Frequency of anemia of inflammation in patients with ankylosing spondylitis requiring anti-TNFa drugs and therapy-induced changes

Objective: Primary: to evaluate the frequency of anemia of inflammation (AOI) in a clinical series of patients with ankylosing spondylitis (AS) requiring anti-TNF (tumor necrosis factor) agents. Secondary: to examine anti-TNF therapy-induced changes in AOI. Method: Prospective, follow-up, 6-month study of all consecutive, new patients with AS requiring anti-TNF alpha drugs observed between January 2004 and December 2008. AOI was defined according to WHO criteria. Primary outcome measure: the proportion of patients showing AOI at baseline. Secondary outcome measures: the proportion of patients achieving resolution of AOI at the 6-month visit; the proportion of patients achieving any improvement in haemoglobin (Hb); the proportion of patients with any improvement in blood results. Results: One hundred and six patients (42 women and 64 men; mean age: 46 years) with AS were evaluated. Sixteen of these (15%) presented with AOI at baseline. After 6 months therapy 13 patients (81%) resolved AOI while two presented an Hb level reduction. After 6 months therapy we did not find a significant statistical improvement in red blood cell numbers (P = 0.85) and transferrin (P = 0.08) levels. Hb, mean corpuscular volume (MCV), iron, ferritin, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) improved reaching statistical significance (P = 0.0002, 0.0001, 0.001, 0.014; 0.007, 0.004, respectively). Conclusion: We found 15% frequency of AOI among a selected series of patients with AS. After 6 months of anti-TNF alpha therapy AOI resolved in the majority of patients with significant improvement of Hb, MCV, CRP and ESR levels.