Objective: To determine the attributable mortality and the excess length of hospital stay resulting from coagulase-negative staphylococcal bacteremia.
Design: Matched historical cohort study.
Setting: Large university-based tertiary care center.
Patients: Of 171 patients with hospital-acquired coagulase-negative staphylococcal bacteremia identified by prospective surveillance of nosocomial infections from 1 July 1984 to 30 June 1987, 118 met criteria for the study and were matched to a control patient by age, sex, primary diagnoses, operative procedures, and date of admission.
Measurements and results: Success was achieved in 621 of 650 (96%) variables used for matching. Staphylococcus epidermidis accounted for 92% of the bacteremias. Twenty cases (17%) had evidence of septic shock, and 10 had disseminated intravascular coagulation. The mortality rate in cases was 36 of 118 (30.5%) compared with 20 of 118 (16.9%) in controls. The attributable mortality was 13.6% (95% CI, 4.2 to 22.9) and the risk ratio for dying was 1.8 (95% CI, 1.2 to 2.7; P = 0.006). The median length of stay was 46 days for cases and 37.5 for controls (P = 0.0002).
Conclusions: Coagulase-negative staphylococci, the leading organisms causing hospital-acquired bacteremias, are associated with mortality in excess of that due to the underlying diseases alone. Moreover, they significantly prolong the length of hospital stay. These findings show the importance of coagulase-negative staphylococcal bacteremia in hospitalized patients.