Background and aims To determine whether stratification of complexity methods in congenital heart surgery (RACHS-1, Aristotle and STS-EACTS) fit to our centre and determine the best method in discriminating hospital mortality.

Methods Surgical procedures in patients under 18 age were allocated to the categories proposed by the three methods currently available. The outcome in-hospital mortality was calculated for each category. Statistical analysis using the chi-square Pearson test was performed to verify whether the categories presented different mortalities. The categories’ discriminatory ability of each method was determined by calculating the area under the ROC curve and a comparison between the curves was performed.

Results 360 patients were allocated by the 3 methods. There was a statistically significant difference between the mortality categories: RACHS -1(1) - 1.3%; (2) - 11.4%; (3) - 27.3%; (4) - 50%, (p < 0.001), Aristotle (1) - 1.1%; (2) - 12.2%; (3) - 34%, (4) - 64.7%, (p < 0.001) and STS - EACTS (1) - 5,5%, (2) - 13.6%, (3) - 18.7%, (4) - 35.8%, (p < 0.001). The three methods had similar accuracy by calculating the area under the ROC curve (RACHS - 1–0.738; STAT - 0.739; Aristotle - 0.766).

Conclusion The three methods of stratification of complexity currently available in the literature are useful with different mortalities among the proposed categories and similar discriminatory capacity for in-hospital mortality in our centre.