Prevalence of fibromyalgia in France: a multi-step study research combining national screening and clinical confirmation: The DEFI study (Determination of Epidemiology of FIbromyalgia).

Background: Fibromyalgia is a common disease, but little is known on its real prevalence in France. This epidemiological study aimed to assess fibromyalgia (FM) prevalence in the French metropolitan population, based on a multi-step sampling analysis, combining national screening and clinical confirmation by trained specialists.

Methods: a sampling method on the entire national territory was used: patients over 18 years of age accepting to take part in the study were contacted by telephone using the LFES Questionnaire, a screening test for FM. The, for patients detected by the LFESQ, a visit with a FM-trained rheumatologist was proposed to confirm FM, based on 1990 ACR criteria. Each detected patient completed the following self-questionnaires: SF36, HADS, stress VAS, Co-morbidities and Regional pain score.

Results: 3081 patients were contacted in 5 representative French regions, of which 232 patients were screened for FM. A fibromyalgia diagnosis was then confirmed by rheumatologist in 20 cases (17 female and 3 male, 56.9 ± 13.2 years). The final estimated FM prevalence was 1.6 (CI95: 1.2%; 2.0%). No significant difference was detected between the patients accepting (CS+) and refusing (CS-) rheumatologist visit for the SF36 score, regional pain score, stress VAS scale and co-morbidities. In patients detected for FM by the LFESQ, we found a statistically significant decrease in quality of life and a statistically significant increase in stress level in patients with a confirmed diagnosis (FM+) (6.3 ± 1.9) compared to patients with an invalidated diagnosis (FM-) (4.4 ± 2.8; p = 0.007). The study also demonstrated a significant association, independently of ACR criteria, between the diagnosis of FM and several factors such as regional pain score > 10, elevated stress level, low SF36 scale score and presence of gastro-intestinal disorder co-morbidities.

Conclusion: Fibromyalgia is a common condition; the 1.6% prevalence calculated in the French population in our study corroborates the figures published in the European literature. Our results also suggest that criteria such as regional pain score, stress level or SF36 quality of life, could represent useful tools in fibromyalgia diagnosis.