Exploring the frequency of anemia in axial spondyloarthritis patients: Implications for Systemic Immune-Inflammation Index and anti-TNF therapy

Objective: The aim of this study is to determine the frequency of anemia in patients with axial spondyloarthritis (axSpA) and to evaluate the interaction with systemic immüne- inflammation index and the results of anti-TNF treatment. Materials and Methods: A total of 102 patients, 51 males and 51 females, who met ASAS (Assessment of SpondyloArthritis İnternational Society) criteria for axSpA, were over 18 years of age, who continued regular anti-TNF treatment and follow-up for at least one year were included in the study. All patients treated with any anti-TNF agent (9 patients with etanercept, 27 patients with adalimumab, 63 patients with certolizumab pegol, 2 patients with golimumab and 1 patient with infliximab). From the laboratory examinations of the patients C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), hemoglobin (Hb), hematocrit (Hct) and mean erythrocyte volume (MCV) counts, and neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and Systemic immune- inflammation index (SII) values were compared before starting therapy and 1 year after the treatment. Results: Anemia was detected in 34 patients (8 men, 26 women) (33.3%) at baseline. After anti-TNF treatment, the rate of anemia was reduced by half (16.7%; 3 men, 14 women). The incidence of anemia in women was significantly higher than in men (p<0.001). ESR values of patients with anemia were significantly higher than those without anemia (p=0.002), but RBC, Hct and MCV values were significantly lower (p<0.001). There was a positive correlation between hemoglobin value and WBC, neutrophil and RBC count, Hct and MCV values (p=0.005, p=0.008, p<0.001, p<0.001, p<0.001, respectively), but there was a negative correlation with ESR (p< 0.001). A statistically significant difference (p<0.001) was found in the decrease in SII levels in the comparison made before and after anti-TNF treatment. There was a statistically significant difference in parameters other than platelet and erythrocyte count before and after anti-TNF treatment. Conclusion: Anemia is a common comorbidity in axSpA patients, often linked to inflammation. Conditions with high levels of inflammation and prolonged disease activity tend to result in more severe anemia. Anti-TNF therapy not only reduces disease activity but can also improve anemia status. Keywords: Axial spondyloarthritis, anemia of chronic disease, anti-TNF therapy