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Major morbidity after video-assisted thoracic surgery lung resections: a comparison between the European Society of Thoracic Surgeons definition and the Thoracic Morbidity and Mortality system.

BACKGROUND
The thoracic morbidity and mortality (TM&M) classification system univocally encodes the postoperative adverse events by their management complexity. This study aims to compare the distribution of the severity of complications according to the TM&M system versus the distribution according to the classification proposed by European Society of Thoracic Surgeons (ESTS) Database in a population of patients submitted to video assisted thoracoscopic surgery (VATS) lung resection.


METHODS
A total of 227 consecutive patients submitted to VATS lobectomy for lung cancer were analyzed. Any complication developed postoperatively was graded from I to V according to the TM&M system, reflecting the increasing severity of its management. We verified the distribution of the different grades of complications and analyzed their frequency among those defined as "major cardiopulmonary complications" by the ESTS Database.


RESULTS
Following the ESTS definitions, 20 were the major cardiopulmonary complications [atrial fibrillation (AF): 10, 50%; adult respiratory distress syndrome (ARDS): 1, 5%; pulmonary embolism: 2, 10%; mechanical ventilation >24 h: 1, 5%; pneumonia: 3, 15%; myocardial infarct: 1, 5%; atelectasis requiring bronchoscopy: 2, 10%] of which 9 (45%) were reclassified as minor complications (grade II) by the TM&M classification system. According to the TM&M system, 10/34 (29.4%) of all complications were considered minor (grade I or II) while 21/34 (71.4%) as major (IIIa: 8, 23.5%; IIIb: 4, 11.7%; IVa: 8, 23.5%; IVb: 1, 2.9%; V: 3, 8.8%). Other 14 surgical complications occurred and were classified as major complications according to the TM&M system.


CONCLUSIONS
The distribution of postoperative complications differs between the two classification systems. The TM&M grading system questions the traditional classification of major complications following VATS lung resection and may be used as an additional endpoint for outcome analyses.