OBJECTIVE: To develop a new composite disease activity score for gout and provide its first validation. METHODS: Disease activity has been defined as ongoing presence of urate deposits that lead to acute arthritis and joint damage. Every measure for each OMERACT core domain was considered. A three-step approach (factor analysis, linear discriminant analysis and linear regression) was applied to derive the gout activity score (GAS). Decision to change treatment or 6-month flare count were used as surrogate criterion of high disease activity. Baseline and 12-month follow-up data of 446 patients included in the Kick-off of the Italian Network for Gout (KING) cohort were used. Construct and criterion-related validity were tested. External validation on an independent sample is reported. RESULTS: Factor analysis identified 5 factors: patient-reported outcomes, joint examination, flares, tophi and serum uric acid (sUA). Discriminant function analysis resulted in a correct classification of 79%. Linear regression analysis identified a first candidate GAS including: 12 month flare count, sUA, visual analogue scale (VAS) of pain, VAS global activity assessment, swollen and tender joint count and cumulative measure of tophi. Alternative scores were also developed. The developed GAS demonstrated a good correlation with functional disability (criterion validity) and discrimination between patient- and physician-reported measures of active disease (construct validity). The results were reproduced in the external sample. CONCLUSION: This study developed and validated composite measure of disease activity in gout. Further testing is required to confirm its generalisability, responsiveness and usefulness in assisting with clinical decisions.
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|Titolo:||Development and first validation of a disease activity score for gout|
|Data di pubblicazione:||2016|
|Appare nelle tipologie:||03.1 Articolo su rivista|