Preoperative Drug Dispensing as Predictor of Surgical Site Infection

Approximately 325,000 surgical site infections occur each year in the United States, generating additional hospital costs in excess of $1 billion (1,2). Surgical site infection is also a major cause of increased hospital stay and death (3-6). Surgical site infection rates are an established measure of quality of clinical care (2,7), and reliable surveillance data are the foundation of effective infection control programs. However, to interpret surgical site infection surveillance rates, an effective risk adjustment system is needed. The National Nosocomial Infections Surveillance (NNIS) program uses a risk adjustment system for surgical site infection that includes three equally weighted variables: wound class, procedure duration, and the American Society of Anesthesiologists (ASA) score (8). The ASA score, a preoperative rating assigned to each patient, is a measure of the patient’s general health status and coexisting conditions (9). Scores range from 1, representing a healthy person, to 5, representing a patient not expected to survive longer than 24 hours. The NNIS risk index assigns one point to patients with an ASA score >3. The ASA score is the only marker of coexisting conditions in the NNIS risk index. Although the ASA score predicts surgical site infection, length of hospital stay, and risk for death (9-11), it is limited as a risk adjustment measure because of its subjectivity and poor inter-rater reliability (12-14). In a study in which 304 anesthesiologists assigned ASA scores to 10 hypothetical patients, the mean number of patients rated identically by the expert panel was 5.9 (13). The range of ASA scores is limited to five potential values; furthermore, there is often limited variation among patients undergoing similar procedures. Finally, the ASA score is not always available or easily accessible. It is typically not assigned for outpatient surgical procedures or procedures not attended by an anesthesiologist. An alternative rating system for coexisting diseases that does not have these limitations is needed. A supplemental or alternative measure of a patient’s underlying risk for surgical site infection is the chronic disease score, a measure Preoperative Drug Dispensing as Predictor of Surgical Site Infection