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 FiRST, evaluate its psychometric properties, and conduct its validation among patients with axial spondyloarthritis.
Patients and methods: We translated and performed the cross-cultural adaptation of FiRST into Polish, followed by its validation on a cohort of 174 patients with axial spondyloarthritis. For criterion validity, we employed the ACR 2016 fibromyalgia diagnostic criteria as the 'gold standard' for fibromyalgia diagnosis.
Results: The Polish version of FiRST demonstrated marginally acceptable internal consistency with a Cronbach's α coefficient of 0.644, but exhibited high test-retest reliability, with a global score correlation coefficient of 0.75 (P <0.001). ROC analysis indicated a good performance of the translated questionnaire (AUC of 0.803). The accuracy of the derived cut-off 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 Cohen's κ coefficient of 0.46.
Conclusions: Our study successfully produced a validated Polish version of FiRST. Although it may not be the 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.