Studying the degeneration of bioprostheses requires specific statistical analysis

Studying the degeneration of bioprostheses requires specific statistical analysis European Journal of Cardio-Thoracic Surgery 53 (2018) 892–896 LETTERS TO THE EDITOR dhvaquero@gmail.com (D. Hernandez-Vaquero). Studying the degeneration of bioprostheses doi:10.1093/ejcts/ezx405 requires specific statistical analysis Advance Access publication 17 November 2017 Daniel Hernandez-Vaquero*, Rocıo Dıaz, Isaac Pascual and Jacobo Silva Department of Cardiac Surgery, Central University Hospital of Asturias, Oviedo, Spain Received 6 September 2017; accepted 28 October 2017 Reply to Hernandez-Vaquero et al. Keywords: Biological prosthesis � Structural valve deterioration Fabio Ius*, Axel Haverich and Serghei Cebotari Department of Cardiothoracic, Transplant and Vascular Surgery, Hannover We have read with admiration the interesting article by Ius et al. [1] on the de- Medical School, Hannover, Germany generation pattern of the Mitroflow aortic valve. On the basis of the product- limit estimator of the Kaplan–Meier survival curves, the authors reported a Received 23 October 2017; accepted 28 October 2017 rate of freedom from structural valve deterioration (SVD) of 95% and 68% at 5- and 9-year follow-up, respectively. Keywords: Bioprosthesis � Degeneration � Statistical analysis Few months ago, a consensus statement on the SVD from the European Association for Cardio-Thoracic Surgery (EACTS) was released [2]. In addition We found the letter to the editor by Hern andez-Vaquero et al. [1] to our re- to establishing a standard definition of SVD, it warned that the Kaplan–Meier cently published article [2] and the article of D ıaz et al. [3] very interesting. We analysis may lead to incorrect estimates due to the presence of competing agree with the authors that the description of outcomes after cardiac valve re- events. However, cumulative incidence function based on the competing-risk placement should not rely only on the Kaplan–Meier survival curves anymore analysis provides the correct probability of SVD, and the Fine and Gray regres- but must also include a competing-risk analysis of outcomes. This ‘real-life’ sion model calculates the subdistribution hazard ratios with a clinical and easy analysis will allow a better comparison of the upcoming long-term results of interpretation [3]. Reporting 95% confidence interval is other recommendation the transaortic valve implantation procedures versus surgical aortic valve of this document that we have missed in their work [2]. replacement. It has been shown that competing-event percentages >10% require specific Indeed, in the first version of our article, we did not report a competing-risk analyses that take them into consideration [3]. Therefore, these methods are analysis of the outcomes of structural valve deterioration (SVD) and mortality. necessary in this population comprising elderly patients with heart disease, However, during the revision, we corrected the original manuscript according which was expected to have a high percentage of deaths during follow-up. to the new statistical and data reporting guidelines [4]. We performed a multi- In fact, we have recently shown great differences between both calculations state analysis using R, and we found that the ‘real’ freedom from SVD at (the competing-event cumulative incidence and the Kaplan–Meier curves) in a 9 years was 82.9% (cumulative incidence of 17.1%), which was comparable to large series of patients treated with the Mitroflow prosthesis [4]. We found a the corrected freedom from SVD reported by Hernandez-Vaquero et al. (inci- real cumulative incidence of SVD using competing-event analysis of 4% and dence of SVD 20.06% at 8 years) [2]. 16% at the 5- and 8-year follow-up. However, when using the Kaplan–Meier Finally, Hernandez-Vaquero et al. noted that we did not follow the stand- estimation, it was 5% and 27%, respectively, which almost coincides with the ardized definitions of structural deterioration and valve failure in assessing 95% and 68% rates of freedom from the SVD reported by Ius et al. [1]. long-term durability of transcatheter and surgical aortic bioprosthetic valves [5]. However, the preparation of our manuscript and its revision preceded the publication of those guidelines, which were accepted for publication in May 2017. REFERENCES [1] Ius F, Schulz J, Roumieh M, Fleissner F, Ismail I, Tudorache I et al. Long- REFERENCES term results of the Mitroflow aortic pericardial bioprosthesis in over 800 patients: limited durability and mechanisms of dysfunction. Eur J Cardiothorac Surg 2017;52:264–71. [1] Hernandez-Vaquero D, Dıaz R, Pascual I, Silva J. Studying the degeneration [2] Capodanno D, Petronio AS, Prendergast B, Eltchaninoff H, Vahanian A, of bioprostheses requires specific statistical analysis. Eur J Cardiothorac Modine T et al. Standardized definitions of structural deterioration and Surg 2018;53:892. valve failure in assessing long-term durability of transcatheter and surgical [2] Ius F, Schulz J, Roumieh M, Fleissner F, Ismail I, Tudorache I et al. Long- aortic bioprosthetic valves: a consensus statement from the European term results of the Mitroflow aortic pericardial bioprosthesis in over 800 Association of Percutaneous Cardiovascular Interventions (EAPCI) patients: limited durability and mechanisms of dysfunction. Eur J endorsed by the European Society of Cardiology (ESC) and the European Cardiothorac Surg 2017;52:264–71. Association for Cardio-Thoracic Surgery (EACTS). Eur J Cardiothorac Surg [3] Dıaz R, Hernandez-Vaquero D, Silva J, Pascual I, de la Hera JM, Leon V 2017;52:408–17. et al. Real structural valve deterioration of the Mitroflow aortic prosthesis: [3] Austin PC, Lee DS, Fine JP. Introduction to the analysis of survival data in competing risk analysis. Rev Esp Cardiol (Engl Ed) 2017; doi: 10.1016/ the presence of competing risks. Circulation 2016;133:601–9. j.rec.2017.02.041. [4] D ıaz R, Hern andez-Vaquero D, Silva J, Pascual I, de la Hera JM, Leon  V [4] Hickey GL, Dunning J, Seifert B, Sodeck G, Carr MJ, Burger HU; EJCTS and et al. Real structural valve deterioration of the mitroflow aortic prosthesis: ICVTS Editorial Committees et al. Statistical and data reporting guidelines competing risk analysis. Rev Esp Cardiol (Engl Ed) 2017; doi: 10.1016/j.rec. for the European Journal of Cardio-Thoracic Surgery and the Interactive 2017.02.041. CardioVascular and Thoracic Surgery. Eur J Cardiothorac Surg 2015;48:180–93. [5] Capodanno D, Petronio AS, Prendergast B, Eltchaninoff H, Vahanian A, *Corresponding author. Department of Cardiac Surgery, Central University Modine T et al. Standardized definitions of structural deterioration and valve Hospital of Asturias, Oviedo, Spain. Tel: +34-985-108000, ext: 36262; e-mail: failure in assessing long-term durability of transcatheter and surgical aortic The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. Downloaded from https://academic.oup.com/ejcts/article-abstract/53/4/892/4638437 by Ed 'DeepDyve' Gillespie user on 16 March 2018 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png European Journal of Cardio-Thoracic Surgery Oxford University Press

Studying the degeneration of bioprostheses requires specific statistical analysis

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1010-7940
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10.1093/ejcts/ezx405
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Abstract

European Journal of Cardio-Thoracic Surgery 53 (2018) 892–896 LETTERS TO THE EDITOR dhvaquero@gmail.com (D. Hernandez-Vaquero). Studying the degeneration of bioprostheses doi:10.1093/ejcts/ezx405 requires specific statistical analysis Advance Access publication 17 November 2017 Daniel Hernandez-Vaquero*, Rocıo Dıaz, Isaac Pascual and Jacobo Silva Department of Cardiac Surgery, Central University Hospital of Asturias, Oviedo, Spain Received 6 September 2017; accepted 28 October 2017 Reply to Hernandez-Vaquero et al. Keywords: Biological prosthesis � Structural valve deterioration Fabio Ius*, Axel Haverich and Serghei Cebotari Department of Cardiothoracic, Transplant and Vascular Surgery, Hannover We have read with admiration the interesting article by Ius et al. [1] on the de- Medical School, Hannover, Germany generation pattern of the Mitroflow aortic valve. On the basis of the product- limit estimator of the Kaplan–Meier survival curves, the authors reported a Received 23 October 2017; accepted 28 October 2017 rate of freedom from structural valve deterioration (SVD) of 95% and 68% at 5- and 9-year follow-up, respectively. Keywords: Bioprosthesis � Degeneration � Statistical analysis Few months ago, a consensus statement on the SVD from the European Association for Cardio-Thoracic Surgery (EACTS) was released [2]. In addition We found the letter to the editor by Hern andez-Vaquero et al. [1] to our re- to establishing a standard definition of SVD, it warned that the Kaplan–Meier cently published article [2] and the article of D ıaz et al. [3] very interesting. We analysis may lead to incorrect estimates due to the presence of competing agree with the authors that the description of outcomes after cardiac valve re- events. However, cumulative incidence function based on the competing-risk placement should not rely only on the Kaplan–Meier survival curves anymore analysis provides the correct probability of SVD, and the Fine and Gray regres- but must also include a competing-risk analysis of outcomes. This ‘real-life’ sion model calculates the subdistribution hazard ratios with a clinical and easy analysis will allow a better comparison of the upcoming long-term results of interpretation [3]. Reporting 95% confidence interval is other recommendation the transaortic valve implantation procedures versus surgical aortic valve of this document that we have missed in their work [2]. replacement. It has been shown that competing-event percentages >10% require specific Indeed, in the first version of our article, we did not report a competing-risk analyses that take them into consideration [3]. Therefore, these methods are analysis of the outcomes of structural valve deterioration (SVD) and mortality. necessary in this population comprising elderly patients with heart disease, However, during the revision, we corrected the original manuscript according which was expected to have a high percentage of deaths during follow-up. to the new statistical and data reporting guidelines [4]. We performed a multi- In fact, we have recently shown great differences between both calculations state analysis using R, and we found that the ‘real’ freedom from SVD at (the competing-event cumulative incidence and the Kaplan–Meier curves) in a 9 years was 82.9% (cumulative incidence of 17.1%), which was comparable to large series of patients treated with the Mitroflow prosthesis [4]. We found a the corrected freedom from SVD reported by Hernandez-Vaquero et al. (inci- real cumulative incidence of SVD using competing-event analysis of 4% and dence of SVD 20.06% at 8 years) [2]. 16% at the 5- and 8-year follow-up. However, when using the Kaplan–Meier Finally, Hernandez-Vaquero et al. noted that we did not follow the stand- estimation, it was 5% and 27%, respectively, which almost coincides with the ardized definitions of structural deterioration and valve failure in assessing 95% and 68% rates of freedom from the SVD reported by Ius et al. [1]. long-term durability of transcatheter and surgical aortic bioprosthetic valves [5]. However, the preparation of our manuscript and its revision preceded the publication of those guidelines, which were accepted for publication in May 2017. REFERENCES [1] Ius F, Schulz J, Roumieh M, Fleissner F, Ismail I, Tudorache I et al. Long- REFERENCES term results of the Mitroflow aortic pericardial bioprosthesis in over 800 patients: limited durability and mechanisms of dysfunction. Eur J Cardiothorac Surg 2017;52:264–71. [1] Hernandez-Vaquero D, Dıaz R, Pascual I, Silva J. Studying the degeneration [2] Capodanno D, Petronio AS, Prendergast B, Eltchaninoff H, Vahanian A, of bioprostheses requires specific statistical analysis. Eur J Cardiothorac Modine T et al. Standardized definitions of structural deterioration and Surg 2018;53:892. valve failure in assessing long-term durability of transcatheter and surgical [2] Ius F, Schulz J, Roumieh M, Fleissner F, Ismail I, Tudorache I et al. Long- aortic bioprosthetic valves: a consensus statement from the European term results of the Mitroflow aortic pericardial bioprosthesis in over 800 Association of Percutaneous Cardiovascular Interventions (EAPCI) patients: limited durability and mechanisms of dysfunction. Eur J endorsed by the European Society of Cardiology (ESC) and the European Cardiothorac Surg 2017;52:264–71. Association for Cardio-Thoracic Surgery (EACTS). Eur J Cardiothorac Surg [3] Dıaz R, Hernandez-Vaquero D, Silva J, Pascual I, de la Hera JM, Leon V 2017;52:408–17. et al. Real structural valve deterioration of the Mitroflow aortic prosthesis: [3] Austin PC, Lee DS, Fine JP. Introduction to the analysis of survival data in competing risk analysis. Rev Esp Cardiol (Engl Ed) 2017; doi: 10.1016/ the presence of competing risks. Circulation 2016;133:601–9. j.rec.2017.02.041. [4] D ıaz R, Hern andez-Vaquero D, Silva J, Pascual I, de la Hera JM, Leon  V [4] Hickey GL, Dunning J, Seifert B, Sodeck G, Carr MJ, Burger HU; EJCTS and et al. Real structural valve deterioration of the mitroflow aortic prosthesis: ICVTS Editorial Committees et al. Statistical and data reporting guidelines competing risk analysis. Rev Esp Cardiol (Engl Ed) 2017; doi: 10.1016/j.rec. for the European Journal of Cardio-Thoracic Surgery and the Interactive 2017.02.041. CardioVascular and Thoracic Surgery. Eur J Cardiothorac Surg 2015;48:180–93. [5] Capodanno D, Petronio AS, Prendergast B, Eltchaninoff H, Vahanian A, *Corresponding author. Department of Cardiac Surgery, Central University Modine T et al. Standardized definitions of structural deterioration and valve Hospital of Asturias, Oviedo, Spain. Tel: +34-985-108000, ext: 36262; e-mail: failure in assessing long-term durability of transcatheter and surgical aortic The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. Downloaded from https://academic.oup.com/ejcts/article-abstract/53/4/892/4638437 by Ed 'DeepDyve' Gillespie user on 16 March 2018

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European Journal of Cardio-Thoracic SurgeryOxford University Press

Published: Apr 1, 2018

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