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Objective To determine which clinical, laboratory and imaging features most accurately distinguished gout from non-gout. Methods A cross-sectional study of consecutive rheumatology clinic patients with at least one swollen joint or subcutaneous tophus. Gout was defined by synovial fluid or tophus aspirate microscopy by certified examiners in all patients. The sample was randomly divided into a model development (2/3) and test sample (1/3). Univariate and multivariate association between clinical features and MSU-defined gout was determined using logistic regression modelling. Shrinkage of regression weights was performed to prevent over-fitting of the final model. Latent class analysis was conducted to identify patterns of joint involvement. Results In total, 983 patients were included. Gout was present in 509 (52%). In the development sample (n=653), these features were selected for the final model (multivariate OR) joint erythema (2.13), difficulty walking (7.34), time to maximal pain < 24 hours (1.32), resolution by 2 weeks (3.58), tophus (7.29), MTP1 ever involved (2.30), location of currently tender joints: Other foot/ankle (2.28), MTP1 (2.82), serum urate level > 6 mg/dl (0.36 mmol/l) (3.35), ultrasound double contour sign (7.23), Xray erosion or cyst (2.49). The final model performed adequately in the test set with no evidence of misfit, high discrimination and predictive ability. MTP1 involvement was the most common joint pattern (39.4%) in gout cases. Conclusion Ten key discriminating features have been identified for further evaluation for new gout classification criteria. Ultrasound findings and degree of uricemia add discriminating value, and will significantly contribute to more accurate classification criteria.

Objectives To examine the performance of ultrasound for the diagnosis of gout using presence of monosodium urate (MSU) crystals as the gold standard. Methods We analyzed data from the Study for Updated Gout Classification Criteria (SUGAR), a large, multi-center observational cross-sectional study of consecutive subjects with at least one swollen joint who conceivably may have gout. All subjects underwent arthrocentesis; cases were subjects with MSU crystal confirmation. Rheumatologists or radiologists, blinded to the results of the MSU crystal analysis, performed ultrasound on one or more clinically affected joints. Ultrasound findings of interest were: double contour sign (DCS), tophus, and ‘snowstorm’ appearance. Sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated. Multivariable logistic regression models were used to examine factors associated with positive ultrasound results among subjects with gout. Results Ultrasound was performed in 824 subjects (416 cases and 408 controls). The sensitivity, specificity, PPV and NPV for the presence of any one of the features were 76.9%, 84.3%, 83.3% and 78.1% respectively. Sensitivity was higher among subjects with disease ≥2 years duration and among subjects with subcutaneous nodules on exam (suspected tophus). Associations with a positive ultrasound finding included suspected clinical tophus (odds ratio 4.77; 95% CI 2.23–10.21), any abnormal plain film radiograph (4.68; 2.68–8.17) and serum urate (1.31; 1.06–1.62). Conclusions Ultrasound features of MSU crystal deposition had high specificity and high positive predictive value but more limited sensitivity for early gout. The specificity remained high in subjects with early disease and without clinical signs of tophi.

Objective-To test the usefulness of the Chapel Hill nomenclature, supplemented with surrogate parameters, as diagnostic criteria for primary vasculitides. Methods-To prospectively evaluate vasculitis patients according to a standardised clinical and para-clinical programme. In accordance with the Chapel Hill publication surrogate parameters were used: proteinuria, haematuria and red blood cell casts (glomerulonephritis), angiographic or ultrasonic demonstration of aneurysms or stenoses (arteritis), radiological lung infiltrates or cavitations of more than one month's duration (granuloma in the lungs), bloody nasal discharge or crusts, chronic sinusitis, otitis and/or mastoiditis, bone and/or cartilage destruction, and acute hearing loss (granuloma in upper airways). Results-The following entities were diagnosed: giant cell arteritis (n=14), Takayasu arteritis (n=1), polyarteritis nodosa (n=2), Wegener's granulomatosis (n=27), ChurgStrauss syndrome (n=2), microscopic polyangiitis (n=12), Henoch-Schönlein purpura (n=2), cutaneous leucocytoclastic angiitis (n=37), and secondary vasculitis (n=21). Giant cell arteritis and cutaneous leucocytoclastic angiitis were in all cases diagnosed by biopsy. Using the Chapel Hill nomenclature supplemented with surrogate parameters, only 8 of 27 patients were diagnosed with Wegener's granulomatosis, and 3 of 12 cases with microscopic polyangiitis. The number of patients in the remaining diagnostic entities were considered to few to evaluate. The most recent proposal was made at the Chapel Hill conference in North Carolina in 1992, where a nomenclature defining 10 primary vasculitides was formulated. Conclusions-The3 The Chapel Hill Group made "great eVorts to adopt names and definitions already widely accepted". However, it diVered fundamentally from other classification schemes in that classic polyarteritis nodosa (PAN) was restricted to necrotising inflammation of medium sized and small arteries only without glomerulonephritis or vasculitis in arterioles, capillaries or venules. Furthermore, IgA dominant immune deposits were required in the definition of HenochSchönlein purpura, and cryoglobulin immune deposits were required for defining essential cryoglobulinaemic vasculitis. In the Chapel Hill description of Wegener's granulomatosis (WG) it was mentioned that necrotising glomerulonephritis was common, and that in microscopic polyangiitis (MPA) necrotising glomerulonephritis was very common. Thus, the presence of glomerulonephritis was not a necessary requirement in the definition of these diseases (table 1).Even though it was emphasised that WG, Churg-Strauss syndrome and MPA are associated with ANCA, the presence of ANCA was not included in the definition of any of these three diseases.Although the Chapel Hill report emphasised that the aim was to create a nomenclature of systemic vasculitides, we felt that the proposals might serve as diagnostic guidelines in the daily clinic, because of the clear definition of the type of vessel involved, and the presence or absen...