Publication date: Jul 03, 2026
Long COVID (LC/PASC) and Fibromyalgia (FM) share prominent pain, fatigue, and cognitive symptoms and are often difficult to distinguish clinically. The authors compared LC/PASC and FM using harmonized questionnaires assessing symptoms, function, and medication burden to quantify phenotype overlap and inform biomarker development. The authors analyzed a harmonized dataset including LC/PASC participants and FM-only comparators. Measures included age, sex, BMI, FIQR/SIQR-equivalent, BDI, CSI, MPQ, VAS pain, medication burden derived from free-text entries, and descriptive SF-36 domains. The sample included 54 LC/PASC and 889 FM-only visits. LC/PASC participants were older and less often female. Across symptom and function measures, partial overlap was observed, with domain-specific differences. Medication burden was common; FM showed greater centrally acting medication use. SF-36 domains showed broad similarity with domain-specific differences. In this preliminary, hypothesis-generating comparison, LC/PASC and FM demonstrate partial and domain-specific overlap across questionnaire measures, while differences in medication exposure may influence symptom reporting and limit direct clinical comparisons. These findings support the need for prospective studies integrating objective biomarkers with standardized clinical phenotyping.
| Concepts | Keywords |
|---|---|
| Clinics | Biomarkers |
| Covid | Central sensitization |
| Female | Centrally acting agents |
| Fibromyalgia | Fibromyalgia |
| Free | FIQR |
| Long COVID | |
| Medication burden | |
| PASC | |
| SF-36 |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | long COVID |
| disease | MESH | fibromyalgia |
| disease | MESH | pain |
| disease | MESH | fatigue |
| disease | MESH | cognitive symptoms |
| disease | MESH | included |