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Ultrasonographic Measurement of Tophi as an Outcome Measure for Chronic Gout FERNANDO PEREZ-RUIZ, IÑAKI MARTIN, and BEGOÑA CANTELI
ABSTRACT. Methods. Patients with crystal-proven gout were included. To evaluate validity, intraarticular and articular deep tophi were evaluated with both magnetic resonance imaging (MRI) and US. Tophi were punctured with US guidance to evaluate face validity. Interobserver and intraobserver measurement studies were done to evaluate reliability, and to estimate the smallest detectable difference. Sensitivity to change was evaluated with a 12-month followup observational study of urate-lowering therapy. Results. US detected at least one tophus in all joints where MRI found nodules considered to be tophi. There was a good correlation, but just fair agreement between measurements with US and MRI. Puncture of nodules suspected of being tophi recovered urate crystals in 83% of the procedures. Intraobserver intraclass correlation was > 0.90 for diameters and volume, while it was 0.71 to 0.83 in the interobserver study. US was found to be sensitive to change, and there was an inverse correlation between serum urate concentrations and change from baseline measurement of tophi. Conclusion. US measurement of tophi fulfilled the OMERACT filter for an outcome measure, although it should be tested further in randomized clinical trials. (First Release July 15 2007; J Rheumatol 2007;34:1888-93) Key Indexing Terms:
GOUT From the Sección de Reumatología and Servicio de Radiología, Hospital de Cruces, Baracaldo, Spain. Dr. Perez-Ruiz received an investigation grant from the Asociación de Reumatólogos del Hospital de Cruces. F. Perez-Ruiz, MD, PhD, Sección de Reumatología; I. Martin, MD; B. Canteli, MD, Servicio de Radiología, Hospital de Cruces. Address reprint requests to Dr. F. Perez-Ruiz, Sección de Reumatología, Hospital de Cruces, Pza Cruces sn, 48903 Baracaldo, Spain. E-mail: fperez@hcru.osakidetza.net Accepted for publication April 21, 2007. |
