Surgical-site infection rates in patients who undergo elective surgery on the same day as their hospital admission

OBJECTIVE: To follow over time surgical-site infection (SSI) rates in patients admitted to the hospital on the same day as their elective surgery (group I), and to compare these rates with those of other surgical patients who also required postoperative hospitalization but either were hospitalized for 1 or more days immediately prior to surgery or underwent surgery on a nonelective basis (group II). DESIGN: Observation of overall SSI rates over time for group I and II patients and study of risk factors associated with increased SSI rate among group I neurosurgical patients. SETTING: A 900-bed, tertiary-care community hospital with >10,000 surgical procedures performed each year on patients requiring postoperative hospital stay. PATIENTS: A total of 48,464 surgical procedures were performed on consecutive patients from 1990 to 1994, with 18,794 (39%) involving group I patients. In addition, 511 consecutive procedures performed on neurosurgical patients requiring postoperative hospitalization from July 1994 to May 1995 were analyzed. RESULTS: In 1990, the overall SSI rate of group I patients was significantly lower than that of group II patients (0.4% vs 1.3%, relative risk [RR], 3.6; 95% confidence interval [CI95], 2-6.4; P<.0001), but, by 1994, there was no longer any significant difference between the SSI rates of group I and II patients (1.8% and 1.6%, respectively; P=.38). In 1994, the SSI rate in group I neurosurgical patients was significantly greater than that of group II patients 3.4% vs 0.4%; RR, 8.3; CI95, 1.05-66; P=.02). During the period April through September 1994 (warm months), group I neurosurgical patients were associated with a significantly lower American Society of Anesthesiologists score and SSI risk index (based on National Nosocomial Infection Surveillance System data) and a higher likelihood of having "clean-class" wounds, but significantly greater-than-expected SSI rate when adjusted for patient risk index and type of procedure (4.7% vs 1.4%; RR, 3.3; CI95, 1.3-8.6; P=.02). During the same period, the observed and expected SSI rates were not significantly different for group II neurosurgical patients. CONCLUSIONS: As a whole, the SSI rates among patients undergoing elective surgery on the same day of their hospital admission is no longer significantly lower than that of other patients who also require postoperative hospitalization. For certain procedures, such as those commonly performed on the neurosurgical service, elimination of preoperative hospital stay may be associated with greater-than-expected risk of SSI.