA-CDI rates.