Infection Control & Hospital Epidemiology

Original Articles

Deriving Measures of Intensive Care Unit Antimicrobial Use from Computerized Pharmacy Data: Methods, Validation, and Overcoming Barriers

David N. Schwartza1 c1, R. Scott Evansa2a3, Bernard C. Caminsa4, Yosef M. Khana5, James F. Lloyda2, Nadine Shehaba6, Kurt Stevensona5 and Centers for Disease Control and Prevention Epicenter Program

a1 John H. Stroger, Jr., Hospital of Cook County and Rush Medical College, Chicago, Illinois

a2 LDS Hospital/Intermountain Healthcare, Salt Lake City, Utah

a3 Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, Utah

a4 Barnes-Jewish Hospital and Washington University School of Medicine, St. Louis, Missouri

a5 Ohio State University Medical Center and College of Medicine, Ohio State University, Columbus, Ohio

a6 Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, Georgia


Objective. To outline methods for deriving and validating intensive care unit (ICU) antimicrobial utilization (AU) measures from computerized data and to describe programming problems that emerged.

Design. Retrospective evaluation of computerized pharmacy and administrative data.

Setting. ICUs from 4 academic medical centers over 36 months.

Interventions. Investigators separately developed and validated programming code to report AU measures in selected ICUs. Use of antibacterial and antifungal drugs for systemic administration was categorized and expressed as antimicrobial-days (each day that each antimicrobial drug was given to each patient) and patient-days receiving antimicrobials (each day that any antimicrobial drug was given to each patient). Monthly rates were compiled and analyzed centrally, with ICU patient-days as the denominator. Results were validated against data collected from manual review of medical records. Frequent discussion among investigators aided identification and correction of programming problems.

Results. AU data were successfully programmed though a reiterative process of computer code revision. After identifying and resolving major programming errors, comparison of computerized patient-level data with data collected by manual review of medical records revealed discrepancies in antimicrobial-days and patient-days receiving antimicrobials that ranged from less than 1% to 17.7%. The hospital from which numerator data were derived from electronic records of medication administration had the least discrepant results.

Conclusions. Computerized AU measures can be derived feasibly, but threats to validity must be sought out and corrected. The magnitude of discrepancies between computerized AU data and a gold standard based on manual review of medical records varies, with electronic records of medication administration providing maximal accuracy.

(Received October 05 2010)

(Accepted November 18 2010)


c1 Division of Infectious Diseases, John H. Stroger, Jr., Hospital of Cook County, 1901 West Harrison Street, Chicago, IL 60612 (