Revisiting the VA MRSA Initiative

Most of our readers know about the VA MRSA Initiative, the results of which were published in the NEJM at the same time as the STAR*ICU study results. These two studies were widely and mistakenly viewed as having contradictory results.

The tremendous success of the VA initiative (see here for my earlier summary of the results) was also mistakenly assumed to be primarily related to the most expensive aspect of the “bundled” initiative, universal active detection and isolation (ADI). This was despite the fact that transmission fell only by 17-21% while infection rates fell by over 60% in ICUs, and infection rates due to non-targeted bugs (VRE and C. difficile) were reduced even more dramatically than was MRSA. In other words, there was plenty in the original paper to suggest that ADI accounted for very little of the observed MRSA infection reduction, and that the bulk of that reduction was due instead to prevention of MRSA infection among those already colonized.

Well, we now have a mathematical model, by Gurieva, Bootsma and Bonten, that demonstrates this point quite clearly. I refer you to their paper and to my colleague Eli’s excellent commentary for details, but the bottom line: transmission prevention was likely responsible for no more than 6% of the reduction in MRSA infection rate. As you’d expect, the proportion of infection reduction due to transmission prevention is strongly correlated to the relative risk for MRSA infection among the newly colonized (via transmission) versus existing MRSA carriers. But as the figure below (from Gurieva paper) shows, even if one assumes a 10-fold higher daily risk for MRSA infection among newly colonized versus existing colonized, transmission prevention would still account for less than a quarter of the observed infection reduction


  1. This is another potential reason for the CLABSI drop. This contract was eventually established, which increased the use of BioPatch in VA Medical Centers. The degree of increase is not documented, but there's reason to think it was sigificant.


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