Review Article| Volume 47, ISSUE 1, P4-10, January 2021

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

Published:March 23, 2019DOI:


      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.



      CRS (Cytoreductive Surgery), DMPM (Diffuse Malignant Peritoneal Mesothelioma), GRADE (Grades of Recommendation, Assessment, Development, and Evaluation), EPIC (Early Post-operative Intraperitoneal Chemotherapy), HIPEC (Hyperthermic Intraperitoneal Chemotherapy), LoE (Level of Evidence), MCPM (MultiCystic Peritoneal Mesothelioma), PICO (Patient, Intervention, Control, Outcome), PM (Peritoneal Mesothelioma), PMP (Pseudomyxoma Peritonei), PSOGI (Peritoneal Surface Oncology Group International), RCT (Randomized Controlled Trial), SC (Steering Committee), SoR (Strength of Recommendation(s)), WDPPM (Well Differentiated Papillary Peritoneal Mesothelioma)
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to European Journal of Surgical Oncology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Rizvi S.A.
        • Syed W.
        • Shergill R.
        Approach to pseudomyxoma peritonei.
        World J Gastrointest Surg. 2018; 10: 49-56
        • Boffetta P.
        Epidemiology of peritoneal mesothelioma: a review.
        Ann Oncol. 2007; 18: 985-990
        • Kusamura S.
        • Baratti D.
        • Younan R.
        The Delphi approach to attain consensus in methodology of local regional therapy for peritoneal surface malignancy.
        J Surg Oncol. 2008; 98: 217-219
        • Thangaratinam S.
        • Redman C.W.E.
        The Delphi technique.
        TOG. 2005; 7: 120-125
        • Rowe G.
        • Wright G.
        • Bolger F.
        Delphi: a re-evaluation of research and theory.
        Technol Forecast Soc Change. 1991; 39: 235-251
        • Powell C.
        Methodological issues in nursing research, the Delphi technique: myths and realities.
        J Adv Nurs. 2003; 41: 376-382
        • Keeney S.
        • Hasson F.
        • McKenna H.
        Consulting the oracle: ten lessons from using the Delphi technique in nursing research.
        J Adv Nurs. 2006; 53: 205-212
        • Guyatt G.H.
        • Oxman A.D.
        • Kunz R.
        GRADE: an emerging consensus on rating quality of evidence and strength of recommendations.
        BMJ. 2008; 336: 924-926
        • Grades of Recommendation
        Assessment, development, and evaluation (GRADE) working group. Education and debate – grading quality of evidence and strength of recommendations.
        BMJ. 2004; 328: 1490-1494
        • Guyatt G.H.
        • Oxman A.D.
        • Akl E.A.
        GRADE guidelines: 1. Introduction – GRADE evidence profiles and summary of findings tables.
        J Clin Epidemiol. 2011; 64: 383-394
        • Higgins J.P.T.
        • Green S.
        Cochrane Handbook for systematic reviews of Interventions.
        978-0-470-69951-5 Wiley Online Library, 2008
        • Huang X.
        • Lin J.
        • Demner-Fushman D.
        Evaluation of PICO as a knowledge representation for clinical questions.
        AMIA Annu Symp Proc. 2006; : 359-363
        • Guyatt G.H.
        • Oxman A.D.
        • Kunz R.
        GRADE guidelines: 2. Framing the question and deciding on important outcomes.
        J Clin Epidemiol. 2011; 64: 395-400
        • Balshem H.
        • Helfand M.
        • Schünemann H.J.
        GRADE guidelines: 3. Rating the quality of evidence.
        J Clin Epidemiol. 2011; 64: 401-406
        • Guyatt G.H.
        • Oxman A.D.
        • Vist G.
        GRADE guidelines: 4. Rating the quality of evidence – study limitations (risk of bias).
        J Clin Epidemiol. 2011; 64: 407-415
        • Andrews J.C.
        • Guyatt G.H.
        • Oxman A.D.
        GRADE guidelines: 14. Going from evidence to recommendations: the significance and presentation of recommendations.
        J Clin Epidemiol. 2013; 66: 719-725
        • Andrews J.C.
        • Schünemann H.J.
        • Oxman A.D.
        GRADE guidelines: 15. Going from evidence to recommendation – determinants of a recommendation's direction and strength.
        J Clin Epidemiol. 2013; 66: 726-735
        • Villeneuve L.
        • Passot G.
        • Glehen O.
        • Isaac S.
        • Bibeau F.
        • Rousset P.
        • et al.
        And on behalf of the RENAPE Network, the RENAPE observational registry: rationale and framework of the rare peritoneal tumors French patient registry.
        Orphanet J Rare Dis. 2017; 12