title: Effect of accounting for multiple concurrent catheters on central line-associated bloodstream infection rates: practical data supporting a theoretical concern.
abstract: BACKGROUND
  Central line-associated bloodstream infection (CLABSI) rates are gaining importance as they become publicly reported metrics and potential pay-for-performance indicators. However, the current conventional method by which they are calculated may be misleading and unfairly penalize high-acuity care settings, where patients often have multiple concurrent central venous catheters (CVCs).
  
  
  OBJECTIVE
  We compared the conventional method of calculating CLABSI rates, in which the number of catheter-days is used (1 patient with n catheters for 1 day has 1 catheter-day), with a new method that accounts for multiple concurrent catheters (1 patient with n catheters for 1 day has n catheter-days), to determine whether the difference appreciably changes the estimated CLABSI rate.
  
  
  METHODS
  Cross-sectional survey.
  
  
  METHODS
  Academic, tertiary care hospital.
  
  
  METHODS
  Adult patients who were consecutively admitted from June 10 through July 9, 2009, to a cardiac-surgical intensive care unit and a surgical intensive and surgical intermediate care unit.
  
  
  RESULTS
  Using the conventional method, we counted 485 catheter-days throughout the study period, with a daily mean of 18.6 catheter-days (95% confidence interval, 17.2-20.0 catheter-days) in the 2 intensive care units. In contrast, the new method identified 745 catheter-days, with a daily mean of 27.5 catheter-days (95% confidence interval, 25.6-30.3) in the 2 intensive care units. The difference was statistically significant (P < .001). The new method that accounted for multiple concurrent CVCs resulted in a 53.6% increase in the number of catheter-days; this increased denominator decreases the calculated CLABSI rate by 36%.
  
  
  CONCLUSIONS
  The undercounting of catheter-days for patients with multiple concurrent CVCs that occurs when the conventional method of calculating CLABSI rates is used inflates the CLABSI rate for care settings that have a high CVC burden and may not adjust for underlying medical illness. Additional research is needed to validate and generalize our findings.
authors: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-7294, USA. raslaks1@jhmi.edu
authors: Rebecca A
authors: RA
authors: Aslakson
authors: Mark
authors: M
authors: Romig
authors: Samuel M
authors: SM
authors: Galvagno
authors: Elizabeth
authors: E
authors: Colantuoni
authors: Sara E
authors: SE
authors: Cosgrove
authors: Trish M
authors: TM
authors: Perl
authors: Peter J
authors: PJ
authors: Pronovost
mesh_terms: D000046:Academic Medical Centers; D015142:Baltimore / Q000453:epidemiology; D057785:Catheters / Q000382:microbiology / Q000706:statistics & numerical data*; D003428:Cross Infection / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000379:methods*; D004866:Equipment Contamination / Q000706:statistics & numerical data*; D006302:Health Services Research; D006801:Humans; D007362:Intensive Care Units; D011787:Quality of Health Care; D018805:Sepsis / Q000453:epidemiology / Q000209:etiology