The STS AVR composite measure uses the same basic statistical approach as in the CABG model with several modifications that reflect the differences between isolated CABG and isolated AVR populations. The AVR composite includes two outcomes domains, risk-adjusted mortality and risk-adjusted morbidity, which includes the same complications as the CABG composite (i.e., reoperation, stroke, kidney failure, infection of the chest wound, or prolonged need to be supported by a breathing machine, or ventilator). However, as there is nothing comparable to the use of the internal mammary artery in valve surgery, and because appropriate medications are less well-defined for valve procedures, these two process domains are not included. In addition, due to the smaller number of AVR patients compared with CABG, a 95% Bayesian credible interval for star rating determination and a data collection period of 3 years (rolling) are used.

STS Public Reporting Online lists participants’ scores for each separate domain as well as the STS AVR overall composite score. As in the CABG composite, numerical scores and star ratings are provided. The star rating calculation again begins by assuming all providers are average and then determines statistically if there is at least a 97.5 percent probability that the performance of any specific provider is lower than average (one star) or higher than average (three star). Otherwise, the participant receives two stars.