Assessment of sensitivity and specificity of ultrasonographic features of gout in intercritical and chronic phases

Abstract

Aim To study the usefulness of ultrasonography (US) in the diagnosis of gouty arthritis and to assess its sensitivity and specificity in intercritical and chronic stages and also its use in comparing patients with high serum uric acid (HSUA) and low serum uric acid (LSUA). Patients and methods We studied 60 patients known to be gouty in either chronic phase or intercritical phase, diagnosed clinically and through laboratory assessments, and 30 controls. Demographic, clinical, and serological data were evaluated. Knee and first metatarsophalangeal joints were assessed by musculoskeletal US by a blinded radiologist. Results A total of 53 (88.3%) patients were in the intercritical stage of gout during the study, and seven (11.6%) patients had chronic gout with clinically detectable tophi. Double contour sign (DCS) was found in 57.5% and tophi were found in 41.6% of first metatarsophalangeal joints. DCS was present in 42 (70%) patients with gout, and in only one of the control group (P < 0.001). Comparing patients with HSUA and LSUA subgroups, DCS was detected in 92.3% in HSUA subgroup, but in only 28.5% in LSUA subgroup, with P value less than 0.004. The sensitivity of DCS increased to 92.9% in patients who had HSUA within the past 6 months before the US was done. In the LSUA subgroup, where sensitivity of DCS was low (28.5%), sensitivity of tophi was 48.7%, and it increased in the presence of both tophi and erosion in any joints to 66.6% compared with the control group. Finally, there was a positive correlation between tophi and erosions and disease duration, with r = 0.81 and P= 0.01 and r = 0.27 and P= 0.035, respectively. Conclusion Musculoskeletal US is useful for diagnosis of gout in intercritical and chronic stages, especially in patients with HSUA level and long disease duration.

Keywords

• double contour sign
• gout
• gout imaging
• ultrasonography in gout
• uric acid