The Delphi and GRADE methodology used in the PSOGI 2018 consensus statement on Pseudomyxoma Peritonei and Peritoneal Mesothelioma

Our plain-English summary of The Delphi and GRADE methodology used in the PSOGI 2018 consensus statement on Pseudomyxoma Peritonei and Peritoneal Mesothelioma, by R.J. Lurvink, L. Villeneuve, K. Govaerts, et al (European Journal of Surgical Oncology, 2021).

The study

• Authors: R.J. Lurvink, L. Villeneuve, K. Govaerts, I.H.J.T. de Hingh, B.J. Moran, M. Deraco, K. Van der Speeten, O. Glehen, V. Kepenekian, S. Kusamura, List of PSOGI collaborators
• Journal: European Journal of Surgical Oncology
• Published: 2021;47(1):4-10
• Type of article: Review, Consensus statement
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Pseudomyxoma Peritonei (PMP) and Peritoneal Mesothelioma (PM) are both rare peritoneal malignancies. Currently, affected patients may be treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy offering long-term survival or even cure in selected patients. However, many issues regarding the optimal treatment strategy are currently under debate. To aid physicians involved in the treatment of these patients in clinical decision making, the PSOGI executive committee proposed to create a consensus statement on PMP and PM. This manuscript describes the methodology of the consensus process. The Delphi technique is a reliable method for attaining consensus on a topic that lacks scientific evidence through multiple voting rounds which feeds back responses to the participants in between rounds. The GRADE system provides a structured framework for presenting and grading the available evidence. Separate questionnaires were created for PMP and PM and sent during two voting rounds to 80 and 38 experts, respectively. A consensus threshold of 51.0% was chosen. After the second round, consensus was reached on 92.9%-100.0% of the questions. The results were presented and discussed in the plenary session at the PSOGI 2018 international meeting in Paris. A third round for the remaining issues is currently in progress. In conclusion, using the Delphi technique and GRADE methodology, consensus was reached in many issues regarding the treatment of PM and PMP amongst an international panel of experts. The main results will be published in the near future.

Copyright © 2019. Published by Elsevier Ltd.

In plain English

This article described the methods used to build an international expert consensus statement on two rare abdominal cancers, pseudomyxoma peritonei (PMP) and peritoneal mesothelioma (PM), organised by the Peritoneal Surface Oncology Group International (PSOGI). The article did not study asbestos or any cause of disease. In two voting rounds in July and August 2018, experts answered questions about diagnosis and treatment, including cytoreductive surgery with heated chemotherapy inside the abdomen (HIPEC). The PM panel had 38 experts from 17 countries, and the PMP panel had 80 experts from 28 countries. For each question, experts rated the evidence quality and recommendation strength using the GRADE system. Agreement by 51.0% of votes counted as consensus. Agreement on evidence quality rose from between 0.0% and 17.6% of questions in round one to between 71.4% and 96.9% in round two. Consensus on recommendations rose from between 60.0% and 71.4% to between 92.9% and 100.0%. After two rounds, 15 questions lacked consensus; the authors had already altered them and planned to include them in a third round. The authors listed limitations, including the 51.0% threshold and few medical oncologists.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Methods report on an expert consensus process (Delphi technique with multiple-choice questionnaires over two online voting rounds, using the GRADE system to rate evidence and recommendations); not a study of patients or exposure
• Who was studied: International expert panels selected by a steering committee. The PM panel had 37 surgeons and 1 medical oncologist from 17 countries (38 experts). The PMP panel had 69 surgeons and 11 medical oncologists from 28 countries (80 experts). Voting took place in July and August 2018.
• Exposure: Not applicable. The article does not study asbestos or any other exposure. The questionnaires covered pathology, pre-operative work-up, contra-indications for CRS and HIPEC, choice of HIPEC drug, systemic chemotherapy, treatment of premenopausal women, and follow-up.
• Main results:
  • There were 42 questions on PM, split into diffuse malignant peritoneal mesothelioma (27), well differentiated papillary peritoneal mesothelioma (8) and multicystic peritoneal mesothelioma (7). There were 69 questions on PMP, split into part I (34) and part II (35).
  • Questionnaire completion rates were 67% to 82% in the first round and 61 to 69% in the second round. Questionnaires that were not fully completed were left out of the analyses.
  • Consensus was defined as 51.0% of the votes on a question, the same cut-off used in an earlier PSOGI consensus.
  • Agreement on the level of evidence was reached for 0.0% to 17.6% of questions in round one, depending on the questionnaire. It was reached for 71.4% to 96.9% in round two.
  • Consensus on recommendations was reached for 60.0% to 71.4% of questions in round one. In round two it rose to 92.9% to 100.0%. Examples from round two: well differentiated papillary peritoneal mesothelioma 8/8 (100%) and PMP part I 65/70 (92.9%).
  • The authors compared the voting of high-volume PMP centres with all PMP centres and reported no significant differences in voting behaviour.
  • The steering committee judged most of the available evidence to be 'low' or 'very low' quality. Participants often rated the same evidence as 'moderate' or 'high'.
  • After two rounds, 15 questions had not reached consensus, mainly because of faults in how the questions were designed. These questions had been altered and were to be included in a third voting round.
• The authors' conclusion: The authors concluded that, using the Delphi technique and GRADE methodology, an international panel of experts reached consensus on many issues regarding the treatment of PM and PMP. They stated that the main results would be published later.
• Limitations the authors state:
  • The 51.0% consensus threshold might be less valid than a higher threshold, and there is no scientific evidence on how to set it.
  • The process skipped the usual open-response first round and started directly with multiple-choice questions, which may have limited the answers and reduced validity.
  • There were few medical oncologists on the panels (1 on the PM panel, 11 on the PMP panel), even though some questions concerned systemic treatment.
  • Evidence is lacking on how experts should be selected and how many are needed for a valid Delphi consensus.
  • Both methods depend on participants' judgment, and a group's judgment is not necessarily correct.
  • Participation fell between the first and second rounds, which the authors attributed to how long the questionnaires took to complete.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma, Peritoneal mesothelioma.

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Cytoreductive Surgery, HIPEC.

Related studies

• Long-term results of laparoscopic cytoreductive surgery and HIPEC for the curative treatment of low-grade pseudomyxoma peritonei and multicystic mesothelioma — F. Mercier, G. Jeremie, et al. (2020)
• Peritoneal mesothelioma: PSOGI/EURACAN clinical practice guidelines for diagnosis, treatment and follow-up — S. Kusamura, V. Kepenekian, et al. (2021)
• Overall survival of pseudomyxoma peritonei and peritoneal mesothelioma patients after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy can be predicted by computed tomography quantified sarcopenia — A. Galan, P. Rousset, et al. (2018)
• Laparoscopic cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for limited peritoneal metastasis. The PSOGI international collaborative registry — A. Arjona-Sanchez, O. Aziz, et al. (2021)
• American College of Chest Physicians consensus statement on the respiratory health effects of asbestos. Results of a Delphi study — D.E. Banks, R. Shi, et al. (2009)
• The role of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy in the treatment of peritoneal carcinomatosis: a systematic review including evidence from Japan — T. Kitai (2021)

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