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DOP053. Clinical significance of C-reactive protein levels in predicting responsiveness to iron therapy in patients with inflammatory bowel disease and iron deficiency anaemia

T. Iqbal1, S. Vel2, 1University Hospital Birmingham, Department of Gastroenterology, Birmingham, United Kingdom, 2Vifor Pharma Ltd, Oncology and Gastroenterology, Glattbrugg, Switzerland

Background

Iron deficiency anaemia (IDA) is a common complication in inflammatory bowel disease (IBD). In clinical practice, many patients receive a trial course of oral iron therapy, although intravenous (IV) iron supplementation is often preferable. It is suggested that chronic inflammation negatively affects response to oral iron. This study aimed to investigate whether baseline C-reactive protein (CRP) can predict response to iron therapy.

Methods

Data from a randomised, multicentre, controlled, phase III trial [1] were retrospectively analysed. Eligibility included Crohn's disease (CD) or ulcerative colitis (UC) and IDA (Hb ≤110 g/L and transferrin saturation [TSAT] <20% or serum ferritin <100 ng/mL). Patients were randomised to either oral iron (ferrous sulphate; 100 mg iron bid for 12 weeks) or IV iron (ferric carboxymaltose; ≤1,000 mg iron at 1-week intervals until total calculated dose). Baseline levels of CRP, IL-6, IL-1β and TNF-α were measured. Patients were stratified by baseline CRP into high and low CRP subgroups, using the median baseline CRP (4 mg/mL) as cut-off. Haemoglobin (Hb) was assessed at baseline and follow-up visits (weeks 2, 4, 8 and 12).

Results

The full analysis set included 196 patients, 60 had received oral and 136 IV iron. Mean baseline Hb and levels of inflammatory markers were similar between treatment groups. Baseline CRP levels were independent of patients' baseline Hb (p = 0.79) and TSAT (p = 0.66). Oral iron-treated patients with high CRP (>4 mg/L) achieved a significantly lower Hb increase at weeks 2, 4 and 8 than those with low CRP (≤4 mg/L; Fig. 1A, p < 0.05). Among the 16 patients with CD receiving oral iron, Hb response was lower in the high CRP group (p < 0.05 vs. low CRP group at week 2; Fig. 1B). Response to IV iron was not significantly different between the two groups at week 2, 4 and 12 (Figs 1C,D). A significant difference was observed at week 8 only (Fig. 1C).

Figure 1. Mean change in Hb.

Conclusion

Patients with elevated baseline CRP (>4 mg/L) achieved a lower Hb response to oral iron than those with low/normal baseline CRP. In contrast, response to IV iron was, in the main, independent of CRP except at week 8. The observed difference at week 8 may reflect delayed release of iron from reticuloendothelial stores in active disease. Our results suggest that elevated CRP may be useful to identify IBD patients who may benefit from IV iron immediately. Validation in a larger patient sample is needed before clinical recommendations can be made.

1. Kulnigg S, Stoinov S, Simanenkov V, Dudar LV, Karnafel W, Garcia LC, Sambuelli AM, D'Haens G, Gasche C, (2008), A novel intravenous iron formulation for treatment of anemia in inflammatory bowel disease: the ferric carboxymaltose (FERINJECT) randomized controlled trial, Am J Gastroenterol, 103, 1182–92.