primary outcome:
Interventions for treating iron deficiency anaemia in inflammatory bowel disease
Response (defined as the number of people with normalisation of haemoglobin levels or increase of haemoglobin at the end of treatment course). This definition is based on a previous systematic review by Aksan 2017, as well as scoping of the wider literature.Data for the primary outcome were reported in both studies. Cumulatively, 47/67 participants in the intravenous iron sucrose group had an increase in haemoglobin greater than 2 g/dL compared to 39/70 in the oral iron sulphate group. There was no clear difference in the number of responders when intravenous iron sucrose was compared with oral iron sulphate (RR 1.22, 95% CI 0.95 to 1.57). The certainty of evidence was low due to high risk of bias and imprecision (Analysis 1.1; summary of findings Table 1).Secondary outcomesAdverse events were described in both studies. In Lindgren 2009, a total of six adverse events were reported in the intravenous iron sucrose group and a total of 28 adverse events in the oral iron sulphate group. In Schroder 2005, a total of 20 adverse events were reported in the intravenous iron sucrose group and a total of 21 adverse events in the oral iron sulphate group.Serious adverse events were only described by Lindgren 2009 and not by Schroder 2005. There was one case of thrombocytopaenia in the intravenous iron sucrose group and no serious adverse events in the oral iron sulphate group. It is uncertain whether there is a difference in severe adverse events when intravenous iron sucrose is compared to oral iron sulphate in people with mild to moderate disease. This is due to very low‐certainty evidence from this one study (RR 3.07, 95% CI 0.13 to 73.32; 1/45 vs. 0/46) (Analysis 1.2).Withdrawal due to adverse events was described in both studies. In Lindgren 2009, one participant withdrew in the intravenous iron sucrose group and 11 in the oral iron sulphate group. In Schroder 2005, two participants withdrew in the intravenous iron sucrose group and five in the oral iron sulphate group. It was unclear for both studies whether there was a difference in adverse events requiring withdrawal between intravenous iron sucrose and oral iron sulphate due to very low certainty of evidence (RR 0.23, 95% CI 0.05 to 1.09; 3/67 versus 16/70) (Analysis 1.3).All reported adverse events are detailed in the Characteristics of included studies tables.Health‐related quality of life was not reported in Lindgren 2009 but was reported in Schroder 2005 which used the SF‐36 questionnaire. Authors mentioned that QoL (quality of life) was not affected during the course of the study, although in both groups a trend toward increased SF‐36 scores was noted. We could not perform an analysis on this as we did not have the mean and SD (standard deviation) scores.Time to response, change in haemoglobin, tolerability and compliance were not reported in any of the two papers.Of the 41 people with active/inactive disease who received oral iron sulphate (21 participants) or oral iron hydroxide polymaltose complex (20 participants), none responded to treatment. It is uncertain whether these treatments lead to a difference in number of responders as the certainty of evidence is very low due to risk of bias and imprecision due to extremely sparse data (Analysis 2.1; summary of findings Table 2).This study assessed 485 participants who had mild to moderate disease. The study found that people with mild to moderate disease may respond with intravenous ferric carboxymaltose (150/244) compared to intravenous iron sucrose (118/239) (RR 1.25, 95% CI 1.06 to 1.46). The certainty of the evidence is moderate due to risk of bias (Analysis 3.1; summary of findings Table 3). The number needed to treat for an additional beneficial outcome (NNTB) was 9.This study, which included 40 people with unknown disease activity, found no clear difference in number of responders when IM (intramuscular) erythropoietin injection + intravenous iron sucrose (18/20) was compared to intravenous iron sucrose + IM placebo (n = 15/20) (RR 1.20, 95% CI 0.90 to 1.61). The certainty of the evidence is low due to moderate risk of bias and imprecision (Analysis 4.1; summary of findings Table 4).This study, which included 128 people with mild to moderate disease, compared oral ferric maltol with oral placebo. The study showed there were more responders in the oral ferric maltol (36/64) group compared to the oral placebo group (n = 0/64) (RR 73.00, 95% CI 4.58 to 1164.36). The certainty of the evidence is low due to moderate risk of bias and imprecision (Analysis 5.1; summary of findings Table 5).This study, which included 252 people with unknown disease activity, compared oral ferric maltol with intravenous ferric carboxymaltose. Intravenous ferric carboxymaltose led to a higher number of responders compared to oral ferric maltol (RR 0.83, 95% CI 0.65 to 1.06; 59/127 vs. 70/125). The certainty of the evidence is low due to high risk of bias and imprecision (Analysis 6.1; summary of findings Table 6).This study, which included 200 people with mild to moderate disease, found no clear difference in number of responders when intravenous ferric carboxymaltose was compared with oral iron sulphate (RR 1.17, 95% CI 0.95 to 1.43; 104/137 vs. 41/63). The certainty of the evidence is low due to high risk of bias and imprecision (Analysis 7.1; summary of findings Table 3)This study of 338 people in remission or with mild disease found no clear difference in number of responders when intravenous iron isomaltoside was compared to oral iron sulphate (RR 1.12, 95% CI 0.93 to 1.34; 147/225 vs. 66/113). The certainty of the evidence is low due to high risk of bias and imprecision (Analysis 8.1; summary of findings Table 8)This study of 34 people with active disease compared IM erythropoietin with oral placebo. It reported a higher number of responders in the IM erythropoietin versus the oral placebo group (RR 3.50, 95% CI 1.44 to 8.48; 14/17 vs. 4/17). The certainty of the evidence is low due to moderate risk of bias and imprecision (Analysis 9.1; summary of findings Table 9)In total, 557 people received intravenous preparations of which 368 responded to treatment, and 373 people received oral preparations of which 205 responded to treatment. Our analysis showed that intravenous iron preparations may result in more patient responders compared to the oral preparations (RR 1.17, 95% CI 1.05 to 1.31; participants = 927; I2 = 0%, NNTB = 11). The certainty of the evidence is moderate due to low risk of bias and inconsistency due to clinical heterogeneity (Analysis 10.1; summary of findings Table 10).This study of 19 participants with active and inactive disease compared oral iron fumarate group (nine participants) with intravenous iron sucrose (10 participants). There were no responders (0/9) in the oral iron fumarate group versus three responders (3/10) in the intravenous sucrose group, however, it was unclear whether the response occurred before or after cross‐over. Therefore, we were unable to analyse the results. It is uncertain whether oral iron fumarate leads to a difference in the number of responders when compared with intravenous iron sucrose.