Objective: Outcome endpoints are still the most widely used indicators of performance. However, they need to be risk-adjusted in order to be reliable instruments of audit. Recently, the European Society Objective Score (ESOS) was developed from the online European Thoracic Surgery Database as an audit tool. In this study, we applied for the first time the ESOS.01 to assess the performance of three European thoracic surgery units during three successive years of activity.
Methods: This study is a retrospective analysis performed on prospective databases. We analysed 695 patients submitted to pneumonectomy (117) or lobectomy (578) for lung neoplasm at three European dedicated thoracic surgery units (unit A 264 patients, unit B 262, unit C 169) from January 2004 through December 2006. Qualified thoracic surgeons performed all the operations. No patients in this series were in the original ESOS development set. ESOS.01 was used to estimate the risk of in-hospital mortality in all patients. Observed and predicted mortality rates were then compared within each unit by the z-test.
Results: Cumulative observed mortality rates in units A, B and C were 2.3% (six cases), 2.7% (seven cases) and 4.1% (seven cases), respectively. We were not able to find statistically significant differences between observed and ESOS-predicted mortality rates. The comparison of risk-adjusted mortality rates between units did not show significant differences (unit A 3.9%, unit B 3.3%, unit C 5.6%).
Conclusions: The use of ESOS.01 revealed that the performances of all units were in line with the predicted ones during each period under analysis and did not differ between each other. The results of our study warrant future efforts to refine the ESOS model and to develop other risk-adjusted outcome indicators with the aim to establish European benchmarks of performance.