ASSESSMENT OF COXITIS PROGRESSION IN EARLY AXIAL SPONDYLOARTHRITIS

Recently, various visualization techniques have been used to study spondyloarthritis (SpA); indices are also being elaborated to assess the progression of radiographic changes in the spine and sacroiliac joints. Most studies dedicated to the problem of coxitis in SpA have shown that its progression parallels with a spinal inflammatory process; however, no indices for assessing the time course of changes in the hip joints (HJs) have been developed.Objective: to develop a method for assessing the radiographic progression of coxitis in early axial SpA (axSpA).Subjects and methods. Examinations were made in 175 patients (mean age, 28±6 years) with axSpA who met the 2009 ASAS criteria and had an inflammatory back pain duration of no more than 5 years. The analysis included 62 patients who had been followed up for at least 2 years and had plain pelvic bone X-ray films at the inclusion in the cohort and at 2 years after starting the follow-up. The sum of stages of radiographic coxitis (ssrC) was used to assess HJ injury progression. During the study, a formula was developed to assess the progression rate of radiographic coxitis.Results and discussion. The median difference in ssrC (ΔssrC) was 0.78 [0; 4] at baseline and at 2 years. During the study period, 63% of the patients showed no progression of ssrC; the latter increased by 1 score in 7 (11%) patients, by 2 scores in 11 (18%), by 3 scores in 1 (2%), and by 4 scores in 4 (6%). The ssrC averaged 0.54±0.79 at baseline and increased by 0.78 up to 1.32±1.34 (p=0.06) at 2 years. At baseline, the coxitis progression rate averaged 0.45 per year (it was conventionally accepted that the patients exhibited no signs of HJ injury at onset of the disease: ssrC was zero); that was 0.54 and 0.1 per year at 1 and 2 years of follow-up, respectively.Conclusion. The proposed calculation procedure is easily feasible and applicable in real practice, does not lead to additional investigations, and is economically feasible. This procedure allows monitoring the rate of radiographic coxitis progression in patients with axSpA throughout the course of the disease.