Objectives: There is no consensus on how to evaluate inflammatory activity in Takayasu's arteritis (TAK). Here we compare biochemical tests and three clinical scores, which evaluate inflammatory activity (IA) in TAK, versus quantitative 18F-FDG PET/CT as the gold standard.
Methods: This prospective study included patients with TA diagnosed according to the American College of Rheumatology (ACR) criteria. IA was assessed through laboratory tests, clinical scores of the National Institute of Health (NIH), Dabague-Reyes (DR) and the Indian Takayasu Clinical Activity Score 2010 (ITAS2010), and the result of these assessments was compared against 18F-FDG PET/CT Standardised Uptake Values (SUVmax).
Results: A total of 35 patients were studied, 86% were women. SUVmax had positive correlations with acute phase reactants and DR and NIH. Agreement of 18F-FDG PET/CT was significant with erythrocyte sedimentation rate (ESR) and DR score. Receiver Operating Characteristic (ROC) curve analysis showed diagnostic value for inflammatory activity in ESR, DR and NIH scores, which had higher specificity when they were estimated with new cut-off points for the Mexican population.
Conclusions: ESR and other phase reactants have good sensitivity but low specificity to evaluate IA in TAK when compared against 18F-FDG PET/CT. Among all the clinical scores, DR had the best diagnostic value, with strong potential as a clinical tool to define the inflammatory status in TAK patients when the study image is not available. However, in complex TAK cases with doubtful diagnosis after assessment by clinical scores or laboratory, 18F-FDG PET/CT remains mandatory.