Association Between Isolated Regional Pain and Subsequent Fibromyalgia Documentation: A Retrospective Text-Mined Cohort Study.

BACKGROUND

Fibromyalgia may be documented after years of regional pain, but the localized presentations associated with subsequent fibromyalgia documentation in pain-clinic practice remain poorly defined. Documentation in health records may reflect delayed recognition rather than biological disease onset.

OBJECTIVE

To quantify subsequent fibromyalgia documentation after isolated, localized non-fibromyalgia pain presentations and to describe associated demographic and diagnostic patterns without inferring causality or biological progression.

METHODS

We conducted a retrospective longitudinal cohort study of 58,650 patients seen from June 2009 to June 2021, with follow-up through June 2026. Inclusion required exactly one localized non-fibromyalgia pain category on the first observed pain-clinic day, no non-negated fibromyalgia signal on that day, and at least five years of observed follow-up. A fibromyalgia signal was defined as at least one prespecified, non-negated fibromyalgia expression on a patient-day. Bilingual rule-based dictionaries identified pain categories and fibromyalgia. Proportions used patient-level denominators and Wilson confidence intervals.

RESULTS

Among 23,103 isolated-index patients, 13,391 had a five-year potential observation window and 2,783 had observed five-year follow-up. Later fibromyalgia was documented in 299 patients (10.74%, 95% CI 9.65-11.95) after a median 4.49 years. Patients with later documentation were younger than those without it. Sex-stratified proportions were 10.91% in women and 8.30% in men; these descriptive estimates do not establish an independent sex effect. High point estimates in small subgroups were imprecise.

CONCLUSION

Selected localized pain documentation phenotypes were associated with subsequent fibromyalgia documentation. These patterns may support earlier clinical assessment but do not establish biological progression or causality.