Evidence Gaps and Research Directions
The ME/CFS economic evidence base has several structural gaps that no single study has addressed:
No U.S. claims-data cost-of-illness study: The IOM estimate is modeled, not measured. An analysis of Medicare/Medicaid/private-insurer claims for patients with ICD-coded ME/CFS (G93.3) would produce the first direct measurement of U.S. ME/CFS healthcare utilization and costs. This is feasible with existing data.
No longitudinal lifetime-cost study: All existing cost data are cross-sectional. A cohort study tracking patients from diagnosis through the disease course would capture the temporal pattern of costs β whether they front-load (diagnostic odyssey), plateau (stable disability), or escalate (progressive worsening) β and would inform the timing of interventions.
No cost-effectiveness of the diagnostic pathway: The economic case for reducing diagnostic delay β that earlier diagnosis prevents inappropriate treatments, reduces healthcare utilization, and preserves employment β is plausible but unquantified. A Markov model comparing diagnosis at 6 months vs diagnosis at 5 years (the current median) would need data on what happens during the 4.5-year gap. Those data do not exist.
No caregiver monetary valuation: The 50.2% family-income reduction (Brittain 2021) is the closest proxy, but a formal willingness-to-pay or replacement-cost valuation would quantify the caregiver burden in terms that health-economic decision models can use.
No developing-country data: Every existing study comes from a high-income country. Post-infectious fatigue follows infectious-disease burden globally (Global and Low-Resource Perspectives on ME/CFS); the countries with the most triggering infections are the countries with zero economic data.
(Certainty: 0.60 β the gaps are confirmed by systematic reviews (Cochrane et al. 2021) and bibliometric analysis (Wan et al. 2024); the list is descriptive, not speculative.)
Consequence: This gap inventory is the research agenda for ME/CFS health economics. Each item is feasibly addressed with existing methods and, in several cases, existing data (U.S. claims, NZ administrative data, UK CPRD). The barriers are not methodological; they are institutional β no funding body has commissioned these studies. This is itself a consequence of the research underfunding documented in this chapter. Severity applicability: the research gaps affect evidence-based policy for all severity levels.