Thursday, August 26, 2010

Daily chlorhexidine in SICU for CLABSI prevention? Not so much.

A nice report is out in Intensive Care Medicine by Kyle Popovich and collegues from Rush University Medical Center in Chicago. In the RUMC SICU the clinicians decided to start using 2% CHG-impregnated clothes in Fall 2005.  The investigators analyzed CLABSI rates using the time-series data in the before period (Sept 2004-October 2005) and after period (November 2005 - October 2006). 

They found no significant difference in the CLABSI rate after the introduction of CHG clothes (3.81/ 1,000 central line days vs. 4.6/1,000 central line days; p = 0.57). A couple things to note.  The first is that they did a great job identifying their study as a quasi-experimental study and using Poisson regression and segmented regression analyses. They reported the Poisson-regression results after segmented regression did not identify changes in slope or intercept around the time of the CHG cloth introduction.  Nice job!  They also used C. diff, BSI, VAP and UTI rates as "control" variables, as they are thought not to be reduced with CHG bathing.  These 'control' variables are called 'non-equivalent dependent variables' and inclusion of these types of "outcomes" improves the internal validity of quasi-experimental studies since they typically would be reduced by other infection prevention interventions but not the intervention under study. Thus, they help rule out the impact of concurrent interventions that could have biased the study findings.

Previous studies, which were also mostly quasi-experimental studies but in MICUs, have found reduced CLABSIs with CHG.  It's great that the authors spent the time writing up and publishing these results and the journal should also be commended.  There's nothing worse than publication bias; negative studies are just as important as positive ones, even if they make decision making more difficult.  The authors concluded that they would not recommend routine use of CHG baths in SICUs; I would recommend further study.

Popovich, et al. Intensive Care Medicine

2 comments:

  1. So their previous study in MICUs:
    Infect Control Hosp Epidemiol. 2009 Oct;30(10):959-63.
    Showed a large effect of CHG baths. It seems that the adjustments were similar.

    Can the SICU/MICU distinction explain most of the difference, or is this all noise? In the MICU paper, CLABSI went to zero after CHG use.

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  2. Good question. First, it's hard to conclude anything from a few quasi-experimental single ICU trials. Second, if we are forced to conclude something, I wonder if there are two things going on in the SICU study. Since SICU patients often have GI issues, I wonder if the NHSN definitions of CLABSI aren't specific enough to rule-out secondary (gut-related) BSI. I also noticed that there was a pathogen shift in the CHG period to yeast and GNR, which perhaps MICU patients are less susceptible to, or perhaps they just represent the secondary BSIs I was worried about. I suspect the CHG would have the biggest effect on the GPC like coag neg staph, which is what they found in this SICU study.

    I emailed the authors, so perhaps they will post a comment.

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