A Pilot Study to Assess the Efficacy and Tolerability of Reduced Dose Oral Iron in the Treatment of Iron Deficiency Anaemia in Inflammatory Bowel Disease Patients.

BACKGROUND:

Anaemia, particularly iron-deficiency anaemia, is a common complication of inflammatory bowel disease (IBD). The prevalence of anaemia (6-74%) and iron deficiency (36-90%) varies widely among reported studies. The predominant cause of iron deficiency in IBD is intestinal blood loss but other factors such as malabsorption and reduced intake may also play a role. Thus, the need for iron supplementation is an often encountered clinical problem in IBD. Although iron is commonly prescribed, the amount of elemental iron needed to achieve clinical efficacy, and the optimal method of supplementation, are under debate. As intravenous (IV) iron supplementation has become safer, calls for increased utilization have appeared. However, there are significant cost implications to using IV iron. On average, a 1-month supply of oral ferrous sulfate costs $12, in comparison with approximately $600-$700 for a treatment cycle of (IV) iron sucrose, excluding the cost of IV administration.

Overall, the comparative studies of IV vs. oral iron do not demonstrate a significant difference in haemoglobin repletion favouring IV iron therapy. Haemoglobin concentrations were similar at the end of treatment in all studies. A single study suggested a superiority for IV iron with a haemoglobin increase greater than 2 g/dl in 47% of the patients on oral iron compared with 66% on IV iron (P = 0.07). However, this could be accounted for by a high withdrawal rate (24%) in the oral iron group. In the largest comparative study, of 196 subjects, median haemoglobin improved similarly, from 8.7 to 12.3 g/dl in the IV group and from 9.1 to 12.1 g/dl in the ferrous sulfate group (P = 0.70). Thus, intravenous iron appears no more effective than oral iron in repletion of iron status as the rate-limiting step appears to be synthesis of red cells, which is not accelerated by IV iron delivery.

The main reason behind the preference of IV iron over oral iron is based on the concern that oral iron may exacerbate IBD. An often-cited study investigating whether oral iron worsens IBD in comparison with IV iron assessed disease activity in 19 IBD patients, 11 with CD and 8 with UC, randomized to either oral ferrous fumarate or IV iron sucrose over a 14-day period. Although the authors argued that disease activity was worsened by oral iron therapy, their use of numerous unconventional assessments weakens this conclusion. The trial was done as a crossover study with a minimum 6-week washout period, so the previous drug therapy may have affected the results. The number of subjects with IBD was small (N = 19). The authors created a synthesized overall disease activity score by combining UC and CD scales and also reported on subscales within activity indexes to identify significant differences. When the two groups were compared, however, there was no statistically significant difference in the overall synthesized disease activity score.

Another factor associated with intolerance of oral iron may be related to the dose of elemental iron administered. In order to maintain iron balance, adult men need to absorb 1-1.5 mg/d, menstruating women need 1-3 mg/d, and pregnant women need approximately 4-5 mg/d. Based on this, the recommended daily allowance of elemental iron is about 8 mg in adult men and postmenopausal women, 18 mg in premenopausal women, and 27 mg in pregnant women. However, most studies investigating the efficacy of oral iron have used a typical dose of 150-200mg/d of elemental iron, 10-20 fold in excess of the recommended daily allowance. Because of the 20% incidence level of intolerance at these conventional doses of elemental iron, recent studies have investigated the efficacy and side effects associated with low-dose oral iron supplementation. A study in the elderly (age >80) randomised 90 patients with iron-deficiency anaemia to 15, 50, or 150 mg of daily oral elemental iron over 2 months. All three dosage groups experienced a similar, statistically significant increase in haemoglobin after 2 months. These studies have not been done in IBD.