Definition and Classification of Intraoperative Complications (CLASSIC): Delphi Study and Pilot Evaluation

Standardized reporting of intraoperative adverse events is important to enhance transparency. To the best of our knowledge, there is no validated definition and classification of intraoperative complications. We conducted a two-round Delphi study to develop a definition and classification of intraoperative complications. Experts were contacted by email and sent a link to the online questionnaire. In a pilot study, two independent raters applied the definition and classification in a sample of 60 surgical interventions of low, intermediate, and high complexity and evaluated practicability. Interrater agreement of the classification was determined (raw categorical agreement, weighted kappa, and intraclass correlation). In the Delphi study, 40 of 52 experts (77 % return rate) from 14 countries took part in each round. The Delphi study resulted in a comprehensive definition of intraoperative complications as any deviation from the ideal intraoperative course occurring between skin incision and skin closure. The classification foresees four grades depending on the need for treatment (no need, grade I; need for treatment, grade II) and the severity of the complication (life-threatening/permanent disability, grade III; death, grade IV). The pilot study showed good practicability (6 on a 7-point scale) and a high raw agreement of 87 %, a weighted kappa of 0.83 [95 % confidence interval (CI) 0.73-0.94] and an intraclass correlation coefficient of 0.83 (95 % CI 0.73-0.90). While the Delphi process enabled to develop definitions and classification of intraoperative complications by severity, further research including a multicentre international full-scale validation needs to be conducted with the ultimate goal to contribute to standardized reporting in surgical practice and research.