A surgical site infection enhancement bundle?

A new paper in the Archives of Surgery evaluated the implementation of a surgical site infection (SSI) prevention bundle for colon surgery (see free text of the paper here). The bundle contained the following components:

• Omission of mechanical bowel preparation
• Preoperative and intraoperative patient warming
• Increased concentration of inspired oxygen during and immediately after the surgical procedure
• Limiting intraoperative intravenous fluid volumes
• Use of wound barriers to protect the surgical wound from contamination during the procedure 

Each component of the bundle was supported by 1 or more randomized trials demonstrating reduction in SSIs. About 200 patients were randomized to receive either the bundle or standard care. SSIs were determined by IPs using CDC case definitions. The study was terminated after a planned interim analysis revealed a <1% chance of showing a positive effect of the bundle were the study to continue to the accrual goal.

The overall rate of infection was 35%. In the control group, 24% of patients developed an SSI vs. 45% in the intervention group (p .003). In multivariate analysis, the bundle was shown to an independent predictor for SSI (RR 2.49, CI95 1.36-4.56).

I was struck by the very high rate of infection in this study, so I looked at CDC's most recent surveillance report, which shows that the mean pooled infection rates for colon surgery depending on risk category ranges from 3.99% to 9.47%. The authors postulate that their case ascertainment may be greater since the study was performed at a VA hospital where outpatient follow-up of patients is much easier to track. However, even in light of that, the rate still seems quite high. But on the other hand, unless there is something very unique about these patients or the care provided at this hospital, you might think that an effective prevention bundle would have even more impact in a setting with exceedingly high infection rates. This raises more concern that the bundle was not just ineffective but actually increased the risk of post-operative infection.

This paper is another example of how immature implementation science remains. I think the authors of this paper are correct to conclude that bundles of evidence-based interventions need to be formally tested before there is wide spread implementation.