Evidence evaluation in rare disease guidelines: a methodological perspective

Rare Disease and Orphan Drugs Journal, vol. 4

Abstract

This paper examines the methodological challenges of developing rare disease clinical guidelines and compares the standard Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach with an enhanced methodology tailored to rare disease constraints. Drawing on European Reference Network working groups, case studies, literature, and discussions from a EURORDIS webinar (April 2024), it identifies strategies to produce evidence-informed recommendations despite limited and heterogeneous data. The enhanced GRADE framework broadens search strategies, integrates qualitative synthesis, real-world evidence, and structured expert/patient input, and uses consensus methods such as Delphi processes and evidence-to-decision frameworks. This enables guideline developers to address sparse data, non-traditional research questions, and variable outcomes while maintaining transparency. For rare diseases, where conventional hierarchies of evidence are often unworkable, this adapted approach provides a flexible, pragmatic, and inclusive pathway. By leveraging registries, expert consensus, and tailored evidence integration, it supports robust, context-sensitive guidelines that remain clinically relevant and improve care for underserved patients.

Authors 7

1. Matt Bolz-Johnson

   European Organisation for Rare Diseases

   Affiliation as printed

   Correspondence to: Dr. Matt Bolz-Johnson, EURORDIS - Rare Diseases Europe, Brussels 1000, Belgium. E-mail: matt.johnson@eurordis.org

2. Charlotte M. W. Gaasterland Aachen

   Leiden University Medical Center

   Affiliation as printed

   Leiden University Medical Center , Leiden 2333 ZA , The Netherlands

3. Muhammad Imran Omar

   University of Aberdeen · European Association of Urology

   Affiliation as printed

   Academic Urology Unit , Health Sciences Building , University of Aberdeen , Aberdeen AB24 3FX , UK

   The Guideline Office , European Association of Urology , Arnhem 6803 AA , The Netherlands

4. Manon Engels

   Radboud University Medical Center

   Affiliation as printed

   Radboud University Medical Center , Nijmegen 6525 GA , The Netherlands

5. Agnies M. van Eeghen

   's Heeren Loo

   Affiliation as printed

   Heeren Loo Care Group , Amersfoort 3818 EN , The Netherlands

   Kinderpolikliniek Klinische Genetica , Amsterdam University Medical Centre , Amsterdam 1105 AZ , The Netherlands

6. Iris den Uijl

   Erasmus MC - Sophia Children’s Hospital

   Affiliation as printed

   Erasmus MC Sophia Children's Hospital , Rotterdam 3015 GD , The Netherlands . 11 Qualicura , Breda 4811 CP , The Netherlands

7. Willemijn F. E. Irvine

   European Organisation for Rare Diseases

   Affiliation as printed

   Bolz-Johnson , EURORDIS -Rare Diseases Europe , Brussels 1000 , Belgium