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How to Track and Report Antibiotic Use and Outcomes in an Antimicrobial Stewardship Program

To be effective, an antimicrobial stewardship program (ASP) must include metrics that permit reporting on antibiotic use. The Centers for Disease Control and Prevention (CDC) recommends that hospitals incorporate three measurement components into their antimicrobial stewardship programs 1:

Process Adoption

Encouraging prescribers to use antibiotics appropriately is a central goal of antimicrobial stewardship (AMS). Consequently, most programs implement a variety of policies that guide providers to carefully consider whether, when and which antibiotics are appropriate in a given situation. These guidelines may include: when to initiate treatment with antibiotics; documentation of dose, duration and indication; adoption of antibiotic time outs after 48 hours without laboratory confirmation of bacterial infection; and preferred drug/bug matches. Hospitals can use antibiotic audit tools developed by the CDC to review adherence to these policies.

A successful antimicrobial stewardship program depends on changing clinician behavior through prompt feedback on prescribing practices, so hospitals will also want to measure the number of interventions made and the acceptance rate for interventions by prescribers over time.

Antibiotic Use

Hospitals use two metrics to capture overall antibiotic use over time:

  • Days of therapy (DOT) aggregates the number of days for which any antimicrobial is prescribed, times the number of antimicrobials prescribed for each patient (numerator) divided by a denominator such as patient days, length of stay or admissions.

  • Defined daily dose (DDD) measures a hospital’s use of an individual antibiotic against the assumed average daily maintenance dose for adults on that drug as set by the World Health Organization (WHO). By their nature, defined daily dose measures work poorly for pediatric populations and patients with renal impairment or other conditions that affect the recommended dose, though they can still provide an indication of antibiotic use over time.

Hospitals frequently implement more specific measures as well, including those targeting particular antibiotics and hospital wards.


Antimicrobial stewardship programs don’t just reduce or alter antibiotic usage. High-performing programs also improve patient and community health and reduce costs.

  • Rates of Clostridium difficile (C. dif.) infections typically drop following introduction of an ASP. As most hospitals already report C. diff. infection rates to the NHSN as part of the Centers of Medicare and Medicaid Services Hospital Inpatient Quality Reporting Program, it’s easy to include these rates in AMS outcome reports for internal use.

  • Tracking the number of patients who develop multidrug resistant infections following admission also makes sense, as the rate of these super-infections tends to drop as antimicrobial stewardship efforts increase.

  • Hospitals typically see significant savings in pharmacy costs when antimicrobial stewardship programs first come online. Other costs, such as unreimbursed care for healthcare associated infections, also decline. Tracking these savings may increase support for ASPs among hospital leadership. Over time, the savings tend to stabilize, but they can increase markedly if antimicrobial stewardship efforts later lag.

Do you use different metrics at your hospital? What else would you measure to determine the success of your antimicrobial stewardship program? Let us know in the comments below.

1 Core Elements of Hospital Antibiotic Stewardship Programs. Get Smart for Healthcare. CDC. March 4, 2014.

Track and report antibiotic use and outcomes with this checklist.

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