Limitations and Strengths
POSTOPERATIVE COMPLICATIONS
One limitation of the trial is the use of the EuroSCORE II as part of the inclusion criteria to identify patients at increased risk for postoperative complications. The inaccuracy of the EuroSCORE II for cardiac surgery preoperative risk assessment is demonstrated in the discordance between the observed and predicted EuroSCORE II.A second limitation is that our population is predominantly male. Biosynthesis of selenoenzymes and selenoproteins is sex specific in a dose-dependent manner.The strengths of this study include its robust scientific methods and high-fidelity implementation, the randomized and blinded design, rigorous determination of selenium laboratory analyses, and intent-to-treat analysis, all of which augment the internal validity of the trial. The high rate of adherence to trial interventions, large number of patients, and enrollment in ICUs in Canada and Germany underline the high degree of precision and external validity.