R. Gancheva¹, A. Koundurdjiev ², T. Kundurzhiev ³ And Z. Kolarov ¹
¹ Clinic of Rheumatology, University Hospital St. Iv. Rilski, ² Clinic of Nephrology, University Hospital St. Iv. Rilski, ³ Faculty of Public Health, Medical University, Sofia, Bulgaria
Background: A lot of data link hyperuricemia and gout with higher thickness and stiffness of the common carotid arteries as well as with higher frequency of the atherosclerotic plaques. In recent years there are studies demonstrating that the presence of subcutaneous tophi in gout predicts arteriosclerotic changes of the common carotid arteries. Whether ultrasound deposits of monosodium urate (MSU) crystals are connected to such type of alterations of the common carotid arteries has not yet been established.
Objective: We aimed to determine whether ultrasound deposits of MSU crystals in the joints of gout patients (pts) associate with higher thickness and stiffness of the common carotid arteries.
Materials and methods: This was a single-center cross-sectional study including 56 consecutive gout pts, 40 males and 16 females, in a mean age 58.9±13.2 years with disease duration 6.42±6.93 years. All of them underwent ultrasound (US) examination of the common carotid arteries and US of the joints of the hands, elbows, knees, ankles and feet. By US of the common carotid arteries done with 10 MHz linear transducer working with pulse Doppler frequency of 5 MHz were measured parameters which are independent predictors of cardiovascular risk: intima-media thickness (IMT), common carotid artery resistive index (CCARI) and the presence of atherosclerotic plaques was recorded. US studies of the joints were performed with a high-frequency, linear transducer, 4-15 MHz. The existence of double contour sign, tendon MSU deposits, snow storm, tophi and tophi with erosions or a combination of these US features was assessed. Examinations were conducted in accordance with the latest published guidelines. Data were analyzed by Kolmogorov-Smirnov, Mann-Whitney, Fisher’s exact test or chi-square, Kruskal Wallis test and Spearman correlation.
Results: 49(87.5%) of the pts had ultrasound evidence of crystal deposits in the joints. Pts with and without MSU deposits in the joints had comparable mean values of serum uric acid (mean±SD; 472.92±113.29 µmol/l vs 440.44±67.30 µmol/l, p=0.569), ESR (mean±SD; 30.95±26.99 mm/h vs 33.63±26.82 mm/h, p=0.713) and CRP (mean±SD; 12.87±22.72 mg/l vs 15.20±37.90 mg/l, p=0.991). Among pts without ultrasound evidence of MSU crystals, subjects who had crystal deposits in one joint area and in those with MSU findings in two or more joint areas we did not establish a difference in the values of IMT (mean±SD; 0.92±0.19 mm vs 0.90±0.22 mm vs 1.19±1.39 mm, p=0.573), CCARI (mean±SD; 0.70±0.04 vs 0.74±0.13 vs 0.71±0.04, p=0.708) and in the distribution of atherosclerotic plaques (p=0.524). The mean values of IMT (p=0.856), CCARI (p=0.585) and the frequency of atherosclerotic plaques (p=0.250) were similar among pts without crystal deposits, those who had a double contour sign, subjects with tendon MSU deposits, pts with snow storm, individuals with tophi and in pts with tophi and erosions. No correlation existed between the number of joints with MSU findings and IMT and CCARI (r=0.072, p=0.955 and r=0.047, p=0.758, respectively).
Conclusions: We consider that the lack of association between US MSU deposits in the joints of gout pts with arteriosclerotic alterations of the common carotid arteries could be due to the lower level of the
systemic inflammatory process which they maintain in comparison to subcutaneous gouty tophi.
Keywords: monosodium urate crystal deposits; gout; arteriosclerotic vascular changes.