PICO Versus Standard Dressing on Groin Incisions After Vascular Surgery - a Prospective Randomized Trial (INVIPS Trial)

As published in the study´s rational and design paper (DOI: 10.4236/ss.2015.612080), we conducted a reanalysis of the material that the original power calculation was based on and included elective cases only which led to a slightly different number of cases needed. Furthermore, it became clear that there were big differences in the infection rates of EVAR (endovascular aortic repair) and open vascular procedures and therefore the need to split the study into two arms, an EVAR arm and an OPEN arm.

To prove a significant effect of the treatment intervention in the EVAR arm with a wound infection rate reduction from previously 4.4% to 1%, 80% power, 5% significance level and Including a margin for loss to follow-up, the EVAR arm requires 497 inguinal incisions. Assuming a surgical site infection rate reduction from 30% to 10% in the OPEN arm of the study, 80% power and 5% significance level, a total of 147 inguinal incisions is required.

We conducted an unannounced interim analysis for a conference presentation that was conducted by the study's principal investigators Stefan Acosta and Julien Hasselmann. Staff in charge of the day-to-day activities of the trial were not involved or actively informed of this. We believe that using an objective wound assessment tool (ASEPSIS score) minimizes any potential bias associated with the interim analysis.

Since the vascular center Malmö has started using closure-devices for almost all EVAR cases and thereby creating virtually no wounds to assess, we have started a multi center extension of the EVAR arm to Örebro University Hospital to be able to include the outstanding cases.

FUNDING