To analyze the diagnostic utility of clinical, laboratory, and imaging items for gout.
A systematic literature search was performed in MEDLINE, EMBASE, and The Cochrane Library; and a manual search of abstracts from the 2010/2011 meetings of the American College of Rheumatology (ACR) and the European League Against Rheumatism, as well as the reference lists of retrieved papers. Studies were included if they evaluated the diagnostic utility of clinical, laboratory, or imaging features or criteria for the diagnosis or classification of gout in adult patients. Two independent reviewers selected papers, extracted the data, and assessed the risk of bias.
Nineteen studies were included in the review; 4 used the identification of monosodium urate (MSU) crystals as the reference standard (RS) and the rest used expert opinion or the ACR preliminary criteria. Most features were evaluated in a single study. Evidence for diagnostic utility, using MSU crystals as RS, of over 50 individual clinical, laboratory, and radiographic features was retrieved. Most items showed a positive likelihood ratio (LR+) < 3, except for the following: response of arthritis to colchicine (LR+ 4.3); presence of tophi on physical examination (LR+ 15.6-30.9); identification of the double-contour sign in ultrasound (US) (LR+ 13.6); and detection of urate deposits by dual-energy computed tomography (DECT) (LR+ 9.5).
Individual clinical features show low diagnostic utility, with the exception of tophi and response to colchicine. Some US and DECT findings show better performance than most clinical features.