Objective To investigate the incidence of anaemia in patients with psoriatic arthritis (PsA) and explore the relationship between serum hemoglobin (Hb) levels and disease activity and treatment outcomes.

Methods Clinical data of PsA patients who visited the Department of Rheumatology and Immunology of the First Affiliated Hospital of Nanjing Medical University from March 2019 to May 2024 were collected. Anemia was determined based on Hb values (female < 110 g/L, male < 120 g/L), and clinical characteristics were compared between anemic and non-anaemic patients. Multivariate Logistic regression analysis was used to identify factors associated with treatment response.

Results Among anemic patients, the proportion of males was higher than that of females, and the difference was statistically significant (P=0.03). The incidence of skin lesions (P=0.002), peripheral arthritis (P < 0.001), spondylitis (P < 0.001), and enthesitis (P < 0.001) was higher in the anemic group than in the non-anemic group, with statistically significant differences. Patients with anemia had higher composite psoriatic disease activity index (CPDAI) (P < 0.008) and acute-phase reactant levels (P < 0.001), and the differences were statistically significant. Multivariate logistic regression analysis showed that patients with concomitant anemia were less likely to achieve the American College of Rheumatology 20% improvement criteria (ACR20) than those without concomitant anemia (OR=0.36, P=0.02).

Conclusion Anaemia is a common complication of PsA, associated with high disease activity and is a predictor of poor treatment response.