Reclassifying by highest complexity operation rather than first operation influences mortality after pediatric heart surgery

Abstract Objective To evaluate the effect on mortality of reclassifying patients undergoing pediatric heart reoperations of varying complexity by operation of highest complexity instead of by first operation. Methods Data from the Virtual Pediatric Systems Database on children aged  Results Of 51,047 patients (73 centers), 22,393 met inclusion criteria. Using index operation as the classifying operation, the number of patients classified in the STAT 1 category increased by approximately 2.5 times compared with the highest-complexity operation (index, 7,077 and highest complexity, 2,654). In contrast, when the highest-complexity classification was used, we noted an increase in the number of patients in other STAT categories. We also noted higher mortality in all STAT categories when patients were classified by index operation instead of by highest complexity (index vs highest STAT category 1, 0.6% vs 0.2%; category 2, 2.4% vs 0.8%; category 3, 3.1% vs 2.1%; category 4, 5.8% vs 5.6%; and category 5, 16.7% vs 16.5%). Conclusions This study demonstrates differences in the reported number of patients and reported mortality in each STAT category among children undergoing various heart reoperations during the same hospitalization by classifying patients based on index operation compared with the operation of highest complexity.