Is anemia a clinical marker of NSAIDs-induced upper gastrointestinal lesions in patients with spondyloarthritis?

Background : Anemia is a frequent comorbid conditions in patients with spondyloarthritis (SpA). Its development is associated with the activity of the underlying disorder, and in some cases can be a complication of medical treatment. Investigation into the particulars of the anemia, its prevalence in SpA patients is of considerable interest due to the long-term inflammatory process, on the one hand, and high frequency of non-steroidal anti-inflammatory drugs (NSAIDs) usage, on the other. Aim : To assess the incidence of NSAID-induced lesions of upper gastrointestinal tract in patients with SpA and anemia. Materials and methods : This cross-sectional observational study included 107 patients with proven SpA (mean age, 44 [36; 53] years; SpA duration, 16 [9; 21] years; men, 61.9%) who were treated in the Department of Rheumatology, Saratov Regional Clinical Hospital, from 2017 to 2018. We assessed their blood cell counts, C-reactive protein levels, iron kinetic parameters (serum iron, transferrin, ferritin, transferrin saturation). Anemia was diagnosed according to the World Health Organization criteria. Two groups were formed depending on the presence of absolute iron deficiency: group 1, 13 patients with anemia of chronic disease (ACD), group 2, 3 patients with iron deficiency anemia (IDA) and 26 patients with ACD + IDA. Esophagogastroduodenoscopy (EGDS) was performed to assess mucous membranes of the upper gastrointestinal tract in patients with anemia. Results : Anemia was found in 42 (39.3%) patients, 38 (90.5%) of them had mild anemia. The increase in the activity of the underlying disorder judged by changes in the laboratory markers of systemic inflammation (erythrocyte sedimentation rate and C-reactive protein levels) significantly correlated with a decrease in hemoglobin concentration (r = -0.5715 and r = -0.3498 respectively, p<0.05). At EGDS, NSAIDs-induced erosions in the esophagus and/or stomach were found detected in 1 (7.7%) patient of the group 1 and in 1 (3.4%) patient of the group 2. A past episode of NSAIDs-induced erosions in the stomach and duodenum was noted in 4 (13.8%) patients of the group 2, whereas at the time of the study no mucous membranes defects were found at EGDS. Conclusion : Anemia was found in more than one third of SpA patients, with 29 of them (69%) having laboratory signs of iron deficiency, but only 1 (3.4%) patient had NSAIDs-induced gastropathy confirmed at EGDS. NSAIDs-associated enteropathy could be the cause of iron deficiency in these patients that would require additional patient examination. The development of iron deficiency can be pathophysiologically associated to prolonged inhibition of alimentary iron absorption against the background of persistent systemic inflammation and depletion of the iron pool in the absence of gastrointestinal blood losses.