Management of gout by Moroccan rheumatologists: a Moroccan Society for Rheumatology National Survey.

To assess the modalities and current practices in gout management reported by Moroccan rheumatologists. We performed a cross-sectional online survey using a questionnaire e-mailed to 360 rheumatologists included 30 multiple-choice questions. 105 rheumatologists responded to the survey with 29% of response rate. The number of gout patients seen per month was five (3-9); they were referred in 58.7% by a general practitioner. The clinical presentation of gout patients was dominated by gout crisis in 71%, and the association gout crisis and gouty arthropathy accounted for 19% of severe forms. 40% of rheumatologists apply the 2015ACR/EULAR classification criteria. Obesity accounted for 85.7% of the associated comorbidities. The most commonly prescribed Urate-lowering therapy (ULT) was allopurinol in 81.3% (± 12). 48% of rheumatologists reported starting allopurinol at 200 mg daily and associated it with colchicine during the first 6 months by 33.3%. The determination of uric acid levels was monitoring in 76.2% every 3 months. Administration of ULT to asymptomatic hyperuricemia was found in 69.5% when patients had renal complications, while only 14.3% recommended dietary and lifestyle measures. The median duration for therapeutic education was 15 min (10, 20). In 96.2%, the education of the patient was done orally. 93.3% of rheumatologists inform their patients on how to manage a gout attack, and 96.2% on the measures of hygiene and diet has adopted. Our survey gives an insight into the elements that should be improved in the management of gout by the Moroccan rheumatologists. It highlights the need to standardize the management of gout, hence the importance of developing Moroccan recommendations on gout.

The performance of dual-energy CT in the classification criteria of gout: a prospective study in subjects with unclassified arthritis.

OBJECTIVE: To establish the performance of (subsets of) the 2015 ACR/EULAR gout classification criteria in patients with unclassified arthritis, and to determine the value of dual-energy CT (DECT) herein. Reference was the MSU crystal detection result in SF at polarization microscopy. METHODS: We included subjects with acute, unclassified mono or oligoarthritis, who underwent SF analysis and DECT. Performance was assessed by calculating area under the receiver operating characteristic curve of (i) the clinical criteria subset, (ii) the clinical+serum urate subset and (iii) the full set (including DECT). RESULTS: Of the 89 subjects enrolled, 40 met the clinical+serum urate subset criteria, and 49 (55%) subjects did not. Of these 49, 30 had a negative microscopy result, of whom 15 had positive DECT; of these 15, 14 met the full set criteria only after adding the positive DECT result. For the clinical-only subset, the areas under the curves (AUCs) were 0.68 and 0.69 without and with DECT result, respectively, and for the clinical+serum urate subset without and with DECT, AUCs were 0.81 and 0.81, respectively (results not significant). CONCLUSION: Adding the serum urate results to the clinical subset improves the performance, but adding the DECT result does not, neither does adding the DECT results to the clinical+serum urate subset. However, DECT seems to have an additive value in gout classification, especially when microscopy of SF is negative; 14/89 of patients (16%) only met the classification criteria with the use of DECT. TRIAL REGISTRATION: ClinicalTrials.gov, http://clinicaltrials.gov, NCT03038386.

Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) consensus statement regarding labels and definitions of disease states of gout.

OBJECTIVE: There is a lack of standardisation in the terminology used to describe gout. The aim of this project was to develop a consensus statement describing the recommended nomenclature for disease states of gout. METHODS: A content analysis of gout-related articles from rheumatology and general internal medicine journals published over a 5-year period identified potential disease states and the labels commonly assigned to them. Based on these findings, experts in gout were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach agreement on disease state labels and definitions. RESULTS: The content analysis identified 13 unique disease states and a total of 63 unique labels. The Delphi exercise (n=76 respondents) and face-to-face meeting (n=35 attendees) established consensus agreement for eight disease state labels and definitions. The agreed labels were as follows: 'asymptomatic hyperuricaemia', 'asymptomatic monosodium urate crystal deposition', 'asymptomatic hyperuricaemia with monosodium urate crystal deposition', 'gout', 'tophaceous gout', 'erosive gout', 'first gout flare' and 'recurrent gout flares'. There was consensus agreement that the label 'gout' should be restricted to current or prior clinically evident disease caused by monosodium urate crystal deposition (gout flare, chronic gouty arthritis or subcutaneous tophus). CONCLUSION: Consensus agreement has been established for the labels and definitions of eight gout disease states, including 'gout' itself. The Gout, Hyperuricaemia and Crystal-Associated Disease Network recommends the use of these labels when describing disease states of gout in research and clinical practice.

Performance of the 2015 American College of Rheumatology/European League against Rheumatism Classification Criteria for Gout in Korean Patients with Acute Arthritis.

BACKGROUND: We aimed to assess the performance of the 2015 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria for gout in Korean patients with acute arthritis and to compare the performance of the ACR/EULAR criteria to that of other sets of criteria for gout classification. METHODS: Patients with acute arthritis who underwent diagnostic arthrocentesis at one of the four participating rheumatology clinics were consecutively enrolled between February and December 2017. Crystal-proven gout was diagnosed upon confirming the presence of monosodium urate (MSU) crystals in patients with a clinical impression of gout as judged by the rheumatologist. The performance of the ACR/EULAR and other gout classification criteria, including the Rome, New York, American Rheumatism Association (ARA), Mexico, and Netherlands criteria, was analyzed regardless of the presence/absence of MSU crystals. RESULTS: The study enrolled 118 gout patients (all crystal-proven) and 95 non-gout patients. According to the area under the curve, the diagnostic performance was the highest for the ACR/EULAR classification criteria (sensitivity, 80.5%; specificity, 95.8%; area under the curve, 0.966), followed by the Netherlands, Rome, ARA, New York, and Mexico criteria. All six sets of criteria demonstrated lower sensitivity in patients exhibiting the first episode of acute arthritis. CONCLUSION: In Korean patients with acute arthritis, the ACR/EULAR classification criteria outperformed other sets of gout classification criteria even in the absence of information regarding the presence of MSU crystals. However, to enhance diagnostic sensitivity, synovial fluid analysis should be considered in patients with the first episode of acute arthritis.

The Validity of Gout Diagnosis in Primary Care: Results from a Patient Survey.

OBJECTIVE: Validate primary care diagnosis of gout by the Mexico and the Netherlands classification criteria. METHODS: Questionnaires on gout characteristics were sent to all individuals aged ≥ 18 with ≥ 1 International Classification of Diseases, 10th ed. diagnosis of gout at 12 primary care centers. RESULTS: Positive predictive values for gout diagnosis ranged from 71% for the Netherlands criteria to 80% for the Mexico criteria. Maximum inflammation within 24 h was the most common reported symptom (86%). CONCLUSION: The vast majority of gout cases in primary care fulfill classification criteria and are valid for research purposes.

Gout, Hyperuricemia, and Crystal-Associated Disease Network Consensus Statement Regarding Labels and Definitions for Disease Elements in Gout.

OBJECTIVE: The language currently used to describe gout lacks standardization. The aim of this project was to develop a consensus statement on the labels and definitions used to describe the basic disease elements of gout. METHODS: Experts in gout (n = 130) were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach consensus on the labeling and definitions for the basic disease elements of gout. Disease elements and labels in current use were derived from a content analysis of the contemporary medical literature, and the results of this analysis were used for item selection in the Delphi exercise and face-to-face consensus meeting. RESULTS: There were 51 respondents to the Delphi exercise and 30 attendees at the face-to-face meeting. Consensus agreement (≥80%) was achieved for the labels of 8 disease elements through the Delphi exercise; the remaining 3 labels reached consensus agreement through the face-to-face consensus meeting. The agreed labels were monosodium urate crystals, urate, hyperuric(a)emia, tophus, subcutaneous tophus, gout flare, intercritical gout, chronic gouty arthritis, imaging evidence of monosodium urate crystal deposition, gouty bone erosion, and podagra. Participants at the face-to-face meeting achieved consensus agreement for the definitions of all 11 elements and a recommendation that the label "chronic gout" should not be used. CONCLUSION: Consensus agreement was achieved for the labels and definitions of 11 elements representing the fundamental components of gout etiology, pathophysiology, and clinical presentation. The Gout, Hyperuricemia, and Crystal-Associated Disease Network recommends the use of these labels when describing the basic disease elements of gout.

The benchmark dose estimation of reference levels of serum urate for gout.

Hyperuricemia is the main risk factor for gout. Although the threshold of hyperuricemia has been recommended, the reference levels of serum urate for gout have not been clarified. In the present study, we estimated the reference levels of serum urate for gout. A study has shown the association between serum urate and incidence of gout during 5-15 years of follow-up. We calculated the reference levels of serum urate for gout based on the previous published data by using the benchmark dose (BMD) method. The subjects were divided into six groups according to serum urate levels (6.0, 6.5, 7.5, 8.5, 9.5, and 10 mg/dL). Gamma, LogLogistic, and LogProbit models were used in BMD calculation. If the benchmark response (BMR) was set at 5%, the 95% lower confidence bounds of BMD (BMDL) of serum urate for the total population were 8.09-8.14 mg/dL during 5 years of follow-up, 7.27-7.30 mg/dL during 10 years of follow-up, and 6.73-6.99 mg/dL during 15 years of follow-up. If the BMR was set at 1%, the BMDL further decreased by 1.4 mg/dL. They were 6.68-6.85 mg/dL, 5.97-6.03 mg/dL, and 5.25-5.36 mg/dL, respectively. Similar results were observed in men and women. A threshold of 7.0 mg/dL of serum urate may be not a sufficient goal for protection against gout. A stricter threshold of serum urate (< 6.0 mg/dL) should be made.

[Dual-energy computed tomography diagnostics for gout]. / Dual-Energy-Computertomographie-Diagnostik bei Gicht.

BACKGROUND: Non-invasive imaging modalities are used for the morphological and functional evaluation and diagnosis of gout; however, none of these methods are sufficiently sensitive or specific for the diagnosis of gout. By the use of dual-energy computed tomography (DECT) the direct visualization of sodium urate deposition is now possible. Moreover, it is possible to show the different pathological situations, disease activity and monitoring of tophaceous gout. The positive DECT scan became one of the 2015 ACR/EULAR classification criteria for gout 2 years ago. MATERIAL AND METHODS: The literature search from 2009-2017 in PubMed, with the search criteria "Dual Energy CT and Gout" revealed 77 publications on the DECT method. RESULTS: The DECT technique has a high sensitivity (90-100%) and a high specificity (83-89%) for diagnosing gout. The development of a semiquantitative scoring method also enables measurement of the severity of urate deposits at specific sites. CONCUSION: The gold standard for the diagnosis of gout is still the detection of monosodium urate monohydrate crystals by polarizing microscopy after a joint punction; however with the DECT it is possible to non-invasively visualize, measure and score urate deposition and is therefore suitable for estimating the severity and prognosis. Although not clinical validated, DECT may sometimes help to detect gout. More studies should be conducted.

GWAS of clinically defined gout and subtypes identifies multiple susceptibility loci that include urate transporter genes.

OBJECTIVE: A genome-wide association study (GWAS) of gout and its subtypes was performed to identify novel gout loci, including those that are subtype-specific. METHODS: Putative causal association signals from a GWAS of 945 clinically defined gout cases and 1213 controls from Japanese males were replicated with 1396 cases and 1268 controls using a custom chip of 1961 single nucleotide polymorphisms (SNPs). We also first conducted GWASs of gout subtypes. Replication with Caucasian and New Zealand Polynesian samples was done to further validate the loci identified in this study. RESULTS: In addition to the five loci we reported previously, further susceptibility loci were identified at a genome-wide significance level (p<5.0×10-8): urate transporter genes (SLC22A12 and SLC17A1) and HIST1H2BF-HIST1H4E for all gout cases, and NIPAL1 and FAM35A for the renal underexcretion gout subtype. While NIPAL1 encodes a magnesium transporter, functional analysis did not detect urate transport via NIPAL1, suggesting an indirect association with urate handling. Localisation analysis in the human kidney revealed expression of NIPAL1 and FAM35A mainly in the distal tubules, which suggests the involvement of the distal nephron in urate handling in humans. Clinically ascertained male patients with gout and controls of Caucasian and Polynesian ancestries were also genotyped, and FAM35A was associated with gout in all cases. A meta-analysis of the three populations revealed FAM35A to be associated with gout at a genome-wide level of significance (p meta =3.58×10-8). CONCLUSIONS: Our findings including novel gout risk loci provide further understanding of the molecular pathogenesis of gout and lead to a novel concept for the therapeutic target of gout/hyperuricaemia.

Diagnosis of Acute Gout: A Clinical Practice Guideline From the American College of Physicians.

Description: The American College of Physicians (ACP) developed this guideline to present the evidence and provide clinical recommendations on the diagnosis of gout. Methods: This guideline is based on a systematic review of published studies on gout diagnosis, identified using several databases, from database inception to February 2016. Evaluated outcomes included the accuracy of the test results; intermediate outcomes (results of laboratory and radiographic tests, such as serum urate and synovial fluid crystal analysis and radiographic or ultrasonography changes); clinical decision making (additional testing and pharmacologic or dietary management); short-term clinical (patient-centered) outcomes, such as pain and joint swelling and tenderness; and adverse effects of the tests. This guideline grades the evidence and recommendations by using the ACP grading system, which is based on the GRADE (Grading of Recommendations Assessment, Development and Evaluation) method. Target Audience and Patient Population: The target audience for this guideline includes all clinicians, and the target patient population includes adults with joint inflammation suspected to be gout. Recommendation: ACP recommends that clinicians use synovial fluid analysis when clinical judgment indicates that diagnostic testing is necessary in patients with possible acute gout. (Grade: weak recommendation, low-quality evidence).

Diagnosis of Gout: A Systematic Review in Support of an American College of Physicians Clinical Practice Guideline.

BACKGROUND: Alternative strategies exist for diagnosing gout that do not rely solely on the documentation of monosodium urate (MSU) crystals. PURPOSE: To summarize evidence regarding the accuracy of clinical tests and classification algorithms compared with that of a reference standard of MSU crystals in joint aspirate for diagnosing gout. DATA SOURCES: Several electronic databases from inception to 29 February 2016. STUDY SELECTION: 21 prospective cohort, cross-sectional, and case-control studies including participants with joint inflammation and no previous definitive gout diagnosis who had MSU analysis of joint aspirate. DATA EXTRACTION: Data extraction and risk-of-bias assessment by 2 reviewers independently; overall strength of evidence (SOE) judgment by group. DATA SYNTHESIS: Recently developed algorithms including clinical, laboratory, and imaging criteria demonstrated good sensitivity (up to 88%) and fair to good specificity (up to 96%) for diagnosing gout (moderate SOE). Three studies of dual-energy computed tomography (DECT) showed sensitivities of 85% to 100% and specificities of 83% to 92% for diagnosing gout (low SOE). Six studies of ultrasonography showed sensitivities of 37% to 100% and specificities of 68% to 97%, depending on the ultrasonography signs assessed (pooled sensitivity and specificity for the double contour sign: 74% [95% CI, 52% to 88%] and 88% [CI, 68% to 96%], respectively [low SOE]). LIMITATION: Important study heterogeneity and selection bias; scant evidence in primary and urgent care settings and in patients with conditions that may be confused with or occur with gout. CONCLUSION: Multidimensional algorithms, which must be validated in primary and urgent care settings, may help clinicians make a provisional diagnosis of gout. Although DECT and ultrasonography also show promise for gout diagnosis, accessibility to these methods may be limited. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality. (Protocol registration: https://effectivehealthcare.ahrq.gov/ehc/products/564/1937/gout-protocol-140716.pdf).

Gout Classification Criteria: Update and Implications.

Gout is the most common inflammatory arthritis, with a rising prevalence and incidence worldwide. There has been a resurgence in gout research, fueled, in part, by a number of advances in pharmacologic therapy for gout. The conduct of clinical trials and other observational research in gout requires a standardized and validated means of assembling well-defined groups of patients with gout for such research purposes. Recently, an international collaborative effort that involved a data-driven process with state-of-the art methodology supported by the American College of Rheumatology and the European League Against Rheumatism led to publication of new gout classification criteria.

Survey Definitions of Gout for Epidemiologic Studies: Comparison With Crystal Identification as the Gold Standard.

OBJECTIVE: To identify the best-performing survey definition of gout from items commonly available in epidemiologic studies. METHODS: Survey definitions of gout were identified from 34 epidemiologic studies contributing to the Global Urate Genetics Consortium (GUGC) genome-wide association study. Data from the Study for Updated Gout Classification Criteria (SUGAR) were randomly divided into development and test data sets. A data-driven case definition was formed using logistic regression in the development data set. This definition, along with definitions used in GUGC studies and the 2015 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) gout classification criteria were applied to the test data set, using monosodium urate crystal identification as the gold standard. RESULTS: For all tested GUGC definitions, the simple definition of "self-report of gout or urate-lowering therapy use" had the best test performance characteristics (sensitivity 82%, specificity 72%). The simple definition had similar performance to a SUGAR data-driven case definition with 5 weighted items: self-report, self-report of doctor diagnosis, colchicine use, urate-lowering therapy use, and hyperuricemia (sensitivity 87%, specificity 70%). Both of these definitions performed better than the 1977 American Rheumatism Association survey criteria (sensitivity 82%, specificity 67%). Of all tested definitions, the 2015 ACR/EULAR criteria had the best performance (sensitivity 92%, specificity 89%). CONCLUSION: A simple definition of "self-report of gout or urate-lowering therapy use" has the best test performance characteristics of existing definitions that use routinely available data. A more complex combination of features is more sensitive, but still lacks good specificity. If a more accurate case definition is required for a particular study, the 2015 ACR/EULAR gout classification criteria should be considered.

What Should Be the Cut Point for Classification Criteria of Studies in Gout? A Conjoint Analysis.

OBJECTIVE: To determine the acceptable level of positive predictive value (PPV) and negative predictive value (NPV) for classification criteria for gout, given the type of study. METHODS: We conducted an international web-based survey with 91 general practitioners and rheumatologists experienced in gout. Conjoint analysis was used as the framework for designing and analyzing pairs of 2 profiles, each describing a study type, a PPV, and an NPV. There were 5 study types presented: a phase III randomized controlled trial (RCT) of a nonsteroidal antiinflammatory drug versus prednisone for acute gout flares, a phase III RCT of a biologic agent for acute gout flares, a phase II RCT of a novel uricosuric drug of unknown efficacy and limited toxicity data, a case-control, genome-wide association study of gout, and a cohort study examining long-term outcomes of gout. PPV and NPV both had 5 levels ranging from 60-99%. RESULTS: The panelists in majority were male (65%) rheumatologists (93%) with an average of 19 years of practice, seeing 5 to 60 gout patients monthly. PPV was most highly weighted in decision making: the relative importance was 59% for PPV, 29% for NPV, and 13% for study type. The preferred PPV was 90% or 80%, with an accompanying NPV of 70% or 80%, dependent on study type. CONCLUSION: Preferred PPVs and NPVs range between 70% and 90% and differ by study type. A single cut point can be a reasonable approach for all study types if a PPV of 90% and NPV of 80% is approximated.

Dual-energy computed tomography has limited sensitivity for non-tophaceous gout: a comparison study with tophaceous gout.

BACKGROUND: Dual-energy computed tomography (DECT) is a new diagnostic tool for gout, but its sensitivity has not been established. Our goal was to assess the sensitivity of DECT for the detection of monosodium urate (MSU) deposits in non-tophaceous and tophaceous gout, both at the level of the patient and that of the individual joint or lesion. METHODS: DECT was performed on 11 patients with crystal-proven non-tophaceous gout and 10 with tophaceous gout and included both the upper and lower extremities in 20/21 patients. DECT images were simultaneously acquired at 80 and 140 kV and then processed on a workstation with proprietary software using a two-material decomposition algorithm. MSU deposits were color coded as green by the software and fused onto grey-scale CT images. The number and location of these deposits was tallied independently by two DECT-trained radiologists blinded to the clinical characteristics of the patient. Sensitivity of DECT was defined as the proportion of patients with a confirmed diagnosis of gout which was correctly identified as such by the imaging technique. All patients provided informed consent to participate in this IRB-approved study. RESULTS: MSU deposits were detected by DECT in ≥1 joint area in 7/11 (64 %) patients with non-tophaceous gout, but were only detected in 3/12 (25 %) joints proven by aspiration to be affected with gout. Inclusion of the upper extremity joints in the scanning protocol did not improve sensitivity. All 10 patients with tophaceous gout had MSU deposits evident by DECT. The sensitivity of DECT for individual gouty erosions was assessed in 3 patients with extensive foot involvement. MSU deposits were detected by DECT within or immediately adjacent to 13/26 (50 %) erosions. CONCLUSIONS: A DECT protocol that includes all lower extremity joints has moderate sensitivity in non-tophaceous and high sensitivity in tophaceous gout. However, DECT has lower sensitivity when restricted to individual crystal-proven gouty joints in non-tophaceous disease or individual erosive lesions in tophaceous gout. The detection of MSU deposits by DECT relates to their size and density and the detection parameters of the DECT scanner and adjustment of the latter might improve sensitivity.

Clinical Inquiry: How do clinical prediction rules compare with joint fluid analysis in diagnosing gout?

Clinical prediction rules effectively diagnose gout without joint fluid analysis. The American College of Rheumatology clinical prediction rules, the most accurate rules developed for research purposes, have a sensitivity of 92%, specificity of 89%, positive likelihood ratio of 8.36, and negative likelihood ratio of 0.09.

2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative.

OBJECTIVE: Existing criteria for the classification of gout have suboptimal sensitivity and/or specificity, and were developed at a time when advanced imaging was not available. The current effort was undertaken to develop new classification criteria for gout. METHODS: An international group of investigators, supported by the American College of Rheumatology and the European League Against Rheumatism, conducted a systematic review of the literature on advanced imaging of gout, a diagnostic study in which the presence of monosodium urate monohydrate (MSU) crystals in synovial fluid or tophus was the gold standard, a ranking exercise of paper patient cases, and a multicriterion decision analysis exercise. These data formed the basis for developing the classification criteria, which were tested in an independent data set. RESULTS: The entry criterion for the new classification criteria requires the occurrence of at least 1 episode of peripheral joint or bursal swelling, pain, or tenderness. The presence of MSU crystals in a symptomatic joint/bursa (i.e., synovial fluid) or in a tophus is a sufficient criterion for classification of the subject as having gout, and does not require further scoring. The domains of the new classification criteria include clinical (pattern of joint/bursa involvement, characteristics and time course of symptomatic episodes), laboratory (serum urate, MSU-negative synovial fluid aspirate), and imaging (double-contour sign on ultrasound or urate on dual-energy computed tomography, radiographic gout-related erosion). The sensitivity and specificity of the criteria are high (92% and 89%, respectively). CONCLUSION: The new classification criteria, developed using a data-driven and decision analytic approach, have excellent performance characteristics and incorporate current state-of-the-art evidence regarding gout.

Autosomal dominant tubulointerstitial kidney disease: diagnosis, classification, and management--A KDIGO consensus report.

Rare autosomal dominant tubulointerstitial kidney disease is caused by mutations in the genes encoding uromodulin (UMOD), hepatocyte nuclear factor-1ß (HNF1B), renin (REN), and mucin-1 (MUC1). Multiple names have been proposed for these disorders, including 'Medullary Cystic Kidney Disease (MCKD) type 2', 'Familial Juvenile Hyperuricemic Nephropathy (FJHN)', or 'Uromodulin-Associated Kidney Disease (UAKD)' for UMOD-related diseases and 'MCKD type 1' for the disease caused by MUC1 mutations. The multiplicity of these terms, and the fact that cysts are not pathognomonic, creates confusion. Kidney Disease: Improving Global Outcomes (KDIGO) proposes adoption of a new terminology for this group of diseases using the term 'Autosomal Dominant Tubulointerstitial Kidney Disease' (ADTKD) appended by a gene-based subclassification, and suggests diagnostic criteria. Implementation of these recommendations is anticipated to facilitate recognition and characterization of these monogenic diseases. A better understanding of these rare disorders may be relevant for the tubulointerstitial fibrosis component in many forms of chronic kidney disease.

Study for Updated Gout Classification Criteria: Identification of Features to Classify Gout.

OBJECTIVE: To determine which clinical, laboratory, and imaging features most accurately distinguished gout from non-gout. METHODS: We performed a cross-sectional study of consecutive rheumatology clinic patients with ≥1 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 (two-thirds) and test sample (one-third). Univariate and multivariate association between clinical features and monosodium urate-defined gout was determined using logistic regression modeling. Shrinkage of regression weights was performed to prevent overfitting 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), the following features were selected for the final model: joint erythema (multivariate odds ratio [OR] 2.13), difficulty walking (multivariate OR 7.34), time to maximal pain <24 hours (multivariate OR 1.32), resolution by 2 weeks (multivariate OR 3.58), tophus (multivariate OR 7.29), first metatarsophalangeal (MTP1) joint ever involved (multivariate OR 2.30), location of currently tender joints in other foot/ankle (multivariate OR 2.28) or MTP1 joint (multivariate OR 2.82), serum urate level >6 mg/dl (0.36 mmoles/liter; multivariate OR 3.35), ultrasound double contour sign (multivariate OR 7.23), and radiograph erosion or cyst (multivariate OR 2.49). The final model performed adequately in the test set, with no evidence of misfit, high discrimination, and predictive ability. MTP1 joint 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.