The Randomized Isoflurane and Sevoflurane Comparison in Cardiac Surgery (RISCCS) is a pragmatic randomized non-inferiority comparative effectiveness clinical trial that began in November 2011. From its inception to conclusion in March 2014, the RISCCS study saw participation of 464 adults having coronary artery bypass graft and/or single valve surgery.
With a recruitment number of 464 adults, this is by far the largest RCT devised and performed by Department faculty to date. In addition, this RCT was conducted and completed exclusively at LHSC University Hospital.
In the July 2016 issue of the Canadian Journal of Anesthesia, Drs. Mathis and Kheterpal then discuss the clinical impact of this study in their editorial, "Newer isn’t always better: comparative effectiveness of sevoflurane and isoflurane in cardiac surgery,"
"The direct ramifications of this study are interesting. For instance, the authors suggest potentially saving millions of healthcare dollars per year if anesthesiologists opt to use isoflurane rather than sevoflurane during cardiac surgery. Of greater interest, however, is the fact that this study was just now performed, despite both anesthetics being available for over 20 years in the context of clinical equipoise.
This work highlights that scientific research should not only strive to push the bounds of basic knowledge but also welcome pragmatic studies performed in real-world settings to address daily clinical conundrums." (Mathis, 2016)
Can J Anaesth. 2016 Jul 27. [Epub ahead of print]
PURPOSE: Volatile anesthetics possess cardioprotective properties, but it is unknown if the cardioprotective effects extend equally to all members of the class. Although sevoflurane is a relatively newer anesthetic than isoflurane, its introduction into practice was not preceded by a head-to-head comparison with isoflurane in a trial focusing on clinically important outcomes. Our objective was to determine whether sevoflurane was non-inferior to isoflurane on a clinically important primary outcome in a heterogeneous group of adults undergoing cardiac surgery.
METHODS: This was a pragmatic randomized non-inferiority comparative effectiveness clinical trial in 464 adults having coronary artery bypass graft and/or single valve surgery during November 2011 to March 2014. The intervention was maintenance of anesthesia with sevoflurane (n = 231) or isoflurane (n = 233) administered at a dose of 0.5-2.0 MAC throughout the entire operation. All caregivers were blinded except for the anesthesiologist and perfusionist. The primary outcome was a composite of intensive care unit (ICU) length of stay ≥ 48 hr and all-cause 30-day mortality. We hypothesized that sevoflurane would be non-inferior to isoflurane (non-inferiority margin < 10% based on an expected event rate of 25%). Secondary outcomes included prolonged ICU stay, 30- and 365-day all-cause mortality, inotrope or vasopressor usage, new-onset hemodialysis or atrial fibrillation, stroke, and readmission to the ICU.
RESULTS: No losses to follow-up occurred. The primary outcome occurred in 25% of sevoflurane patients and 30% of isoflurane patients (absolute difference, -5.4%; one-sided 95% confidence interval, 1.4), thus non-inferiority was declared. Sevoflurane was not superior to isoflurane for the primary outcome (P = 0.21) or for any secondary outcomes.
CONCLUSION: Sevoflurane is non-inferior to isoflurane on a composite outcome of prolonged ICU stay and all-cause 30-day mortality. Sevoflurane is not superior to isoflurane on any other of the clinically important outcomes. This trial was registered at clinicaltrials.gov; NCT01477151.
To encourage and further promote research transparency, the authors have ensured that the full-text and anonymized data of the RISCCS study has been published with open access. Open data allows anyone to freely download the RISCCS dataset, reproduce the analyses done by the authors, and also perform additional analyses as they see fit (the original RISCCS authors should be involved as authors when additional analyses based on the data are submitted for publication). Open data promotes transparency at a time when questionable or fraudulent research is at an all-time high.