Considering "Trifecta" as a Single Outcome when Comparing Robotic With Open Partial Nephrectomy: A Mathematical Model of Volume Conservation and Systematic Review

Trifecta represents a composite outcome reflecting the quality level of treatment in nephron sparing surgery. However, there is substantial heterogeneity concerning the criteria required for its fulfilment. The present study aimed to highlight the potential of a unified view for the different definitions of trifecta when comparing robotic and open approaches in partial nephrectomy. A systematic literature search was carried out for all relevant comparative studies published until April 2022. Trifecta definitions were clustered according to two criteria for postoperative renal function reduction. The first set as an upper limit the 10% decrease in the estimated glomerular filtration rate, while the second set as an upper limit 25 min of ischemia. To mathematically investigate the point of intersection between the above two groups, a suitable model of volume conservation equations was formulated. A total of 11 studies were investigated for their methodological features and grouped accordingly. The ischemic zone volume surrounding the tumor resection site emerged as the central parameter connecting the two main definitions. Specifically, for patients with solitary renal masses, a given change in the value of one parameter resulted in a fixed change in the value of the other. The two main definitions of the "trifecta outcome" extracted from the international literature represent the two sides of the same coin. Thus, trifecta achievement rates could be utilized by future studies as aggregate data to yield a quantitative estimate of the comparative effect between robotic and open approaches in partial nephrectomy procedures.