Iron deficiency and fatigue in inflammatory bowel disease: a systematic review

Introduction

The impact of iron deficiency without anaemia (IDWA) on fatigue in people with inflammatory bowel disease (IBD) is unclear. This systematic review examined the evidence whether iron deficiency with or without anaemia was associated with fatigue in inflammatory bowel disease to better inform the detection and treatment of iron deficiency in clinical practice.

Methods

The databases searched were MEDLINE, OVID, CINAHL and Web of Science. Inclusion criteria were studies measuring iron deficiency (ID) in accordance with recognised guidelines and patient-reported outcome measures (PROMs) of fatigue in patients with IBD of any level of disease activity. Assessment of bias was conducted using the Newcastle Ottawa Scale. Studies were grouped for syntheses according to if the exposure was iron deficiency without anaemia or iron deficiency regardless of haemoglobin level.

Results

252 database results were identified and screened; 33 full records were reviewed from which 7 studies with a total of 1425 individuals were deemed eligible for inclusion in the results synthesis. Considerable variation in the methods and statistical analysis used to investigate the relationship between iron deficiency and fatigue prevented any quantitative synthesis. Studies varied by disease activity levels in the cohort under investigation and approaches used to define iron deficiency with different PROMs used to measure fatigue. Three studies directly compared fatigue scores in IDWA to those who were not ID, two of which showed patients with IDWA in mixed groups of people with Crohn’s disease (CD) and ulcerative colitis (UC) had significantly lower fatigue scores. The other four studies used iron deficiency irrespective of anaemia as the exposure and reported mixed results on fatigue, with only one study reporting higher prevalence of fatigue in the ID group of UC patients.

Conclusions

Marked heterogeneity in mixed UC and CD populations, disease activity, and approach to determining iron deficiency and fatigue precludes definitive conclusion. Two studies report greater fatigue with IDWA but do not differentiate between CD and UC. Further studies are required using standardised design and measures to better understand the role of iron deficiency in fatigue in both CD and UC.