Impact of multiple concurrent central lines on central-line-associated bloodstream infection rates.

Background: The current methodology for calculating central-line-associated bloodstream infection (CLABSI) rates, used for pay-for-performance measures, does not account for multiple concurrent central lines.
Objective: To compare CLABSI rates using standard National Healthcare Safety Network (NHSN) denominators to rates accounting for multiple concurrent central lines.
Design: Descriptive analysis and retrospective cohort analysis.
Methods: We identified all adult patients with central lines at 2 academic medical centers over an 18-month period. CLABSI rates were calculated for intensive care units (ICUs) and non-ICUs using the standard NHSN methodology and denominator (a patient could only have 1 central-line day for a given patient day) and a modified denominator (number of central lines in 1 patient in 1 day count as number of line days). We also compared characteristics of patients with and without multiple concurrent central lines.
Results: Among 18,521 hospital admissions, there were 156,574 central-line days and 239 CLABSIs (ICU, 105; non-ICU, 134). Our modified denominator reduced CLABSI rates by 25% in ICUs (1.95 vs 1.47 per 1,000 line days) and 6% (1.30 vs 1.22 per 1,000 line days) in non-ICUs. Patients with multiple concurrent central lines were more likely to be in an ICU, to have a longer admission, to have a dialysis catheter, and to have a CLABSI.
Conclusions: Using the number of central lines as the denominator decreased CLABSI rates in ICUs by 25%. The presence of multiple concurrent central lines may be a marker of severity of illness. The risk of CLABSI per lumen of a central line is similar in ICUs compared to wards.