The detection of erosive changes in the joints of hands and feet in rheumatoid arthritis: a comparison of ultrasound and radiology methods

BACKGROUND: The detection of bone tissue erosions in cases of rheumatoid arthritis has a fundamental importance for the purpose of defining the treatment strategy and it indicates the unfavorable outcomes. It is recognized that the sensitivity of X-ray in detecting the bone tissue erosions is lower comparing to the ultrasound examination, especially at the early stages of the disease. The application of non-invasive and safe methods for the diagnostics of rheumatoid arthritis opens new possibilities for successful treatment. AIM: to compare and to evaluate the results of ultrasound and radiological detection of destructive changes in the joints of the hands and feet in rheumatoid arthritis patients. METHODS: The research included 76 patients with an established diagnosis of rheumatoid arthritis. Radiography and ultrasound examination of the joints in the hands and feet were carried out at the moment of enrollment into the research and later on in 1 and 4 years. RESULTS: The findings included a slight degree of correlation between the two absolute values — the number of joints with erosions according to the data from the ultrasound examination and according to the radiology examination findings. The rate of progression of the erosive changes was more pronounced in the data from ultrasound examination comparing to the radiology findings: from 0.5 [0; 1] to 2.5 [0; 6.0] (p=0.001) and from 0 [0; 1] to 0 [0; 3] (p=0.001), respectively. When evaluating the comparability of the two methods used for detecting the erosive changes in the joints of the hands and feet at each observation point by means of using the Bland–Altman method, it was shown that the results from both methods partially reach the outside of the margins of two standard deviations, which indicates the low degree of agreement between them. The mean difference between the measurements was -0.38 (95% CI -0.63…-0.13) before treatment, -1.15 (95% CI -1.5…-0.79) at the follow-up point of 12 months and -1.52 (95% CI -2.32…-0.73) in 4 years, which indicates the presence of systematic deviations. No correlation was detected between the difference in the number of joints with erosions and the mean number of joints with erosions according to the ultrasound examination and according to the radiography findings. CONCLUSION: Ultrasound examination and radiography are not equivalent methods of detecting erosions in rheumatoid arthritis, however, ultrasound examination helps detecting early progression of the process, which is a key to successful therapy of rheumatoid arthritis.