A morbidity score for congenital heart surgery based on observed complications

The aim of this study was to develop a morbidity score based on observed postoperative complications after congenital heart surgery. Conditions or diseases that impair patients after congenital heart surgery or increase costs of hospital stay were called complications and attributed to scores ranging from 1 (mild) to 4 (severe) points, according to estimated severity or costliness. 'No complication' was assigned 0.5 points. From January to March 2011, scores for each observed 'complication' for every main (primary) surgical procedure were recorded and a morbidity score was calculated. In conformity with the Aristotle score methodology, if the sum of observed complication scores amounted to more than 5 points, a morbidity score of only 5 points was attributed. The estimated morbidity score was compared with the morbidity score attributed by the Aristotle basic complexity (ABC) score. One hundred and thirty-nine primary procedures were carried out. The mean ABC and Aristotle comprehensive complexity scores reached 8.31 +/- 2.52 and 9.62 +/- 3.47 points, respectively. Two patients died. No complication was detected after 46 procedures. Overall, there were 185 listed 'morbidity' conditions in connection with the other 93 surgical procedures, rendering a total score of 385 points. The most frequent event was 'mechanical ventilation 25-95 h': n = 39. The mean morbidity score was 2.14 +/- 1.63. The morbidity scores ranged from 0.5 points (n = 46) to 5 points (n = 23) with a median of 2.0 points. The scores for 11 different procedures that were performed at least five times positively correlated with the corresponding Aristotle morbidity scores: Pearson's coefficient r = 0.75. But the morbidity score for bidirectional cavopulmonary anastomosis (3.14 +/- 1.77) was higher than the corresponding Aristotle morbidity score (2.0). It was lower for 'conduit placement, right ventricle to pulmonary artery': 1.08 +/- 0.97, versus 2.0, and for arterial switch operation: 2.08 +/- 1.11, versus 3.0. The reported morbidity scores need to be tested on larger series and in different institutions. The introduced morbidity score has the potential to quantify postoperative complications accurately. Its estimation over time can facilitate the assessment of quality of congenital heart surgery. It will allow comparison of morbidity outcomes across institutions with different case-mixes.