N Lijftogt1, T W F Luijnenburg2, A C Vahl3, E D Wilschut1, V J Leijdekkers3, M F Fiocco4,5, M W J M Wouters6,7, J F Hamming1. 1. Departments of Vascular Surgery, Leiden University Medical Centre, Leiden, The Netherlands. 2. Departments of Medicine, Leiden University Medical Centre, Leiden, The Netherlands. 3. Department of Surgery Onze Lieve Vrouwe Gasthuis, Dutch Cancer Institute - Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands. 4. Department of Medical Statistics and Bioinformatics, Leiden University, Leiden, The Netherlands. 5. Institute of Mathematics, Leiden University, Leiden, The Netherlands. 6. Scientific Bureau, Dutch Institute for Clinical Auditing, Leiden, The Netherlands. 7. Department of Surgery, Dutch Cancer Institute - Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Abstract
BACKGROUND: The introduction of endovascular aneurysm repair (EVAR) has reduced perioperative mortality after abdominal aortic aneurysm (AAA) surgery. The objective of this systematic review was to assess existing mortality risk prediction models, and identify which are most useful for patients undergoing AAA repair by either EVAR or open surgical repair. METHODS: A systematic search of the literature was conducted for perioperative mortality risk prediction models for patients with AAA published since 2006. PRISMA guidelines were used; quality was appraised, and data were extracted and interpreted following the CHARMS guidelines. RESULTS: Some 3903 studies were identified, of which 27 were selected. A total of 13 risk prediction models have been developed and directly validated. Most models were based on a UK or US population. The best performing models regarding both applicability and discrimination were the perioperative British Aneurysm Repair score (C-statistic 0·83) and the preoperative Vascular Biochemistry and Haematology Outcome Model (C-statistic 0·85), but both lacked substantial external validation. CONCLUSION: Mortality risk prediction in AAA surgery has been modelled extensively, but many of these models are weak methodologically and have highly variable performance across different populations. New models are unlikely to be helpful; instead case-mix correction should be modelled and adapted to the population of interest using the relevant mortality predictors.
BACKGROUND: The introduction of endovascular aneurysm repair (EVAR) has reduced perioperative mortality after abdominal aortic aneurysm (AAA) surgery. The objective of this systematic review was to assess existing mortality risk prediction models, and identify which are most useful for patients undergoing AAA repair by either EVAR or open surgical repair. METHODS: A systematic search of the literature was conducted for perioperative mortality risk prediction models for patients with AAA published since 2006. PRISMA guidelines were used; quality was appraised, and data were extracted and interpreted following the CHARMS guidelines. RESULTS: Some 3903 studies were identified, of which 27 were selected. A total of 13 risk prediction models have been developed and directly validated. Most models were based on a UK or US population. The best performing models regarding both applicability and discrimination were the perioperative British Aneurysm Repair score (C-statistic 0·83) and the preoperative Vascular Biochemistry and Haematology Outcome Model (C-statistic 0·85), but both lacked substantial external validation. CONCLUSION: Mortality risk prediction in AAA surgery has been modelled extensively, but many of these models are weak methodologically and have highly variable performance across different populations. New models are unlikely to be helpful; instead case-mix correction should be modelled and adapted to the population of interest using the relevant mortality predictors.