Comparison of Rates of Central Line Associated Bloodstream Infections (CLABSI) in Pediatric ICUs using NHSN definitions pre-2008 and as of 1/1/08

Background:  As of 1/1/08, NHSN modified the CLABSI surveillance definition to require at least 2 positive blood cultures with the same organism for common skin contaminants.

Objective: To determine the effect of the change in the definition on the Pediatric ICU CLABSI rates at Children’s Medical Center Dallas in 2008.

Methods: All positive blood cultures from 2 PICUs (C11-trauma; C12-medical-surgical), 1 CICU (cardiac surgery), and 1 NICU (Level II-III, outborn) were identified by prospective laboratory-based surveillance. Medical record review was performed to determine if culture results met definition of CLABSI using both pre-2008 and new 2008 definitions. Rates were calculated for each unit according to NHSN methodology (# CLABSIs/# central line days x 1000).  The number and rates of CLABSIs determined by each definition were compared by the Fisher Exact test.

Results: The number and rates of CLABSI and the device utilization ratios for the 4 ICUs are presented in the table.

	CICU (Cardiac)	C11 (Trauma)	C12 (Med-Surg)	NICU-CVC (Level II-III, outborn)	NICU-UC (Level II-III, outborn)	Total # CLA-BSIs
Pre-2008	7.7 (31/4037)	6.0 (9/1502)	4.3 (17/3935)	6.9 (11/1603)	4.2 (1/237)	69
As of 1/1/2008	5.9 (24/4037)	4.7 (7/1502)	2.5 (10/3935)	6.2 (10/1603)	0    (0/237)	51
Device Utilization Ratio	.87 (4037/4652)	.48 (1502/3113)	.63 (3935/6278)	.36 (1603/4501)	.05 (237/4501)	NA

Using the new definition established on 1/1/08, only 73% of the CLA-BSIs defined by the pre-2008 definition met surveillance criteria.  The differences were most notable in the Cardiac Intensive Care and Medical-Surgical Pediatric Intensive Care units, the units with the largest number of central line days, but differences were not significant statistically. The 18 episodes that did not meet the new criteria were likely contaminants treated by clinicians. 2-5 cultures were drawn for each of 13 (72%) episodes. Median time to positivity for the 18 episodes was 30 hrs. (range 10-87) with only 3 cultures positive at < 24 hrs. For 1 episode, 3 of 3 cultures were positive for coagulase negative staphylococcus at 10, 33, 87 hrs., but susceptibilities and species did not match.

Conclusions: The change in NHSN CLABSI definition eliminates contaminants and is an improvement. Although the differences were not significant, caution is advised when comparing CLABSI rates from before 2008 with those calculated using the new 2008 defintion to assess effectiveness of interventions because lower rates in 2008 may reflect exclusion of contaminants rather than a true reduction in CLABSI.