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2018 – 2019 REVIEW

Environmental health

Consensus process to develop clinical case definitions



The Centre for Effective Practice (CEP) was engaged to recruit and convene a panel of experts to develop consensus-based clinical case definitions for Environmental Sensitivities/Multiple Chemical Sensitivity (ES/MCS), Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), and Fibromyalgia (FM).

The goal of this work is to support the future potential development of guidelines, care pathways, and/or supports for patients living with these conditions and their caregivers. Since new research is emerging, these documents are intended as a starting point. This work is the result of recommendations put forward by the MOHLTC’s Task Force on Environmental Health (the Task Force), which highlighted a lack of knowledge and resources for providers about these conditions and a need for consensus on case definitions to support improved standardization of patient care.


The CEP team facilitated a modified Delphi process, with phases of work including:

  • Literature search for existing case definitions, indicators and review of findings
  • Selection, recruitment and engagement of the expert panel
  • Three rounds of anonymous Delphi surveys
  • Online (virtual) panel meeting
  • Final review period of draft materials

The Delphi method is a commonly used approach to achieve consensus amongst a group of experts.* The CEP team has conducted a number of Delphi panels in the past and leveraged previous experience/expertise as well as existing literature/best practices for the purposes of this project.

*Hsu C, Sandford BA. The Delphi Technique: Making Sense of Consensus. Practical Assessment, Research & Evaluation. 2007 August; 12(10).



  • Guiding Principles for the Diagnosis of Fibromyalgia

  • Guiding Principles for the Diagnosis of Environmental Sensitivities/Multiple Chemical Sensitivity

  • Guiding Principles for the Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

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