Evaluation of two retrospective active surveillance methods for the detection of nosocomial infection in surgical patients

OBJECTIVE: To compare the sensitivity and specificity of two retrospective active surveillance methods based on review of the medical record and review of the discharge form in identifying nosocomial infection, taking the prospective surveillance method as the reference standard. DESIGN: Blind comparison of three active nosocomial infection surveillance methods. SETTING: Department of General Surgery of a tertiary-care hospital with a referral population of 266,000 people. METHODS: All operated patients admitted to the Department of Surgery for more than 24 hours and discharged from January 1, 1994, to December 31, 1994, were included. Prospective surveillance consisted of daily review of the patient's record during hospitalization Retrospective surveillance consisted of review of the medical record and the discharge form. Sensitivity and specificity of both retrospective methods were calculated. RESULTS: Of the 1,514 patients included in the study, 1,476 (97.5%) were reviewed by means of the retrospective surveillance system. A total of 20, 8, and 4 hours per week was needed for the active prospective system, review of the medical record, and review of the hospital discharge form, respectively. The documented cumulative incidence of nosocomial infection was 21.8% for the prospective system, 19.6% iol review of the medical record, and 12.6% for review of the discharge form. The overall sensitivity of review of the medical record was 88% and of the discharge form 56%, with a specificity of 99%. For review of the medical record, the highest sensitivity was 93%, for urinary tract infections; for review of the discharge form, the highest was 57%, for surgical-wound infection. CONCLUSIONS: The retrospective method of review of the medical record was the most efficient active surveillance strategy in detecting nosocomial infection in surgical patients (Infect Control Hosp Epidemiol 2000;21:24-27).