Development and validation of the AF score for diagnosis of adult-onset Still's disease in fever of unknown origin

To develop and validate a diagnostic score to identify adult-onset Still's disease (AOSD) in fever of unknown origin (FUO). A single center, retrospective case-control study of inpatients with FUO from January 2018 to December 2021. Using clinical and laboratory data from 178 cases with AOSD and 486 cases with FUO, we developed an AOSD/FUO (AF) score with a Bayesian Model Averaging approach. AF score and Yamaguchi's criteria were evaluated by sensitivity, specificity, accuracy, and positive/negative predictive value for diagnosis of AOSD in developmental and validation samples. Persistent pruritic eruptions (PPEs) in patients with rashes was higher in AOSD group than FUO group (52.3% vs 7.4%; P