Comparison of antimicrobial utilization metrics: Food for thought for an antimicrobial stewardship programme

•It is vital for antimicrobial stewardship programmes to measure and assess the use of antimicrobials.•Commonly used metrics are days of therapy (DOT), defined daily doses (DDD) and standardized antimicrobial administration ratio (SAAR).•DOT is the preferred antimicrobial use metric over DDD.•SAAR helps to compare an institution's use of antimicrobials with the national benchmark.•None of these metrics provide insights into antimicrobial appropriateness. Given the overuse of antimicrobials and increasing antimicrobial resistance, the World Health Organization and Centers for Disease Control and Prevention recommend antimicrobial stewardship programmes to measure and assess the use of antimicrobials. Several antimicrobial use metrics have been described, including days of therapy, defined daily doses and standardized antimicrobial administration ratio. Understanding these metrics, including the advantages and disadvantages, can help antimicrobial stewardship programmes to monitor antimicrobial use at their institution, and assess the impact of antimicrobial stewardship efforts. This review discusses the three commonly used antimicrobial use metrics, their pros and cons, and how antimicrobial stewardship programmes can use these metrics to help assess the use of antimicrobials.