Purpose
Fibromyalgia diagnosis and treatment response depend mostly on patient report, making patient-reported outcomes central to trial evidence. The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials provides recommendations for standardized outcome domains and endorsed patient-reported instruments in chronic pain trials. Whether fibromyalgia trials have converged on a common set of instruments remains unclear. We evaluated instrument standardization and IMMPACT alignment among registered fibromyalgia trials.
Methods
We conducted a cross-sectional meta-research analysis of 916 interventional fibromyalgia trials registered on ClinicalTrials.gov. Outcomes were classified against an inductively built dictionary of patient-reported outcome instruments, with alignment defined as registration of at least one consensus-body-endorsed instrument. Completeness and alignment were assessed relative to the consensus body’s 2005 publication, and cohort assembly and instrument detection were independently verified.
Results
Of 916 eligible trials, 778 (84.9%) named a patient-reported outcome instrument, rising from 47.4% in 2005 to a peak near 98% in 2021. Ninety-five distinct instruments were registered, but only 49.1% of these trials included one the consensus body endorses. The most common measure was the Fibromyalgia Impact Questionnaire, an unendorsed fibromyalgia-specific tool, and the non-endorsed Visual Analog Scale was registered nearly twice as often as the consensus-body-endorsed Numeric Rating Scale (348 vs. 192 trials).
Conclusion
Fibromyalgia trials have largely resolved whether to measure patient-reported outcomes, but instrument selection remains fragmented despite two decades of guidance, limiting comparability across trials. Requiring a consensus-body-endorsed instrument alongside a disease-specific measure would close this gap without sacrificing disease-specific detail.
Micaylon Moore, Hayden Keeler, Lauren Kocour, Noah Calvert, Makalie Lackey, Tanner Livsey, Ryan Langerman, Amy Nguyen, Arnab Mukherjee, Alicia Ito Ford & Matt Vassar
Disease Category: Rheumatology
Disease Name: Fibromyalgia
Age Range: 0 - 120
Sex: Either
Nature of Intervention: Any
- COS uptake study
- Other
- Systematic review
Search: Trials were identified by searching the ClinicalTrials.gov web interface for “fibromyalgia” on 14 July 2026, limited to interventional studies with no additional filters.
Alignment and COS: Alignment analyses were descriptive and exploratory, intended to characterize how closely registration practice tracked IMMPACT recommendations rather than assess adherence against a predefined threshold. Overall alignment was calculated as the proportion of named PRO trials registering at least one IMMPACT-endorsed instrument in any primary or secondary outcome. Because alignment is defined solely against the IMMPACT-endorsed instrument set, a trial registering a well-validated, disease-specific instrument such as the FIQR—without also registering an IMMPACT-endorsed measure—is scored as non-aligned under this operational definition; this reflects the scope of the definition rather than a judgment of instrument quality.