Congenital heart surgery: surgical performance according to the Aristotle complexity score.

OBJECTIVES Aristotle score methodology defines surgical performance as 'complexity score times hospital survival'. We analysed how this performance evolved over time and in correlation with case volume. METHODS Aristotle basic and comprehensive complexity scores and corresponding basic and comprehensive surgical performances were determined for primary (main) procedures carried out from 2006 to 2009. Surgical case volume performance described as unit performance was estimated as 'surgical performance times the number of primary procedures'. RESULTS Basic and comprehensive complexity scores for the whole cohort of procedures (n=1828) were 7.74±2.66 and 9.89±3.91, respectively. With an early survival of 97.5% (1783/1828), mean basic and comprehensive surgical performances reached 7.54±2.54 and 9.64±3.81, respectively. Basic surgical performance varied little over the years: 7.46±2.48 in 2006, 7.43±2.58 in 2007, 7.50±2.76 in 2008 and 7.79±2.54 in 2009. Comprehensive surgical performance decreased from 9.56±3.91 (2006) to 9.22±3.94 (2007), and then to 9.13±3.77 (2008), thereafter increasing up to 10.62±3.67 (2009). No significant change of performance was observed for low comprehensive complexity levels 1-3. Variation concerned level 4 (p=0.048) which involved the majority of procedures (746, or 41% of cases) and level 6 (p<0.0001) which included a few cases (20, or 1%), whereas for level 5, statistical significance was almost attained: p=0.079. With a mean annual number of procedures of 457, mean basic and comprehensive unit performance was estimated at 3447±362 and 4405±577, respectively. Basic unit performance increased year to year from 3036 (2006, 100%) to 3254 (2007, 107.2%), then 3720 (2008, 122.5%), up to 3793 (2009, 124.9%). Comprehensive unit performance also increased: from 3891 (2006, 100%) to 4038 (2007, 103.8%), 4528 (2008, 116.4%) and 5172 (2009, 132.9%). CONCLUSIONS Aristotle scoring of surgical performance allows quality assessment of surgical management of congenital heart disease over time. The newly defined unit performance appears to well reflect the trend of activity and efficiency of a congenital heart surgery department.