Identifying Comorbid Fibromyalgia in Inflammatory Arthritis: The Role of Disease Activity in Fibromyalgia Survey Questionnaire Performance.

OBJECTIVE

To evaluate the utility of the Fibromyalgia Survey Questionnaire (FSQ) as a screening tool for fibromyalgia (FM) in patients with inflammatory arthritis (IA) and to determine optimal cutoff points according to arthritis disease activity.

METHODS

Patients with rheumatoid arthritis (RA), axial spondyloarthritis (SpA), and psoriatic arthritis (PsA), with and without comorbid fibromyalgia (FM) at a 1:1 ratio were invited to participate in this cross-sectional study. FM status was defined by an expert physician's diagnosis. Disease activity indexes were recorded. Participants completed the FSQ through a structured online interview. ROC analysis and the area under the curve (AUC) were calculated to identify the optimal FSQ cutoff values.

RESULTS

A total of 152 IA patients were included (72% RA, 11% SpA, and 17% PsA), 51% of whom had comorbid FM. The ability of the FSQ to differentiate comorbid FM among patients in remission or with low disease activity (n=80) was high (AUC=0.896), showing 88% sensitivity and 88% specificity at a cutoff >12. In contrast, the FSQ performance was lower in patients with moderate to very high disease activity (n=72, AUC=0.695), with 83% sensitivity and 56% specificity at a cutoff >15.

CONCLUSIONS

The FSQ is a useful screening tool for identifying comorbid FM in IA patients with low disease activity or in remission, with performance comparable to the general population (cutoff value >12). Results should be interpreted cautiously in those with active disease. These findings may facilitate the recognition and management of comorbid FM in IA patients.