Coexistent rheumatoid arthritis and hyperuricemia: clinical and immunological features

BACKGROUND: Currently, the negative role of asymptomatic hyperuricemia (HU) in the development and progression of cardiovascular pathology, metabolic disorders and chronic kidney disease is generally recognized. There is not much data in the literature on the effect of HU on the course of rheumatoid arthritis (RA), therefore, the study of the relationship of HU with clinical, radiological and immunological features of RA seems relevant.

AIM: To study the relationship between HU with the clinical, radiological and immunological features of RA.

MATERIALS AND METHODS: The data of 262 patients with RA and HU and 262 with RA without HU (comparison group) included in the city register from January 2000 to April 2020 have been analyzed. The information included demographic features (gender, age), diagnosis, presence and duration of HU, duration of observation, disease activity, laboratory, immunological, radiological and functional parameters, therapy of the underlying disease. HU was understood as a recorded ≥1-fold increase in the level of uric acid (UA) in the blood serum >360 mmol/l. The study has been approved by the local ethics committee.

RESULTS: The data of 524 patients with rheumatoid arthritis for the period from January 2000 to April 2020 have been analyzed. The study included 440 women and 84 men. The average age of the patients was 60.0 ± 13.6 y. The patients with HU have been divided into two subgroups: the first – with the level of UA less than 500 mmol/l, the second — with the level of UA more than 500 mmol/l. The number of males was significantly higher among the patients with high HU than among the patients with low HU and the comparison group. Every third patient had significant structural changes in the joints (radiological stage III-IV) and 98% of the patients had moderate and pronounced functional limitations (functional class 2-3). The patients with HU were older, had more follow-up visits, were observed for a longer period of time, had a lower frequency of radiological progression, a greater number of painful and swollen joints, less often and at a smaller dose had methotrexate and more often sulfasalazine in comparison with the patients without HU (p < 0.05).

CONCLUSIONS: 1) Thus, we can emphasize the negative impact of hyperuricemia on the course of rheumatoid arthritis: if it is present, there are direct (more PJ, SJ) and indirect signs of a more severe course (longer duration of observation and the number of visits). 2) Immunosuppressive therapy is associated with the absence of differences with the generally recognized markers of disease activity (ESR, CRP, DAS28), the immunological profile (RF, ACCP) and the ambiguous relationship with radiological progression and functional insufficiency of the joints, as well as unreliable relationship with a higher frequency of bone density reduction.