Severity grading of unexpected events in paediatric surgery: evaluation of five classification systems and the Comprehensive Complication Index (CCI(R))

Background Postoperative adverse events may be associated with substantial morbidity and mortality. Numerous severity grading systems for these events have been introduced and validated but have not yet been systematically applied in paediatric surgery. This study aimed to analyse the advantages and disadvantages of these classifications in a paediatric cohort. Methods Unexpected events associated with interventional or organizational problems in the department of paediatric surgery during 2017-2020 were prospectively documented daily for all children. Events were classified according to the Clavien-Dindo grading system during monthly morbidity and mortality conferences. All events were also classified according to five additional grading systems: T92, contracted Accordion, expanded Accordion, Memorial Sloan Kettering Cancer Center, and Comprehensive Complication Index (CCI)(R). Results Of 6296 patients, 673 (10.7 per cent) developed adverse events and 240 (35.7 per cent) had multiple events. Overall, 1253 adverse events were identified; of these, 574 (45.2 per cent) were associated with surgical or medical interventions and 679 (54.8 per cent) included organizational problems. The grading systems demonstrated high overall correlation (r(pears) = 0.9), with minor differences in sentinel events. The Clavien-Dindo classification offered the most detailed assessment. However, these details had only limited additional value. The CCI(R) scores were correlated with other grading systems (r(pears) = 0.9) and were useful in analysing multiple events within individual patients. Conclusion Grading systems demonstrated similar scoring patterns for minor and sentinel events, with none being superior for unexpected events in children. However, the CCI(R) can be a major improvement in assessing morbidity in patients with multiple events. Its use is therefore recommended in prospective studies on paediatric surgery. The authors described the use of different severity grading systems and their advantages and disadvantages in a paediatric cohort. None of the five assessed classification systems were shown to be superior. However, the CCI(R) can be a major improvement in assessing morbidity in children with multiple events.