Routine use of oral iron for people with heart failure and iron deficiency in primary care; retrospective cohort study

Aims: Iron deficiency is common among people with heart failure and associated with morbidity and mortality. While intravenous iron improves clinical outcomes, oral iron continues to be prescribed in routine practice despite limited evidence of benefit. Methods: We completed a retrospective primary care cohort study (2016 to 2021) to investigate the proportion of people with an incident diagnosis of heart failure who had iron deficiency identified (defined as ferritin <100 micrograms/L) and subsequently received a first prescription for oral iron within 12 months. Multivariable logistic regression was used to report the odds ratio (OR) of receiving oral iron in relation to key demographic covariates and co-morbidities. Results: Among 105,749 people with an incident diagnosis of heart failure, 35,688 underwent a ferritin test within the first year of whom 11,237 had iron deficiency and no prior prescription for oral iron. Of these, 2,734 (24.3%) were subsequently prescribed oral iron. Increasing age (OR per 10-year increase 1.14, 95%CI: 1.10-1.19), Asian ethnicity (1.33, 1.08-1.64), cirrhosis (2.01, 1.29-3.14) and diabetes (1.36, 1.24-1.49) were associated with increased odds of receiving oral iron. Among 1,357 (49.6%) people who had their ferritin level re-tested, the median change was 26 micrograms/L (interquartile range 7 to 61) among people who were prescribed oral iron compared to 4 micrograms/L (IQR -9 to 34) among people not prescribed oral iron. Conclusions: One in four individuals with heart failure and low ferritin received oral iron replacement, despite this not being recommended in international guidelines. Treatment could be improved and standardised in primary care.