Clinical, Laboratory, and Treatment Characteristics of Rheumatology Patients Receiving Biologic and Targeted Synthetic Disease-Modifying Anti-rheumatic Drugs: Prevalence and Factors Associated with Elevated Hemoglobin Levels in a Real-life Cohort

Abstract

Objective: To investigate the prevalence of high hemoglobin (Hgb) levels and associated factors in patients receiving biologic and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) for rheumatic diseases. Methods: This retrospective single-center study included 267 patients receiving b/tsDMARDs between September 2023 and May 2025. Demographic, laboratory, and treatment data were recorded. Patients were classified as rheumatoid arthritis (RA), ankylosing spondylitis (AS), or other rheumatic diseases. Factors associated with high Hgb levels were evaluated using binary logistic regression analyses. Results: Among 267 patients, 155 (58.1%) were female. Patients with RA were more frequently female, whereas patients with AS were predominantly male and had higher smoking rates. High Hgb levels were detected in 34 (12.7%) patients and were more frequent in AS than RA patients (22.4% vs. 5.8%, P = .001). In univariate analysis, younger age, male sex, AS diagnosis, smoking, and lower erythrocyte sedimentation rate (ESR) were associated with high Hgb levels. In multivariable analysis, male sex (odds ratio [OR]: 4.87, 95% CI: 1.64- 14.44, P = .004) and lower ESR (OR: 0.93, 95% CI: 0.87-0.99, P = .023) remained independently associated with high Hgb levels, whereas AS diagnosis was not independently associated with high Hgb levels after adjustment. Conclusion: High Hgb levels were more frequent in AS patients; however, AS diagnosis was not independently associated with high Hgb levels in the multivariable analysis. Male sex and lower ESR were independently associated with high Hgb levels in rheumatology patients receiving b/tsDMARDs.