Validation of the Fibromyalgia Rapid Screening Tool in patients with axial spondyloarthritis: Polish version adaptation and value in clinical practice.

Introduction: Fibromyalgia frequently co‑occurs with axial spondyloarthritis. The Fibromyalgia Rapid Screening Tool (FiRST) is a well‑recognized screening tool for fibromyalgia and has been translated into multiple languages. Yet, it has not been adapted into Polish, nor has it been validated in the context of axial spondyloarthritis.

Objectives: This study aimed to create a Polish version of the FiRST, evaluate its psychometric properties, and conduct its validation among patients with axial spondyloarthritis.

Patients and methods: We translated and performed a cross‑cultural adaptation of the FiRST into Polish, followed by its validation in a cohort of 174 patients with axial spondyloarthritis. For criterion validity, we employed the 2016 American College of Rheumatology fibromyalgia diagnostic criteria as the gold standard for fibromyalgia diagnosis.

Results: The Polish version of the FiRST demonstrated marginally acceptable internal consistency with the Cronbach α coefficient of 0.644, but exhibited high test‑retest reliability, with a global score correlation coefficient of 0.75 (P <0.001). Receiver operating characteristic analysis indicated a good performance of the translated questionnaire (area under the curve of 0.803). The accuracy of the derived cutoff value for the global score (5+ points, consistent with the original instrument) was 75.3%, featuring higher specificity (82.6%) than sensitivity (63.1%), and a fair level of diagnostic agreement, as indicated by the Cohen κ coefficient of 0.46.

Conclusions: Our study provided a validated Polish version of the FiRST. Although it may not be an ideal tool for screening in axial spondyloarthritis cases and should be used cautiously in research, it proves to be a useful instrument in daily clinical settings.