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Case-mix adjustment to compare hospital performances regarding complications after cytoreductive surgery for ovarian cancer: a nationwide population-based study
  1. Marc Daniël Algera1,2,3,
  2. Nishita M S Baldewpersad Tewarie2,4,
  3. Willemien J van Driel5,
  4. Maaike A P C van Ham4,
  5. Brigitte F M Slangen1,3,
  6. Roy F P M Kruitwagen1,3 and
  7. Michel W J M Wouters2,6
  8. Participants of the Dutch Gynecological Oncology Audit Collaborator Group
    1. 1Gynecologic Oncology, Maastricht University Medical Centre+, Maastricht, The Netherlands
    2. 2Scientific Bureau, Dutch Institute for Clinical Auditing, Leiden, The Netherlands
    3. 3GROW School for Oncology and Reproduction, Maastricht, The Netherlands
    4. 4Department of Obstetrics and Gynecology, Radboudumc, Nijmegen, The Netherlands
    5. 5Gynaecology, Netherlands Cancer Institute, Amsterdam, The Netherlands
    6. 6Department of Surgical Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands
    1. Correspondence to Marc Daniël Algera, Gynecologic Oncology, Maastricht University Medical Centre+, Maastricht, 2333, The Netherlands; m.algera{at}nki.nl

    Abstract

    Objective Complication rates after cytoreductive surgery are important quality indicators for hospitals that treat patients with advanced-stage ovarian cancer. Case-mix factors are patient and tumor characteristics that may influence hospital outcomes such as the complication rates. Currently, no case-mix adjustment model exists for complications after cytoreductive surgery; therefore, it is unclear whether hospitals are being compared correctly. This study aims to develop the first case-mix adjustment model for complications after surgery for advanced-stage ovarian cancer, enabling an accurate comparison between hospitals.

    Methods This population-based study included all patients undergoing cytoreductive surgery for advanced-stage ovarian cancer registered in the Netherlands in 2017–2019. Case-mix variables were identified and assessed using logistic regressions. The primary outcome was the composite outcome measure ‘complicated course’. Patients had a complicated course when at least one of the following criteria were met: (1) any complication combined with a prolonged length of hospital stay; (2) complication requiring reintervention; (3) any complication with a prolonged length of stay in the intensive care unit; or (4) 30-day mortality or in-hospital mortality during admission following surgery. Inter-hospital variation was analyzed using univariable and multivariable logistic regressions and visualized using funnel plots.

    Results A total of 1822 patients were included, of which 10.7% (n=195) had a complicated course. Comorbidity and tumor stage had a significant impact on complicated course rates in multivariable logistic regression. Inter-hospital variation was not significant for case-mix factors. Complicated course rates ranged between 2.2% and 29.1%, and case-mix adjusted observed/expected ratios ranged from 0.20 to 2.67 between hospitals. Three hospitals performed outside the confidence intervals for complicated course rates. These hospitals remained outliers after case-mix adjustment.

    Conclusion There is variation between hospitals regarding complicated course rates after cytoreductive surgery for ovarian cancer in the Netherlands. While comorbidity and tumor stage significantly affected the complicated course rates, adjusting for case-mix factors did not significantly affect hospital outcomes. The limited impact of case-mix adjustment could be a result of the Dutch centralized healthcare model.

    • Postoperative complications
    • Cytoreduction surgical procedures
    • Ovarian Cancer

    Data availability statement

    Data are available upon reasonable request.

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    Data availability statement

    Data are available upon reasonable request.

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    Footnotes

    • MDA and NMSBT contributed equally.

    • Collaborators Participants of the Dutch Gynecological Oncology Audit Collaborator Group: A J Kruse, gynecologist, Isala Klinieken, Zwolle; R Yigit, gynecologist, University Medical Center Groningen, Groningen; M van der Aa, senior investigator, National Cancer Care Network (NCCN); J W M Mens, radiation oncologist, Erasmus Medical Center Cancer Institute, Rotterdam; T C Stam, radiation oncologist, Haaglanden Medical Center, The Hague; M J A Engelen, gynecologist, Zuyderland Medisch Centrum, Heerlen; L S Nooij, gynecologist, Leiden University Medical Center, Leiden; J Diepstraten, patient advocate, Stichting Olijf; A van der Kolk, patient advocate, Stichting Olijf; H P M Smedts, gynecologist, Amphia Ziekenhuis, Breda; N Reesink, gynecologist, Medisch Centrum Twente, Enschede; K N Gaarenstroom, gynecologist, Leiden University Medical Center, Leiden; P M L H Vencken, gynecologist, Bravis Ziekenhuis, Roosendaal; D Boll, gynecologist, Catharina Ziekenhuis, Eindhoven; G Fons, gynecologist, Amsterdam University Medical Center, Academic Medical Center, Amsterdam; A Baalbergen, gynecologist, Reinier de Graaf Groep, Delft; E B L van Dorst, gynecologist, University Medical Center Utrecht, Utrecht; M Y Tjiong, gynecologist, Amsterdam University Medical Center, Vrije Universiteit Medisch Centrum, Amsterdam; E M Roes, gynecologist, Erasmus Medical Center Cancer Institute, Rotterdam; C G Gerestein, gynecologist, Meander Medisch Centrum, Amersfoort and University Medical Center Utrecht, Utrecht; H T C Nagel, gynecologist, Haaglanden Medical Center, The Hague; A L Aalders, gynecologist, Rijnstate Ziekenhuis, Arnhem; I Ebisch, gynecologist, Cansius Wilhelmina Ziekenhuis, Nijmegen; J de Waard, gynecologist, Fransiscus Gasthuis & Vlietland, Rotterdam; M Huisman, gynecologist, Gelre Ziekenhuis, Apeldoorn.

    • Contributors MDA and NMSBT were the principal authors. MDA was guarantor and performed the analyses. MDA, NMSBT, WJvD, MvH, BS, RK, and MW performed interpretation of the data and revision of the manuscript. The participants of the Dutch Gynecological Oncology Audit (DGOA) Collaborators Group collected data for the DGOA registry and read and approved the manuscript.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.