Clinical and Experimental Rheumatology 2014; 32: 533-538. Diagnostic outcomes associated with ankle synovitis in early infammatory arthritis: a cohort study A. Abhishek 1 , P. de Pablo 2 , M.Z. Cader 3 , C.D. Buckley 4 , K. Raza 4 , A. Filer 2 1 University of Birmingham; Department of Rheumatology, University Hospital Birmingham NHS Foundation Trust, Birmingham; and Addenbrooke’s Hospital, Cambridge University Hospital NHS Foundation Trust, Cambridge, United Kingdom; 2 University of Birmingham, and Dept. of Rheumatology, University Hospital Birmingham NHS Foundation Trust, Birmingham, United Kingdom; 3 University of Birmingham, Birmingham, United Kingdom; 4 University of Birmingham, and Dept. of Rheumatology, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, United Kingdom. Abstract Objective To examine the diagnostic outcomes associated with clinical ankle synovitis in an early infammatory arthritis cohort. Methods Data from the Birmingham early infammatory arthritis cohort (BEACON) were used to obtain information about baseline disease and demographic variables and diagnostic outcomes at 18 month follow-up. The prevalence of clinical ankle synovitis (defned as joint swelling on examination) was calculated. Relative risk (RR) and 95% confdence interval (95% CI) were used to estimate whether clinical ankle synovitis at baseline predicts diagnostic outcomes independent of age, sex, baseline 66-joint swollen joint count, and presence of either rheumatoid factor (RF) or anti-CCP antibody. Results 324 patients (52% women) were included. 103 had clinical ankle synovitis at the frst clinic visit. Patients with bilateral ankle synovitis were more likely to be classifed as having acute sarcoid arthritis (aRR (95%CI) 10.15 (1.13–90.89)). Among patients presenting with oligoarthritis and seronegative for RF and anti-CCP antibodies those with ankle synovitis were signifcantly more likely to be classifed as having seronegative spondyloarthritis (RR (95%CI) 6.15 (1.58–23.88) and unclassifed arthritis (RR (95%CI) 4.07 (1.05–15.81)) than RA. Conclusion Current predictive algorithms for patients with early arthritis focus on the prediction of RA or persistent arthritis. This alternative approach focused on a specifc joint shows that baseline ankle synovitis predicts specifc diagnostic outcomes besides RA. Future work should address the development of models to predict the totality of potential outcomes based on clinical phenotype and the results of routinely available investigations and clinical data. Key words sarcoidosis, ankle synovitis, early infammatory arthritis.