Table 3 Strategies for development of diagnostic biomarkers in ME/CFS

1. Standardization of sample collection and assay procedures

2. Use of an uniform clinical case definition

3. Use of questionnaires to assess symptoms and severity to define subgroups

4. Stratification of patients according to sex, disease onset, and disease duration

5. Include sex- and age-matched control groups

6. Sufficient sample size and predefined hypotheses (statistical power)

7. Confirmation of results in validation and multi-center cohort studies

8. Study combinations of biomarkers, perform pathway analysis or functional studies